Validity of retrospective occupational exposure estimates of lead and manganese in a case–control study

Objectives The validity of surrogate measures of retrospective occupational exposure in population-based epidemiological studies has rarely been evaluated. Using toenail samples as bioindicators of exposure, we assessed whether work tasks and expert assessments of occupational metal exposure obtained from personal interviews were associated with lead and manganese concentrations. Methods We selected 609 controls from a case–control study of...