or iron with other B-complex vitamins, such as thiamin, niacin, vitamin B6, and pantothenic acid. A systematic review of clinical research on the efficacy of rice fortification showed the strategy had the main effect of reducing the risk of iron deficiency by 35% and increasing blood levels of hemoglobin. The guideline established a major recommendation: "Fortification of rice with iron is recommended as a public health strategy to improve the iron status of populations, in settings where rice is a staple food." Rice grown experimentally under elevated carbon dioxide levels, similar to those predicted for the year 2100 as a result of human activity, had less iron, zinc, and protein, as well as lower levels of thiamin, riboflavin, folic acid, and pantothenic acid. The following table shows the nutrient content of rice and other major staple foods in a raw form on a dry weight basis to account for their different water contents. Arsenic concerns As arsenic occurs in soil, water, and air, the United States Food and Drug Administration (FDA) monitors the levels of arsenic in foods, particularly in rice products used commonly for infant food. While growing, rice plants tend to absorb arsenic more readily than other food crops, requiring expanded testing by the FDA for possible arsenic-related risks associated with rice consumption in the United States. In April 2016, the FDA proposed a limit of 100 parts per billion (ppb) for inorganic arsenic in infant rice cereal and other foods to minimize exposure of infants to arsenic. For water contamination by arsenic, the United States Environmental Protection Agency has set a lower standard of 10 ppb. Arsenic is a Group 1 carcinogen. The amount of arsenic in rice varies widely with the greatest concentration in brown rice and rice grown on land formerly used to grow cotton, such as in Arkansas, Louisiana, Missouri, and Texas. White rice grown in Arkansas, Louisiana, Missouri, and Texas, which account collectively for 76 percent of American-produced rice, had higher levels of arsenic than other regions of the world studied, possibly because of past use of arsenic-based pesticides to control cotton weevils. Jasmine rice from Thailand and Basmati rice from Pakistan and India contain the least arsenic among rice varieties in one study. China has set a limit of 150 ppb for arsenic in rice. Bacillus cereus Cooked rice can contain Bacillus cereus spores, which produce an emetic toxin when left at