Occurrence, Origin, Ecological and Human Health Risks of Organochlorine Pesticides in Soils from Selected Urban, Suburban and Rural Storm Water Reservoirs

Abstract

ABSTRACT This study evaluated the occurrence characteristics to trace the origin and associated risks of organochlorine pesticides (OCPs) in soils from urban, suburban, and rural stormwater reservoirs. Samples were collected from the topsoil (0–15 cm) and subsoil (15-30 cm), and quantified for Ʃ20OCPs using a gas chromatography-mass spectrometry (GC-MS) after extraction with n-hexane and dichloromethane. The concentrations of ∑20OCPs ranged from 29.3 to 77.9 ng g−1. The average concentration of Σ20OCPs in the catchments and the isomer compositional pattern is in the order of urban > sub-urban > rural and ∑HCHs > ∑Chlordane > ∑Drins > ∑Endosulfan > ∑DDTs respectively. The HI levels for infants’ exposure were seven-fold that of adults' exposure and were > 1. The human exposure risk is in the order of RiskIng > RiskDerm > RiskInh. The RiskIng and RiskDerm in infants’ exposure were higher than in adults’ exposure, while the RiskInh in adult exposure was higher than that of infants' exposure. The total cancer risk was higher than the acceptable total cancer risk value. The ecological risk indicated a significant biological effect in 56% of the samples. The source apportionment showed that Ʃ20OCPs were of historical and fresh inputs from the non-point and direct origin. Standard clean-up and source-directed mitigation actions should be carried out to assuage the associated risks.