Iodine in biology
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for iodine in 2000. For people age 14 and up, the iodine RDA is 150 μg/day; the RDA for pregnant women is 220 μg/day and the RDA during lactation is 290 μg/day. For children 1–8 years, the RDA is 90 μg/day; for children 8–13 years, 130 μg/day. As a safety consideration, the IOM sets tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. The UL for iodine for adults is 1,100 μg/day. This UL was assessed by analyzing the effect of supplementation on thyroid-stimulating hormone. Collectively, the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
Methyl iodide
It is considered a potential occupational carcinogen by the U.S. National Institute for Occupational Safety and Health (NIOSH), the U.S. Occupational Safety and Health Administration and the U.S. Centers for Disease Control and Prevention. The International Agency for Research on Cancer concluded based on studies performed after methyl iodide was Proposition 65 listed that: “Methyl iodide is not classifiable as to its carcinogenicity to humans (Group 3).” the Environmental Protection Agency classifies it as "not likely to be carcinogenic to humans in the absence of altered thyroid hormone homeostatis," i.e. it is a human carcinogen but only at doses large enough to disrupt thyroid function (via excess iodide). However this finding is disputed by the Pesticide Action Network which states that the EPA’s cancer rating "appears to be based solely on a single rat inhalation study in which 66% of the control group and 54-62% of the rats in the other groups died before the end of
the study". They go on to state: "The EPA appears to be dismissing early peer-reviewed studies in favor of two nonpeer-reviewed studies conducted by the registrant that are flawed in design and execution." Despite requests by the U.S. EPA to the Pesticide Action Network to bring forth scientific evidence of their claims, they have not done so.