04
Jan
Neonicotinoid Insecticides Add to the Growing List of Chemicals that Transfer between Mother and Fetus
(Beyond Pesticides, January 4, 2022) A study published in Environmental Science and Technology finds neonicotinoids (neonics) and their breakdown products (metabolites), like other chemical pesticide compounds, can readily transfer from mother to fetus. The National Health and Nutrition Examination Survey (NHANES) finds U.S. pregnant women experience frequent exposure to environmental pollutants that pose serious health risks to both mother and newborn. Many known pollutants (i.e., heavy metals, polychlorinated biphenyl, and pesticides) are chemicals that can move from the mother to the developing fetus at higher exposure rates. 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 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.
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; insecticides and Attention Deficit/Hyperactivity Disorder.
The study evaluated the transplacental transfer rates (TTR) of neonics from mother to fetus via prenatal exposure. Researchers collected 95 paired samples from mothers’ serum (MS) and accompanying (umbilical) cord serum (CS) to measure the levels of five neonics (acetamiprid, imidacloprid, clothianidin, thiacloprid, and thiamethoxam) and two metabolites of acetamiprid and imidacloprid. After calculating the transplacental transfer efficiencies (TTEs) of each neonics and metabolite, researchers focus on three chemical mechanisms: passive diffusion, active transport, and pinocytosis. Lastly, a multilinear regression analysis explores the association between blood biomarkers for neonics in mothers and related birth outcomes among fetuses.
The most abundant neonic in MS and CS samples is imidacloprid, whereas acetamiprid’s metabolite is the most abundant in CS and MS. Both parent and metabolite neonics have a high TTE, with imidacloprid having the highest transfer rate (1.61). Even the neonic with the lowest TTE of 0.81, thiamethoxam, is within the high TTE range, indicating proficient placental transfer of these chemicals from mother to fetus. Researchers identify that transplacental transfer of these chemicals mainly occurs through passive mechanisms depending on chemical structure. Therefore, neonics like acetamiprid and thiacloprid (known as cyanoamidines) have higher TTE values than neonics like clothianidin and thiamethoxam (known as nitroguanidines). Lastly, the multilinear regression demonstrates that most neonics in MS samples have associations with blood biomarkers related to hepatotoxicity (liver toxicity) and renal (kidney) toxicity.
Studies find pesticide compounds in the 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 exposure rates increasing the risk of neonatal abnormalities like acute lymphoblastic leukemia and Attention-Deficit/Hyperactivity Disorder (ADHD).
Over the past 20 years, neonicotinoids have replaced four major chemical classes of insecticides in the global market (organophosphates, carbamates, phenyl-pyrazoles, and pyrethroids). These systemic agricultural pesticides are highly toxic, resembling nicotine, and affect the central nervous system of insects, resulting in paralysis and death, even at low doses. Like other pesticides, neonics readily contaminate water and food resources as traditional wastewater treatments typically fail to remove the chemical from tap water, and the systemic nature of neonics allows the chemical to accumulate within treated plants. According to the Centers for Disease Control and Prevention (CDC), nearly half the U.S. population encounters at least one type of neonic daily, with children ages three to five having the highest exposure risk. Health impacts of exposure to neonics include neurotoxicity, reproductive disorders, liver/kidney damage, and an increase in gene expression and enzyme production linked to hormone-dependent breast cancer.
Although previous studies demonstrate pesticide classes like pyrethroids, organophosphate, carbamates, and organochlorines readily transfer from mother to fetus, this study is one of the first to document and identify the occurrence and distribution specific to neonics in MS and CS. This conclusion supports long-known concepts regarding the hazards of pesticides for children’s health. Early life exposures during “critical windows of vulnerability” can predict the likelihood or otherwise increase the chances of an individual encountering a range of pernicious diseases. In addition to findings on learning and development, early life exposures have links to increased risks of cancer, asthma, birth disorders, among others. Thus, a parent’s exposure to pesticides during these critical periods indicates an increased risk in childhood disease.
Pesticide exposure not only 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 disabilities. Although the United States 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. Moreover, these exposures have real, tangible effects on society. Environmental disease in children costs an estimated $76.8 billion annually. Exposure that harms learning and development also impact future economic growth in the form of lost brain power, racking up a debt to society in the hundreds of billions of dollars.
The study concludes, “This is the first study to associate maternal hematological parameters with p-NEOs [parent neonics] or their metabolites in MS, and further studies with larger sample sizes are needed to confirm our findings. […]A recent study reported that urinary IMI [imidacloprid] and ACE [acetamiprid] concentrations in pregnant women (n = 296) were significantly negatively associated with neonatal HC. This finding implied the influence of NEOs on cognitive and neurologic development in neonates.”
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. 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.
Fortunately, the wide availability of non-pesticidal 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.
Organic agriculture represents a safer, healthier approach to crop production that does not necessitate toxic pesticide use. Beyond Pesticides encourages farmers to embrace and consumers to support regenerative, organic practices. A compliment to buying organic is contacting various organic farming organizations to learn more about what you can do. 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.
