Arsenic and cadmium in food-chain Fig. Concentrations of arsenic and cadmium in raw and cooked rice (cooked by process A) * Raw Cooked g k /g 150 µ 300 250 200 100 50 0 Khan SI et al. cooking vegetables to avoid loss of micronutrients retained arsenic in cooked vegetables. In the present study, we found high concentrations of arsenic in rice-grains collected from Matlab, sug- gesting that rice is being contaminated with ar- senic. This might be due to the contaminated water from deep and shallow tubewells used for irrigation. The cooking process also affects the concentration of arsenic in rice. In our study, cooking process A removed 67% of arsenic from the cooked rice dur- ing washing with arsenic-free water and by discard- ing excess water. In process B, we found that 85% of the total arsenic was retained in the cooked rice, thereby significantly increasing the risk of arsenic ingestion through contaminated rice-grains and by the cooking process. The cooking process A, used widely in rural Matlab, is a good practice for reduc- ing contamination of arsenic in cooked rice, pro- vided arsenic-free water is used. Earlier studies have As in rice Cd in rice Data are expressed as mean±standard deviation in bars. *Denotes the signiﬁcant difference (p=0.002) of arsenic between raw and cooked rice; As=Arsenic; Cd=Cadmium Table 2. Concentrations of arsenic in raw and cooked vegetables Raw (µg/kg) Cooked (µg/kg) % of increase Item No. Range Mean±SD Range Mean±SD after cooking Amaranth 8 18-26 22.8±3.7 62-309* 145.6±141 539 Arum 9 6-7 7.03±0.07 49-236* 110.3±85 1,470 Spinach 8 14-16 15.1±0.6 36-49 44.2±6.3 193 Amaranth stem 4 0.5-3 1.3±1.1 Banana 4 4-7 5.3±1.6 Bitter gourd 4 1-6 3.1±2.6 Eggplant 4 3-9 7.0±3.0 Potato 4 4-6 5.4±0.4 *Food cooked using arsenic-contaminated tubewell water. The tubewells of those villages showed high arsenic concentration (81-96% yielded water with more than 50 μg As/L); NA=Not analyzed; SD=Standard deviation spinach, amaranth (leafy part), and arum was about 193%, 539%, and 1470% respectively. The mean concentration of arsenic in raw rice was significantly higher than that in raw vegetables (p<0.001). Cadmium in foodstuff Assessment of cadmium in rice and vegetables (Ta- ble 3) showed that the mean cadmium concentra- tion levels were similar in the raw rice (33.1 µg/kg) and raw vegetables (27 µg/kg) (p=0.6). Rice cooked by process A (discarding excess water) did not re- duce the concentration of cadmium in the cooked rice (Fig.). DISCUSSION The results showed that the practice of discarding excess water while cooking rice reduced the con- centration of arsenic but not of cadmium in the cooked rice. Again, not discarding water when Volume 28 | Number 6 | December 2010 also shown that cooking of rice following the tra- ditional method of the subcontinent, i.e. process A, eliminated up to 54-57% of the total arsenic from cooked rice (17,18). The arsenic-contaminated rice may be considered a catastrophic situation in South-East Asia where concentration of arsenic in underground water is high, and rice being the staple food, could be an emerging threat locally and globally since rice is exported from these countries to many western re- Table 3. Concentrations of cadmium in raw andcooked rice and vegetables Food Type Cadmium (µg/kg) Rice Raw 33.1±8.5 Rice Cooked* 34.8±12.2 Amaranth Raw 33.0±1.0 Bitter gourd Raw 21.1±0.5 Eggplant Raw 27.0±1.8 *Cooked by process A 581