Increase in Rice Grain Arsenic for Regions of Bangladesh Irrigating Paddies with Elevated Arsenic in Groundwaters

Abstract

Concern has been raised by Bangladeshi and international scientists about elevated levels of arsenic in Bengali food, particularly in rice grain. This is the first inclusive food market-basket survey from Bangladesh, which addresses the speciation and concentration of arsenic in rice, vegetables, pulses, and spices. Three hundred thirty aman and boro rice, 94 vegetables, and 50 pulse and spice samples were analyzed for total arsenic, using inductivity coupled plasma mass spectrometry (ICP-MS). The districts with the highest mean arsenic rice grain levels were all from southwestern Bangladesh: Faridpur (boro) 0.51 > Satkhira (boro) 0.38 > Satkhira (aman) 0.36 > Chuadanga (boro) 0.32 > Meherpur (boro) 0.29 µg As g -1 . The vast majority of food ingested arsenic in Bangladesh diets was found to be inorganic; with the predominant species detected in Bangladesh rice being arsenite (As III ) or arsenate (As V ) with dimethyl arsinic acid (DMA V ) being a minor component. Vegetables, pulses, and spices are less important to total arsenic intake than water and rice. Predicted inorganic arsenic intake from rice is modeled with the equivalent intake from drinking water for a typical Bangladesh diet. Daily consumption of rice with a total arsenic level of 0.08 µg As g -1 would be equivalent to a drinking water arsenic level of 10 µg L -1 .

Geographical Variation in Total and Inorganic Arsenic Content of Polished (White) Rice

“…As in those papers, powdered rice NIST CRM 1568a was used with each batch to monitor analytical performance, and the results from this certified material were within the ranges reported by Williams et al (3,19).…”

“…Rice for major population centers is supplied, in the main, from the nonarsenic-impacted northwestern region as reported in Williams et al (3). Thus, this survey reflects urban population exposure, not that of subsistence farmers who are dependent on very locally produced rice, and therefore have the potential to be exposed to high arsenic concentrations when local irrigation sources are arsenic contaminated (18,19).…”

“…The study of Mondal and Polta et al (35), for an arsenic drinking water affected area of West Bengal, India, found that drinking water contributed 48% of arsenic intake while for rice this figure was 44%, with the remaining 8% coming from the cooking water. Other studies that have looked at inorganic arsenic in specific food items such as common vegetables, spices, and pulses have shown that rice is by far the dominant food source of dietary inorganic arsenic (19). In a U.S. market basket survey, Schoof et al (4) found "that rice has higher inorganic arsenic concentrations than most other foods, and consequently, diets that rely heavily on rice may contain the most inorganic arsenic".…”

Survey of arsenic and its speciation in rice products such as breakfast cereals, rice crackers and Japanese rice condiments

“…For all of the rice products for speciation, the predominant As species are inorganic (75.2-90.1%), with the remainder being DMA. Inorganic As and DMA are known to be the main As components of both white and brown rice (Laparra et al, 2005;Meharg et al, 2008a,b,c;Smith et al, 2006;Williams et al, 2005Williams et al, , 2006Williams et al, , 2007a, while Meharg et al (2008c) has shown that inorganic arsenic is elevated in the bran layer of rice, resulting in brown rice having a higher inorganic content than corresponding white rice.…”

“…This is in part due to rice being particularly efficient at taking up As from soil (Williams et al, 2007b) and exacerbated in major rice growing regions of the world with elevated As in paddy soil caused by to anthropogenic contamination (Meharg 2004;Williams et al, 2005Williams et al, , 2006Williams et al, , 2007a.…”