(Beyond Pesticides, April 20, 2022) A University of Michigan study is the first to highlight that maternal poison exposure during pregnancy adversely affects sleeping patterns for offspring later in life, specifically for females. Prenatal development is one of the most vulnerable periods of exposure as the fetus is most susceptible to the harmful effects of chemical contaminants. Many studies indicate that prenatal and early-life exposure to environmental toxicants increases susceptibility to diseases, from learning and developmental disabilities to cancer. However, the toxicity of pesticide exposure ad its full impact on the nonagricultural population in the US, especially women. Given research links to sleep-related disorders and neurological and cognitive development, studies like this can help government and health officials identify how pesticides’ impact on the brain elevates health concerns. The authors note, “Overall, these results are of public health importance considering the continued widespread agricultural and possibly residential use of pyrethroids and chlorpyrifos [in Mexico]…Thus, our results underline the importance of additional research studies that include both larger samples and assessment of unregulated pesticides, as well as studies that consider the underlying explaining mechanisms sex differences.”
Levels of inadequate sleep patterns are rising among children and adolescents. Reports find variability in sleep duration results in higher rates of depression, anxiety, and fatigue among juveniles. Since sleep is an important factor in normal brain development, disturbance in sleep patterns, such as sleeping too much or too little, can result in long-term associations between sleep and the brain’s white matter integrity (responsible for age-dependent cognitive function).
University of Michigan scientists in this study assesses measure urinary concentrations of two pesticides, pyrethroids, and chlorpyrifos, in samples from 137 pregnant women during their third trimester. The scientists followed up with the offspring during adolescence, a sleep study test to determine whether maternal pesticide exposure during pregnancy affected the offspring’s sleep pattern.
The results demonstrate that exposure to chlorpyrifos, but not pyrethroids, during pregnancy have greater associations with longer sleep duration and changes in sleep patterns among offspring. However, these sleep effects only occurred among adolescent girls, demonstrating sex-specific health outcomes. Although longer amounts of sleep may seem desirable, the study authors suggest that longer sleep duration is indicative of difficulties falling or staying asleep.
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. Furthermore, pregnant women already have over 100 detectable chemicals in blood and umbilical cord samples, including banned persistent organic pollutants (POPs). However, 89 percent of these chemical contaminants are from unidentified sources, lack adequate information, or were not previously detected in humans. Therefore, pesticide exposure during pregnancy has implications for both 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 have an increased risk of birthing a baby with abnormalities, including acute lymphoblastic leukemia and Attention-Deficit/Hyperactivity Disorder (ADHD). Regular household pesticide use (eg, disinfectants) during pregnancy can increase nephroblastoma (kidney cancer) and brain tumor risk among children.
Environmental contaminants like pesticides are ubiquitous in the environment, with 90 percent of Americans having at least one pesticide compound in their body. These pollutants have a global distribution, with evaporation and precipitation facilitating long-range atmospheric transport, deposition, and bioaccumulation of hazardous chemicals in the environment. Many of these chemical compounds remain in soils, water (solid and liquid), and the surrounding air at levels exceeding US Environmental Protection Agency (EPA) standards. The increasing ubiquity of pesticides concerns public health advocates as current measures safeguarding environmental against pesticide use do not adequately detect and assess total chemical contaminants. Therefore, individuals will continuously encounter varying concentrations of pesticides and other toxic chemicals, adding to the body burden of those toxic chemicals currently in use.
This study is the first to examine the links between pesticide exposure during pregnancy and sleep health among adolescent offspring. Pesticides can function as an endocrine disruptor that affects the hormone responsible, including melatonin for sleep. However, this study is not the first to demonstrate a risk to offspring. Although studies find glyphosate exposure has a negligible impact on pregnant rats’ health, incidents of prostate, ovarian, and kidney cancer increase in the two subsequent generations. However, chemical exposure encompasses more than just current-use, toxic pesticides like glyphosate. Many long-banned pesticides still cause adverse effects to human health. 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 pesticides’ impact on sleep specifically affects female offspring, this study is not the first to demonstrate the sex-specific effect of pesticide exposure. In 2017, scientists presented a study at the 99th meeting of the Endocrine Society, demonstrating instances of early onset puberty in boys after exposure to common pyrethroid insecticides. Furthermore, a 2021 study demonstrates that exposure to current-use pesticides, like organophosphates, poses a greater health risk to women. Women with organophosphate exposure are more likely to develop cardiovascular disease, bronchitis, asthma, and various cancers. Proximity to heavy chemical use during a mother’s third trimester increases the risk of childhood autism by 87%. Considering rates of preterm births, miscarriages/stillbirths, and birth malformations are increasing, it is necessary to assess chemical exposure effect on mothers and offspring to safeguard future generations’ health.
There is a consensus among pediatricians that pregnant mothers and young children should avoid pesticide exposure during critical periods of development. Various pesticides products act similarly or in conjunction with other chemicals. Individuals can encounter these simultaneously substances, resulting in more severe health outcomes. Therefore, advocates urge that policies 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 from pesticide dependency. For more information on the multiple harms that pesticides can cause, see PIDD pages on Birth/Fetal Effects, Learning/Developmental Disorders, Endocrine Disruption, Cancer, Body Burdens, and other diseases.
Beyond Pesticides advocates a precautionary approach to pest management in land management and agriculture by transiting to organic. Buying, growing, and supporting organic can help eliminate the extensive use of pesticides in the environment and from your diet. For more information on how organic is the right choice for consumers and the farmworkers who grow our food, see the Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: University of Michigan, Environmental Research