High arsenic in rice is associated with elevated genotoxic effects in humans

Abstract

Arsenic in drinking water may cause major deleterious health impacts including death. Although arsenic in rice has recently been demonstrated to be a potential exposure route for humans, there has been to date no direct evidence for the impact of such exposure on human health. Here we show for the first time, through a cohort study in West Bengal, India, involving over 400 human subjects not otherwise significantly exposed to arsenic through drinking water, elevated genotoxic effects, as measured by micronuclei (MN) in urothelial cells, associated with the staple consumption of cooked rice with >200 μg/kg arsenic. Further work is required to determine the applicability to populations with different dietary and genetic characteristics, but with over 3 billion people in the world consuming rice as a staple food and several percent of this rice containing such elevated arsenic concentrations, this study raises considerable concerns over the threat to human health.

Soil Pollution Due to Irrigation with Arsenic-Contaminated Groundwater: Current State of Science

“…6 mg/kg [13]) to greater than 10 mg/kg, a value that has been shown to lead to crop As concentrations that have harmful impacts on human health ( Fig. 1) [44]. This calculation roughly agrees with field studies from Bangladesh and India, where irrigation with Ascontaminated groundwater over periods of 7 to 18 years raised topsoil As concentrations from baseline concentrations of 6.6 to >10 mg/kg [28•].…”

“…1) [45]. The consumption of crops grown on As-polluted soils may pose a health threat from As exposure [45], particularly in areas where the contaminated crops are dietary staples [44]. The specific extent of the risk is partially dictated by factors that control the concentration of As in the food product, such as the soil As concentration, edaphic conditions, and As plant uptake efficacy, each of which will vary for different cropping systems.…”

“…Where contaminated groundwater is extensively used for irrigation of rice-field soils, As can be transferred from soil into rice at levels sufficient to decrease yields and create dangerous grain concentrations [1, 11, 12, 28•, 48, 49, 50•, 51]. Routine consumption of rice with grain As concentrations above 200 μg/kg has been linked to genotoxic effects in humans [44], and polluted soils may yield rice with grain As concentrations that are nearly an order of magnitude higher than this threshold level ( Table 1).…”

“…Crop As is shown for only the edible portion of each crop: rice grain, bulb (onion), fruit (cauliflower), and tuber (potato). The red and black dashed lines represent the estimated concentration of As observed in rice and maize (200 and 286 μg/kg), respectively, for which genotoxic effects could occur following routine dietary consumption (BArsenic Pollution of Soils Due to Groundwater Irrigation^) [44] arsenic [59]. People in households who consume rice with higher As concentrations (e.g., the upper range in Fig.…”

Elemental composition of Malawian rice

“…The mean and median concentrations of inorganic As (i-As) were 0.060 and 0.066 mg kg -1 which is low compared to white rice samples from most other countries, despite being measured on the 17 samples with highest As concentration in this study, i.e. (mean ± SD, mg kg Rice may be a significant source of As exposure in some contexts with consequences for cancer risk (Mondal and Polya 2008;Banerjee et al 2013). The oral reference dose is set at 3*10 -4 mg kg -1 of body weight for i-As (US EPA 1998).…”