Toxic exposure and rates of suicidal thoughts and behaviors among U.S. military veterans.

Exposure to toxic substances has been linked to poorer mental health among U.S. military veterans broadly, but less is known about specific psychiatric outcomes, such as suicidal thoughts and behaviors (STBs). In the current observational cohort study, we investigated toxic exposure and STBs using data from 248,926 veterans enrolled in the Million Veteran Program (MVP). Exposures to nine toxins (Agent Orange, chemical/biological weapons, anthrax vaccine, solvents/fuels, petroleum combustion products, lead, other metals, pesticides, and open-air burn pits) were assessed using self-report, and subsequent health records were used to assess STBs. Veterans with more toxic exposures were more likely to have STBs (OR = 1.17, 95% CI [1.16, 1.18], p < .001). In secondary analyses, we found associations were comparable (1.11 ≤ ORs ≤ 1.19) across major service cohorts in the MVP (pre-Vietnam, Vietnam, post-Vietnam, Gulf War, and post-9/11 eras). We also present rates and associations for specific toxic exposures, associations for specific categories of STBs, and show that PTSD and depressive symptoms accounted for the association between toxic exposure and STBs. Our results suggest that veterans who report more toxic exposure are also more likely to have STBs, and this association can be interpreted as a broader association between toxic exposure and poorer mental health. Future research is needed to determine whether toxic exposure might interact with genetic vulnerability to predict STBs for veterans, as well as how toxic exposure might result in increased risk for STBs.