Occurrence, Distribution, and Accumulation of Pesticides in Exterior Residential Areas.

Pesticides are commonly applied around residential homes, but their occurrence on exterior surfaces (e.g., pavement) has not been thoroughly evaluated. We collected 360 dust samples from curbside gutters, sidewalks, and street surfaces at 40 houses in southern California to evaluate pesticide occurrence on urban paved surfaces as well as their spatial and temporal distributions. Pesticides and select degradates were ubiquitously detected in dust, with the median concentration of total target analytes at 85 μg kg-1. A total of 75% of samples contained at least five pesticides. As a result of recurring pesticide applications, concentrations increased throughout the summer. The pyrethroids bifenthrin and permethrin accounted for 55% of total pesticides detected in the dust. The highest concentrations in dust were found on the sidewalk and in the gutter. Relative to indoor environments, human exposure risk to pesticides on paved surfaces was estimated to be lower, with the highest potential oral and dermal exposure predicted to be 38 ng day-1 for permethrin. The ubiquitous detection of pesticides on residential outdoor surfaces and the fact that the exterior concentrations did not correlate to the indoor areas highlight the necessity to measure pesticides in both indoor and outdoor areas for complete residential pesticide risk assessment.