Washington: This week, Dr. Mehmet Oz, MD, American television star of The Dr. Oz Show, caused a stir with claims that a popular brand of apple juice contained high levels of a not-so-tasty toxin.

In his investigation, Dr. Oz commissioned a private lab, which tests yielded high levels of arsenic in some top-shelf brands. The US-based Food and Drug Administration (FDA) responded to the show by running their own tests, which found considerably lower amounts of arsenic.

In particular, their tests distinguished between various forms of arsenic, and found only trace amounts of inorganic arsenic, which they say is poisonous to humans.

The Environmental Protection Agency sets a standard of 10 parts per billion (ppb) of arsenic in drinking water, as does the European Union. According to the U.S. Agency for Toxic Substances and Disease Registry, drinking water contains about 2 ppb of arsenic, although some areas have much higher levels. The FDA says it spot checks juice products containing 23 ppb or more of arsenic.

Dr. Oz's study tested three dozen samples from five different brands of apple juice across three different American cities. In the tests, Juicy Juice brand apple juice contained as much as 16 ppb of arsenic while Gerber brand contained as much as 36 ppb.

The FDA spot checks juice products and automatically does further tests on any juice containing 23 ppb or more of arsenic. Meanwhile, the agency isn't raising a red flag in response to the show and is reassuring American consumers that their apple juice is safe to drink.