Arsenic is a natural element that is found widely in earth's crust. It occurs in drinking water as it is soluble. Rain and snow cleanse the air by washing airborne arsenic particles onto the earth and thence into rivers, lakes and streams, for example.
Not much is known about this element. It is being studied actively. It is considered to be a carcinogen (cancer causing).
The Journal of the American Medical Association published an article, 20 August 2008, indicating there may be a link between low exposure to arsenic in urine which can lead to Type-2 Diabetes. It is only a theory just now - it requires considerable more study, apparently.
A study of ~700 adults aged older than 20, those with Type-2 Diabetes had a 26% higher level of total arsenic in their urine than participants not having Type-2 Diabetes. The study was seen to be too small to form any conclusions.
There are many drinking water systems in the USA having too high concentrations of arsenic.
October 28/08: The U.S. Environmental Protection Agency has ordered 11 public drinking water systems throughout the state of California to reduce the level of arsenic in their respective drinking water systems or face penalties of up to $32,500 per day for each violation.
The EPA’s orders require the public drinking water systems to develop and meet a schedule to comply with the federal Safe Drinking Water Act’s arsenic standard of 10 ppb.
“Providing people with safe drinking water is essential and public water systems must take the steps necessary to comply with all federal standards,” said Alexis Strauss, the Water Division director for the EPA’s Pacific Southwest region.
The EPA has issued orders to the following California public water systems: