Arsenic is a naturally occurring element that is toxic to human beings in some forms. It can cause skin, lung and bladder cancers, and other diseases. The US Environmental Protection Agency permits drinking water to contain no more than 10 parts per billion of arsenic. Researchers have now revealed that many red wines in the US contain arsenic levels that exceed what is allowed in drinking water. The arsenic content in red wine samples ranged from 10 to 76 parts per billion, with an average of 24 parts per billion.

Rain, rivers or wind erode rocks that contain arsenic. This toxic metalloid leaches into water and soil, from where it works its way into the food chain.

Researchers Denise Wilson, professor at University of Washington in Seattle, said, "Unless you are a heavy drinker consuming wine with really high concentrations of arsenic, of which there are only a few, there is little health threat if that is the only source of arsenic in your diet. But consumers need to look at their diets as a whole. If you are eating a lot of contaminated rice, organic brown rice syrup, seafood, wine, apple juice - all those heavy contributors to arsenic poisoning - you should be concerned, especially pregnant women, kids and the elderly."