What we know about health effects from arsenic is based on long term exposure to very high exposures, such as in populations exposed to contaminated water in Taiwan, India and Bangladesh or from those occupationally exposed at smelters and agricultural sites. Short term health effects after high level exposure generally include symptoms such as nausea, vomiting, abdominal pain and diarrhea, but are extremely unlikely to occur at the levels observed in studies of typical U.S. foods. The long-term problem with arsenic includes its association with a variety of cancers (skin cancer, lung cancer, and bladder cancer) as well as its contribution to skin changes, heart disease, lung disease, neurologic disease, kidney disease, and type 2 diabetes. Generally, these diseases are seen with high levels of arsenic exposure, above what is found in drinking water in the United States.
The health effects of very low-level arsenic in foods, as described in these recent reports, are less clear. Several studies of populations outside of the United States raise concerns about a possible cumulative effect of long-term low-level exposure to arsenic (possibly at levels higher than anticipated from ingesting normal amounts of these food products) on learning and neuromotor function.
Currently, there is no level of inorganic arsenic exposure that has been shown to be completely safe, but most experts believe that ingestion of these small amounts of arsenic pose minimal risk when eaten as part of a balanced diet. There have been no long-term follow-up studies of populations exposed through food at the very low levels experienced in the U.S. that have attempted to answer this question, although we can take some direction from guidance developed for drinking water.
While different policy experts have reached different conclusions about the maximum amount that can be eaten safely, in general, the less arsenic the better.