06
Jul
Prenatal Exposure to Organophosphate Pesticides Have Links to Behavior
(Beyond Pesticides, July 6, 2023) A study published in Environmental Health Perspectives finds concentrations of organophosphate (OP) metabolites in urine during the prenatal phase have links to adolescent/young adult externalizing (e.g., hyperactivity, aggression, attention problems) and internalizing (e.g., depression) behavior problems. Thus, prenatal exposure to OP pesticides can permanently affect behavioral health as children mature into adulthood. This study adds to the growing body of research reinforcing the adverse effects of organophosphate (OP) exposure on cognitive health and neurological development, especially for infants and children. 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. Given research links to pesticide exposure and neurological and cognitive development, studies like this can help government and health officials identify how pesticides’ impact on the brain elevates health concerns.
Researchers gathered two urine samples from mothers during pregnancy (at weeks 13 and 26) and five urine samples from offspring from the ages of six months to five years old to measure urinary dialkylphosphates (DAPs) (nonspecific OP metabolites). Subsequently, the study also assesses reports of externalizing and internalizing behavior problems using the Behavior Assessment System for Children ages 14, 16, and 18. The results find an association between maternal DAP concentrations during pregnancy and more behavioral problems, including hyperactivity, aggression, attention problems, and depression. However, after birth, OP metabolite concentrations in the urine of the offspring between six months and five years find less of an association with behavioral problems but suggest an association with mood disorders like depression.
Pesticide use is widespread and direct exposure from applications or indirect exposure from residues threatens human health. Children are more vulnerable to the impact of pesticides as their bodies are still developing. Their bodies also inhale, absorb, and ingest more chemical than adults relative to body weight. 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 pesticide exposure can increase disease risk. A pregnant mother’s exposure to environmental toxicants can increase the likelihood of developmental disabilities, as most developmental disabilities begin before birth. Many studies link childhood pesticide exposure to lower IQ, but prenatal pesticide exposure even more so. Moreover, women living near areas of highly toxic chemical use have an increased risk of birthing a baby with cognitive function, like Attention-Deficit/Hyperactivity Disorder (ADHD). Even many long-banned pesticides still cause adverse effects on 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).
Research on pesticide-induced diseases commonly investigates pesticide exposure concerning the development of various physical illnesses. However, there is a lack of information connecting pesticide exposure to the subsequent psychological (psychiatric) effects on the general population. According to the World Health Organization (WHO), mental health disorders affect 970 million people globally, with the number of people living with these disorders increasing by 26 to 28 percent in the past three years. Although the etiology of psychiatric disorders is often genetic, studies suggest that other etiological factors, like pesticide exposure, play a role in mental health incidents. Poor mental health has a tangible influence on physical health (e.g., depression and cardiovascular disease); therefore, the combination of pesticide exposure and mental illness worsens the adverse effects on human health. If pesticide exposure exacerbates psychiatric disorder symptoms, it is important to evaluate how pesticide exposure affects mental health, in addition to physical health.
For over two decades, research concerning pesticide exposure and psychiatric disorders, such as depression, focused on occupational hazards, especially for agricultural farmworkers. Exposure to agricultural pesticides puts farmers at a six times greater risk of exhibiting depressive symptoms, including chronic anxiety, irritability, restlessness, and sadness. Linear models reveal an association between lifelong pesticide poisoning episodes and the increased risk of developing mental disorders among tobacco farmers. Tobacco farmers using organophosphate pesticides have a higher prevalence of minor psychiatric disorders. However, pesticide exposure from nearby agricultural fields also threatens residential (nonoccupational) human health. Previous studies found that populations living near farms are more likely to have high depressive symptoms. Similarly, a 2019 study found that teens and adolescents living in agricultural areas, where organophosphate exposure is prevalent, are at higher risk of depression. Uniquely, gender (female), physical health, and age (young adult) indicate the likelihood of having depressive symptoms, with the most adverse effects on women, those in poor physical health, and children under 14.
Whether pesticide exposure is occupational or residential, the development of depression symptoms is of concern. Nearly half of Americans with a mental health diagnosis seek treatment for symptoms every year. Untreated symptoms of depression can increase the risk of suicide, a severe sign of depression. Commonalities between occupational and household pesticide exposure are suicidal thoughts and pesticide provocation as a suicide agent. A study published in the WHO Bulletin found that people storing organophosphate pesticides in their homes are more likely to have suicidal thoughts as the exposure rate is higher. The study found an association between suicidal thoughts and ease of household pesticide accessibility. Geographic areas with more frequent home storage of pesticides have higher rates of suicidal thoughts than the general population. WHO scientists recognize pesticide self-poisoning as one of the most significant global methods of suicide. Robert Stewart, Ph.D., a researcher for the WHO Bulletin, stated that: “Organophosphate pesticides are widely used around the world. They are particularly lethal chemicals when taken in overdose and are a cause of many suicides worldwide.” With that in mind, researchers say it is vital to recognize how pesticide exposure and accessibility can influence mental illnesses.
Chemical exposure during pregnancy harms the offspring’s health, especially neurological development. Understanding the mental health implications of conventional pesticide exposure can help identify the various physiological mechanisms attributed to psychiatric disorders. Additionally, a past study demonstrates pregnant women already have over 100 detectable chemicals in blood and umbilical cord samples. Thus, pesticide compounds present in the mother’s blood can transfer to the fetus via the umbilical cord. This discovery ignites concerns over prenatal exposure to chemicals from consumer and industrial products and sources. The number of children with neurodevelopmental disabilities is increasing in the U.S., and many children in rural areas—where pesticide use is most prevalent—have a higher rate of neurological disabilities. Therefore, it is essential to effectively monitor and assess pesticide exposure for the sake of human health.
The findings of OP exposure and behavioral problems are not new. Therefore, healthcare providers must have sufficient information on signs and symptoms of chemical exposure to address health issues regarding pesticide exposure and mental health incidents. Farmers, landscapers, and other individuals encountering chemical exposure through ingestion, inhalation, and skin (dermal) contact are unaware of the nonphysical side effects. Considering depression related to acute pesticide exposure may persist long after initial exposure, those working with toxic pesticides must have adequate protective equipment to minimize exposure. Advocates urge government agencies to assess the provocation of psychiatric disorders accompanying acute and chronic pesticide exposure to protect human health. Given the rise in mental health problems among agricultural workers and the potential health risks to the general population, analyzing existing studies is crucial.
This research highlights the significance of researching potential mental health detriments resulting from pesticide exposure, especially as society tends to rank mental health risks second to physical health. Mental health is just as—if not more–important than physical health, and reviews such as this highlight the importance of knowing pesticide implications beyond physical ailments. Through its Pesticide Induced Diseases Database (PIDD), Beyond Pesticides tracks the most recent studies related to pesticide exposure. For more information on the multiple harms of pesticides, see PIDD pages on brain and nervous system disorders, endocrine disruption, cancer, and other diseases. Additionally, buying, growing, and supporting organic can help eliminate the extensive use of pesticides in the environment. Our choices encourage the protection of the people who help put food on our table daily by purchasing organic products. By buying and using organic products, you not only support an agricultural system that does not heavily rely on the widespread application of dangerous pesticides but also a residential system. For more information on how organic is the right choice for consumers and the farmworkers that grow our food, see the Beyond Pesticides’ webpage, Health Benefits of Organic Agriculture.
Lastly, suicide is the tenth leading cause of death among adults (3rd for adolescents) in the U.S., with more than 34,000 individuals succumbing to the disease annually. Suicidal thoughts and behaviors are dangerous and harmful and are therefore considered a psychiatric emergency. An individual experiencing these thoughts should seek immediate assistance from a health or mental health care provider. If you or someone you know is in an emergency, call the National Suicide Prevention Lifeline at 1-800-273-TALK (8255) or 911 immediately.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
