Occupational exposure to organophosphate esters and depression in United States Air Force aircraft maintainers

Jennifer E Hardos, The University of Texas School of Public Health


Research has demonstrated that aircraft maintenance workers may be exposed to organophosphates in hydraulic fluid and engine oil. Studies have also illustrated a link between long-term low level organophosphate pesticide exposure and depression. This study assessed inhalation exposure to tributyl phosphate (TBP), triphenyl phosphate (TPP), and tricresyl phosphate (TCP) via personal air sampling and estimated dermal exposure to tricresyl phosphate for U.S. Air Force aircraft propulsion and hydraulic workers via observation methods in order to characterize exposure. A questionnaire was e-mailed to 52,080 aircraft maintenance workers (with n=4,801 complete responses) to determine depression prevalence, severity and exposure group based on job description. No individual air samples were above the laboratory detection limit (0.5 µg/filter), so 8-hour time-weighted averages (TWA) were not calculated. Skin exposure was estimated using visual means for workers handling TCP during the air sampling period. There was no significant difference between reported depression prevalence or severity in exposed similar exposure groups (SEGs) (determined based on use of the chemicals) and those in unexposed SEGs. However, binomial depression prevalence was significantly associated with self-reported exposure level and with each exposure route. Categorical depression severity was also associated with self-reported categorical exposure level; however, causality cannot be established using self-reported exposure and outcome data from the questionnaire because temporality cannot be established from a one-time measurement. Future study recommendations include larger sample size for air sampling, characterizing crew chief exposures, more accurately estimating total exposure through blood or urine bioassay, and investigating the relationships between self-reported exposure vs. measurements and formal estimates.^

Subject Area

Mental health|Occupational safety|Environmental health

Recommended Citation

Hardos, Jennifer E, "Occupational exposure to organophosphate esters and depression in United States Air Force aircraft maintainers" (2015). Texas Medical Center Dissertations (via ProQuest). AAI3720082.