The research drew on residual blood samples collected during the 2019 endline survey of the FAARM trial, a cluster-randomized study conducted in rural Bangladesh. In total, 719 participants—433 women and 286 children—were included in the investigation. The team, led by Nicholas N. A. Kyei of the Institute of Public Health at Charité – Universitätsmedizin Berlin together with colleagues at Heidelberg University, the Potsdam Institute for Climate Impact Research, and the Institute of Food Chemistry at Universität Münster, analyzed 712 whole blood and 578 serum samples using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry, or UHPLC-MS/MS. This technique can detect and quantify multiple fungal toxins and their metabolites at vanishingly low concentrations, making it the gold standard for human biomonitoring of mycotoxins.

The starkest result concerned ochratoxin A, a nephrotoxic and possibly carcinogenic mycotoxin produced by Aspergillus and Penicillium fungi that frequently contaminates cereals, spices, and dried fruit. OTA was detected in 100 percent of whole blood samples, and its lesser-known isomer, 2′R-ochratoxin A, appeared in 98 percent. Citrinin, a toxin produced by the same fungi and known to damage the kidneys, was found in 91 percent of samples, while Enniatin B, an emerging mycotoxin with antimicrobial and cytotoxic properties, was present in 92 percent. Beauvericin, another emerging toxin, was detected in 6 percent of samples. The sheer ubiquity of these compounds in human blood underscores how difficult it is to avoid mycotoxin exposure where contaminated staple foods form the daily diet.

Perhaps the most consequential finding involved aflatoxin B1, one of the most potent liver carcinogens known to science. Because AFB1 itself is rapidly metabolized, researchers instead measured AFB1-lysine adducts—molecules formed when the toxin’s reactive metabolite binds covalently to the blood protein albumin. Serum samples were enzymatically digested and cleaned up by solid-phase extraction before analysis. The adduct, a biomarker of chronic exposure over the preceding two to three months, was detected in nearly one-quarter of the women and 4 percent of the children with serum samples. Chronic aflatoxin exposure is linked to liver cancer, immune suppression, and child growth impairment, so its presence in a substantial fraction of reproductive-age women is a serious public health signal.

To translate blood concentrations into estimates of actual intake, the team calculated the probable daily intake, or PDI, for the most frequently detected toxins using toxicokinetic-based approaches. The results were alarming. The PDI of ochratoxin A exceeded health-based guidance values in 80 percent of the women and a striking 99 percent of the children. Citrinin intake was of concern for 12 percent of women and 27 percent of children. Children, with their lower body weight and developing organs, emerged as the most vulnerable group, absorbing comparable toxin burdens through smaller bodies and facing proportionally higher risks.

The study’s co-exposure findings add another layer of concern. Toxicology has traditionally assessed chemicals one at a time, yet mycotoxins frequently co-occur on the same food items because the fungi that produce them thrive under similar conditions of humidity, poor storage, and inadequate drying. OTA and citrinin, for instance, are often produced together by the same fungal species, and their combined kidney toxicity may be greater than either alone. With every participant carrying at least two mycotoxins and most carrying three or more, the realistic exposure scenario in rural Bangladesh is a complex toxicological cocktail whose interactions remain poorly understood.

Why is exposure so pervasive? In rural Bangladesh, maize, rice, wheat, and groundnuts are dietary staples, and these crops are highly susceptible to fungal contamination in the country’s hot, humid climate. Smallholder households often lack access to proper drying facilities, hermetic storage, or the means to sort and discard moldy grain. Food safety regulations, where they exist, are difficult to enforce in informal markets. As a result, mycotoxins enter the food supply at the farm level and travel directly to the family plate, with no practical means of avoidance for the households most affected.

The health implications extend beyond acute toxicity. Ochratoxin A is associated with chronic kidney disease and has been classified as possibly carcinogenic to humans. Aflatoxin B1 is a Group 1 human carcinogen that synergizes with hepatitis B infection to multiply liver cancer risk, a particularly worrying combination in regions where hepatitis B remains prevalent. Emerging toxins like enniatin B and beauvericin are only beginning to be characterized, and their long-term effects at chronic low doses are unknown. For children, chronic mycotoxin exposure has been linked in previous research to growth faltering, immune dysfunction, and reduced vaccine response—burdens that compound the already heavy challenges of malnutrition and infectious disease.

The authors emphasize that their findings demonstrate widespread co-exposure to multiple mycotoxins, with OTA, citrinin, and aflatoxin B1 posing notable risks, and they call for urgent, targeted interventions to protect vulnerable populations. Such interventions could include promoting improved post-harvest handling and drying practices, introducing hermetic storage bags that block fungal growth, supporting biocontrol agents that competitively exclude toxigenic fungi in the field, and strengthening food monitoring systems. Because blood biomonitoring captures actual internal exposure rather than estimated dietary intake, the approach used here could serve as a model for other low- and middle-income countries where mycotoxin contamination is suspected but poorly quantified.

The study also highlights the value of repurposing existing trial infrastructure for environmental health surveillance. By analyzing residual samples from the FAARM trial, the researchers obtained population-scale exposure data at a fraction of the cost of a dedicated biomonitoring campaign. As climate change expands the geographic range of toxigenic fungi and staple food systems come under increasing stress, the silent burden of mycotoxins documented in rural Bangladesh is likely a warning of what many other communities face. Making the invisible visible, this study suggests, is the first step toward reducing a health risk that has been simmering in the blood of millions for generations.

Subject of Research: Chronic blood-borne exposure to the mycotoxins aflatoxin B1, ochratoxin A, and citrinin among women and children in rural Bangladesh

Article Title: Chronic exposure to aflatoxin B1, ochratoxin A, and citrinin in women and children and associated health risk characterization: blood biomonitoring evidence from rural Bangladesh

Article References: Kyei, N. N. A., Cramer, B., Humpf, H.-U., Kuhn, M., Sobhan, S., Veerkamp, J., & Gabrysch, S. (2026). Chronic exposure to aflatoxin B1, ochratoxin A, and citrinin in women and children and associated health risk characterization: blood biomonitoring evidence from rural Bangladesh. Environmental Health, 25(1), Article 75. https://doi.org/10.1186/s12940-026-01330-7

Image Credits: AI Generated

DOI: 10.1186/s12940-026-01330-7

Keywords: mycotoxins, aflatoxin B1, ochratoxin A, citrinin, biomonitoring, Bangladesh, blood analysis, risk characterization, food safety, public health, children's health, UHPLC-MS/MS