18
Nov
Pesticide Exposure Contributes to Preterm Births and Low Birth Weight
(Beyond Pesticides, November 18, 2021) A study published by King George’s Medical University, India, finds exposure to xenobiotic substances like pesticides during pregnancy increases risks associated with preterm birth, including a rise in cesarean section (C-section) deliveries and a decrease in fetal body weight. Preterm births occur when a fetus is born early or before 37 weeks of complete gestation. Premature births can result in chronic (long-term) illnesses among infants from lack of proper organ development and even death.
Birth and reproductive complications are increasingly common among individuals exposed to environmental toxicants, like pesticides. The Center for Disease Control (CDC) reports the preterm birth rate is increasing annually. Therefore, studies like this can help government and health officials safeguard human health by assessing adverse effects following prevalent chemical exposure. The study notes, “To the best of our knowledge, this was a pioneering study, and it may help to increase our knowledge with regard to xenobiotic exposure in biological systems and the need for stringent guidelines for agricultural use of pesticides.”
The study examines the association between the transfer of xenobiotics (foreign synthetic substances like pesticides) from mother to fetus. Transferal of these toxic substances can result in biological and chemical changes (i.e., genotoxicity and oxidative stress). Using a cohort of 221 pregnant women in India, researchers collected blood samples from the mother and the fetal umbilical cord. The researchers separated blood samples by gestational (period of development inside the womb) and newborn birth weight. A comet assay examined genotoxicity or genetic DNA damage resulting in mutations from xenobiotic substances.
The results demonstrate that exposure to xenobiotic organochlorine pesticides (OCPs) during pregnancy increases risks associated with genotoxicity and other adverse birth outcomes. Overall, high maternal age and gestation length combined with xenobiotic exposure influence preterm birth and genotoxicity patterns. Nearly half (47 percent) of all pregnant women in the study gave birth prematurely or before 36 weeks of gestation. Preterm births have the highest associations with cesarean section deliveries and low birth weight. All of the blood samples from premature newborns and their mothers have higher levels of OCPs than full-term newborns. Aldrin, dieldrin, and hexachlorocyclohexane (HCH) are the most prominent OCPs present in maternal and umbilical cord blood samples, followed by DDT, endosulfan, and endrin aldehyde. However, blood samples also contain concentrations of other pesticide types including, organophosphates (OPs) (i.e., dichlorvos, malathion, chlorpyrifos, profenofos), synthetic pyrethroids (i.e., cypermethrin, fenvalerate, cyhalothrin-L, deltamethrin, cyfluthrin), and neonicotinoids (neonics) (i.e., imidacloprid). Regarding specific birth outcomes, DDT metabolite DDE and dieldrin have significant associations with low birth weight.
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 a plethora of 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 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 present in the mother’s blood can transfer to the fetus via the umbilical cord. A 2021 study finds pregnant women already have over detectable 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 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. Some of these birth abnormalities include 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 toxins like pesticides increases susceptibility to disease for both mother and child’s health.
Pesticide exposure not only poses a risk to mothers and their subsequent offspring but also 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 many 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 the effects pesticides have on mothers and newborns. The results indicate that pesticide exposure during pregnancy negatively affects the mother’s metabolism, promoting genotoxicity and oxidative stress among fetuses. An imbalance in reactive oxygen species (ROS) or the antioxidant system can lead to oxidative stress. Thus, the birthing process is hypoxic, with oxygen levels changing from low to high after delivery. Upon delivery, the change in partial pressure of oxygen within the uterine and outside of the uterus during birth results in cell and tissue destruction. However, preterm newborns have an immature antioxidant system, resulting in more severe cellular and tissues damage and increasing pediatric morbidity risk. Furthermore, DNA repair mechanisms among preterm and full-term newborns are inadequate and promote genotoxic effects.
In this study, OCP concentration levels are the highest among the Indian population compared to previously reported levels from past studies. Even at low concentrations, OCPs and their breakdown products reduce birth weight, most likely via interference with internal hormones like estrogens, androgens, and thyroid hormones. This interference is also known as endocrine disruption, with chemical compounds binding to hormone receptors, mimicking their mechanisms.
Considering rates of preterm births, miscarriages/stillbirths, and birth malformations are increasing, it is necessary to mitigate chemical exposure to safeguard future generations’ health. The authors conclude, “[N]on-occupational OCPs contamination to pregnant women may cause (1) DNA damage, (2) biochemical alterations, (3) reduction in infant birth weight, and other pregnancy outcomes. Our results also indicated that there is no transplacental barrier to OCPs across the mother-fetus axis and consequently nuclear damage linked with it, and it is of great concern. There is an urgent need of implementation of proper legislation and awareness programs to educate farmworkers for safe handling and spraying techniques, effective personal hygiene and cleanliness.”
There is a growing consensus that exposure to environmental toxicants before pregnancy can impair fertility, pregnancy, and fetal development. Thus, doctors and pediatricians strongly agree that pregnant mothers should avoid pesticide exposure during critical development periods. Exposure concerns about POPs are increasing significantly, especially for adults and children more vulnerable to their toxic effects. Moreover, many contaminants are subject to regulatory standards that do not fully evaluate disease implications associated with exposure. Advocates say that addressing the manufacturing and use of pesticides is essential to mitigate risks from chemical exposure to toxic pesticides. Therefore, advocates urge that policies strengthen 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 the 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, Sexual and Reproductive Dysfunction, Body Burdens, and other diseases. To learn more about how the lack of adequate pesticide regulations can adversely affect human and environmental health, see Beyond Pesticides’ Pesticides and You article “Highly Destructive Pesticide Effects Unregulated.”
One way to reduce human and environmental contamination from pesticides is buying, growing, and supporting organic. Numerous studies find that levels of pesticide metabolites in urine significantly drop when switching to an all-organic diet. Furthermore, given the wide availability of non-pesticidal alternative strategies, families and agroindustry workers alike can apply these methods to promote a safe and healthy environment, especially among chemically vulnerable individuals. For more information on how organic is the right choice for consumers, see Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Environmental Research (King George’s Medical College), Deccan Herald
