There is a growing concern about heavy or toxic metals pollution in foodcrops, since dietary intake is considered to be one of the major routes of metal(loid) exposure to humans. Cadmium (Cd), lead (Pb) and Arsenic (As) are among the most common toxic heavy metals. The excessive levels of these metals in foodcrops are associated with etiology of a number of diseases, especially cardiovascular, kidney, nervous as well as bone diseases. Therefore, food safety has emerged as an urgent issue and there is a great need to assess the health risks from ingesting toxic metals-contaminated foodcrops.

Dr. Zhuang Ping from South China Botanical Garden, Chinese Academy of Sciences investigate the effects of cooking on the toxic metals (e.g. Cd, Pb and As) bioaccessibility in rice and vegetables. Results indicated that cooking reduced bioaccessibility of Cd and As in rice. Cooking resulted in a significant increase (p < 0.01) of Cd and As concentrations in the residual fraction. Low volume water-cooking of rice to dryness reduced total Cd by about 10% for rices A and B, while medium or high volume water-cooking had no effect on Cd bioaccessibility in all rice types. In contrast, low volume cooking did not remove As, but a significant decrease (p < 0.05) was observed when cooking with higher volumes of water. For market vegetables, Cadmium and Pb bioaccessibility were 35–66 % and 20–51 % in the raw vegetables, respectively, and found to be significantly higher than the cooked vegetables with 34–64 % for Cd and 11–48 % for Pb. The results indicated that Cd bioaccessibility was higher in the gastric phase and Pb bioaccessibility was higher in the small intestinal phase (except for fruit vegetables). Cooking slightly reduced the total concentrations and bioaccessibility of Cd and Pb in all vegetables.

Reference: Zhuang P, et al., Assessment of influences of cooking on cadmium and arsenic bioaccessibility in rice, using an in vitro physiologically-based extraction test Food Chemistry, 2016, 213(15): 206–214; and Zhuang P, et al., Oral bioaccessibility and human exposure assessment of cadmium and lead in market vegetables in the Pearl River Delta, South China, Environmental Science and Pollution Research (DOI: 10.1007/s11356-016-7801-z, online).

http://www.eedu.org.cn/Article/academia/papers/literature/201610/104171.html

http://www.eedu.org.cn/Article/academia/papers/literature/201610/104172.html