25
Oct
Study Further Strengthens Link Between Common Insecticide Class and Psychiatric Disorders
(Beyond Pesticides, October 25, 2023) A study published in Environmental Pollution finds farming and organophosphate (OP) pesticide exposure are risk factors for depression, with pesticide poisoning being a risk factor for suicidal behavior. Additionally, psychiatric disorder prognosis affects men more than women, with depression and suicidal outcomes more common among pesticide-exposed males. Age also affected depression and suicidal consequences, with elevated rates among older farmers.
Research on pesticide-induced diseases commonly investigates pesticide exposure concerning the development of various physical illnesses. However, previous studies show that occupational (work-related) risks of developing depression are high in agriculture, where pesticide use is widespread. Acute exposure to chemicals, including organophosphate, organochlorine, triazine, and carbamate pesticides, tends to put farmers at elevated risk. More study is needed on pesticide exposure and similar psychological (psychiatric) effects in the general population.
According to the World Health Organization (WHO), 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.
To investigate the link between chronic occupational exposure to pesticides and depression, anxiety, and suicide-related outcomes in farmers, researchers performed a systematic review to find related studies. The review found 57 total studies meeting the criteria for the investigation: 29 on depression, 12 on suicide, and 14 on pesticide poisoning or self-poisoning and death. Overall, the studies demonstrate a similar pattern; there is an increase in the prevalence of psychiatric disorders among pesticide-exposed farmers and an increase in depression in the general population. Individuals who experience past pesticide exposure have an increased risk of depression or other mood disorders comparable with those chronically exposed to pesticides. The more severe and frequent the pesticide poisoning event, the more likely the exposed individual displays depressive symptoms. Concerning the locality of pesticide exposure, individuals working or residing in areas devoted to chemical-intensive practices like agriculture (e.g., farms) display higher suicide rates, with the highest rates among farmers. Thus, the study “suggests more attention to the farmer’s mental health and more detailed studies on occupational exposure to the mixture of these compounds.â€
For over two decades, research concerning pesticide exposure and psychiatric disorders, such as depression, focused on occupational hazards, especially for farmworkers. Exposure to agricultural pesticides puts farmers at a six times greater risk of exhibiting depressive symptoms, including chronic anxiety, irritability, restlessness, and sadness. Specifically, exposure to organochlorines (OCPs) and fumigants (gaseous pesticides) heightens an individual’s risk of depression by 90% and 80%, respectively. Organochlorines are chemicals of concern as they can induce a myriad of health problems, including reproductive dysfunction, endocrine disruption, cancer, and fetal defects. Although most organochlorine pesticides have been withdrawn from the U.S. market, these chemicals can still expose individuals to volatile concentrations as they are highly persistent in the environment. However, OCPs are far from the only class of pesticide involved in increased risk of developing mental disorders. Linear models reveal tobacco farmers using organophosphate pesticides have a higher prevalence of psychiatric disorders.
Although individuals suffering from occupational pesticide exposure face a disproportionate risk of developing depression, pesticide exposure from nearby agricultural fields threatens residential (nonoccupational) human health. Previous studies find 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 in women, those in poor physical health, and children under 14.Â
Pesticides have long been linked to various mental health issues, with this study highlighting specific impacts OPs have on behavioral and cognitive function, indicating the prominent neurotoxic impacts of chemical exposure. Organophosphates are a family of insecticides derived from World War II nerve agents. They are cholinesterase inhibitors, meaning they bind irreversibly to the active site of an essential enzyme for standard nerve impulse transmission, acetylcholine esterase (AchE), inactivating the enzyme. Like this review, past research finds that organophosphates have significant associations with depressive symptom development, including disturbing normal nerve impulses. So, scientists can analyze information to determine if the lack of normal nerve impulses contributes to non-pesticide-induced depression. Additionally, pesticide poisoning can lead to neurotoxicity via low serotonin levels and cholinergic changes, further exacerbated by oxidative stress and neuronal cell death. A decrease in AChE activity has links to higher depression scores observed in individuals with increased suicide risk.
A study published in the WHO Bulletin finds that people storing organophosphate pesticides in their homes are more likely to have suicidal thoughts as the exposure rate is higher. The study finds 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 that “Organophosphate pesticides are widely used around the world. They are particularly lethal chemicals in overdose and cause many suicides worldwide.â€
Suicide is a public health crisis, and 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. Therefore, understanding the mental health implications associated with chemical-intensive agriculture and pest management can help identify the various physiological mechanisms attributed to psychiatric disorders. Advocates support the call to enact a toxic pesticide ban, with aÂ
Despite the urgings of public health scientists and professionals, organophosphate insecticides continue to be used in the United States. This and other studies indicate that farmers and those in agricultural communities are at disproportional 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. Through our 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. Organic contributes to a system that respects the natural environment and stops exposure to toxic pesticides. Still, it also reduces demand for toxic pesticides in areas where farmer suicides are alarmingly high. Coupled with evidence from past studies that link pesticide exposure to suicidal ideations and depression, even in developed countries, this research strongly supports a ban on toxic pesticides in favor of organic practices. Our choices encourage the protection of the people who help put food on our table daily by purchasing organic products. 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.Â
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.
Source:Â Environmental Pollution
