Article Orignally published by: https://beyondpesticides.org
(Beyond Pesticides, May 28, 2020) Exposure to agricultural and industrial pesticides, solvents (thinners), electromagnetic fields, and heavy metals predispose humans to amyotrophic lateral sclerosis (ALS), according to an Italian research study, “Environmental and Occupational Risk Factors of Amyotrophic Lateral Sclerosis: A Population-Based Case-Control Study,” published in the International Journal of Environmental Research and Public Health. Although research supports ALS’s genetic etiology, epidemiologic research associating ALS risks and to environmental, or work-related risk factors (i.e., pesticide use, pollutant exposure, heavy metal exposure, etc.) has been inconsistent and non-definitive. This research demonstrates the importance of assessing aggregate health risks associated with occupational pesticide exposure, especially when determining potential exposure routes in specific occupational sectors. In the study, researchers note, “In particular, having an occupation in the agricultural sector, especially with a long duration of the working activity as well as occupational exposure to some chemicals…might increase ALS risk.”
While scientists extensively study the epidemiology of amyotrophic lateral sclerosis (ALS)—a rare, yet fatal neurodegenerative disease—occupational and environmental hazards inducing random (sporadic) or hereditary ALS diagnoses remain vague. With researchers predicting a global ALS incidence increase of 69% by 2040, identifying ALS’s causal factors are important to future research.
In this research, Italian researchers conducted a case-control, population-based study for four Italian provinces (Catania, Sicily; Modena, Italy; Novara, Italy; and Reggio Emilia, Italy) to evaluate occupational and environmental components associated with ALS triggers. The study’s test group encompassed 95 (n=95) people diagnosed with ALS, while the control group included 135 (n=135) people without ALS, all of whom researchers matched by sex, age, and location. Each group member responded to a self-administered questionnaire via regular-mail or in-person at the neurology department of each study’s hospital. Study participants reported their career division, job type, education status, military service status, as well as exposure to various unique environmental factors: heavy metals, pesticides, chemicals, and electromagnetic fields. Researchers estimated ALS risk using an unconditional logistic regression model to calculate the odds ratio (OR)—a measure of association between exposure and an outcome—with a 95% confidence interval, adjusting for sex, age, and education level.
Results find that agricultural workers have higher risks of developing ALS, with the highest risk association for those who experience over ten years of pesticide exposure in agricultural work. Results show a positive association between work-related solvents exposure (i.e., paint thinners; and paint removers) and disease risk. Non-environmental, occupational pesticide exposure, namely fungicides, augments threats of developing ALS. The risk of developing ALS intensifies indiscriminately with exposure to heavy metals such as lead, mercury, and selenium. Electromagnetic fields marginally foster disease risk via both occupational and environmental exposure. Lastly, participants living near bodies of water are at higher risk for developing ALS, possible due to neurotoxic outgassing from cyanobacteria (blue-green algae).
The agricultural industry has a long-standing history of synthetic chemical use, which disproportionally affects farmworkers’ health. Farmworkers’ children are at greater risk as their immune system response is immature and especially vulnerable to stressors from pesticide exposure. Synthetic chemicals present in pesticides, cosmetics, industrial solvents, heavy metals, etc. accumulate in our bodies, causing an amalgamation of health effects, or body burns. Although many chemicals bacteria metabolize in—and eliminate from the body, pesticides (like organochlorine pesticides) can bioaccumulate over a lifetime. Pesticides expose farmers, farmworkers, and their families to heightened risks of various cancers (i.e., prostate, hepatic, liver, etc.), mental health problems (i.e., depression), respiratory illnesses (asthma), endocrine disruption, and many other pesticide-induced diseases. Extensive pesticide use can predispose human pathogenic to antibiotic resistance, bolstering bacterial virulence.
Currently, this study indicates agricultural occupations as frontrunners for major pesticide exposure scenarios significantly associated with ALS development. Agricultural employees have a 2.1 times higher likelihood of developing ALS, principally due to extensive pesticide use, whereas industrial employees have a 1.48 times higher risk of developing ALS, in comparison to military occupations. Long-time (≥ 10 years) field farmworkers have a 2.7 times higher likelihood of developing ALS. Importantly, vast agricultural fungicide use can cause deadly fungi, like Candida Auris, to have antifungal resistant properties, which echo bacterial antibiotic resistance. The study points to pesticide runoff from agricultural fields into nearby water sources as contaminants that increase nutrient inputs for the growth of harmful neurotoxic cyanobacteria. Although residential pesticide use lacks comprehensive research regarding ALS risk, studies suggests residential use of herbicide pesticides, specifically gardening, play an etiological role in developing ALS.
Although occupational and environmental factors, like pesticides, adversely affect human health —disproportionately affecting vulnerable population groups – there are several limitations in defining real-world poisoning, as captured by epidemiologic studies in Beyond Pesticides’ Pesticide-Induced Diseases Database. The adverse health effects of pesticides, exposure, and the aggregate risk of pesticides showcase a need for more extensive research surrounding occupational and non-occupational pesticide exposure, especially in agriculture. Beyond Pesticides encourages farmers to embrace regenerative, organic practices. A complement to buying organic is contacting various organic farming organizations to learn more about what you can do. Those impacted by pesticide drift can refer to Beyond Pesticides’ webpage on What to Do in a Pesticide Emergency and contact the organization for additional information.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.