Case-control study of environmental toxins and risk of amyotrophic lateral sclerosis involving the national ALS registry.
Level 4 - case-series / case-control
Matched case-control study
PubMed 38591179 · doi:10.1080/21678421.2024.2336108
What was done
Researchers conducted a matched case-control study using 243 matched pairs of confirmed amyotrophic lateral sclerosis (ALS) cases from the CDC National ALS Registry and controls matched on age, sex, and county (mean age 62.9 years, 61.7% male). Participants completed a risk factor survey and provided blood samples to measure 29 persistent organochlorine pesticides (OCPs). Conditional logistic regression was used to evaluate associations between ALS risk and self-reported exposures and serum OCP concentrations.
What was found
Fifteen of the 29 evaluated OCPs had sufficient detectable levels for analysis. Self-reported years of residential pesticide exposure significantly correlated with serum OCP levels (p < .001). Significantly increased odds of ALS were found for occupational lead exposure (OR = 1.77, 95% CI: 1.11–2.83), avocational gardening (OR = 1.57, 95% CI: 1.04–2.37), and detectable versus non-detectable heptachlor (OR = 3.57, 95% CI: 1.50–8.52). In addition, each 10 ng/g increase in serum concentration increased ALS risk for α-Endosulfan (OR = 1.42, 95% CI: 1.14–1.77) and oxychlordane (OR = 1.24, 95% CI: 1.01–1.53).
Why it matters
This study links both survey-reported exposures and biological measurements of persistent legacy pesticides and lead to increased ALS risk, demonstrating that long-half-life neurotoxins remain relevant despite regulatory bans.
Limits
The retrospective case-control design cannot establish temporality or causality. Questionnaire responses are susceptible to recall bias. Serum biomarkers were collected post-diagnosis, making it possible that ALS-associated weight loss and metabolic changes altered circulating levels of lipophilic pesticides (reverse causation). Fourteen of 29 OCPs lacked sufficient detection levels for evaluation.
Cited by
- context A published study has linked green space workers to an increased risk of developing amyotrophic lateral sclerosis (ALS).