On September 14, Dr. Oz claimed on his TV show that apple juice has dangerous levels of arsenic (chemical symbol As). The Federal Drug Administration (FDA), in what has to be an unprecedented move, wrote a letter to Dr. Oz explaining to him that testing for inorganic arsenic (the dangerous form) is much more complicated than testing for total arsenic (which Dr. Oz tested for.) In a second letter, the FDA showed the results from its own tests that demonstrate that Dr. Oz's results were "erroneously high."
In both letters, the FDA states that "it would be irresponsible and misleading for the Dr. Oz Show to suggest that apple juice is unsafe based on tests for total arsenic."
Now for the science.
Arsenic comes in two predominate types: pentavalent As(+5) and trivalent As(+3). Pentavalent arsenic is also referred to as organic arsenic while trivalent arsenic is called inorganic arsenic. An article on Wikipedia claims that organic arsenic is 500 times less toxic than the inorganic form, but I couldn't verify that in a trusted source. What I did find from the Environmental Protection Agency (EPA) is that the EPA and the Center for Disease Control (CDC) is most concerned with exposure to inorganic arsenic.
Inorganic arsenic is nasty stuff. A lethal dose of inorganic arsenic is about 100 to 200 mg (milligrams) for a 150 lb person. Roughly speaking, that is about 1/50 of a teaspoon. Dissolved in a quart of water gives a concentration of about 200,000 ppb. How much arsenic are you exposed to? So the EPA has set the limit for drinking water at 0.01 mg/L or 10 ppb (parts per billion). What does this mean? Imagine taking a quart of water (about one liter) and then dissolving 1 teaspoon of sugar. That would be about 4,000,000 ppb. To get down to 10 ppb, take your sugar water and pour in 400,000 quarts of water. That's one hundred thousand gallons.
The EPA sets such a stringent limit, because our country's water supply must be safe. No water on Earth is as safe as city tap water. Many cases of arsenic poisoning occurs in the Third World where the drinking water is contaminated with inorganic arsenic.
What about other sources of arsenic like apple juice, rice, and carrots? Dr. Oz claims that the samples of apple juice he tested had levels 36 ppb while the EPA measurements were between 2.0 and 6.0 ppb. Furthermore, Dr. Oz tested for total arsenic not inorganic arsenic. The EPA did the same, but the agency's policy is that when the total arsenic level is above 23 ppb, they will run additional tests for inorganic arsenic. The implication here is that nearly all the arsenic found in food is organic arsenic, and not nearly the concern that inorganic arsenic is.
Rice has arsenic in it in concentrations anywhere from 100 ppb to 800 ppb depending on where it's grown. Compare that to the apple juice. By the way, Texas and Louisiana rice tends to be higher in arsenic; California's rice is among the lowest. Carrots have about half the amount of rice.
1. During the Chosun dynasty in Korea, arsenic was used as a form of capital punishment.
2. In the play Arsenic and Old Lace, the old ladies killed by spiking their home made elderberry wine with arsenic. I'll stick to Pinot Noir.
3. Political statement - I know that in certain political quarters it is quite fashionable to question federal oversight and the money spent in doing so, but I thank our federal officials who make my life healthier, longer, and more enjoyable, because they are monitoring our country's food, water, and drugs.