Distribution and health risk assessment of some organochlorine pesticides in water, sediments, and fish from Hawul river basin

Abstract

The distribution of organochlorine pesticides Methoxychlor, DDT and its metabolites in water, sediments and fish was carried out to assess the contamination status in some surface waters. The QuChERS method was employed for pesticide extraction and cleanup. Gas chromatography in tandem with a mass spectrometer was used in the identification and quantification of these pesticides. The results showed that total OCPs burden in water, sediments, and fish ranged between 0.1mg/L – 3.6mg/L, 0.07mg/kg - 0.38 mg/Kg and 0.25mg/kg – 3.6 mg/kg respectively. The mean concentrations of methoxychlor range between 0.01 mg/L – 0.1 mg/L, ND – 0.07mg/kg, 0.04mg/kg – 0.1mg/kg for water, sediments, and fish samples respectively. The Hazard index due to OCPs consumption of fish is in the sequence Garkida (WB) > Kiri > Ndabna > Kopri > Garkida > Daba. The incremental lifetime cancer risk (ILCR) due to water ingestion ranges between 6.75 × 10^-4 – 3.1167 × 10^-2 and 4.048 × 10-3 – 1.87 × 10^-1 for adults and children respectively. The trend of ILCR is in a sequence Kopri > Garkida WB> Daba > Kiri > Ndabna > Garkida. The incremental lifetime cancer risk due to fish ingestion ranges between 3.86 ×10^-5 - 5.17 × 10^-4 and 2.31×10^-4 - 3.103 ×10^-3 for an Adult and a child of 10kg weight respectively. This risk value implies that between 39 to 231 people in a million who are exposed to these pollutants may develop cancer in their lifetime.