Arsenic in rice

RICE is known to be an efficient accumulator of arsenic. Nine of the 19 districts of West Bengal are known to have arsenic contamination in groundwater, and this water is used to irrigate crops, in particular rice in the rural areas of these districts. Scientific studies done a couple of years ago had warned of the high possibility of arsenic levels in rice increasing beyond safe limits for human consumption via the water-soil-plant-human pathway if the prevalent practice of irrigation continued.

In a study published in the latest issue of Journal of Hazardous Materials, Piyal Bhattacharya and others from the University of Kalyani have shown that accumulation of arsenic exceeded the World Health Organisation (WHO)- permitted limit. While arsenic in the soil did not seem to affect the chlorophyll content, carbohydrate accumulation was found to be positively correlated to the arsenic dose introduced in the soil used for the study. The researchers studied three high-yielding, one hybrid and four local rice varieties and found that arsenic accumulation in the hybrid and all the high-yielding varieties was higher than that in all but one local rice variety. The arsenic dose in these grains was at 20 mg/kg, much above the WHO limit of 1.0 mg/kg. They also found that irrespective of the rice variety, arsenic accumulation in the plant was found to increase with increasing arsenic doses.