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Daily News Blog

21
Mar

Hazardous Pesticide with Reproductive and Developmental Effects Enters U.S. Food Supply through Imported Food

Image of oats in a bowl

(Beyond Pesticides, March 21, 2024) Alarming levels of a hazardous pesticide plant growth regulator linked to reproductive and developmental effects, chlormequat, is found in 90% of urine samples in people tested, raising concerns about exposure to a chemical that has never been registered for food use in the U.S. but whose residues are permitted on imported food. Published in the Journal of Exposure Science and Environmental Epidemiology in February 2024 and led by Environmental Working Group toxicologist Alexis Temkin, PhD, a pilot study finds widespread chlormequat exposure to a sampling of people from across the country. U.S. Environmental Protection Agency (EPA) regulations only permit the use of chlormequat on ornamental plants and not food crops grown in the U.S. As explained in the journal article, “In April 2018, the U.S. EPA published acceptable food tolerance levels for chlormequat chloride in imported oat, wheat, barley, and some animal products, which permitted the import of chlormequat into the U.S. food supply.” In 2020, EPA increased the allowable level of chlormequat in food. Then in April 2023, EPA proposed allowing the first-ever U.S. use of chlormequat on barley, oat, triticale (a hybrid of wheat and rye), and wheat. Existing regulatory standards explain the higher detections of the chemical in U.S. residents tested, as observed in the study and pending domestic use allowances will only increase exposure further. Advocates note that this study on one pesticide reflects systemic failures in the regulatory review process. 

Like many other pesticides, exposure to chlormequat raises significant concerns about the potential impact on public health, as animal studies have linked chlormequat to reduced fertility, harm to the reproductive system, and altered fetal growth, including negative impacts on reproduction and post-birth health, and proper weight and bone development. The study notes that published toxicological research has found potential health effects from chlormequat exposure at doses lower than the current regulatory limits set by the EPA and European Food Safety Authority (EFSA). 

Additionally, chlormequat residues are found in over 90% of conventional oat-based products, while organic food products showed minimal contamination. The report argues the necessity for ongoing biomonitoring to assess the potential health impacts of chlormequat exposure at environmentally relevant levels, especially during critical periods such as pregnancy. Advocates point to the chlormequat findings as evidence of the importance of supporting organic agriculture and organic food products as a means of avoiding harmful chemical exposure.

Research findings and methods

This study investigates the presence of chlormequat in urine samples collected from adults in the U.S. between 2017-2023. Study results detect chlormequat in most urine samples, with detection frequencies increasing from 69% in 2017 to 90% in 2023. Food products purchased in the U.S. and U.K. were also tested, with chlormequat found more frequently in U.S. non-organic oat products than wheat. U.K. oat food samples have 15 times higher chlormequat levels than U.S. samples. The study suggests exposure levels may rise further if chlormequat is approved for domestic agricultural use in the U.S. It raises potential health concerns given toxicology studies linking chlormequat exposure to reduced fertility and impacts on fetal growth.

Toxicological effects at doses lower than EPA’s allowed reference dose (and below the safety limit set by the European regulatory agency)

The pervasive presence of chlormequat in the U.S. population and its detection in conventional oat-based and some wheat-based products demand a comprehensive reevaluation of the risks associated with this chemical, which should raise alarm at the EPA’s current consideration of allowing chlormequat to be used in the U.S. on non-organic agricultural products. The report notes, “Additionally, the regulatory thresholds do not consider the adverse effects of mixtures of chemicals that may impact the reproductive system, which have been shown to cause additive or synergistic effects at doses lower than for individual chemical exposures [22], raising concerns about the potential health effects associated with current exposure levels, especially for individuals on the higher end of exposure in general populations of Europe and the U.S.”

Specifically, the report noted that animal studies showed:

  • Mice and pigs exposed to doses under the EPA’s reference dose (allowed exhibited reduced fertility, harm to the reproductive system, and altered fetal growth.
  • Pregnant mice exposed to a dose equal to the no observed adverse effect level used to set the EPA limit experienced altered fetal growth and metabolic/body composition changes in neonatal mice.

Additionally, the regulatory thresholds do not account for potential additive or synergistic effects from mixtures of chemicals that impact the reproductive system, as some studies have demonstrated.

This raises concerns that the current exposure levels in some populations, especially those with elevated exposures, could still pose health risks. The study argues that the toxicology research suggests a reevaluation of the safety thresholds may be warranted to better protect public health, and expanded biomonitoring is warranted. Beyond Pesticides advocates for consumers to avoid unnecessary exposure by eating organic food and certified organic food products and to support a systemic change to organic and regenerative organic agriculture.

Assessing chlormequat exposure in U.S. food products purchased between 2022 and 2023

To assess whether chlormequat levels detected in U.S. urine samples correspond to potential dietary exposure, analysis was conducted on oat and wheat-based food products acquired in the U.S. during 2022 and 2023. Results found that non-organic oat products contain chlormequat with a median concentration of 104 parts per billion (ppb). This variability could be attributed to differences in product sourcing, including domestic versus Canadian origins (chlormequat is widely used in Canadian grain crops, while not currently allowed in U.S. agriculture), and whether the oats were treated with chlormequat. In contrast, U.K. food samples demonstrated a higher prevalence of chlormequat, especially in wheat-based products like bread, where 90% of samples had detectable chlormequat levels, and in oat products, where levels were over 15 times higher than those found in U.S. samples. Beyond Pesticides reported in 2014 on U.K. contamination of bread supply, when it was found that over 60% of the country’s bread supply was tainted with chlormequat and glyphosate pesticide residues.  

The presence of chlormequat in urine samples prior to 2018 suggests exposure despite the absence of established food tolerance levels for this pesticide in the U.S. The study hypothesizes that such exposure likely resulted from dietary sources, considering chlormequat’s rapid degradation. According to the authors, “These data indicate likely continuous exposure given the short half-life of chlormequat in vivo, with low levels from 2017 to 2022 and higher exposure levels in 2023.” The formation of chlormequat from choline precursors in wheat and egg powder has been observed under the high temperatures used in food processing, leading to concentrations ranging from 5 to 40 ng/g. These findings imply that dietary exposure to chlormequat could stem from its formation during food processing and from imported products treated with chlormequat. Factors such as geographical location, dietary habits, and occupational exposure in environments like greenhouses could influence individual exposure levels.

This research underscores the need for a broader and more varied analysis of processed foods to thoroughly investigate potential dietary sources of chlormequat, especially in individuals with elevated exposure levels. Future research should encompass the examination of historical urine and food samples, alongside dietary and occupational surveys, to provide a comprehensive understanding of chlormequat exposure sources within the U.S. population. Given that chlormequat is presently restricted to imported oat and wheat products in the U.S., with its domestic use on non-organic crops under review by EPA, there is potential for increased chlormequat levels in the food supply and, consequently, higher exposure levels among the U.S. population.

This study constitutes the first biomonitoring of chlormequat presence in the urine of adults in the United States, expanding the scope of monitoring beyond limited research focused on the United Kingdom and Sweden. A comprehensive pesticide biomonitoring effort involving over 1,000 Swedish adolescents from 2000 to 2017 revealed a 100% detection rate for chlormequat, underscoring the widespread use of chlormequat in the UK, European Union (and Canada), and resulting human exposure levels. 

The discernible spike in urinary chlormequat concentrations in 2023, relative to preceding years, is potentially indicative of its recent introduction into the American food chain, a development that coincides with EPA  of permissible chlormequat levels in food in 2018 and an increase in these limits for oats in 2020.

In assessing whether the urinary chlormequat concentrations reflected potential dietary exposure, this research measured chlormequat levels in oat and wheat-based food products available in the U.S. market in 2022 and 2023. Oat products exhibited a higher frequency of chlormequat presence compared to wheat products, with significant variability in chlormequat content among oat-based items, potentially attributable to differences in sourcing of oats from the U.S. versus Canada. The study suggests that exposure to chlormequat predates 2018, prior to the establishment of food tolerance levels in the U.S., hypothesizing that such exposures were likely dietary in nature given chlormequat’s short half-life. The absence of chlormequat monitoring in U.S. food products and historical data complicates this assertion. However, the natural formation of chlormequat from choline precursors under high-temperature conditions typical of food processing has been documented, leading to chlormequat concentrations within a similar specific range. The variability in chlormequat levels observed in food samples, including those from the only organic oat-based product out of eight organic oat products tested, had low levels of chlormequat, aligning with this phenomenon of natural formation, and suggesting dietary exposure as a plausible source of the pre-2023 urinary chlormequat levels. The elevated levels detected in 2023 may result from dietary exposure to naturally occurring chlormequat and the consumption of imported, chlormequat-treated products. What is unequivocal is the widespread use of chlormequat in Canada, the U.K., and the European Union, where, as previously noted, human biomonitoring studies showed the U.K. and Sweden have almost 100% exposure in the population tested. 

Solutions found in buying organic oat and wheat products, supporting organic farming

Organic food products have been found to have zero contact with pesticides unless due to herbicidal drift from other farming operations. The best defense against pesticide exposure is, whenever possible, choosing to purchase and consume organic. For more information on pesticide residue exposure for different organic versus non-organic forms of common produce, please check out the pages on Eating with a Conscience and Buying Organic Products (on a budget!). For those with some background experience or interest in gardening, see Grow Your Own Organic Food for best practices, tips, and resources to get started. If you believe that you were exposed to pesticides, please click to access our section on Pesticide Emergencies.

Beyond Pesticides continues to closely monitor potential EPA actions to register chlormequat for use in the U.S. on non-organic crops. Click here to subscribe to action alerts and a weekly newsletter of the Daily News! 

All unattributed positions and opinions in this piece are those of Beyond Pesticides.

Sources

A pilot study of chlormequat in food and urine from adults in the United States from 2017 to 2023, Journal of Exposure Science and Environmental Epidemiology, February 15, 2024 https://www.nature.com/articles/s41370-024-00643-4 

A mixture of 15 phthalates and pesticides below individual chemical no observed adverse effect levels (NOAELs) produces reproductive tract malformations in the male rat, Environment International, November 2021 https://www.sciencedirect.com/science/article/pii/S0160412021002403

Maternal chlormequat chloride exposure disrupts embryonic growth and produces postnatal adverse effects, Toxicology, September 2020 https://pubmed.ncbi.nlm.nih.gov/32622971/

Currently used pesticides and their mixtures affect the function of sex hormone receptors and aromatase enzyme activity, Toxicology and Applied Pharmacology, 2013 https://www.sciencedirect.com/science/article/abs/pii/S0041008X13003013  

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