Determinants of exposure to captan in fruit growing

A series of studies investigated occupational exposure to pesticides among fruit growers in The Netherlands during spraying and reentry of orchards between 1990 and 1992 to identify and quantify determinants of exposure. Determinants of exposure are discussed as a starting point for hazard identification and control. Captan was used as a marker for exposure. Cabin use of the tractor was the most prominent determinant of dermal exposure during spraying. For respiratory exposure, factors related to preparation of pesticides were most prominent. A long duration of exposure may reflect a different exposure situation compared with a short duration of exposure. As different determinants of exposure prevailed for each subgroup, consideration should be given to constructing exposure models for each group separately. Dislodgeable foliar residue (DFR) was the most prominent determinant of exposure for both respiratory and dermal exposure during reentry. However, no significant relation between DFR and dermal exposure of forehead and sternal area was found, perhaps because there was no direct contact with foliage here. Therefore, use of a transfer factor based on DFR to estimate total dermal exposure is only a crude estimate. The half-life of captan on crops varied from 10-17 days, so substantial exposure when entering the orchard is very likely, particularly when spraying frequency is high. The main starting points for reduction of exposure are use of a cabin, DFR, and individual time spent on different tasks. Determinants that are constant over time (cabin use) may have an especially great influence on grouping workers, according to long-term exposure in epidemiological studies. As determinants of exposure vary for the different exposure routes and body locations (for dermal exposure), the measure of interest for a specific study design will decide which determinants are most relevant.