Risk assessment from exposure to arsenic and other elements in rice from Brazil

Introduction: Rice can be the main source of exposure to inorganic arsenic (iAs), which is classified as carcinogenic and is also associated with non-cancer effects. Rice products, such as infant cereals, and drinking water are also important sources of exposure to iAs. Although rice is a staple food in Brazil, there have been few studies about the health risks for the Brazilian population. Objective: The objective of this study was to assess the risks of exposure to iAs and other toxic and essential elements from brown rice, white rice (only iAs), infant cereal (made of rice and different raw materials), and drinking water (only iAs) in Brazil, and to identify possible measures to mitigate those risks. Method: The incremental lifetime cancer risk (ILCR) and the non-cancer risk, or hazard quotient (HQ), and hazard index (HI) were calculated. A probabilistic analysis was performed with Monte Carlo simulation. Results and discussion: The mean ILCR was 1.3 × 10-04 for exposure to iAs in white rice and 5.4 × 10-06 for brown rice, and for exposure to Pb it was 2.5 x 10-8 for brown rice. The HQ was under 1 for all elements in brown rice, as the HI, suggesting that health effects are unlikely. The mean ILCR for exposure to iAs from drinking water was 6.5 × 10-05, above the tolerable value of 1 × 10-5 recommended by the World Health Organization, and the HQ was below 1. Rice cereal was the kind of infant cereal with highest ILCR (4.0 x 10-5) and with more elements with HQ above 1. All the infant cereals had an HQ above 1 for at least one element. Cd was the non-essential element more significative in this scenario, and Zn was the essential element more relevant. Various mitigation measures discussed in this dissertation are estimated to reduce the risk from rice consumption by 68%, and from infant cereal by 24%. The ILCR for white and brown rice was high, even though the iAs concentration in rice is below the maximum contaminant level. The risk for brown rice consumption was lower because the iAs concentrations were low in the brown rice samples evaluated, which possible reasons were explored, such as the location of cultivation, agricultural practices and the kind of rice cultivar. The estimated cancer and non-cancer risk from exposure to Pb is low, however no exposure to this element from diet is considered safe. Conclusions: The ILCR for rice, infant cereal and water consumption was considered high. The non-cancer risk was not tolerable only for infant cereal, including essential and non-essential elements, and rice cereal showed to be more concerning. Water consumption represents a small part of the risk for adults, although it was estimated to be not tolerable. With the support of public policies, measures to reduce these risks from rice and infant cereal would have a positive impact on public health in Brazil.