The research, published in Environmental Monitoring and Assessment, was carried out by a team from Hassan II University, the Moroccan National Centre for Nuclear Energy, Science and Technology (CNESTEN) and the National Institute of Agricultural Research, working within an International Atomic Energy Agency coordinated research project on radionuclide transfer in arid and semiarid environments. Led by Zineb Elaboudi, the scientists sampled soil and nine commonly consumed crops, including coriander, red pepper, potato, onion, pomegranate, cardoon, beet, tomato and eggplant, from farmland in a semiarid Moroccan agricultural area. Their goal was to quantify activity concentrations, calculate soil-to-plant concentration ratios and estimate the potential annual effective dose that people could receive from eating locally grown food.

The analytical work relied on high-resolution alpha- and gamma-spectrometry using high-purity germanium detectors, instruments capable of distinguishing the characteristic energy signatures of individual isotopes even at very low concentrations. The team measured eight radionuclides in both soil and plants: polonium-210, thorium-234, radium-226, thorium-228, radium-228, lead-210, potassium-40 and cesium-137. Together these isotopes span the full spectrum of environmental radioactivity, from members of the uranium and thorium decay chains that have leached slowly through bedrock for millennia, to potassium-40 dispersed uniformly through all living tissue, to cesium-137, a fission product whose global fallout from mid-twentieth-century nuclear weapons testing still lingers in surface soils.

In the soil, activity concentrations painted a picture of typical natural background. Polonium-210 ranged from 16.37 to 39.59 becquerels per kilogram, thorium-234 from 6.21 to 29.15, radium-226 from 4.84 to 26.26, thorium-228 from 9.37 to 46.04, radium-228 from 10.10 to 51.04, and lead-210 from 5.92 to 31.39. Potassium-40, as expected, dominated with values between 107.21 and 434.20 becquerels per kilogram, while cesium-137, the sole anthropogenic contributor, registered only 1.15 to 2.98 becquerels per kilogram, a faint residue of atmospheric fallout rather than any local contamination source.

Inside the plants, the story changed dramatically. Activity concentrations were generally far lower than in the underlying soil, with polonium-210 between 0.12 and 4.76 becquerels per kilogram, radium-226 between 0.36 and 5.89, and thorium-228 between 0.22 and 1.61. Potassium-40, however, ran in the opposite direction, reaching 386.33 to 3265.53 becquerels per kilogram, sometimes exceeding its soil concentration. The reason is biochemical rather than radiological: potassium is an essential plant macronutrient, recruited in large quantities to regulate osmotic pressure and enzyme function, and potassium-40 constitutes a fixed fraction of all natural potassium. Because the isotope cannot be separated chemically from its stable siblings, plants that accumulate potassium necessarily accumulate its radioactivity. Meanwhile thorium-234, radium-228, lead-210 and cesium-137 mostly fell below detection limits in the crops, indicating that roots act as effective barriers against these species.

The concentration ratio, defined as the activity concentration in plant tissue divided by that in dry soil, is the single most important parameter in radiological dose models, and the Moroccan values revealed striking crop-specific differences. Ratios spanned 0.01 to 0.14 for polonium-210, 0.02 to 0.43 for radium-226, and 0.01 to 0.17 for thorium-228, but climbed as high as 20.03 for potassium-40. Two crops stood out as the strongest accumulators: cardoon, a thistle-like vegetable with deep roots and a place of honor in North African cuisine, and eggplant. Elevated transfer in these species suggests that rooting depth, plant family physiology and nutrient demand all shape which isotopes cross the root membrane, a finding consistent with observations from Syria, Saudi Arabia, Abu Dhabi and other dry regions where comparable studies have been conducted.

Perhaps the most scientifically valuable contribution lies in the correlation analysis linking radionuclide uptake to soil chemistry. The researchers found strong interrelationships among the measured isotopes and demonstrated that transfer processes are governed primarily by soil physicochemical properties, particularly organic matter content, cation exchange capacity and the suite of exchangeable cations held on clay and humus surfaces. These parameters control how tightly radionuclides are bound to soil particles and therefore how available they are for root uptake. In contrast, carbonate content and salinity tended to restrict radionuclide mobility, effectively locking the isotopes in place. This has a counterintuitive implication for semiarid agriculture: the very conditions that make soils challenging for crop productivity, including high carbonate levels and salt accumulation under intense evaporation, may also suppress the movement of radioactive elements into the food chain.

The study also estimated the potential annual effective dose from food ingestion, the standard metric used by the International Commission on Radiological Protection to translate environmental measurements into health-relevant terms. By combining crop activity concentrations with consumption rates and isotope-specific dose coefficients, the team could assess whether locally grown vegetables contribute meaningfully to the radiation burden that residents already receive from cosmic rays, radon and terrestrial gamma radiation. The dominance of potassium-40 in plant tissues means it inevitably drives much of the ingested dose, yet because the human body maintains potassium homeostasis, biologically regulated excretion keeps the internal burden from this isotope essentially constant regardless of dietary source, a nuance that distinguishes potassium-40 from radium or polonium, which follow bone and soft-tissue metabolism and are treated with greater regulatory caution.

For the wider scientific community, the Moroccan dataset fills a recognized gap. The IAEA has repeatedly noted that most soil-to-plant transfer parameters in its handbooks derive from temperate European and North American ecosystems, while arid and semiarid environments, home to a large share of the world’s irrigated agriculture, remain underrepresented. Studies from Turkey, Jordan, Nigeria, Vietnam, Australia and now Morocco are steadily building the evidence base needed to adapt radiological environmental impact assessment to dry climates. The finding that organic matter and cation exchange capacity promote transfer while carbonates and salinity suppress it offers modelers concrete, measurable soil descriptors that can be incorporated into transfer predictions without requiring site-specific experiments at every location.

The practical message for consumers is reassuring. Cesium-137 was barely detectable, the natural radionuclides were mostly well below levels of concern, and the estimated doses fall within the range regarded as normal background exposure from food. Yet the research carries lasting value beyond its immediate conclusions. As phosphate fertilizer use, water scarcity and climate change reshape agriculture across the semiarid world, understanding the soil chemistry that governs radionuclide mobility becomes essential for protecting both food safety and the environmental systems that sustain it. This Moroccan study, rooted in rigorous gamma and alpha spectrometry and framed by international collaboration, demonstrates that even the quiet radioactivity of an ordinary vegetable patch can be measured, modeled and managed with precision.

Subject of Research: Soil-to-plant transfer of natural and artificial radionuclides and associated radiological doses in semiarid Moroccan agriculture

Article Title: Radiological impact of radionuclides in Moroccan food crops under semiarid conditions

Article References: Radiological impact of radionuclides in Moroccan food crops under semiarid conditions. (n.d.). https://doi.org/10.1007/s10661-026-15992-w

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15992-w

Keywords: radionuclides, soil-to-plant transfer, concentration ratio, potassium-40, radium-226, polonium-210, cesium-137, semiarid agriculture, Morocco, gamma spectrometry, radiological dose, soil chemistry

The review, published in Environmental Monitoring and Assessment by researchers at Ghana’s CSIR-Crops Research Institute and partner institutions, followed PRISMA 2020 guidelines and combed three databases for peer-reviewed studies published between January 2020 and January 2025. The team focused on five potentially toxic elements, lead, cadmium, chromium, mercury and arsenic, in the four vegetables that define Ghanaian cuisine. From an initial sweep of the literature, 45 eligible studies spanning 11 mining districts made the cut, supplemented cautiously by a single grey-literature technical report used only for site-level data unavailable elsewhere. Study quality was scored against a four-criterion framework, and agreement between the researchers doing the appraisals was strong, with a Cohen’s kappa of 0.87, a statistic that indicates the independent assessors rated the same studies in near-identical ways.

Because the underlying studies varied widely in design and sampling intensity, the authors chose a narrative synthesis with descriptive, sample-size-weighted aggregation rather than a formal inverse-variance meta-analysis. That methodological honesty matters: the review is designed to map where the evidence is strong and where it is thin, not to overstate precision. Even so, the patterns that emerge across the pooled data are difficult to dismiss.

The standout finding concerns cadmium. This heavy metal, which accumulates in kidneys and bones over years of chronic exposure, showed the highest soil-to-plant transfer of all five elements in tomato and garden egg, with transfer factors exceeding 1.0. A transfer factor above unity means the concentration in the edible plant tissue exceeds that in the soil on a mass basis. The authors are careful to note that such a ratio describes a concentration relationship rather than, by itself, proof of an active-uptake mechanism, but the practical implication is the same: cadmium moves readily from mining-affected soils into two of Ghana’s most consumed vegetables.

Chromium tells a different story, and a subtler one. Its soil-to-plant transfer was comparatively restricted, staying below 0.50 even at sites where soil concentrations climbed past 300 milligrams per kilogram. A casual reading might suggest chromium is the least worrying of the five. The review warns against that conclusion. Almost none of the studies examined distinguished between chromium(III), a relatively immobile and less toxic form, and chromium(VI), a carcinogenic oxidized species classified by the International Agency for Research on Cancer as a group 1 human carcinogen. Without speciation data, a low transfer factor for total chromium says little about the actual toxicological risk, because the small fraction that does enter plants, or the fraction that people inhale from dust, could be dominated by the dangerous form.

The regional picture is stark. Across the four regions covered by the evidence, vegetable concentrations of lead, arsenic and mercury exceeded the WHO/FAO Codex limits at several sites, with the worst exceedances concentrated in Ashanti and Western Region samples. At the single most contaminated sites reported in the literature, arsenic levels in vegetables reached up to 200 times the Codex threshold, and mercury up to 400 times. Those extremes come from the highest-contamination locations and should not be read as typical of every farm in every district, but they illustrate how severe localized contamination can become where mining waste and irrigation water intersect. Comparable regional breakdowns for Eastern and Central Region were more limited in the available literature, a gap the review flags explicitly.

To translate contamination into health terms, the researchers extracted hazard quotients and hazard indices, standard non-carcinogenic risk metrics that compare estimated intake against reference doses, drawing on the United States Environmental Protection Agency’s Integrated Risk Information System toxicity values. The result was consistent: the cumulative hazard index exceeded 1.0 in every mining-adjacent community for which it could be calculated. An index above 1.0 signals that regular consumers of locally grown vegetables face elevated non-carcinogenic risk, meaning combined exposures across the five metals surpass the thresholds regulators consider safe for chronic intake. Because the index aggregates across elements, a community can cross the line even when no single metal alone would trigger concern, which is precisely why mixture exposure is the more realistic framing for people eating these vegetables daily.

The review also extends its lens beyond the farm gate, examining the post-harvest stages of the value chain where contamination can be introduced or amplified. Handling, washing and market conditions all shape the final dose a consumer receives, and the evidence base for these stages is even patchier than for soil-to-plant transfer. Related work cited in the review, including studies on vegetable washing as a risk-reduction measure in urban agriculture, suggests simple interventions can lower exposure, but the review stops short of endorsing any single fix without site-specific data. The authors call instead for improved post-harvest handling practices grounded in local measurement rather than assumption.

What distinguishes this review is its refusal to flatten a complicated picture into a single alarm. The magnitude of risk, the authors conclude, varies by metal, by crop, by location and by the exposure assumptions each underlying study adopted. Cadmium’s mobility in tomato and garden egg does not imply the same behavior in onion. A 400-fold mercury exceedance at one site does not describe the neighboring valley. This unevenness is itself the central finding: Ghana’s vegetable value chain is a plausible and, in places, severe exposure pathway, but it is unevenly quantified, and policy built on averages will misallocate resources. The evidence supports targeted monitoring of the worst sites, source-specific risk assessment that traces which mining operations feed which fields, and site-specific rather than uniformly prescribed agricultural buffer zones between mines and cropland.

The research agenda that follows is equally concrete. Chromium and arsenic speciation studies top the list, since total-element measurements cannot distinguish benign forms from carcinogenic ones. Cumulative and synergistic risk modelling comes next, capturing the reality that consumers absorb mixtures, not single metals. And longitudinal human biomonitoring, tracking metal burdens in residents of mining-adjacent communities over time, would finally connect the environmental measurements to actual health outcomes. For now, the review delivers a clear message to Ghanaian regulators and consumers alike: the vegetables grown beside the gold pits carry a measurable mining signature, the risk is real but uneven, and the first step toward managing it is knowing precisely where, and in what chemical form, the danger lies.

Subject of Research: Mining-related potentially toxic element contamination of Ghana's vegetable value chain and associated human health risks

Article Title: Potentially toxic element contamination in Ghana’s vegetable value chain: a systematic review of mining-related soil-to-food transfer and human health risk

Article References: Bonsu, E. O., Osei, M. K., Okyere, H., & Korang, J. (2026). Potentially toxic element contamination in Ghana’s vegetable value chain: a systematic review of mining-related soil-to-food transfer and human health risk. Environmental Monitoring and Assessment, 198(10), Article 1116. https://doi.org/10.1007/s10661-026-15934-6

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15934-6

Keywords: Ghana, artisanal and small-scale mining, cadmium, arsenic, mercury, lead, chromium speciation, vegetable contamination, soil-to-plant transfer, hazard index, food safety, systematic review

The team, led by Nina Dyakova with colleagues Dmitry Lyubashevsky, Julia Shcherbina and Julia Lyubashevskaya, measured the specific activity of five radionuclides in paired samples of soil and plantain leaves collected across the Voronezh Region of Russia. Two of them, cesium-137 and strontium-90, are artificial isotopes that trace the legacy of twentieth-century nuclear activities and atmospheric fallout. The other three, potassium-40, thorium-232 and radium-226, are natural radionuclides that have always been present in the Earth’s crust. By analysing soil and leaf material from the same sampling points, the researchers could calculate how efficiently each isotope crosses the soil-to-plant boundary.

The headline result is reassuring for public health: every sample examined fell comfortably within radiological safety limits. The researchers computed an integral safety index for each sample, and all values ranged between 0.17 and 0.45, well below the threshold value of 1.0 that would signal a concern. In other words, the plantain leaves harvested in the region are radiologically safe as raw material for herbal preparations, a finding that matters because demand for wild-harvested medicinal plants has been rising steadily in the Russian pharmaceutical market and elsewhere.

Beneath that reassuring surface, however, the study uncovered a rich structure in how different radionuclides behave. Strong positive Pearson correlations between soil concentrations and leaf concentrations confirmed that the plant is genuinely taking these isotopes up from the ground rather than accumulating them from atmospheric deposition. The correlations were remarkably tight for strontium-90, cesium-137 and potassium-40, each with a coefficient of about 0.89, followed closely by radium-226 at 0.86. Thorium-232 showed a weaker but still meaningful correlation of 0.47, consistent with its well-known tendency to remain locked in soil minerals and resist root uptake.

The accumulation factor, defined as the ratio of the radionuclide concentration in leaves to its concentration in the corresponding soil, revealed a clear hierarchy of mobility. Cesium-137 proved the most readily accumulated isotope, with an accumulation factor of 2.55, meaning plantain leaves can concentrate this isotope to more than twice its soil level. Potassium-40 followed at 1.47, then strontium-90 at 1.12. Radium-226 hovered near parity at 0.93, while thorium-232 lagged far behind at just 0.37. This ordering makes chemical sense: cesium and potassium are alkali metals that travel through the same membrane transport channels in plant roots, while strontium mimics calcium, and thorium forms highly insoluble complexes that plants largely exclude.

Perhaps the most striking insight emerged when the researchers plotted accumulation factors against soil radionuclide concentrations. Across the dataset, they identified a universal inverse relationship: the more concentrated a given radionuclide is in the soil, the lower the accumulation factor measured in the plant. This pattern suggests active homeostatic regulation, a kind of internal control system by which the plant moderates its ion uptake. Rather than absorbing isotopes in strict proportion to their availability, plantain leaves appear to dampen accumulation as soil levels rise, a phenomenon with major implications for how transfer of radioactivity from environments to food and medicine chains is modelled.

This finding speaks to a long-standing debate in radioecology. Classic models of radionuclide transfer, including widely used handbooks of parameter values published by the International Atomic Energy Agency, rely on concentration ratios that assume a broadly linear relationship between soil and plant burdens. Earlier experimental work by researchers such as Sheppard and Evenden in the late 1980s had already questioned the linearity assumption, and subsequent studies on radium and thorium uptake by groups including Vandenhove and colleagues confirmed that soil properties and plant physiology can bend the transfer curve substantially. The new plantain dataset adds a medicinal-plant data point to that critical tradition, showing that the deviation from simple proportionality is systematic enough to be described with regression equations.

Those regression equations, together with the measured accumulation factors, are the study’s most practical product. By fitting linear models to the paired soil and leaf data, the authors produced predictive parameters that can be used to estimate radionuclide content in plantain leaves directly from soil measurements. For environmental monitoring agencies, this means soil surveys could become a screening tool for the safety of wild-harvested medicinal raw materials, reducing the need to analyse every batch of plant material. For pharmaceutical regulators, the derived transfer parameters offer a defensible basis for setting harvesting guidance, particularly in regions where residual contamination from historical fallout or industrial activity remains a concern.

The choice of study region is significant. The Voronezh Region sits within Russia’s Central Black Earth belt, famous for its fertile chernozem soils, and it hosts an active tradition of harvesting wild medicinal plants. Earlier work by the same research group had examined radionuclide accumulation in nettle leaves and in burdock roots, and the plantain study extends that programme into one of the most commonly gathered species. Because plantain is harvested for its leaves, which are used in expectorant and wound-healing preparations, the leaf-soil transfer parameters generated here apply directly to the part of the plant that enters commerce.

The authors conclude that the region enjoys a favourable radiation status and that plantain’s homeostatic mechanisms actively regulate isotope uptake in a predictable way. Beyond the immediate reassurance for consumers of herbal medicine, the study demonstrates how a humble, ubiquitous weed can serve as a bioindicator of environmental radioactivity. As demand for plant-based remedies grows worldwide, systematic soil-to-plant transfer measurements of this kind, grounded in paired sampling and quantitative modelling, provide exactly the kind of evidence base needed to keep natural products both trusted and safe.

Subject of Research: Soil-to-plant transfer of natural and technogenic radionuclides in the medicinal plant Plantago major L.

Article Title: Radionuclide accumulation in leaves of the medicinal plant Plantago major L

Article References: Radionuclide accumulation in leaves of the medicinal plant Plantago major L. (n.d.). https://doi.org/10.1007/s11104-026-08754-7

Image Credits: AI Generated

DOI: 10.1007/s11104-026-08754-7

Keywords: Plantago major, radionuclides, cesium-137, strontium-90, medicinal plants, soil-to-plant transfer, radiation safety, environmental monitoring, accumulation factor, Voronezh Region, radioecology, herbal medicine