Arsenic is a common metal found naturally in our environment. Arsenic occurs naturally in both organic (typically non-toxic) and inorganic forms. Inorganic arsenic is toxic and carcinogenic (cancer-causing).
Sources of Exposure
Arsenic is widely present in nature. In the United States, there are higher concentrations of arsenic in the southwestern states, eastern Michigan, and parts of New England.
In addition to being naturally present in the environment, arsenic has also been used for many years for industrial purposes including pest control, animal antimicrobial treatment, wood preservation, petroleum refining, and in the mining/smelting industries. Most industrial uses of arsenic employ the more toxic inorganic forms. Release of arsenic through these processes can lead to increased inorganic arsenic in the atmosphere, in water, and in soil.
Foods, particularly seafoods, can naturally contain large quantities of nontoxic, organic forms of arsenic. These nontoxic forms accumulate in foods through exposure to arsenic-containing soil and water. However, foods can also become contaminated with inorganic (toxic) arsenic from past use, inadvertent use, or misuse of pesticides or other industrial products. For example, chickens may have small amounts of inorganic arsenic-containing pesticides added to their feed to prevent infections, which can be transferred to humans through the environment or through the food supply. Drinking water can also contain small amounts of inorganic arsenic.
Arsenic can affect every organ. Inorganic arsenic, in particular, has been associated with serious health effects including bladder, lung, and skin cancers.
Prevention of Arsenic Exposure
Public health policies have primarily focused on control of arsenic in water. The EPA, through the Safe Drinking Water Act, is required to regulate the concentration of arsenic in water. Beginning in 1947, the maximum contaminant level of arsenic in water was 50 parts per billion (ppb). Following recommendations by the Institute of Medicine, the acceptable level was lowered to 10 ppb. Lower standards have been proposed to reduce cancer risk, but municipal water systems are not currently capable of reducing levels further at reasonable cost with existing technology. The EPA also banned most home pesticide uses in 1991, and is phasing out some other industrial; i.e., agricultural, uses of arsenic. The US Food and Drug Administration (FDA) has also been monitoring arsenic levels in food and beverages. While there is no current federal limit of arsenic for most foods and beverages, the FDA is considering whether new guidelines are needed.