Introduction Twenty-first century occupational and environmental (OE) exposures arising from military service encompass combustion byproducts, particulate matter, and traditional job exposures.

Rationale Multiple potentially collinear exposures can require data reduction to facilitate epidemiological analyses. Our data provided an opportunity to characterize relationships among a range of interrelated exposures.

Methods We analyzed interim data from the Veterans Affairs ‘CSP #595: Service and Health Among Deployed Veterans’ study. As of May 2020, survey responses were available from 1962 randomly selected Veterans with one or more deployments to Afghanistan, Iraq, or elsewhere in southwest Asia between 2001 and 2017. The interviewer-administered questionnaire yielded 3-level responses to 32 OE deployment-associated exposures included in this analysis. We identified a priori six anticipated exposure factors: burn pit (4 items); other open combustion sources (5 items); combustion engine byproducts (5 items); mechanically generated dust/dust storms (4 items); occupational vapors, gas, dust, and fumes (VGDF; 11 items); and other toxicants (3 items). We used confirmatory factor analysis (CFA) to assess construct validity of these groupings.

Results In preliminary CFA, two of six groupings that were highly collinear (combustion engine byproducts/mechanically generated dust) required combination for model viability. The resulting 5 factor model performed adequately (incremental or Comparative Fit Index [CFI]= 0.945). After excluding 4 of 32 items with lower factor loadings ( 0.50 for 28 3-level items on five factors.

Conclusion These findings provide a basis for item reduction in an expansive survey battery of exposure items addressing occupational and environmental military exposures. We identified 28 items (three response levels) comprising five distinct factors. These results suggest that among previously deployed Veterans, multiple OE exposures can be simplified to exposure-related factors as part of assessing health effects.