Abstract
Soil contamination by pesticide residues is a primary concern because of the high soil persistence of pesticides and their toxicity to humans. We investigated pesticide concentration and distribution at 3 soil depths in 147 soil samples from agricultural land and assessed potential health risks due to non-dietary human exposure to pesticides in Nepal. About sixty percent of the soil samples had pesticides (25% of the soil samples had single residue, 35% of the soil samples had mixtures of 2 or more residues) in 39 different pesticide combinations. Pesticide residues were found more frequently in topsoil. Overall, the concentration of pesticides ranged from 1.0 μg kg−1 to 251 μg kg−1, with a mean of 16 μg kg−1. The concentration of the primary group, organophosphates (OPs), ranged from 1.23 μg kg−1 to 239 μg kg−1, with a mean of 23 μg kg−1. Chlorpyrifos and 3,5,6-trichloro-2-pyridinol (TCP) were the predominant contaminants in soils. The ionic ratio of DDT and its degradation products suggested a continuing use of DDT in the area. Human health risk assessment of the observed pesticides in soil suggested negligible cancer risks and negligible non-cancer risks based on ingestion as the primary route of exposure. The predicted environmental concentrations (PECs) of pesticides were higher than the values found in the guidance for soil contamination used internationally. Low concentrations of residues in the soils from agricultural farms practicing integrated pest management (IPM) suggest that this farming system could reduce soil pollution in Nepal.
Highlights
IntroductionChemical pesticides have been used in agriculture for decades inG. Bhandari et al / Chemosphere 253 (2020) 126594 the effort to reduce crop loss and to meet the world’s growing food demands
Chemical pesticides have been used in agriculture for decades inG
Thirty-nine pesticide combinations were detected in soils
Summary
Chemical pesticides have been used in agriculture for decades inG. Bhandari et al / Chemosphere 253 (2020) 126594 the effort to reduce crop loss and to meet the world’s growing food demands. Chemical pesticides have been used in agriculture for decades in. In 2012, on average, around 3.8 million tons of chemical pesticides were applied to agricultural land (FAO, 2020). This amounts to a value of >40 billion US dollars (Pimentel, 2009). The rate of pesticide use varies across the globe, even within the same region. The average rate of pesticide use is observed highest in Asia, where 6.5e60 kg haÀ1 insecticides are used (Carvalho, 2017). In the regions of Nepal, pesticide use is relatively low at
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