Age-stratified models also placed the estimated margins of exposure for infants and young children far below the benchmark of 10,000 used to identify a public-health concern for a genotoxic carcinogen. These results come from a screening-level assessment that combined separate literatures rather than measuring feed and milk from the same Bangladeshi herds. The review assembled evidence from PubMed, Scopus, Web of Science and ScienceDirect for studies published from January 2000 through January 2026.

Of 318 records identified, 96 were removed as duplicates and 188 were excluded during title and abstract screening; 32 full texts were assessed, and 12 reports met the eligibility criteria. The 20 analysed datasets represented division-, site- or milk-type-specific strata within 10 distinguishable sources, including raw, pasteurised and ultra-high-temperature milk. Nine datasets were classified as being at low risk of bias, five at moderate risk and six at high risk.

All measurements used competitive enzyme-linked immunosorbent assay, or ELISA, and none was confirmed chromatographically. The investigators also prespecified subgroup analyses by region, milk type and risk of bias, along with sensitivity analyses intended to test whether clustered datasets, methodological choices or unusually high measurements altered the results. Aflatoxin B1 is the most prevalent aflatoxin congener in food and feed and the most potent naturally occurring hepatocarcinogen, according to the source article.

When lactating animals consume aflatoxin B1-contaminated feed, hepatic cytochrome-P450 hydroxylation converts part of the toxin to aflatoxin M1, which is secreted into milk. Aflatoxin M1 retains about one-tenth of the carcinogenic potency of its parent compound but resists pasteurisation and ultra-high-temperature processing, allowing it to remain in milk after those treatments. Bangladesh’s tropical monsoon climate supports fungal growth during crop filling, harvest and on-farm storage, while maize, a cereal particularly susceptible to aflatoxigenic fungi, is now a principal energy ingredient in compound feed.

The country’s expanding dairy sector remains dominated by smallholder and informal supply chains with limited cold-chain infrastructure, fragmented quality control and weak enforcement. Although aflatoxin also contaminates rice and other foods, the assessment focused on the milk pathway and did not estimate dietary exposure from those additional sources. The pooled concentration distribution was strongly right-skewed, making the choice of central measure important.

The sample-weighted arithmetic mean across datasets was 143 nanograms per litre, the sample-weighted geometric mean was 92 nanograms per litre, the median of dataset means was 88 nanograms per litre and the unweighted mean was 118 nanograms per litre. Typical regional raw-milk means ranged from 35 to 120 nanograms per litre, but one Dhaka dataset reported a mean of 699.1 nanograms per litre. Removing that single dataset, which represented 8% of all samples, reduced the weighted mean to 93 nanograms per litre, a 35% decrease.

The interquartile range of dataset means was 57 to 111 nanograms per litre, whereas the complete range extended from 6.6 to 699.1 nanograms per litre. Prevalence and mean concentration were largely decoupled: two datasets with 100% positivity had among the lowest means, and the highest concentration occurred at a prevalence close to the pooled value. The assessment therefore relied on the concentration distribution rather than treating the proportion of positive samples as a sufficient measure of exposure.

Milk type did not significantly explain differences in prevalence, whereas region did. Raw milk had a pooled prevalence of 60.4%, compared with 59.0% in pasteurised milk and 69.5% in ultra-high-temperature milk, but the between-subgroup test found no significant difference among the three categories. The ultra-high-temperature estimate was not considered interpretable because it was based on only two datasets, one reporting 20% positivity and the other 100%, and its prediction interval spanned the complete possible range.

Region showed a more consistent pattern: prevalence was 43.7% in Chattogram, 55.3% in Dhaka and 66.8% across other divisions and national samples, with a Q-between value of 13.5, two degrees of freedom and a nominal p value of 0.001. This was the only pre-specified subgroup comparison to remain significant after Holm adjustment, with an adjusted p value of 0.004, although the authors classified it as hypothesis-generating rather than an established geographic gradient. Residual heterogeneity was also 21% to 23% in exploratory one-covariate meta-regressions, leaving variation potentially associated with unmeasured differences in season, analytical kit, detection threshold, sampling frame and position within the supply chain.

The feed evidence showed that the upstream contamination burden was compatible with the milk observations, but it did not establish a causal relationship within Bangladesh. Published surveys reported aflatoxin B1 at 0 to 160 micrograms per kilogram in poultry feed and 1 to 103 micrograms per kilogram in maize, with both matrices frequently exceeding the 20 micrograms per kilogram general feed maximum. Compound beef-cattle feed ranged from 7.78 to 14.66 micrograms per kilogram, while oil cakes, bran, rice straw and soybean meal had means of approximately 9.8 to 12 micrograms per kilogram.

Although many cattle-feed means remained below 20 micrograms per kilogram, they exceeded the European Union limit of 5 micrograms per kilogram for dairy-cattle feed. Maize and other feed ingredients also contained fumonisins, zearalenone and sterigmatocystin, revealing a multi-mycotoxin burden not captured by the aflatoxin-specific risk metrics. Feed and milk measurements both showed a June-to-August maximum, consistent with a humidity-driven mechanism, but the series came from independent studies, sites and years and therefore did not demonstrate coupling within a shared production system.

For the mechanistic check, the researchers transferred a published yield-dependent carry-over function from controlled trials of 12 high-yielding Israeli-Holstein cows to three ration scenarios representing Bangladeshi smallholder practice. The function predicted transfer of approximately 0.67% to 1.13% at milk yields of 5 to 15 kilograms per day, with reconstructed milk concentrations spanning 24 to 282 nanograms per litre and a central prediction of 80 nanograms per litre. That envelope contained 18 of the 20 observed dataset means, or 90%, and the central prediction was close to the observed geometric mean of 92 nanograms per litre.

Reproducing the sample-weighted mean of 143 nanograms per litre required a ration-weighted aflatoxin B1 concentration of about 18 micrograms per kilogram, while reproducing the extreme Dhaka mean would have required about 89 micrograms per kilogram. The two tails, at 6.6 and 699.1 nanograms per litre, lay outside the envelope. This result shows that the independent feed and milk literatures were quantitatively compatible under the transferred model; it does not show that a particular feed sample caused a particular milk residue.

Moreover, the carry-over relationship was extrapolated below the 30-to-46-kilogram daily-yield range represented in its original calibration. Using Bangladesh-specific milk-intake and body-weight parameters, the central scenario estimated aflatoxin M1 exposure at 4.22 nanograms per kilogram of body weight per day for infants aged 0.5 to 1 year, 2.29 for toddlers aged 1 to 3 years, 1.08 for children aged 4 to 9 years, 0.38 for adolescents aged 10 to 17 years and 0.24 for adults aged 18 years or older. Corresponding margins of exposure were 95, 175, 372, 1,055 and 1,649, all below the benchmark of 10,000, while hazard indices were 21.1, 11.4, 5.4, 1.9 and 1.2, all above one.

Under a high-concentration scenario of 250 nanograms per litre, the infant margin fell to 54. The central model estimated incremental hepatocellular carcinoma incidence of 0.0108 cases per 100,000 infants per year, rising to 0.0189 in the high scenario. These cancer estimates were order-of-magnitude indicators rather than case counts because they depended on an aflatoxin M1 relative potency factor of 0.1 and an HBsAg-weighted potency model using an approximately 5.4% hepatitis-B surface antigen carrier prevalence.

A 100,000-iteration Monte Carlo simulation incorporated variability in milk concentration, intake and body weight, treating the three inputs as independent. Median margins of exposure were 157 for infants, 286 for toddlers, 612 for children, 1,720 for adolescents and 2,735 for adults; fifth-percentile values were 30, 55, 119, 340 and 543, respectively. The simulation produced a margin below 10,000 in 100% of infant and toddler iterations, 99.7% of child iterations, 96.2% of adolescent iterations and 90.4% of adult iterations.

For infants, 32.8% of iterations produced a margin below 100, while the median hazard index was 12.8 for infants, 7.0 for toddlers, 3.3 for children, 1.2 for adolescents and 0.7 for adults. These probabilistic medians were higher than the deterministic margins because the fitted concentration distribution was centred on the 92 nanogram per litre geometric mean rather than the 143 nanogram per litre arithmetic mean. The numerical exposure estimates therefore varied with the central tendency used, but the principal conclusion remained stable: no tested scenario or restriction raised the infant margin above 158, at least 60-fold below the 10,000 benchmark.

Several limitations constrain the assessment. All included measurements relied on competitive ELISA without chromatographic confirmation, and inconsistent reporting of detection limits, recovery and within-dataset concentration distributions prevented the investigators from reconstructing individual exposures. Most surveys used convenience samples from markets, collection points or farms rather than probability samples of the national milk supply.

Six datasets had uncertain provenance or a high risk of bias, and four reports contributed multiple strata, so the 20 datasets did not represent 20 fully independent sources. A 50% downward correction for possible ELISA overestimation reduced the weighted concentration to 96 nanograms per litre but left the infant margin at 142. Restricting the evidence to fully referenced peer-reviewed datasets produced a weighted mean of 172 nanograms per litre and an infant margin of 79, while removing the influential Dhaka dataset produced a mean of 93 nanograms per litre and a margin of 146.

Alternative heterogeneity estimators left pooled prevalence between 58.7% and 59.0%, and no plausible single uncertainty or tested combination reversed the finding. The authors identified paired feed-and-milk sampling from the same herds across monsoon and dry seasons, chromatographic confirmation, individual milk-consumption data and replication of the high-concentration Dhaka milk shed as priorities for converting this literature-based screening assessment into a more precise national exposure model.

Subject of Research: Systematic review and meta-analysis of aflatoxin contamination in Bangladeshi milk and animal feed, with modelled dietary risk by age.

Article Title: Aflatoxin M1 in Milk and Aflatoxin B1 in Animal Feed in Bangladesh: A Systematic Review, Meta‐Analysis and Literature‐Based Dietary Risk Assessment

Article References: Fattah, M. A., & Habib, M. A. (2026). Aflatoxin M 1 in Milk and Aflatoxin B 1 in Animal Feed in Bangladesh: A Systematic Review, Meta‐Analysis and Literature‐Based Dietary Risk Assessment. Veterinary Medicine and Science, 12(6), Article e71284. https://doi.org/10.1002/vms3.71284

Image Credits: AI Generated

DOI: 10.1002/vms3.71284

Keywords: aflatoxin M1, aflatoxin B1, Bangladesh, milk contamination, animal feed, food safety, dietary exposure, infant nutrition, hepatocellular carcinoma, meta-analysis, Aflatoxin, Milk

Sharks sit near the top of marine food webs, a position that makes them efficient accumulators of methylmercury, the organic and most toxic form of mercury. This compound is produced by microbes in aquatic sediments from inorganic mercury and then absorbed by plankton and small organisms. As prey are eaten by predators, the methylmercury climbs each step of the food chain, a process known as biomagnification. Because methylmercury binds strongly to proteins in muscle and other tissues and is excreted very slowly, large, long-lived predatory fish can carry concentrations thousands of times higher than the surrounding seawater. Previous studies of shark populations worldwide, including a systematic review of elasmobranch pollutants published in 2020, have repeatedly documented elevated mercury burdens in shark meat, cartilage, and organs, and earlier Korean research has already linked shark meat consumption among workers in Gyeongsangbuk-do province to higher blood mercury levels.

What makes Doochi unusual as an exposure route is that it uses parts of the shark that most cuisines discard: the skin and the intestine. Local producers boil these by-products, slice them, and serve the resulting chewy, gelatin-rich dish, which has been marketed as a signature specialty of the Gampo coastal area. Efforts to scale up production were reported in Korean media as early as 2009, and the Gyeongju city government has listed Doochi among its local specialty products. In other words, a food traditionally eaten a few times a year by a small community may soon appear on far more plates, which is precisely the scenario that motivates the new risk assessment.

The research team approached the problem in two phases, separated by nearly a decade. In 2013, they purchased 32 servings of prepared Doochi from local markets, along with 32 pieces of raw shark skin sold as the dish’s ingredient, and measured total mercury in untreated fragments of the boiled skin and in the raw material. Total mercury analysis, performed according to Korean food code test methods, captures all forms of the element but does not by itself distinguish methylmercury from less harmful inorganic species. Because established regulations in Korea and the European Union are expressed as limits on total mercury for shark, and as methylmercury limits for deep-sea fish in Korea, the researchers worked with both frameworks, estimating methylmercury content using standard conversion assumptions.

The 2013 data already told a striking story. The geometric mean total mercury concentration in the boiled skin fragments was 0.349 micrograms per gram, while the raw skin measured 0.122 micrograms per gram in its outer layer and 0.137 micrograms per gram in its inner layer. More alarming than the averages, however, was the scatter. Concentrations among individual fragments of boiled skin varied by a factor of 167, and a statistical test of variance, Levene’s test, confirmed that the fragment measurements were far more dispersed than those of the raw skin, with a p-value below 0.001. The authors attribute this extreme patchiness to the nature of the dish itself: a single serving of Doochi is assembled from irregular pieces of skin, so a fragment taken from one corner of a plate might contain vastly more mercury than one taken from another.

Recognizing that analyzing small untreated fragments could either miss or exaggerate the true mercury content of a serving, the team repeated the work in 2022 with a more rigorous design. A fresh serving of Doochi was carefully separated into its skin and intestine components, each of which was fully homogenized into a uniform mixture before analysis. The homogenized samples were then measured in triplicate at an accredited laboratory to ensure the results reflected genuine contamination rather than analytical noise or sampling bias. This approach effectively answers a different and more practical question: if you ate an entire serving of Doochi, how much mercury would you actually ingest on average?

The answer was sobering. The fully homogenized boiled skin contained between 2.667 and 2.882 micrograms of total mercury per gram, a level that clearly exceeds the European Union maximum limit of 1.0 microgram per gram set for shark products. The estimated methylmercury concentration likewise surpassed the Korean limit of 1.0 microgram per gram that applies to deep-sea fish. The intestine, by contrast, contained far less mercury, at 0.295 to 0.333 micrograms per gram, suggesting that mercury is concentrated predominantly in the skin. Because the skin is the main ingredient and the signature component of the dish, its outsized contribution dominates the exposure calculation for anyone eating Doochi in the traditional way.

To translate these concentrations into health risk, the researchers compared estimated mercury intake with the United States Environmental Protection Agency reference dose for methylmercury, the daily exposure level considered likely to be without appreciable harmful effects over a lifetime. Under the traditional pattern of ceremonial consumption, the calculated hazard quotients ranged from 0.15 to 0.57 depending on the assumptions used, meaning that a typical diner eating Doochi a few times a year would remain below the threshold of concern. The intake estimates under this pattern corresponded to 7 to 25 percent of the provisional tolerable weekly intake established by the Joint FAO/WHO Expert Committee on Food Additives. However, the margins shrink rapidly as frequency increases: the hazard quotient would exceed 1, the conventional line separating acceptable from potentially harmful exposure, at somewhere between 10 and 36 servings per year depending on the assumptions, and the provisional tolerable weekly intake would be reached at between 22 and 81 servings annually.

Those numbers may sound like a generous allowance, but the authors caution that the traditional consumption frequency is precisely what may change as Doochi gains commercial traction. A dish once confined to memorial rites in a handful of coastal towns is being positioned as a regional brand, and anyone eating it weekly rather than seasonally could cross into the risk zone. The researchers also emphasize that body weight matters. The reference dose is defined per kilogram of body weight per day, so the same number of servings delivers a proportionally larger dose to lighter individuals. Children, smaller adults, and women who are pregnant or planning pregnancy are the groups for whom methylmercury is most concerning, given its well-documented developmental neurotoxicity and its ability to cross the placenta and accumulate in the fetal brain.

The study carries broader lessons beyond one Korean specialty. It demonstrates that fishery by-products, the skins, organs, and trimmings usually hidden inside processed foods, can carry contaminant burdens as heavy as or heavier than the fillets that dominate regulatory attention. It also highlights a methodological pitfall in food monitoring: analyzing untreated fragments of a heterogeneous dish can produce wildly misleading estimates in either direction, which is why the authors’ shift to full homogenization and triplicate accredited analysis in 2022 matters so much. Under the assumptions of the analysis, traditional levels of Doochi consumption remain below the methylmercury reference dose, and the researchers do not call for a ban on the dish. What they do call for is vigilance, in the form of continued monitoring as availability widens, clearer guidance for frequent consumers and vulnerable groups, and awareness that a cherished local tradition, like the shark it comes from, has been quietly collecting the ocean’s mercury all along.

Subject of Research: Mercury contamination and dietary risk assessment of a traditional Korean shark skin and intestine dish

Article Title: High mercury levels in Doochi, a local shark skin and intestine dish of the Eastern coast of Korea

Article References: Park, J. W., Lee, E.-S., & Baek, K. (2026). High mercury levels in Doochi, a local shark skin and intestine dish of the Eastern coast of Korea. Environmental Monitoring and Assessment, 198(11), Article 1222. https://doi.org/10.1007/s10661-026-16032-3

Image Credits: AI Generated

DOI: 10.1007/s10661-026-16032-3

Keywords: mercury, methylmercury, shark, Doochi, Korea, food safety, seafood contamination, biomagnification, risk assessment, dietary exposure, heavy metals, Environmental Monitoring and Assessment

The research team, led by Aleeza Jalil with Mehwish Jamil Noor as corresponding author, set out to answer a deceptively simple question: how much toxic metal do consumers actually ingest when they eat vegetables purchased from local markets, and does that dose matter for health? To find out, they obtained nine vegetable species from wholesale markets in Islamabad and Rawalpindi, cities that together anchor the Pothohar plateau and supply a large urban population. The vegetables were analyzed using Flame Atomic Absorption Spectrophotometry, a well-established analytical technique in which a sample is ashed, dissolved, and aspirated into a flame that excites metal atoms; the wavelength and intensity of the light those atoms absorb reveal which metals are present and at what concentration. This method allowed the team to quantify four target metals: cadmium, chromium, nickel, and copper.

The numbers the spectrophotometer returned were striking. Cadmium ranged from 0.103 milligrams per kilogram in spearmint, Mentha spicata, sampled in Islamabad, to 2.28 milligrams per kilogram in potato, Solanum tuberosum, from Rawalpindi. Chromium varied from 0.09 milligrams per kilogram in Islamabad samples to a high of 7.52 milligrams per kilogram in coriander, Coriandrum sativum, purchased in Rawalpindi. Nickel spanned from 1.24 milligrams per kilogram in coriander from Islamabad to 21.18 milligrams per kilogram in bitter gourd, Momordica charantia, from Rawalpindi. Copper, the least toxic of the four but still problematic in excess, ranged from 1.37 milligrams per kilogram in bitter gourd from Rawalpindi to 24.98 milligrams per kilogram in tomato, Solanum lycopersicum, from Islamabad. Several vegetables, the authors report, exceeded permissible limits particularly for cadmium, chromium, and nickel.

What makes these figures concerning is the toxicology of the metals themselves. Cadmium, ranked among the highest on the United States Agency for Toxic Substances and Disease Registry’s substance priority list, accumulates in the kidneys and skeleton over decades and is classified as a human carcinogen; there is no beneficial biological role for it in the human body. Chromium, depending on its oxidation state, can range from an essential trace nutrient to the highly toxic hexavalent form that damages DNA. Nickel exposure is associated with dermatitis, respiratory irritation, and carcinogenic outcomes in certain compounds. Copper, in contrast, is an essential micronutrient required for enzyme function, but chronic overexposure damages the liver and gastrointestinal tract. Because plants take up these metals from soil and irrigation water and concentrate them in edible tissues, vegetables act as a direct conduit from contaminated growing environments to the human dinner plate.

The Pothohar region’s contamination profile has plausible sources rooted in its rapid urbanization. Rawalpindi and Islamabad host dense traffic corridors and industrial activity, and earlier work by some of the same research community has documented air pollution in the twin cities linked to heavy transportation and industry. Atmospheric deposition of metal particles onto leafy surfaces, irrigation with contaminated water, and application of fertilizers or sewage-derived amendments to peri-urban fields are all recognized pathways by which metals enter vegetable crops. Leafy herbs such as coriander and mint are particularly efficient accumulators because their large surface areas intercept airborne particles, while their fine root systems mine the soil intensively. The fact that some of the highest concentrations in this study appeared in coriander and bitter gourd from Rawalpindi is consistent with that pattern, although the study’s market-based design means it captures the produce supply as a whole rather than tracing individual farms.

To translate concentrations into health consequences, the team deployed the standard battery of dietary risk metrics used by environmental health agencies worldwide. The Estimated Daily Intake, or EDI, multiplies the measured metal concentration by the amount of vegetable a typical person eats each day, divided by body weight, yielding a dose in milligrams per kilogram of body weight per day. The Target Hazard Quotient, or THQ, compares that dose against a reference dose, the level below which regulatory agencies assume no appreciable harm over a lifetime of exposure. A THQ below one is considered acceptable; values above one signal potential non-carcinogenic risk. Summing the THQs across metals and vegetables produces the Hazard Index, or HI, which captures the cumulative burden of exposure to a mixture of metals. Finally, the Target Cancer Risk, or TCR, estimates the incremental lifetime probability of developing cancer from carcinogenic metals such as cadmium and chromium.

The results of this risk calculus reveal an important nuance. When each metal was evaluated on its own through the Estimated Daily Intake, exposures remained within acceptable limits, suggesting that no single vegetable delivers a dangerous dose of any one metal in a typical serving. But the cumulative indices told a different story. The Hazard Index and the Target Cancer Risk both suggested potential non-carcinogenic and carcinogenic risks, especially among children. The reason is arithmetic: children eat more food per kilogram of body weight than adults, so the same metal concentration in a vegetable translates into a higher dose for a smaller body. Their developing organs and longer remaining lifetimes further amplify both non-carcinogenic effects and lifetime cancer probability. A diet built around multiple contaminated vegetables, consumed daily over years, quietly stacks exposures that individually look tolerable but collectively cross thresholds.

This distinction between individual and cumulative risk is where the study’s significance lies, and it echoes a broader shift in how food safety is being assessed globally. Recent probabilistic assessments of dietary heavy metal exposure in China, Bangladesh, India, and Nigeria have converged on the same conclusion: single-metal, single-food evaluations systematically underestimate real-world risk because diets are diverse and contaminants co-occur. A companion systematic review by members of the same team, also published in Environmental Monitoring and Assessment, documented the global trend of rising heavy metal concentrations in vegetables and the spread of health risk assessment frameworks to quantify them. The Pothohar findings slot into that international picture while adding locally specific data from a region where such measurements had been sparse.

The authors frame their results as a call for action on three fronts. First, continuous monitoring of food quality is needed, since market surveillance of vegetables for metal contamination is not currently routine in Pakistan, and contaminated produce can move through wholesale channels without detection. Second, agricultural practices require improved regulation, including controls on irrigation water quality, fertilizer composition, and the siting of vegetable plots near roads and industry, because preventing uptake at the source is far more effective than testing finished produce. Third, public awareness must increase, so that consumers understand which vegetables and which markets carry higher burdens and how washing, peeling, and dietary diversification can modestly reduce exposure. The research was funded by Fatima Jinnah Women University under grant ORIC/FJWU/2025/308 as part of a project evaluating heavy metal dietary exposure and health risks from vegetable consumption in the twin cities.

For the millions of people who shop in the bazaars of Rawalpindi and Islamabad, the study does not mean vegetables should be abandoned; plant foods remain central to nutrition and disease prevention, and the authors themselves emphasize food safety rather than dietary avoidance. What it does mean is that the safety of those foods depends on environmental conditions far upstream of the market stall, in the soil, water, and air of the farms that supply them. As urbanization intensifies across South Asia and demand for fresh produce grows, the invisible chemistry of contamination will increasingly determine public health outcomes. Studies like this one, which convert parts-per-million measurements into concrete risk estimates for adults and children, provide the evidence base that regulators, farmers, and consumers need to act before cumulative exposure becomes cumulative harm.

Subject of Research: Heavy metal contamination of market vegetables and associated dietary health risks in the Pothohar region of Punjab, Pakistan

Article Title: Dietary exposure and health risks associated with selected vegetables from Pothohar Region of Punjab, Pakistan

Article References: Jalil, A., Noor, M. J., Bukhari, A. L., Shaban, A., & Iram, S. (2026). Dietary exposure and health risks associated with selected vegetables from Pothohar Region of Punjab, Pakistan. Environmental Monitoring and Assessment, 198(9), Article 1020. https://doi.org/10.1007/s10661-026-15848-3

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15848-3

Keywords: heavy metals, cadmium, chromium, nickel, copper, vegetables, food safety, dietary exposure, health risk assessment, Pakistan, Pothohar region, Environmental Monitoring and Assessment

The research team, led by Juan Zhao and Bigui Lin of the Chinese Academy of Tropical Agricultural Sciences together with colleagues from the South China Institute of Environmental Sciences, assembled one of the more comprehensive multi-media datasets assembled for a Chinese coastal population. They analyzed 284 fish specimens spanning 12 species, 50 rice samples, and 449 human hair samples. Hair is a well-established biomarker for methylmercury exposure because the compound binds strongly to the sulfur-rich proteins in growing hair, providing a time-integrated record of dietary intake over weeks to months. By pairing hair measurements with detailed dietary questionnaires, the researchers could connect contamination in the food supply directly to accumulation in people.

The numbers tell a vivid story of unequal exposure. Fish from the fishing community carried a mean total mercury concentration of 158.9 micrograms per kilogram, while hair from residents of that same community averaged 3,317.6 micrograms per kilogram, substantially higher than levels measured in the urban study areas. Rice, the other dietary staple examined, contributed minimally to mercury exposure, confirming that in coastal China the seafood platter, not the rice bowl, is the dominant pathway for this particular contaminant. That distinction matters because methylmercury, formed when microbes convert inorganic mercury in aquatic sediments, is far more readily absorbed by the human body than the inorganic forms found in terrestrial crops.

Not all fish are equal when it comes to mercury, and the study quantified exactly which biological factors matter most. Mercury accumulation in fish was associated with the source of the catch, the habitat the species occupies, its trophic level, and its species identity. Marine wild-caught fish, carnivorous species, and neritic species that live in coastal waters close to shore showed the highest mercury burdens. This pattern reflects a well-known ecological process called biomagnification: methylmercury is absorbed at the base of the food web and becomes progressively more concentrated as it moves up through predatory fish, which eat smaller contaminated prey over long lifetimes. A carnivorous species near the top of the food chain effectively integrates decades of mercury from everything below it.

The human side of the analysis focused on the 207 participants who had complete demographic and dietary data. Using multivariable statistical models, the researchers identified four key factors associated with mercury levels in hair: working in the fishing industry, older age, the frequency of fish consumption, and the daily amount of fish eaten. Together, these variables explained more than 60 percent of the variance in hair total mercury and methylmercury concentrations, a remarkably strong result for an environmental exposure study. In other words, knowing what someone does for a living and how often they eat fish predicts their mercury body burden with considerable accuracy.

A region-level ecological analysis added another layer, linking the mercury profile of fish available in each area to the hair mercury burdens of the people living there. The authors are careful to note that this association should be interpreted at the regional rather than the individual level, since ecological comparisons of aggregated data cannot establish what any single person ate. Still, the finding suggests that the contamination profile of the local seafood supply shapes population-level exposure, meaning that two communities with different fish markets can carry systematically different mercury loads even with similar dietary habits.

The public health implications are most acute for the fishing community itself. Fish consumption accounted for the majority of methylmercury intake across the study population, and a substantial proportion of fishing community residents exceeded the provisional tolerable daily intake for methylmercury, the safety benchmark established by the Joint FAO/WHO Expert Committee on Food Additives. Methylmercury is a potent neurotoxin, and the developing nervous system is particularly vulnerable, which is why women of childbearing age and young children are the focus of most international advisories. Chronic exposure in adults is also a concern, with documented associations between elevated methylmercury and cardiovascular and neurological effects at high intakes.

What makes this study particularly valuable is its refusal to treat fish as a single food category. The species-level and habitat-level analysis provides exactly the granularity needed for practical dietary guidance. Advisories that simply tell people to eat less fish risk discarding the well-documented nutritional benefits of seafood, including omega-3 fatty acids that support cardiovascular and brain health. A smarter approach, the authors argue, is to target advice by species and by population: carnivorous, wild-caught, neritic species carry the highest mercury loads and can be substituted with lower-trophic alternatives, while the fishing community, whose members both catch and consume high-mercury fish at high frequencies, needs tailored guidance rather than generic national recommendations.

The Guangdong findings also fit into a larger global picture. China is both a major emitter of mercury and one of the world’s largest consumers of seafood, and recent research has shown that global fishing patterns can amplify human methylmercury exposure as fleets target different species and waters. The Minamata Convention on Mercury, the international treaty governing mercury pollution, depends on accurate exposure data to evaluate whether emission controls are translating into lower human burdens. Studies like this one, which connect environmental measurements to human biomarkers within the same food system, provide the kind of ground-truth evidence that such evaluations require.

For the residents of Guangdong’s coastal communities, the study’s message is not that fish should leave the table, but that the choice of fish matters enormously. The authors call for species- and population-specific fish consumption advisories built on updated food-contamination monitoring and human biomonitoring data in high-exposure coastal areas. As mercury continues to cycle through marine food webs, the simple act of knowing which species carry the heaviest loads, and which neighbors eat the most of them, may prove to be one of the most effective public health tools available.

Subject of Research: Mercury exposure from fish consumption in urban and fishing communities in Guangdong, China

Article Title: Associations between fish consumption and human hair mercury: a multi-media assessment across urban and fishing communities in Guangdong Province, China

Article References: Zhao, J., Gao, Z., Chen, X., Wang, J., Liu, B., Wei, C., Gou, J., Liang, Z., & Lin, B. (2026). Associations between fish consumption and human hair mercury: a multi-media assessment across urban and fishing communities in Guangdong Province, China. Environmental Geochemistry and Health, 48(16), Article 638. https://doi.org/10.1007/s10653-026-03533-w

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03533-w

Keywords: mercury, methylmercury, fish consumption, hair biomarker, Guangdong, dietary exposure, biomagnification, coastal communities, food safety, risk assessment, public health, China

The research team, led by I. Guagliardi of Italy’s National Research Council together with colleagues from the Center for Ecological-Noosphere Studies in Yerevan, Armenia, collected 126 agricultural topsoil samples and 45 potato tubers from fields across the Sila Massif. Arsenic and lead concentrations in both soils and potato tissues were determined using inductively coupled plasma mass spectrometry, a technique sensitive enough to detect these elements at very low levels, while soil acidity was measured potentiometrically. The soils turned out to be predominantly slightly acidic, with a mean pH of 5.74, a condition that matters because acidity strongly influences how readily trace elements dissolve in soil water and become available for plant uptake.

The mean concentrations recorded were 2.85 milligrams per kilogram for arsenic and 31.3 milligrams per kilogram for lead in the topsoils. Both figures describe a landscape in which these elements are present but not dramatically elevated on average. What the spatial analysis revealed, however, was that the distribution is far from uniform. Instead of a smooth background level across the massif, the researchers identified localized enrichments of both elements, patches where concentrations rise noticeably above the regional norm. These hotspots appear to reflect the geological character of the Sila Massif itself, particularly the weathering of granitoid and metamorphic rocks that underlie the area, along with localized inputs from human activity.

This geological signature is central to interpreting the results. Granitoid rocks naturally contain minerals that release arsenic as they break down over millennia, and the slow chemical weathering of such bedrock can seed overlying soils with trace levels of toxic elements without any industrial involvement. Distinguishing geogenic enrichment from anthropogenic contamination is one of the persistent challenges in environmental geochemistry, and the Sila Massif study illustrates why it matters: a farmer looking at an arsenic hotspot cannot assume a polluter is to blame, nor can regulators assume nature is. The spatial patterns documented here give both groups a baseline against which future changes could be judged.

The most technically interesting part of the work concerns what happens between soil and tuber. The researchers calculated transfer factors, ratios that express how efficiently an element moves from soil into plant tissue, and found that both arsenic and lead showed limited transfer, on the order of ten to the power of minus three. In practical terms, only a tiny fraction of the arsenic and lead present in the soil made its way into the potato. This is consistent with the chemistry of both elements: lead tends to bind strongly to soil particles and organic matter, while arsenic, though more mobile under certain conditions, is generally taken up by plants in modest quantities relative to its soil concentration.

Yet the tissue-by-tissue comparison produced a striking result. Arsenic and lead concentrations were consistently higher in the potato skin than in the flesh, and the soil-to-skin transfer exceeded the soil-to-flesh transfer by a factor of 4.5 for arsenic and 2.8 for lead. The pattern makes physiological sense: the skin is the tuber’s interface with the soil, the first tissue to contact soil particles, soil water, and any adhering dust, so it acts as a partial barrier that intercepts elements before they reach the interior. For consumers, the implication is straightforward. Peeling removes a disproportionate share of the toxic element load, a simple kitchen practice that meaningfully reduces exposure from this particular food source.

To translate concentrations into health consequences, the team performed a dietary exposure assessment based on consumption of potato flesh, the fraction people actually eat most. For adults, the estimated exposure and associated risk indicated no appreciable health concerns from arsenic or lead in Sila Massif potatoes. The picture was more nuanced for the youngest consumers. For lead, the researchers estimated a margin of exposure of 1.5 for developmental neurotoxicity in young children, a relatively lower margin that reflects the higher vulnerability of small bodies to dietary exposure. Children eat more food per kilogram of body weight than adults, and their developing nervous systems are especially sensitive to lead, a metal for which no safe threshold has been established.

A margin of exposure of 1.5 does not mean that children eating these potatoes will be harmed; it is a benchmark used by risk assessors to gauge how close an estimated exposure sits to levels at which effects have been observed in studies. Regulatory guidance typically treats margins of exposure for lead-related developmental neurotoxicity with caution when they approach low single digits, so the finding signals a need for attention rather than alarm. The authors emphasize that potatoes may contribute to cumulative dietary exposure, particularly among sensitive population groups, and should therefore be considered within broader dietary risk assessments that tally up every source of arsenic and lead in a person’s diet, from rice and leafy vegetables to drinking water.

The study’s methodology also carries lessons for how such assessments are done elsewhere. By sampling both soils and tubers from the same agricultural landscape, and by separating flesh from skin rather than analyzing whole tubers, the researchers captured a level of detail that whole-tuber studies miss. The fresh-weight basis of the tuber measurements matters too, since water content dilutes concentrations and comparisons across studies can mislead if dry and fresh weights are conflated. The work was supported by a bilateral research agreement between Italy’s National Research Council and Armenia’s Ministry of Education, Science, Culture and Sport, a collaboration aimed specifically at unveiling soil-to-potato transfer factors of potentially toxic elements using geochemical compositional data analysis.

For the Sila Massif itself, the message is one of reassurance with a footnote. The region’s potatoes, on the evidence of this study, are not a significant arsenic or lead hazard for the general adult population, and the limited soil-to-tuber transfer reflects both the chemistry of these elements and the slightly acidic but not extreme soil conditions under which the crop is grown. The localized enrichments mapped in the soils are a reminder that geology, not only industry, shapes the trace element landscape of farmland, and that understanding the natural background is the essential first step in spotting genuine contamination. For young children, whose diets concentrate risk in ways adult assessments can overlook, the study argues for keeping staple crops like the potato firmly on the radar of public health monitoring, even when the individual contribution looks small.

Subject of Research: Arsenic and lead accumulation in agricultural soils and cultivated potatoes in the Sila Massif, southern Italy

Article Title: Arsenic and lead spatial distribution and tissue specific accumulation in soils and cultivated potato of the Sila Massif Southern Italy

Article References: Guagliardi, I., Ricca, N., Beglaryan, M., Pipoyan, D., & Tepanosyan, G. (2026). Arsenic and lead spatial distribution and tissue specific accumulation in soils and cultivated potato of the Sila Massif Southern Italy. Discover Sustainability. https://doi.org/10.1007/s43621-026-04947-3

Image Credits: AI Generated

DOI: 10.1007/s43621-026-04947-3

Keywords: arsenic, lead, potato, soil geochemistry, Sila Massif, Calabria, transfer factors, dietary exposure, ICP-MS, food safety, heavy metals, risk assessment

The research, conducted by Hongbing Sun of Rider University, took an unusually rigorous dual approach to a question that has long been difficult to answer. Rather than relying on a single modeling strategy, the study combined two complementary methods: an intake-based model that multiplies measured PFAS concentrations in foods and water by national consumption data, and a regression-based analysis that links what people report eating and drinking to the PFAS levels actually measured in their blood. The data backbone for both approaches was the National Health and Nutrition Examination Survey, or NHANES, the Centers for Disease Control and Prevention’s ongoing program that collects detailed dietary recall information and blood serum samples from a representative cross-section of the U.S. population. Because NHANES has consistently measured the same seven legacy PFAS compounds across survey cycles, it allowed the researcher to track exposure pathways over the 2015 to 2020 period.

The headline number from the intake-based model is a population-average total PFAS intake of approximately 17.4 nanograms per day from 2015 to 2020. That figure may sound small—nanograms are billionths of a gram—but PFAS compounds are defined by their extraordinary persistence. Their carbon-fluorine bonds, among the strongest in organic chemistry, resist degradation in the body and the environment alike, so compounds like perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) accumulate over years and decades. The serum half-life of PFOS in humans has been estimated at several years, meaning that even small daily doses compound into measurable body burdens. This toxicokinetic reality is precisely why identifying the dominant intake pathways matters: cutting off the largest source, even a modest one in absolute mass terms, can bend the curve of long-term accumulation.

When the researcher broke down that 17.4 nanograms per day by source, the results were striking. Shellfish alone accounted for 43.2 percent of estimated intake, with finfish contributing another 9.2 percent—meaning aquatic foods supplied more than half of the total. Drinking water, despite its cultural prominence as the symbol of PFAS contamination, contributed 15.5 percent. Dairy products came in at 14.4 percent, meat at 10.4 percent, and plant foods at 7.4 percent. The explanation for shellfish’s dominance lies in the biology of the animals themselves. Bivalves such as clams, oysters, and mussels are filter feeders that pump enormous volumes of water through their bodies, concentrating dissolved contaminants including PFAS. Because these compounds bind readily to proteins in animal tissue, filter-feeding organisms effectively act as biological concentrators, accumulating PFAS at levels that can far exceed those in the surrounding water.

Crucially, the regression-based analysis—grounded in actual biomonitoring rather than modeled intake—told the same story. Using survey-weighted standardized regression coefficients, the study examined how self-reported consumption of different food categories and drinking water related to interindividual variability in serum PFAS concentrations across the population. Shellfish consumption again emerged as the largest contributor to variability in blood PFAS levels across survey periods, while drinking water consumption contributed relatively little at the national level between 2015 and 2020. This convergence of two methodologically independent approaches is what gives the finding its weight. Intake models can be criticized for depending on uncertain concentration data, and regression analyses for confounding, but when both point to the same conclusion, the signal becomes difficult to dismiss.

The finding does not mean drinking water is unimportant, and the study’s national averages deserve careful interpretation. PFAS contamination of water is intensely local. Communities near industrial sites, airports, and military installations where aqueous film-forming foam has been used can face drinking water concentrations orders of magnitude above the national norm, and for those residents, water may well be the dominant exposure route. Earlier research, including a 2016 analysis in Environmental Science & Technology Letters, linked PFAS detections in U.S. drinking water supplies to proximity to industrial facilities, military fire-training areas, and wastewater treatment plants. More recent surveys by the U.S. Geological Survey have detected PFAS in tap water across the country, with private wells often facing distinct exposure profiles from public supplies. What the new study establishes is that at the population scale, after averaging across contaminated hotspots and clean supplies alike, the food supply—seafood above all—carries the larger share of legacy PFAS exposure.

The results also align with a growing body of international evidence. The European Food Safety Authority concluded in 2020 that food is the primary exposure route for PFAS among Europeans, with fish and seafood prominent among the contributing categories. Swedish market-basket analyses published in 2025 reached similar conclusions, and the Danish Veterinary and Food Administration has implemented some of the world’s strictest PFAS limits in foods, targeting exactly the animal-derived products that bioaccumulate these compounds. In the United States, the Food and Drug Administration has been testing seafood, dairy, and produce for PFAS, and Consumer Reports reported in 2024 on PFAS detections in some milk samples, including organic varieties. The new NHANES-based analysis stitches these fragmented observations into a coherent national picture, quantifying each pathway’s relative contribution with survey-weighted statistics.

There are important caveats and open questions. The study focused on seven legacy PFAS compounds consistently measured in NHANES—chemicals like PFOA, PFOS, PFHxS, and PFNA that have been phased out of major industrial uses in the United States but persist in the environment and in human blood. The replacement chemistry now flooding the market, including short-chain and fluorotelomer compounds, is largely invisible to standard biomonitoring panels, and their dietary accumulation patterns remain poorly characterized. The author explicitly calls for continued monitoring of both legacy and emerging replacement PFAS in foods and drinking water to improve exposure assessment. Moreover, intake estimates depend on PFAS concentration data drawn from published monitoring studies of varying scope and vintage, and dietary recall instruments capture consumption patterns imperfectly. Concentrations in specific seafood items vary widely by species, harvest location, and whether the product is farmed or wild-caught, so the population-average figures conceal substantial heterogeneity among individual consumers.

For public health policy, the implications are significant. Regulatory attention in the United States has concentrated heavily on drinking water—the Environmental Protection Agency’s health advisories for PFOA and PFOS and its Fifth Unregulated Contaminant Monitoring Rule have driven billions of dollars in anticipated water-treatment investment. Those efforts remain essential, particularly for overburdened communities that bear disproportionate contamination burdens, as studies of New Jersey water systems have documented. But the new findings suggest that a comprehensive exposure-reduction strategy must also encompass the food supply: surveillance of PFAS in retail seafood, guidance for high-consuming populations, and consideration of how contaminated water used in aquaculture and food processing propagates the chemicals into the diet. They also complicate a common public health dilemma, since seafood offers well-established nutritional benefits, including omega-3 fatty acids, and blanket avoidance advice could cause harm of its own.

What makes this study resonate beyond the technical literature is how it upends intuition. The invisible threat, it turns out, may arrive not through the faucet we scrutinize but through the oyster platter and the salmon fillet we consume without a second thought. As PFAS regulation matures and water treatment strips the compounds from municipal supplies, the relative importance of dietary pathways will only grow, making food-based exposure assessment an increasingly urgent frontier. The 17.4 nanograms per day flowing into the average American body is a small number with large consequences—and more than half of it, this analysis shows, comes from the sea.

Subject of Research: Relative contributions of dietary and drinking water pathways to PFAS exposure in the U.S. population

Article Title: Relative contributions of dietary and drinking water pathways to PFAS exposure in the U.S. population: intake-based and biomonitoring analyses

Article References: Sun, H. (2026). Relative contributions of dietary and drinking water pathways to PFAS exposure in the U.S. population: intake-based and biomonitoring analyses. Environmental Science and Pollution Research, 33(30), 15638-15648. https://doi.org/10.1007/s11356-026-38233-6

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38233-6

Keywords: PFAS, forever chemicals, shellfish, seafood, drinking water, NHANES, biomonitoring, dietary exposure, PFOA, PFOS, food contamination, exposure assessment

The research, carried out by Olawale Gabriel Olowomofe of the Federal University, Oye Ekiti, and Babatope Ebenezer Faweya of Ekiti State University, Ado Ekiti, focused on paired samples of soil and edible plant tissue collected from fertilized farms at five locations across Kaduna State. The crops chosen for scrutiny were okra, a widely eaten vegetable; maize, the dominant cereal; and cassava, the starchy root that anchors food security for millions of smallholders. Thirty paired soil-and-crop samples were collected in total, a design that allowed the researchers to compare, plot by plot, what was present in the ground against what actually ended up in the portion of the plant that people eat.

Each sample was digested using the United States Environmental Protection Agency’s standard acid digestion method 3050B and then analysed by flame atomic absorption spectrometry, a workhorse technique that quantifies metal concentrations by measuring the light absorbed by atoms excited in a flame. The team targeted six metals: lead, copper, iron, zinc, cadmium and nickel. These were not chosen arbitrarily. Lead and cadmium are toxic even at low exposures and have no known physiological benefit, while copper, zinc and nickel are essential or trace nutrients that become harmful at elevated doses. Iron, abundant in tropical soils, served as a useful benchmark for natural geochemical background.

The soil numbers told the first part of the story. Mean concentrations across the surveyed farms were 20.54 milligrams per kilogram for lead, 42.95 for copper, 3,350 for iron, 116.47 for zinc, 0.141 for cadmium and 38.41 for nickel. The edible tissues, by contrast, contained far lower levels: 0.650 milligrams per kilogram of lead, 15.83 of copper, 908.57 of iron, 50.07 of zinc, 0.014 of cadmium and just 0.174 of nickel. That gap between soil and plant is expected, because plant roots act as selective filters, but the size of the gap varies enormously from metal to metal and from crop to crop, and that variation is precisely what determines dietary exposure.

To capture that variation, the researchers calculated transfer factors, simple but powerful ratios that express the concentration of a metal in edible tissue relative to its concentration in the corresponding soil. A transfer factor near one would mean the plant takes up the metal almost without discrimination; a factor far below one means the soil-plant barrier is doing its job. Across all three crops, lead transfer remained low, a reassuring sign that even where soil lead is elevated, the metal is strongly bound to soil particles and poorly mobilized into food. Yet the crops were not identical. Maize accumulated more lead in its edible tissue than either cassava or okra, a difference the authors attribute to the physiology of the cereal and the specific tissues harvested.

The team went beyond simple ratios, deploying multivariate statistics to untangle the relationships among metals, soil properties and crop types. Multivariate approaches such as correlation and factor analysis can reveal whether metals move together, which in turn hints at shared sources. Metals that co-vary across fields may share a common origin, such as phosphate-based fertilizers, which are known to carry trace cadmium and lead as impurities, or they may reflect background geology. Previous work on fertilizers sold commercially in Nigeria has documented trace metal content in inorganic products, and global assessments, including a 2025 analysis in Science, have warned that toxic metal pollution of agricultural soils now threatens both crop productivity and human health on a planetary scale.

The most consequential part of the study, however, was the dietary risk assessment. The researchers computed the target hazard quotient, or THQ, a standard screening metric that estimates the ratio of a contaminant’s estimated daily intake to a reference dose considered safe over a lifetime of exposure. A THQ below one is conventionally interpreted as negligible non-carcinogenic risk; values above one signal that the screening threshold has been crossed and that more detailed assessment is warranted. For maize, the combined THQ came out at 2.98, nearly three times the threshold, with copper and lead driving most of the hazard. Cassava also edged over the line at 1.07, while okra registered a negligible 0.011, roughly 270 times below the limit.

Carcinogenic risk was assessed separately for the two metals with recognized cancer potency, lead and cadmium, using slope factors drawn from regulatory toxicology databases. The combined lead-plus-cadmium cancer risk was again highest for maize, at 3.17 multiplied by ten to the power of minus five. In risk communication terms, this figure sits within the range that many agencies treat as acceptable or borderline, typically one in a million to one in ten thousand, but its position near the upper end of that band, driven by a staple consumed daily, gives it practical weight. The authors emphasize that these are screening-level estimates based on average consumption patterns and mean concentrations, not measurements of individual exposure, and that real-world risk will vary with diet, portion size and local soil conditions.

Why does maize stand out? The answer likely lies in a combination of plant biology and consumption volume. Cereals are known in the soil-plant literature to translocate certain metals more efficiently than fruiting vegetables or root crops, and maize kernels constitute a dietary staple eaten in large quantities across Nigeria, multiplying any per-kilogram hazard by sheer intake. Cassava’s marginal exceedance reflects a similar logic: the root stores what it takes up, and cassava is eaten in volume. Okra, consumed in smaller amounts and apparently efficient at excluding metals from its fruit, poses little concern despite growing in the same fields. The study’s crop-specific design is what makes this hierarchy visible; a single-crop survey would have missed it entirely.

The practical implications reach beyond Kaduna State. The findings identify maize and cassava as priority crops for continued monitoring of copper and lead in agricultural fields subject to routine fertilizer use, and they suggest that fertilizer composition deserves attention as a manageable input in the metal balance of tropical farmland. Simple interventions, from sourcing lower-impurity fertilizers to periodic soil testing and crop rotation, could bend the exposure curve without undermining the productivity that fertilization is meant to deliver. The authors have deposited their underlying data in the Zenodo repository, making the dataset available for reuse in wider regional assessments. As global attention turns to the slow accumulation of toxic metals in the world’s farmland, this study offers a granular, crop-by-crop picture of where the risk actually sits on the plate, and a reminder that the safety of a harvest depends as much on what farmers put into the soil as on what the soil already contains.

Subject of Research: Heavy metal transfer from fertilized tropical smallholder soils to food crops and associated dietary health risks in Kaduna State, Nigeria

Article Title: Assessment of crop-specific heavy metal transfer and dietary exposure in fertilized tropical smallholder soils in Kaduna State Nigeria

Article References: Olowomofe, O. G., & Faweya, B. E. (2026). Assessment of crop-specific heavy metal transfer and dietary exposure in fertilized tropical smallholder soils in Kaduna State Nigeria. Environmental Geochemistry and Health, 48(15), Article 622. https://doi.org/10.1007/s10653-026-03521-0

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03521-0

Keywords: heavy metals, soil contamination, fertilizer, maize, cassava, okra, dietary exposure, transfer factor, target hazard quotient, Nigeria, smallholder agriculture, food safety

The findings, published in Discover Chemistry, challenge a widespread household assumption in resource-constrained settings: that washing grains in hot water before cooking reduces contaminant levels. In southeastern Nigeria, where access to clean water and reliable energy can be limited, many families routinely rinse staples with warm or hot water to shorten cooking times and save fuel. The practice is often believed to strip away impurities, including pesticide residues. But dieldrin, formed in the environment through the epoxidation of the related pesticide aldrin, is a notoriously stubborn molecule. Its high chemical stability, low volatility, and strong lipophilicity allow it to bind tightly to soil organic matter, persist in sediments for decades, and accumulate in the fatty tissues of living organisms, climbing the food chain through biomagnification.

To test whether domestic processing could dislodge the compound, the research team, led by Ogechi Irene Eboh-Ajoku of Nnamdi Azikiwe University, collected composite samples of local and imported rice, yellow and white corn, red and white guinea corn, pearl and finger millet, three wheat varieties, and several bean types from five Awka markets between May and August 2024, the peak rainy season when pesticide application is at its highest. The 162 samples were divided into three treatment groups: washing with tap water at ambient temperature around 25 degrees Celsius, mild heating at 50 degrees Celsius for fifteen minutes, and boiling at 100 degrees Celsius for ten minutes. These conditions were chosen to mirror real household practices, from warm-water pre-washing to standard cooking durations.

Residues were extracted using a modified QuEChERS method, a technique prized for being quick, easy, cheap, effective, rugged, and safe, and then quantified with gas chromatography coupled to mass spectrometry. The analytical method showed strong performance: calibration curves spanning 0.005 to 1.000 milligrams per kilogram displayed correlation coefficients between 0.992 and 0.999, detection limits ranged from 0.001 to 0.005 milligrams per kilogram, and mean recovery of spiked samples reached 95 percent. Procedural blanks and calibration verification standards were run throughout to guard against background contamination. Dieldrin was identified by matching retention times and mass spectra against certified reference standards and the National Institute of Standards and Technology spectral library.

The results were sobering. Concentrations ranged from undetectable to 0.376 milligrams per kilogram, with white soft wheat showing the highest contamination, followed by iron white beans at 0.258 milligrams per kilogram and brown beans at 0.244. Local Anam rice carried 0.030 milligrams per kilogram, more than double the 0.013 found in imported foreign rice, a disparity the authors attribute to differences in agricultural practices, pesticide application intensity, storage conditions, and the stricter adherence to international residue standards that imported rice may enjoy. Yellow corn registered 0.071 milligrams per kilogram. Across all treatment conditions, approximately 66.6 percent of food crop samples met or exceeded the FAO/WHO maximum residue limit of 0.01 milligrams per kilogram.

Thermal processing barely moved the needle. Local rice held steady at 0.030 milligrams per kilogram through ambient washing and 50-degree heating, dipping only slightly to 0.027 after boiling. Iron white beans fell from 0.258 to 0.213 milligrams per kilogram at 100 degrees, a marginal reduction that leaves the residue far above the safety threshold. An independent samples t-test comparing concentrations at 50 and 100 degrees found no statistically significant difference, with p-values of 0.128 to 0.135 across standard, unequal-variance, Monte Carlo permutation, and exact permutation tests. The explanation lies in dieldrin’s molecular architecture: as a highly chlorinated cyclodiene compound with a rigid structure and strong carbon-chlorine bonds, it resists breakdown at kitchen-scale temperatures. Meaningful degradation of such compounds typically requires advanced oxidation conditions far beyond any cooking process.

Perhaps the most intriguing finding concerns the cooking wastewater itself. Dieldrin is poorly soluble in water, yet the researchers detected it in the liquid left behind after washing, at concentrations ranging from 0.001 to 0.017 milligrams per liter depending on the crop and temperature. In some samples, such as white hard wheat, wastewater concentrations rose from 0.004 to 0.015 milligrams per liter as heating progressed. The authors caution that these variations were not statistically significant and likely represent minor numerical fluctuations rather than thermally enhanced desorption. Still, the detection of dieldrin in wastewater suggests that thermal washing primarily induces partitioning, redistributing a fraction of the compound from the food matrix into the aqueous phase, rather than eliminating it. That raises the possibility of secondary exposure pathways, since contaminated cooking water is often discarded into household surroundings or reused.

The health risk calculations are where the study becomes genuinely alarming. Using United States Environmental Protection Agency guidelines, the team estimated daily intakes based on a consumption rate of 0.33 kilograms per person per day and a standard adult body weight of 65 kilograms, then divided by the World Health Organization’s acceptable daily intake of 0.0001 milligrams per kilogram of body weight to yield a hazard index. Any value above unity signals potential non-carcinogenic risk. At ambient temperature, white soft wheat scored a hazard index of 19.09 and white hard wheat 10.92, while iron white beans reached 13.10 and brown beans 12.39. Local rice and yellow corn also exceeded the threshold, at 1.52 and 3.60 respectively. Even after boiling, local rice (1.37), yellow corn (3.35), white soft wheat (18.02), white hard wheat (10.71), iron white beans (10.81), and brown beans (10.71) remained above the risk line. The authors acknowledge that their uniform consumption and body weight assumptions are conservative and do not capture variability among sensitive populations such as children, meaning actual risks for some groups could differ.

The toxicological stakes are considerable. Dieldrin is associated with carcinogenic, teratogenic, endocrine-disrupting, and reproductive effects. Experimental studies cited in the paper show it interferes with steroidogenesis, estrogen signaling pathways, and thyroid hormone homeostasis, contributing to reduced fertility, altered fetal development, spontaneous abortion, and gestational abnormalities. Its teratogenic effects include skeletal malformations, cleft palate, and increased fetal resorption. Acute neurotoxicity arises from the compound’s ability to interfere with neuronal action potentials, producing symptoms ranging from headache, dizziness, and nausea to muscle twitching, tremors, convulsions, and, in extreme cases, death. Because dieldrin resists both abiotic and microbial degradation, it poses long-term ecological hazards to fish, birds, mammals, and humans alike.

A multivariate layer of the analysis added further texture. Bray-Curtis hierarchical clustering grouped the food crops into four clusters with remarkably high similarity coefficients of 98 to 99 percent, pairing local rice with iron white beans and white soft wheat with yellow corn, among others. The wastewater samples formed three distinct clusters. The authors interpret these groupings as reflecting similar contamination levels rather than confirmed shared sources, noting that dieldrin’s hydrophobicity and persistence promote consistent adsorption across different crop matrices, and that shared post-harvest handling and market aggregation may contribute. The study’s limitations are acknowledged: sampling was confined to Awka markets during a single four-month window, so regional and seasonal variation remains unexplored. Even so, the baseline it establishes is unsettling. If routine cooking cannot mitigate exposure to a pesticide banned across much of the world, the burden of protection falls squarely on monitoring, agricultural reform, and regulatory enforcement, and the researchers argue that without targeted interventions, chronic dietary exposure will continue to accumulate among populations who depend on these staples most.

Subject of Research: Dieldrin pesticide residues and dietary health risks in Nigerian staple crops and cooking wastewater

Article Title: Multivariate analysis and dietary risk assessment of dieldrin in Nigerian staple crops and cooking wastewater

Article References: Eboh-Ajoku, O. I., Nduka, J. K., Anagboso, M. O., & Offor, C. C. (2026). Multivariate analysis and dietary risk assessment of dieldrin in Nigerian staple crops and cooking wastewater. Discover Chemistry, 3(1), Article 556. https://doi.org/10.1007/s44371-026-01012-w

Image Credits: AI Generated

DOI: 10.1007/s44371-026-01012-w

Keywords: dieldrin, organochlorine pesticides, food safety, Nigeria, staple crops, thermal processing, GC-MS, QuEChERS, hazard index, dietary exposure, bioaccumulation, maximum residue limits

The study, conducted by scientists at the Seoul Metropolitan Government Research Institute of Public Health and Environment and published in Food Science and Biotechnology, analyzed 99 café products using high-performance liquid chromatography, a gold-standard analytical technique that separates and quantifies individual compounds in complex mixtures. The results reveal a striking division of labor between the two halves of the classic café pairing. Beverages delivered the bulk of the caffeine, averaging 88.02 milligrams per serving with a large standard deviation of 62.77 milligrams, while desserts contributed most of the added sugars, averaging 20.41 grams per serving compared with just 7.21 grams in beverages.

That asymmetry matters because the two nutrients carry very different risk profiles across age groups. Caffeine is a central nervous system stimulant whose safe intake levels are defined per kilogram of body weight, meaning children and adolescents face far lower absolute thresholds than adults. Added sugars, by contrast, are judged against recommendations expressed as a percentage of total energy intake, a criterion that the study found far fewer pairings violated.

To translate laboratory measurements into real-world risk, the team employed two complementary assessment frameworks. The first was a deterministic approach, which simply adds the measured caffeine and sugar contents of each beverage–dessert combination and compares the totals against dietary reference values. Across the age groups spanning young children aged 9 to 11 through adolescents aged 15 to 18, between 28 and 43 of the 90 possible pairings—roughly 31 to 48 percent—exceeded the caffeine reference value under this straightforward calculation. Only 4 pairings, or 4.4 percent, exceeded the added sugars threshold.

Deterministic assessment, however, treats every serving as identical, ignoring the natural variability in how products are prepared and consumed. To capture that uncertainty, the researchers turned to Monte Carlo simulation, a probabilistic technique widely used in dietary exposure assessment. Rather than assuming fixed values, the method repeatedly samples from the measured distributions of caffeine and sugar content, generating thousands of hypothetical pairing scenarios and calculating how often each one crosses the threshold. The approach, guided by methodology frameworks from the European Food Safety Authority, produces an exceedance probability for every pairing rather than a simple yes-or-no verdict.

The probabilistic results were sobering. Between 17 and 40 pairings—18.9 to 44.4 percent depending on age group—showed a greater than 50 percent probability of exceeding the caffeine dietary reference value. For added sugars, only 3 pairings, or 3.3 percent, crossed their threshold with that level of probability. The convergence of both methods on the same conclusion strengthens the finding: caffeine, not sugar, is the dominant driver of exceedance risk when café beverages are paired with desserts, particularly for younger consumers.

The analytical rigor underpinning these conclusions followed internationally harmonized guidelines. Method validation adhered to standards from the International Council for Harmonisation and the Association of Official Analytical Collaboration, with detection and quantification limits established for both analytes. Statistical comparisons of product categories relied on non-parametric tests appropriate for the skewed distributions typical of food composition data, and normality was formally assessed before parametric procedures were applied.

Why should caffeine thresholds be so easy to breach? The answer lies in developmental physiology. Children and adolescents have lower body masses and, according to toxicological reviews, may exhibit differential sensitivity to stimulant compounds compared with adults. Health authorities including the European Food Safety Authority have established age-graduated caffeine limits precisely because the margin between a typical serving and a problematic dose narrows considerably with decreasing body weight. A single large coffee-based beverage can approach or exceed a child’s entire daily allowance before any dessert is factored in, and the pairing structure of café menus makes combined consumption the norm rather than the exception.

The sugar findings, while less alarming on their own, add context to ongoing public health debates. The World Health Organization recommends limiting free sugars to less than 10 percent of total energy intake, and national surveys in South Korea have documented rising sugar consumption driven substantially by beverages and processed foods. The fact that most pairings stayed within sugar limits suggests that dessert portions in Seoul cafés, while sweet, are calibrated to adult energy budgets. The concern is cumulative: a child consuming a sugary café drink plus a dessert may derive a substantial fraction of daily energy from added sugars even when no single pairing formally exceeds the threshold.

For regulators and public health officials, the study’s dual-method framework offers a practical template. Deterministic screening quickly flags the worst offenders, while Monte Carlo simulation quantifies how confident one can be that a given pairing poses genuine risk, accounting for serving variability and analytical uncertainty. Applied to Seoul’s café market, the combined approach identified a substantial subset of popular combinations—particularly those built around high-caffeine beverages—that warrant attention when marketed to or consumed by younger customers. As café culture continues its global expansion, the message for parents is straightforward: the caffeine in the cup, not the sugar on the plate, is what most deserves scrutiny when children order dessert alongside a drink.

Subject of Research: Caffeine and added sugar content of café beverage–dessert pairings and their dietary exceedance risk in children and adolescents

Article Title: Caffeine and sugars in café beverage–dessert pairings in Seoul: deterministic and probabilistic exceedance assessment

Article References: Kim, M. J., Park, Y. A., Kwak, J. E., Park, Y. H., Jo, J. Y., Jang, H. I., Kim, M. S., Kim, T. R., Kim, H. J., & Park, J. S. (2026). Caffeine and sugars in café beverage–dessert pairings in Seoul: deterministic and probabilistic exceedance assessment. Food Science and Biotechnology. https://doi.org/10.1007/s10068-026-02312-8

Image Credits: AI Generated

DOI: 10.1007/s10068-026-02312-8

Keywords: caffeine, added sugars, café beverages, desserts, dietary reference values, Monte Carlo simulation, HPLC, food analysis, children's health, Seoul, dietary exposure, public health

PFAS are a sprawling family of thousands of synthetic compounds prized for their resistance to water, grease, and heat. Since the mid-twentieth century they have been incorporated into nonstick cookware, food packaging, stain-resistant carpets and clothing, firefighting foams, and countless industrial processes. Their defining chemical feature, a backbone of carbon atoms sheathed in fluorine, makes them extraordinarily stable, which is precisely why they accumulate in soil, water, wildlife, and people. Two of the most studied members of the family, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), have been phased out of production in the United States but remain detectable in the blood of nearly all Americans, a testament to their persistence and to continued exposure through imported goods, contaminated water, and legacy contamination.

Children are a population of particular concern. Relative to their body weight, they eat, drink, and breathe more than adults, and their developing organs and immune, endocrine, and nervous systems are more vulnerable to disruption. Prior research has linked elevated childhood PFAS exposure to reduced vaccine antibody responses, altered lipid profiles, changes in kidney function, and possible effects on growth and neurodevelopment. Yet most exposure studies have drawn on broad national samples that average away the differences between communities, leaving minority and immigrant populations underrepresented. The new Northern Virginia study was designed to close that gap, focusing specifically on Hispanic children in a region where suburban sprawl, industrial legacy sites, and busy transportation corridors coexist with rapidly changing demographics.

The research team recruited families from the Northern Virginia community and measured concentrations of multiple PFAS compounds in the children’s blood, pairing those biomarkers with detailed questionnaires about diet, food sourcing, household characteristics, and social and economic factors. This combination of exposure biomonitoring and rich behavioral data allowed the investigators to move beyond simply documenting that children carry PFAS in their blood and toward identifying which features of daily life push exposures higher or keep them lower. Such information is critical for designing interventions that families and public health agencies can actually act upon, rather than issuing blanket warnings that offer little practical guidance.

Among the dietary findings, certain food patterns stood out as meaningful contributors to exposure. Diets that included more frequently consumed prepared and restaurant foods, which often involve contact with grease-resistant packaging and processing equipment, were associated with higher levels of some PFAS compounds in the children’s blood. Seafood consumption, long recognized in the exposure literature as a route through which PFAS enter the human body because these chemicals bioaccumulate in aquatic food webs, also emerged as a relevant predictor. At the same time, the study underscored that no single food explains exposure; rather, it is the cumulative pattern of dietary choices, filtered through availability, affordability, and cultural preference, that shapes the chemical signature found in a child’s serum.

The social dimension of the findings is arguably the most consequential. The researchers report that indicators of social position, including household economic circumstances, parental education, and the length of time families had lived in the United States, were intertwined with exposure patterns. Families navigating the constraints of lower incomes may rely more heavily on packaged and convenience foods, may live in housing closer to potential contamination sources, or may have fewer options when it comes to choosing water supplies and food retailers. Recent immigrants may encounter different food environments than those they left behind, and acculturation can shift diets in ways that alter exposure profiles. The study’s authors emphasize that these are not simply lifestyle variables; they are structural conditions that determine which choices are realistically available to a family on a given evening.

This framing matters because it reframes PFAS exposure not as a matter of individual responsibility but as an environmental equity issue. If the chemicals that resist breakdown in the body are also more likely to accumulate in the bodies of children from socially disadvantaged households, then the burden of a largely invisible industrial legacy falls unevenly on communities with the fewest resources to detect or avoid it. Hispanic children in the United States represent a large and growing population, and studies like this one provide the community-specific evidence base that has historically been missing from regulatory deliberations, which have often relied on data from predominantly white, higher-income cohorts.

The technical approach of the study reflects the current state of the art in exposure science. Serum PFAS concentrations were quantified using liquid chromatography coupled with tandem mass spectrometry, the gold-standard analytical method capable of detecting these compounds at the parts-per-billion and parts-per-trillion levels found in human blood. Statistical modeling was then used to estimate the independent contribution of each dietary and social predictor while adjusting for the others, a necessary step because diet, income, and acculturation are deeply correlated in real households. The researchers also had to contend with the changing composition of PFAS exposures themselves: as legacy compounds like PFOA and PFOS decline following their phase-out, replacement chemistries and less-studied congeners are becoming proportionally more important, complicating both measurement and interpretation.

The implications of the work extend in several directions at once. For regulators, the results strengthen the case for reducing PFAS at the source, in food-contact materials and water systems, because expecting families to navigate a contaminated food supply is neither fair nor effective. The recent designation of PFOA and PFOS as hazardous substances under federal superfund law, along with the first national drinking water standards for several PFAS compounds, signals a policy environment that is finally moving, and community-specific exposure research helps ensure that these interventions reach the populations that need them most. For clinicians and public health practitioners, the study suggests that dietary counseling aimed at reducing exposure should be culturally tailored and sensitive to economic realities, rather than translated wholesale from recommendations developed for other populations.

For the families of Northern Virginia, and for Hispanic communities across the country, the study offers both a warning and a measure of agency. The warning is that the forever chemicals are not a distant problem confined to contaminated military bases or industrial towns; they travel through grocery carts, takeout containers, and tap water into the bloodstream of nearly every child. The agency lies in the demonstration that exposure is patterned and therefore predictable, and that what can be predicted can, in principle, be prevented. As the researchers and their community partners continue to follow this cohort, the hope is that the data will translate into practical protections, from cleaner food packaging to targeted health communication, so that the next generation of children in this rapidly changing region carries a lighter chemical inheritance than the last.

Subject of Research: Dietary and social predictors of PFAS exposure among Hispanic children in Northern Virginia

Article Title: Dietary and social predictors of PFAS exposure in Hispanic children from Northern Virginia

Article References: Mohsin, R., Gerona, R. R., Gallo, S., Jones, M. T., McKay, A. J., Mehlenbeck, R., Krall, J. R., Espina, V., Tomer, D., Sanchez, V. G., Chiwaka, L., & Bloom, M. S. (2026). Dietary and social predictors of PFAS exposure in Hispanic children from Northern Virginia. Journal of Exposure Science & Environmental Epidemiology. https://doi.org/10.1038/s41370-026-00975-3

Image Credits: AI Generated

DOI: 10.1038/s41370-026-00975-3

Keywords: PFAS, forever chemicals, Hispanic children, Northern Virginia, exposure science, biomonitoring, dietary exposure, environmental justice, PFOA, PFOS, children's health, food packaging