title: Human health risk from arsenical pesticide contaminated soils: a long-term greenhouse study.
abstract: Arsenic (As) bioaccessibility is an important factor in estimating human health risk. Bioaccessibility of As in soils is primarily dependent on As adsorption, which varies with residence time. This study evaluated the effect of soil aging on potential lifetime cancer risk associated with chronic exposure to As contaminated soils. Four soils, chosen based on their differences in As reactivity, were amended with two arsenical pesticides--sodium arsenate, and dimethylarsinic acid (DMA) at two rates (675 and 1500 mg kg(-1)). Rice was used as the test crop. Soil was sampled immediately after spiking, after 6 months, 1 year, and 3 years. Bioaccessible and total soil As concentrations were used to calculate lifetime excess cancer risk (ECR), which decreased significantly with soil-pesticide equilibration time. Immokalee soil, with the least As adsorption capacity, showed the highest decrease in ECR after 6 months resulting in values lower than the USEPA's cancer risk range of 1 × 10(-4) to 1 × 10(-6). For all other soils, the ECR was much higher than the target range even after 3 years. In the absence of significant changes in As bioaccessibility with time, the total soil As concentration more directly influenced the changes in ECR values with soil aging.
authors.affiliation: Environmental Geochemistry Laboratory, University of Texas at San Antonio, San Antonio, TX, USA. Electronic address: shahida.quazi@gmail.com.
authors.forename: Shahida
authors.initials: S
authors.lastname: Quazi
authors.forename: Dibyendu
authors.initials: D
authors.lastname: Sarkar
authors.forename: Rupali
authors.initials: R
authors.lastname: Datta
mesh_terms: D000327:Adsorption; D000818:Animals; D001149:Arsenates / Q000737:chemistry; D001151:Arsenic / Q000032:analysis* / Q000633:toxicity; D001152:Arsenicals / Q000737:chemistry*; D001646:Bile / Q000378:metabolism; D001682:Biological Availability; D002101:Cacodylic Acid / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009369:Neoplasms / Q000139:chemically induced / Q000517:prevention & control; D012275:Oryza / Q000187:drug effects; D010434:Pepsin A / Q000737:chemistry; D010575:Pesticides / Q000737:chemistry* / Q000633:toxicity; D018570:Risk Assessment; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry*; D013552:Swine; D013997:Time Factors
chemical_list: D001149:Arsenates; D001152:Arsenicals; D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; C009277:sodium arsenate; D002101:Cacodylic Acid; D010434:Pepsin A; D001151:Arsenic; C025657:arsenic acid
keywords: Arsenic; Dimethylarsinic acid; Lifetime cancer risk; Sodium arsenate; Soil aging