20
Dec
Mother and Child Health: Learning Disorders and Prenatal Pesticide Exposure Study Results Released
(Beyond Pesticide, December 20, 2022) A meta-analysis published in Chemosphere finds prenatal pesticide exposure, or pesticide exposure during pregnancy has a positive association with autism spectrum disorder (ASD) and attention deficit/hyperactive disorder (ADHD). Particularly, exposure to chemical classes organophosphate (OP) and pyrethroid (PYR) insecticides, in addition to the mother’s age during pregnancy (≥30 years old), increased the risk factor of ASD. ADHD risk increases among offspring whose mothers encounter organochlorine pesticides (OCPs) during gestation. The etiology or cause of ASD and ADHD involves the interaction of multiple components, including lifestyle and genetics. However, emerging evidence indicates that environmental contaminants like pesticides (e.g., occupational exposures, air pollution, solvents, dietary residues, etc.) play a role in disease etiology. Pesticide contamination is widespread in all ecosystems, and chemical compounds can accumulate in human tissues resulting in chronic health effects.
ADHD is estimated to affect 8-12% of school-age children worldwide. While it is a complex disease, and genetics may play a role, no specific genes have been identified, and there is increasing evidence that environmental factors like pesticide exposure facilitate the development of the condition. Additionally, U.S. Centers for Disease Control and Prevention (CDC) estimates that 1 in 54 children have been diagnosed with an autism spectrum disorder. Rates of autism have skyrocketed over the last several decades. While some of the rise is due to the increase in testing, and an expansion of the diagnostic criteria for the disorder, it is unable to entirely account for the increase in ASD cases. In 1997, 0.1% of children had autism, while in 2010, that number rose to 1%. Considering several studies associate early-life exposure to toxic chemicals with adverse birth/health effects, additional exposure through maternal contamination poses an even greater risk to children’s health. The report notes, “The findings indicate that maternal pesticide exposure should be avoided, especially for older pregnant women in agricultural areas, to protect early brain development in offspring.”
Beyond Pesticides has covered a variety of pregnancy risks from pesticides and other toxic chemicals, including these in just the last three years: pesticides and children’s sleep disorders; prenatal exposures to a multitude of chemicals; insecticides and childhood leukemia; and, insecticides and Attention Deficit/Hyperactivity Disorder.
The analysis reviews documents from five databases (i.e., PubMed, Embase, Web of Science, Medline, PsycINFO) related to pesticide exposure during pregnancy and ASD and ADHD in children. Factors considered for ASD and ADHD risk include pesticide type, window of exposure, and mother’s age. The review identifies 949 studies but opted to use the 19 studies with more robust information. There were 11 studies on ASD, seven studies on ADHD, and one study on both disorders. The analysis confirms that a mother’s exposure to pesticides increases offspring’s risk of ASD and ADHD.
Pesticide exposure during pregnancy is of specific concern as health effects for all life stages can be long-lasting. Just as nutrients are transferable between mother and fetus, so are chemical contaminants. Studies find pesticide compounds present in the mother’s blood can transfer to the fetus via the umbilical cord. Therefore, pesticide exposure during pregnancy has implications for both the mother and child’s health. Many studies indicate prenatal and early-life exposure to environmental toxicants increases susceptibility to disease. A 2020 study finds the first few weeks of pregnancy are the most vulnerable periods during which prenatal exposure to pesticides can increase the risk of the rare fetal disorder holoprosencephaly. This disorder prevents the embryonic forebrain from developing into two separate hemispheres. Moreover, women living near agricultural areas experience higher exposure rates that increase the risk of birthing a baby with abnormalities, including cancers like acute lymphoblastic leukemia.
This determination, and the present study’s findings, are supported by previous scientific literature. Similar to this study, a range of research demonstrates that pregnant mothers’ exposure to specific pesticides has links to autism, evidenced by laboratory and epidemiological research. Scientific studies have consistently found elevated rates of ASD in areas of high pesticide use. A 2014 study from the University of California, Davis, found that pregnant women living near crops sprayed with organophosphates, like insecticide chlorpyrifos, increased the chance of their child being diagnosed with ASD by 60%. For women in their second trimester, chlorpyrifos increased ASD odds by 3.3x. Synthetic pyrethroids increased autism risk by 87 percent. Like the aforementioned insecticides, fungicides also have links to autism disorders. A separate study from California researchers connected autism to the herbicide glyphosate, the banned insecticide diazinon, the fumigant methyl bromide, and fungicide myclobutanil. Moreover, studies find that higher rates of ADHD have associations with direct exposure in children and pyrethroid metabolites found in children’s urine. The Cincinnati Children’s Hospital Medical Center found a strong association between urinary pyrethroid concentrations and ADHD, primarily in boys. Any concentrations found above the level of detection corresponded to a three-fold increase in the chance of developing ADHD when compared to boys without detectable levels. Another study from Rutgers University found that, of over 2,000 children who had ever received an ADHD diagnosis, children with higher urinary pyrethroid metabolite levels were more than twice as likely to be diagnosed with ADHD.
While some well-meaning health advocates focus on controversial studies relating vaccines to ASD and ADHD, the connection to pesticide exposure has much research and is likely a contributing factor to the rise of the disorder over the last several decades. Although more research is needed to further define the connection, there is enough evidence to warrant a precautionary approach and restrictions on hazardous ASD and ADHD-linked pesticides. The study concludes, “Our findings contribute to our understanding of health risks related to maternal pesticide exposure and indicate that the in-utero developmental period is a vulnerable window-of-susceptibility for ASD and ADHD risk in offspring. These findings should guide policies that limit maternal exposure to pesticides, especially for pregnant women living in agricultural areas.”
There is a strong consensus among pediatricians that pregnant mothers and young children should avoid pesticide exposure during critical windows of development. However, the general population should follow this advice as the effects of pesticide exposure can affect every individual. Fortunately, the wide availability of non-pesticidal and nontoxic alternative strategies allows for choices in residential and agricultural management to promote a safe and healthy environment, especially among chemically vulnerable individuals. For instance, buying, growing, and supporting organic land management reduces human and environmental contamination from pesticides. Organic agriculture has many health and environmental benefits, which curtail the need for chemical-intensive agricultural practices. Numerous studies find that pesticide metabolite levels in urine significantly decrease when switching to an all-organic diet. For more information on how organic is the right choice for both consumers and the farmworkers that grow our food, see the Beyond Pesticides webpage on the Health Benefits of Organic Agriculture.
Beyond Pesticides tracks the most recent studies on pesticide exposure through the Pesticide Induced Diseases Database (PIDD). This database supports the need for strategic action to shift away from pesticide dependency. For more information on the multiple harms of pesticide exposure, see PIDD pages on learning/developmental disorders, Birth/Fetal Effects, Sexual and Reproductive Dysfunction, Body Burdens, and other diseases. Additionally, learn more about the hazards posed to children’s health through Beyond Pesticide’s Pesticide and You Journal article, “Children and Pesticides Don’t Mix.”
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Chemosphere
