14
Jun
Study Links Recurring Pregnancy Loss (RPL) with Pesticide Exposure
(Beyond Pesticides, June 14, 2023) A study published in Scientific Reports finds a link between pesticide exposure and recurrent pregnancy loss (RPL) through oxidative stress and apoptosis (cell death) in the placenta. Recurrent pregnancy loss (RPL) is the loss of three or more successive pregnancies before 24 weeks of gestation (pregnancy) and signifies an underlying reproductive health issue. The study highlights that pesticides’ endocrine-disrupting (ED) properties can have varying adverse impacts on biological processes, including immunology, metabolism, and reproduction.
Pregnant women experience frequent exposure to environmental pollutants that pose serious health risks to both mother and newborn. Many known pollutants (e.g., heavy metals, polychlorinated biphenyl, and pesticides) are chemicals with ED properties that can move from the mother to the developing fetus at higher exposure rates. Additionally, pregnant women are experiencing exposure to an increasing number of dangerous industrial chemicals. With a range of scientific data highlighting chemical exposures during pregnancy as a critical window of vulnerability, public awareness of these threats is growing. The study notes, “They are associated with an increasing placental OS [oxidative stress] and placental apoptosis. Specific measures should be taken to decrease maternal exposure to these pollutants’ sources, especially in underdeveloped and developing countries.”
For RPL, the research investigated pesticide components in blood plasma, specifically polychlorinated biphenyls (PCBs), dieldrin (organochlorine), dichlorodiphenyldichloroethylene (DDE, organochlorine), ethion (organophosphate), malathion (organophosphate), and chlorpyrifos (organophosphate). The research tested plasma to determine the associations between chemical exposure, oxidative stress (OS) biomarkers, and apoptotic/antiapoptotic indices in the placenta. OS markers include the presence of nitric oxide (NO.), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), and superoxide dismutase (SOD). Gas chromatography-mass spectrometry analyzed pesticide levels in plasma. Levels of PCBs, DDE, dieldrin, and ethion are higher in the plasma of individuals in RPL cases. The concentration of these chemicals also reflects a significant association between OS and apoptosis in the placenta and a decrease in human chorionic gonadotropin (HCG) levels, which are biomarkers for RPL risk.
Environmental contaminants, like pesticides, are ubiquitous in the environment, with 90 percent of Americans having at least one pesticide compound in their body. Numerous studies indicate chemical exposure mainly stems from dietary exposure, like food and drinking water, and researchers caution that there are hundreds to thousands of chemicals that humans are likely to encounter. Although many countries ban most organochlorine compounds, these chemicals remain in soils, water (solid and liquid), and the surrounding air at levels exceeding U.S. Environmental Protection Agency (EPA) standards. These compounds have a global distribution, with evaporation and precipitation facilitating long-range atmospheric transport, deposition, and bioaccumulation of hazardous chemicals in the environment. Thus, exposure to these toxicants can cause many adverse environmental and biological health effects. The scientific literature demonstrates pesticides’ long history of severe adverse effects on human health (i.e., endocrine disruption, cancer, reproductive/birth problems, neurotoxicity, loss of biodiversity, etc.) and wildlife and biodiversity. With the increasing ubiquity of pesticides, current measures safeguarding against pesticide use and exposure must adequately detect and assess total environmental chemical contaminants.
Pesticides’ presence in the body has implications for human health, especially during vulnerable life stages like childhood, puberty, pregnancy, and old age. 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 in a mother’s blood can transfer to the fetus via the umbilical cord. A 2021 study finds pregnant women already have over 100 chemicals in blood and umbilical cord samples, including banned POPs. However, 89 percent of these chemical contaminants are from unidentified sources, lack adequate information, or were not previously detectable in humans. Considering the first few weeks of pregnancy are the most vulnerable periods of fetal development, exposure to toxicants can have much more severe implications. A 2020 study finds prenatal pesticide exposure 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 pesticide exposure, increasing the risk of birthing a baby with abnormalities, including acute lymphoblastic leukemia and Attention-Deficit/Hyperactivity Disorder (ADHD). Even common household pesticides use during pregnancy can increase nephroblastoma (kidney cancer) and brain tumor risk in children. Therefore, prenatal and early-life exposure to environmental toxicants, like pesticides, increases susceptibility to disease for both mother and child’s health.
Not only does pesticide exposure poses a risk to mothers and their subsequent offspring, but also to future generations. Current-use pesticides and metabolites (or breakdown products) of many long-banned pesticides still impart adverse effects on human health. These negative effects can continue into childhood and adulthood and may have multigenerational consequences. Researchers at Drexel University report that higher levels of some organochlorine compounds, like DDT, during pregnancy are associated with autism spectrum disorder (ASD) and intellectual disability (ID). Although the U.S. bans most organochlorine compounds, the ongoing poisoning and contamination underscore how pervasive and persistent these chemicals are and their continued adverse impact on human health.
This study amplifies the growing body of scientific research evaluating how pesticides affect mothers and their offspring. Like this study, past research highlights that pesticide exposure during pregnancy negatively affects the mother’s metabolism, promoting genotoxicity and oxidative stress among fetuses. Occupationally, pregnant veterinarians who have work-related exposures to pesticides, anesthetic gases, or radiation may have twice the risk of miscarriage. Furthermore, consuming foods with high pesticide residues lowers the probability of live births. An imbalance in reactive oxygen species (ROS) or the antioxidant system can lead to oxidative stress. Additionally, many chemicals that cause OS are EDs that detrimentally affect the fetus during pregnancy. But this type of health problem that individuals live with is only one example. Exposure can likewise result in a range of health impacts.
Pesticide exposure during pregnancy is associated with a range of long-term health hazards. Research finds that early exposure to pesticides in the womb increases the risk of the rare fetal disorder holoprosencephaly. This disorder prevents the embryonic forebrain from developing into two separate hemispheres. Pesticides can result in early births and low birth weight, and evidence is growing that pesticides, like glyphosate in particular, are primary contributors to this phenomenon. Overwhelming data links prenatal pesticide exposure to an increased risk of cancer. Whether acute childhood leukemia (see coverage of another study on this health outcome here), nephroblastoma (kidney cancer), or brain tumors, the data is consistent and concerning. Exposure during pregnancy can increase the probability of childhood ear infections, risking hearing loss that can set back childhood development and change an individual’s future life. ADHD is another example, with pregnant mothers who have used insecticides at 98% increased odds of having children with ADHD scores in the 90th percentile.
While peer-reviewed science continues to sound the alarm, federal regulators at the U.S. Environmental Protection Agency (EPA) continue to allow harmful exposures, permitting increases in application rates of chemicals linked to prenatal and early childhood health impacts in some cases. Hence, prenatal exposure to these chemicals may increase the prevalence of birth-related health consequences like natal abnormalities and learning/developmental disabilities. Children are particularly vulnerable to the impacts of pesticide exposure as their developing bodies cannot adequately combat exposure effects. Moreover, a mother’s pesticide exposure can have a stronger association with health disorders than childhood exposure, and a potential newborn can still encounter pesticides. Therefore, it is essential to understand how pesticides impact the health and well-being of individuals during critical developmental periods.
A strong consensus among pediatricians highlights that pregnant mothers and young children should avoid pesticide exposure during critical development periods. Therefore, policies should enforce stricter pesticide regulations and increase research on the long-term impacts of pesticide exposure. Beyond Pesticides tracks the most recent studies related to pesticide exposure through our Pesticide Induced Diseases Database (PIDD). This database supports the clear need for strategic action to shift away from pesticide dependency. For more information on the multiple harms of pesticide exposure, see PIDD pages on Birth/Fetal Effects, Learning/Developmental Disorders, Endocrine Disruption, Body Burdens, and other diseases. To learn more about the inadequacy of pesticide regulations and how they can adversely affect human and environmental health, see Beyond Pesticides’ Pesticides and You article “Highly Destructive Pesticide Effects Unregulated.”
Human and environmental contamination from pesticides can be reduced through buying, growing, and supporting organic. Numerous studies find that levels of pesticide metabolites in urine drop when switching to an all-organic diet. Furthermore, given the wide availability of non-pesticidal alternative strategies, families and agro-industry workers can apply these methods to promote a safe and healthy environment, especially among chemically vulnerable individuals. For more information on how organic choice is the right choice, see the Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Scientific Reports
