Food chain aspects of arsenic contamination in Bangladesh: effects on quality and productivity of rice.

The total arsenic content of 150 paddy rice samples collected from Barisal, Comilla, Dinajpur, Kaunia, and Rajshahi districts, and from the BRRI experimental station at Rajshahi city in the boro and aman seasons of 2000 was determined by hydride generation-inductively coupled plasma emission spectroscopy (ICP). Arsenic concentrations varied from 10 to 420 microg/kg at 14% moisture content. Rice yields and grain arsenic concentrations were 1.5 times higher in the boro (winter) than the summer (monsoon) season, consistent with the much greater use of groundwater for irrigation in the boro season. Mean values for the boro and aman season rices were 183 and 117 microg/kg, respectively. The variation in arsenic concentrations in rice was only partially consistent with the pattern of arsenic concentrations in drinking water tube wells. There was no evidence from yield or panicle sterility data of arsenic toxicity to rice. Processing of rice (parboiling and milling) reduced arsenic concentrations in rice by an average of 19% in 21 samples collected from households. Human exposure to arsenic through rice would be equivalent to half of that in water containing 50 microg/kg for 14% of the paddy rice samples at rice and water intake levels of 400 g and 4 L/cap/day, respectively.