Besides drinking water, rice is another route to arsenic exposure in countries such as Bangladesh, China, India and Vietnam, where rice is a staple.

Research in Bangladesh shows heavy arsenic contamination in the groundwater

Rice readily takes up arsenic from soil and groundwater. This is especially a problem in Bangladesh, where it is estimated that groundwater pumped from shallow aquifers for irrigation adds one million kilogrammes of arsenic per year to arable soil.

The Codex Alimentarius Commission, the UN body responsible for setting food safety standards and jointly run by the World Health Organization (WHO) and the UN Food and Agriculture Organization (FAO), has set a maximum limit of 0.2 milligrammes of arsenic per kilogramme of polished rice.

Husked whole grain parboiling lets inorganic arsenic escape, the researchers explained. On the other hand, when parboiling unhusked rice, the high levels of arsenic in the husk can get transferred to the grain during the parboiling process.

The scientists, led by Andrew Meharg from Queen’s University, Belfast, Northern Ireland, tested the efficiency of the modified parboiling process at 13 locations across Bangladesh and found that it removed 25 per cent of arsenic in whole grain rice across all sites.

Parboiling whole grain fortifies polished rice grain with calcium by 213 per cent.