18
Dec
Elevated Levels of Pesticides, Known Nervous System Poisons, During Pregnancy Tied Directly to Diet
(Beyond Pesticides, December 18, 2025) A study in the International Journal of Hygiene and Environmental Health finds peak concentrations of organophosphate pesticide (OP) metabolites in the urine of pregnant mothers 6-12 hours after consuming contaminated fruits and vegetables. “High detection rates were observed for dimethylthiophosphate (DMTP, 96%), dimethylphosphate (DMP, 94%), diethylphosphate (DEP, 89%), and diethylthiophosphate (DETP, 77%) among 431 urine samples taken from 25 pregnant women, over two 24-hr periods, early in pregnancy,†the researchers report. The levels of metabolites within the urine correlate to the consumption of foods treated with organophosphate pesticides, highlighting the importance of adopting an organic diet—particularly for pregnant individuals and their children.
“In 2009–2010, 80 pregnant women were recruited from Ottawa, Canada for the Plastics and Personal-care Product use in Pregnancy (P4) Study,†the authors say. “A subset (n = 25) collected multiple spot urines (up to 10 each; total n = 431) over two 24-h periods in early pregnancy—one weekday and weekend day—while logging their food consumption beginning 24 h prior to the first urine void and continuing through the following 24-h urine collection period.†This is the first study looking at the variability of organophosphate metabolites within 24 hours in maternal urine, giving insight into “the primary sources of exposure and the temporal variability in a population of Canadian pregnant participants.â€
Study Importance and Background
The organophosphate pesticide metabolites analyzed in the study are the breakdown products of many different pesticides that have current or historical uses in both the U.S. and Canada, including malathion, chlorpyrifos, fenitrothion, parathion, diazinon, dimethoate, and others. As the researchers state: “OP metabolism typically involves the production of three dialkyl phosphates (DAPs), which are excreted in urine. In 2010, the same year as the data for this study were collected, 586,288 kg of active pesticide ingredients in the dithiophosphates, phosphates, and thiophosphates chemical groups were sold in Canada.â€
They continue: “OPs are widely used in agriculture; thus, it is not surprising that the most common route of exposure to OPs for the general population is via ingestion of foods treated with these pesticides. However, prior studies have compared food consumed prior to a single measure of urinary DAP and not considered daily variation.†(A history of research is found here, here, here, here, here, here, here, and here.)
As Beyond Pesticides has previously reported, organophosphates are a family of insecticides derived from World War II nerve agents. They are cholinesterase inhibitors, meaning they bind irreversibly to the active site of an essential enzyme for standard nerve impulse transmission, acetylcholine esterase (AchE), inactivating the enzyme. Research finds that organophosphates have significant associations with depressive symptom development, including disturbing normal nerve impulses. Additionally, pesticide poisoning can lead to neurotoxicity via low serotonin levels and cholinergic changes, further exacerbated by oxidative stress and neuronal cell death. A decrease in AChE activity has links to higher depression scores observed in individuals with increased suicide risk, among other deleterious health effects. (See additional related Daily News coverage here.)
Methodology and Results
In the current study, 431 urine samples are analyzed for six dialkyl OP metabolites, including dimethyldithiophosphate (DMDTP), dimethylthiophosphate (DMTP), dimethylphosphate (DMP), diethyldithiophosphate (DEDTP), diethylthiophosphate (DETP), and diethylphosphate (DEP), that correlate with a range of organophosphate pesticide active ingredients. As the authors note: “In this study we aim to examine the within-subject variability in urinary DAP concentrations over two 24-h periods, and to examine the sensitivity and specificity of a single void to classify a participant’s exposure as high or low. Secondly, we aim to describe the change in urinary OP metabolites (dimethyl phosphates, diethyl phosphates, and total dialkyl phosphates) over two 24-h periods since last consuming a particular food group among a small cohort of pregnant participants who completed food diaries and provided individual urine voids.â€
During the two study periods, participants kept a detailed time log of food and beverages in which there were 3753 foods and drinks recorded, containing 73 distinct items from 14 main food categories, such as meats, vegetables, grains, dairy, fruits, and more. The results show the highest detection rates for DMTP (96%), DMP (94%), DEP (89%), and DETP (77%), with concentrations peaking between 6-12 h post-consumption of certain foods. “In conclusion, this study found DAP concentrations increased post-consumption of fruits and vegetables in samples collected over a 24 h period on a weekend day, similar to trends found in literature,†the researchers state.
Previous Research
There is a wide body of science on the health effects of organophosphate pesticide exposure, particularly in pregnant women, with subsequent effects on infants/children. Cited within the current study are “numerous investigations in the epidemiological literature regarding possible effects of OP pesticide exposure on the behaviour and development of infants and children, driving home the importance of accurately representing exposure.†This includes:
- Higher maternal DAP metabolite levels are associated with an increased number of abnormal reflexes, as found in a study from the Centre for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) in California.
- “A similar study in Shenyang, China, reported statistically significant associations between the highest quintile of prenatal exposures to OP pesticides and increased number of abnormal reflexes in 3-day-old infants, as measured in the Neonatal Behavioural Neurological Assessment (NBNA).â€
- Additional studies report that higher maternal DAP metabolite levels are “associated with a decrement in mental development at 12 months among blacks and Hispanics. In older infants and children, an association was reported between increasing in utero exposure to OP pesticides and maternal report of pervasive developmental disorder at 24 months of age in the CHAMACOS cohort and at 36 months in the Mount Sinai cohort.†(See here, here, and here.)
- “A study of 350 mother-infant pairs, from Ohio… reported that more frequent consumption of fresh fruits and vegetables had higher concentrations of OP metabolites during pregnancy.â€
- A study in the Netherlands shows high levels of OPs are associated with high consumption of fruit, “where each 100 g/d difference in fruit consumption was associated with a 7% higher total DAP metabolite concentration across pregnancy.â€
- In the Canadian Health Measures Survey (CHMS), “participants with a high frequency of fruit consumption, on average, had total DAP concentrations approximately 43 times higher than those with low fruit consumption.â€
- Another study finds similar results, with higher consumption of fruits and grains linked to elevated DAP concentrations while meat intake was associated with lower levels.
As covered by Beyond Pesticides, prenatal OP exposure can cause negative birth outcomes, as well as metabolic disorders in males. Additional health implications from exposure throughout a lifetime include immune system dysfunction that can lead to immunosuppression, allergies, and autoimmune disorders; reproductive effects; brain cancer; endocrine disruption and obesity; and more. (See here, here, and here.)
The Organic Solution
These studies add to the ever-growing mountain of research that links pesticide exposure to adverse health effects, as can be seen in the Pesticide-Induced Diseases Database (PIDD). Organophosphates are one of many classes of chemicals that threaten human health, as well as all wildlife and the environment, with transgenerational impacts that are not captured in current risk assessments. The only solution to these health threats are to remove exposure to these harmful compounds. Organic agriculture and land management makes that possible.
Without using petrochemical pesticides and synthetic fertilizers, organic farmers are able to produce crops on a large scale that are not only profitable but are healthier for consumers and farm workers. In Daily News earlier this year, titled Study Demonstrates Health Benefits of Organic Diet Over That Consumed with Toxic Pesticides, Beyond Pesticides shared how adopting a fully organic diet can reduce pesticide levels in urine within just two weeks “by an average of 98.6%†and facilitate faster DNA damage repair relative to a diet of food grown with chemical-intensive practices, according to findings from a randomized clinical trial published in Nutrire.
In additional coverage this year, Beyond Pesticides states that a study published in European Journal of Nutrition finds that consumption of organic animal-based and plant-based foods is positively associated with higher cognitive scores. Among women, there is both better cognitive function before testing (at baseline) and up to a 27 percent lower MCI [mild cognitive decline] score over the course of the study period for participants identifying as organic consumers, even if there was consumption of just one of the seven food categories. Over the 3.7-year study period, the authors conclude, “Our study found that organic food consumption was associated with higher cognitive scores for both sexes, yet the association with reduced incidence of MCI was observed exclusively in female participants.â€
Learn more about the health effects of pesticides and the organic solution from the speakers at the second session of the 42nd National Pesticide Forum, The Pesticide Threat to Environmental Health: Advancing Holistic Solutions Aligned with Nature. The Forum brought together cutting-edge science and medical experts from Brazil, Italy, Belgium, Rwanda, Canada, and the United States to sharpen the voices of advocates who are saying that the time for action to eliminate the current reliance on petrochemical pesticides and fertilizers is past due, and the transition away from them is now urgent. The speakers bring years of experience in research and clinical work, writing articles in peer-reviewed journals that characterize the dimensions of health threats that call for urgent action to stop toxic chemical use, according to Beyond Pesticides, the convenor of the Forum. (See more here, including session recordings and materials.)
The Forum helps to make important findings accessible to the lay public so that they can inform local and state decisions in the U.S. and across the globe, with the second session in December following an earlier session in October that brought together robust presentations on the critical benefits of land management in sync with nature, with experts explaining the importance of ecosystem services—recognizing the value of ecological balance and the importance of healthy ecosystems on which life depends. Recordings of both sessions can be found here.Â
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source:
Caton, L. et al. (2025) Organophosphate pesticide metabolite concentrations in a pregnancy cohort: daily variability, and predictors of exposure, International Journal of Hygiene and Environmental Health. Available at: https://www.sciencedirect.com/science/article/pii/S1438463925001981.
