environmental conditions and activities were not significant predictors of urinary concentrations of PYR, some fac-tors might be used to predict trends of PYR exposure. Frequency of PYR use in farms and households was likely related to increased concentrations of PYR metabolite. Furthermore, proximity to a rice farm was possibly associated to increased PYR exposure. Participants who played on rice farms and placed nonedible objects in their mouth tended to be more exposed to PYR as a result of their activities.