16
Jul
Adding to Similar Findings, Organophosphate Insecticide Linked to Depression and Suicide, Farm to Home
(Beyond Pesticides, July 16, 2024) Yet another study in the August 2024 journal Ecotoxicology and Environmental Safety has found that exposure to organophosphorus pesticides (OPPs) is correlated with increased suicidal thoughts in some people. This study is just the latest in a long line of studies from around the world that have linked pesticide exposure to mental health conditions, including sleep disorders, depression, and suicidal ideation (SI). As the rate of suicide increased by 30% between 2000 and 2020, there is an urgent public health need to investigate and address all potential contributing factors. A 2019 study, covered in Daily News, found that teens and adolescents living in agricultural areas and exposed to organophosphate (OP) insecticides are at higher risk of depression, In July and January this year, other studies link farmer psychiatric episodes to pesticide exposure, adding to the body of science. Exposure to household pesticides is also linked to depression in a 2020 study. Â
Study and MethodologyÂ
The study entitled “Association between exposure to organophosphorus pesticide and suicidal ideation among U.S. adults: A population-based study,†analyzes information on the mental and physical health of over 5,000 individuals aged 20 and up in the United States. The study aims to provide key epidemiological insights about the relationship between single and mixed exposure to OPs and SI. The authors note that mixed exposure to OPs is “more commonplace than single exposures, yet there is limited understanding regarding mixed exposures…†This study models OP single and mixed exposures using, as the authors continue, “advanced statistical methodology emerging in environmental epidemiology to address the complex associations… of multi-pollutant mixtures with specific health outcomes.â€Â
The study examined covariates such as gender, age, body mass index, smoking status, hypertension, and diabetes. The data was collected through the National Health and Nutrition Examination Survey (NHANES), an in-depth survey started in 1971 by the Centers for Disease Control and Prevention (CDC) and conducted annually since 1999. Responses to the survey’s Patient Health Questionnaire correlate with data on the concentrations of six OP metabolites in urine samples used to model suicidal ideation and OP exposure. Â
Results
The study finds that one OP metabolite alone (dimethylthiophosphate—DMTP) is associated with suicidal ideation, but also that mixtures of other organophosphate metabolites were associated with suicidal ideation. This study finds that men ages 20-40 and those over 60 are likely to experience a correlation between suicidal ideation and OP exposure. These results confirm previous studies cited by the authors which found people working with these chemicals or living in agricultural areas are more prone to mental health issues such as depression and anxiety, which are closely linked to suicidal thoughts.
The study finds that long-term exposure to OPs may lead to a decrease in certain protective substances in the brain, making older men who have had more long-term exposure than others more susceptible to the harmful effects of OPs. These factors combine to make older men particularly vulnerable to developing anxiety, depression, and cognitive problems when exposed to OP, also known as risk factors for suicidal thoughts.
Organophosphates and the Brain
Organophosphates are a family of insecticides derived from World War II nerve agents. They are cholinesterase inhibitors, meaning that they bind irreversibly to the active site of an essential enzyme for normal nerve impulse transmission, acetylcholinesterase (AChE), inactivating the enzyme. A decrease in AChE activity has links to higher depression scores observed in individuals with increased suicide risk. (See Beyond Pesticides reporting here).
Consistent with a 2022 study, the current study reports that OPs can harm the brain in several ways. They interfere with important chemical messengers in the brain, like acetylcholine, serotonin, and dopamine, which help regulate mood or may trigger a buildup of cortisol, which is associated with depression and suicide. OPs also can cause inflammation in the brain, which may lead to mood disorders and cognitive problems. They can damage mitochondria, the energy-producing parts of cells, leading to further brain dysfunction. Exposure to OPs might alter the brain’s reward and motivation systems, potentially contributing to depression. (See here for reporting in multiple Daily News pieces on studies linking pesticide exposure to depression and suicide).
The World Health Organization (WHO) reports that depression affects 322 million people globally, with the number of diagnosed patients increasing by 18.4% from 2005 to 2015. Although the etiology of depression—and many other psychiatric disorders—is often genetic, studies suggest that other etiological factors, like pesticide exposure, play a role in depression 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.
The results of this most recent study confirm prior research published in the WHO Bulletin, which found 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, as increases in pesticide toxicity make them potentially lethal substances. Robert Stewart, PhD, a researcher for the WHO Bulletin, stated, “Organophosphate pesticides are widely used around the world. They are particularly lethal chemicals in overdose and cause many suicides worldwide.â€
Broader Implications
While Beyond Pesticides has been reporting on the mental health adverse effects of pesticides since its founding, this area of research is still limited. This research highlights yet again a significant public health concern, particularly for farmers, farm workers, and people living near agricultural land. Farmworkers, their families, and those living near farms or chemical plants are at elevated risk of exposure, causing disproportionate impacts. (See Beyond Pesticides Agricultural Justice and disproportionate risks web pages). Additionally, OPs are used in many settings, including urban areas, and their residues can be found in food and water, affecting the general population and contributing to cumulative exposures to organophosphate and other pesticides.
Despite pressure from public health scientists and professionals, organophosphate insecticides continue to be used in the United States. This study and others indicate that farmers and those in agricultural communities are at disproportionate risk of mental health problems due to pesticide use, in addition to the myriad of neurodevelopmental, reproductive, respiratory, and other health problems individuals risk from exposure to organophosphates. Beyond Pesticides’ Pesticide Induced Diseases Database (PIDD), tracks the most recent studies related to pesticide exposure. For more information on the multiple harms of pesticides, see PIDD pages on depression, suicide, brain and nervous system disorders, endocrine disruption, and cancer.
To help support the move away from these toxic petrochemical pesticides, see Beyond Pesticides’ webpage, Health Benefits of Organic Agriculture, and Tools for Change. For more about disproportionate harm to farmworkers from pesticide use in conventional agriculture and why organic certification should recognize agricultural justice issues, see Beyond Pesticides’ Keeping Organic Strong and Agricultural Justice web pages.
Purchasing organic products encourages the protection of the farmworkers and those who eat the bounty of their labor. See Eating With A Conscience to understand the risks of pesticide exposure through commonly eaten fruits and vegetables, while considering the health benefits of eating organic (even on a budget).
Suicide Prevention Resources
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, please call 988 or the National Suicide Prevention Lifeline at 1-800-273-TALK (8255) immediately. If you are in a medical emergency or suicidal crisis and cannot connect, please call 911.
[988 Lifeline is a national network of local crisis centers that provides free and confidential emotional support to people in suicidal crisis or emotional distress 24 hours a day, 7 days a week in the United States. When calling 988, press 2 to connect to a trained Spanish-speaking crisis counselor. For people who speak languages other than English or Spanish, call 988 and translation will be provided in more than 240 additional languages through Language Line Solutions (available 24/7 through voice calling only.]
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources:
Association between exposure to organophosphorus pesticide and suicidal ideation among U.S. adults: A population-based study, Ecotoxicology and Environmental Safety, August 2024
Depressive symptoms and suicide attempts among farmers exposed to pesticides, Environmental Toxicology and Pharmacology, June 2024
