Wastewater-based epidemiology to assess human exposure to pyrethroid pesticides

Pesticides are active substances with potentially adverse effects on human health, and therefore great effort is addressed to study the relation between their widespread use and the effects on humans. To track human exposure to pesticides, novel approaches are needed to give additional information on exposure at population level. In this study, a novel application of Wastewater-Based Epidemiology (WBE) was developed to measure the intake of pyrethroid pesticides in a population. Three human urinary metabolites of pyrethroids were selected and validated as biomarkers of exposure by evaluating their sources and stability in wastewater. They were measured by liquid chromatography-tandem mass spectrometry in raw urban wastewater collected from the wastewater treatment plants of six Italian cities. Their concentrations were used as biomarkers to back-calculate the intake of pyrethroid pesticides in the population. WBE results were in line with the urinary biomarker levels of biomonitoring studies considering dilution in wastewater. Significant differences in the metabolites levels were observed among different cities. Seasonal variations in human intake of pyrethroids were also seen, as expected, with higher intakes during spring/summer. Intakes in the six cities were compared with the acceptable daily intake (ADI) and it was concluded that some of the populations examined might face significant health risks. Results confirm that this method can provide supplementary information to biomonitoring studies and can be a valuable tool for obtaining objective, direct information on the real levels of exposure to pyrethroids of different populations.