Reliability and factorial validity of a questionnaire to assess organophosphate pesticide exposure to agricultural workers in Maule, Chile

The aim was to evaluate the reliability and validity of a questionnaire to assess organophosphate pesticide (OP) exposure in agricultural workers. We then enrolled a random sample of 114 agricultural workers from the region of Maule, Chile (mean age = 50 years [SD = 12]). An internal consistency analysis (Cronbach’s alpha> 0.70) and a Varimax rotational factorial analysis were applied. The instrument had a high reliability to predict likely occupational pesticide exposures: Cronbach’s alpha = 0.95, the Kaiser–Meyer–Olkin (KMO) measure was 0.90 and the Bartell sphericity test = p < 0.001. Four factors explaining 68% of the variance were extracted. The factors identified were as follows: (1) labor conditions during application of OPs; (2) use of personal protective equipment; (3) workplace conditions related to OP exposure and (4) home conditions related to OP exposure. The questionnaire has adequate metric properties to characterize likely OP exposure of agricultural workers and to explore associated working and home conditions.