Arsenic naturally occurs in apple seeds. Anything with apple juice in it will have traces arsenic due to the pressing of apples with the seeds still intact. New studies say it is not arsenic, it is cyanide. I still believe the old ones, as I don't think people are dumping rat poison in apple juice. Organic farmers supposedly don't spray the apples with chemicals, so where would the source be there?
ETA: Okay, wiki says it can commonly occur in drinking water. All others seem to be with heating metals, but I'm not sure I understand all this stuff:
Arsenic - Wikipedia, the free encyclopedia
Quote from article:
"In the United States, arsenic is most commonly found in the ground waters of the southwest.[62] Parts of New England, Michigan, Wisconsin, Minnesota and the Dakotas are also known to have significant[clarification needed] concentrations of arsenic in ground water. Increased levels of skin cancer have been associated with arsenic exposure in Wisconsin, even at levels below the 10 part per billion drinking water standard.[63] According to a recent film funded by the US Superfund, millions of private wells have unknown arsenic levels, and in some areas of the US, over 20% of wells may contain levels that exceed established limits.[64]"