Transfer of arsenic, manganese and iron from water to soil and rice plants: An evaluation of changes in dietary intake caused by washing and cooking rice with groundwater from the Bengal Delta, India

Abstract

Contamination of groundwater with arsenic from natural sources is endemic in the West Bengal region of India. Despite increased awareness regarding the consumption of safe water for drinking, the use of groundwater for agricultural purposes, cooking and other domestic tasks still prevails. This study investigates the accumulation of As, Mn and Fe in paddy soils irrigated with groundwater and evaluates the levels of these elements in the different parts of the rice plants. The results show that although there is a significant accumulation of As, Mn and Fe in the soils irrigated with groundwater, the uptake by the grains is not proportional to the concentrations in the soils. Arsenic is accumulated mainly in the roots, followed by straw and grains, and significant amounts of arsenic are removed by de-husking of the rice (86–88 % of As in the wholegrain). The evaluation of the effect of washing and cooking the rice with groundwater shows that there is a marked increase in the arsenic levels of cooked rice (up to 232 %). However, the accumulation is highly dependent on the type of rice, with processed commercial samples (parboiled) having a lower capacity to retain arsenic than the rice varieties utilised by the local villagers.