Gas chromatographic–tandem mass spectrometric analytical method for the study of inhalation, potential dermal and actual exposure of agricultural workers to the pesticide malathion

New analytical gas chromatographic–tandem mass spectrometric approaches have been developed for assessing both potential and actual exposure of agricultural workers to malathion. The metabolites α- and β-malathion monocarboxylic acids have been determined after a derivatisation process in order to obtain their hexafluoroisopropyl esters. Whole body dosimetry was used for potential dermal exposure assessment. Potential exposure by inhalation was estimated using personal air samplers and polyurethane foam plugs as sorbents. The intern dose measurements were carried out by analysing samples of urine after solid-phase extraction with C18. The recoveries of the analytes of the three matrices were between 90 and 102%. Quantification limits were lower than 0.24 ng L−1. The proposed methods have been applied to evaluate potential and actual exposure of applicators spraying malathion in greenhouses.