On arsenic and apple juice: Is the EPA’s drinking water limit even safe?

There’s been a lot of chatter about the arsenic-in-apple-juice debacle involving TV’s Dr. Mehmet Oz, the FDA and Consumer Reports. If you don’t know the backstory, fellow PLoS blogger Deborah Blum has written two great posts about it, which you can find here and here.

I only have one thing to add. I’ve heard some people react to the Consumer Reports findings with comments like, “well, most of the arsenic levels were at or below the EPA’s limit for drinking water, so it can’t be that bad.” But for this to be true, the EPA’s arsenic limit has to be adequately protecting the public. I don’t think it is.

Here’s my analysis of how the EPA regulates arsenic in drinking water from a piece I wrote for NYU’s Scienceline several years ago:

The Environmental Protection Agency, which regulates drinking water, considers arsenic a class A carcinogen, meaning that data have definitively shown it to cause cancer. Other health effects from chronic low-level exposure include partial paralysis, blindness and diabetes. Although the EPA tightened its regulations for arsenic levels in drinking water this past January [2006], lowering it from a maximum of 50 parts per billion (ppb) to 10 ppb, this new level still exceeds the agency’s recommendations for exposure to a carcinogen by a factor of 50.

The EPA typically recommends that the amount of a carcinogen in drinking water should not cause more than one person in 100,000 to develop cancer as a result of drinking that water daily. But Americans who are regularly drinking water containing 10 ppb of arsenic are at a 50-fold higher cancer risk than this: in other words, one out of every 2,000 of those Americans is likely to develop cancer because of the arsenic in their tap water. And the EPA estimates that 12 million Americans are currently drinking water containing more than 10 ppb of arsenic—making their cancer risk even higher.

The EPA isn’t meeting its own safety standard for arsenic because the recommended amounts “are set at a level which water systems cannot meet,” according to agency press officer Dale Kemery. After preparing a cost / benefit analysis, the EPA set its arsenic limits at a level that maximized risk reduction while minimizing cost to the consumer, he says.

If you’re curious about the math, the EPA provides data here (scroll down to “Quantitative Estimate of Carcinogenic Risk from Oral Exposure”) showing that water arsenic levels would need to be 0.2 µg/L, or 0.2 ppb, for only one in 100,000 people to develop cancer from chronic exposure. And 10 ppb is 50 times greater than 0.2 ppb.

My point is not that we should all be freaking out about the arsenic in apple juice.  I haven’t spent a lot of time investigating the issue, and of course, most Americans drink far less apple juice than they do tap water. But I do think it’s important for people to realize that when they compare exposures to agency limits, the latter may not be as protective as they think.

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4 Responses to On arsenic and apple juice: Is the EPA’s drinking water limit even safe?

  1. John Lowe says:

    There’s more! that cancer risk estimate is the soon-to-be-outdated one (http://cfpub.epa.gov/ncea/iris_drafts/recordisplay.cfm?deid=219111). What’s coming up is going to be about 5 to 10-fold more stringent. Many years ago when the revision of the arsenic drinking water standard was starting up, a couple of the issues being wrestled with were treatment methods that didn’t render water undrinkable and analytical methods for detecting low levels of arsenic, so that you could show that the treatment methods were working. The 10 ppb level was settled on at the time not so much because it achieved the 1 in 10,000 to 1 in one million target cancer risk (the gold standard in cancer risk management) but that it was achievable with the current technologies. Maybe the treatment and chemical analysis methods have improved considerably in the intervening years – I haven’t followed them.

    Is the current MCL safe? Would a lower MCL be safer? We don’t know. The best that we do know is that consuming drinking water with much higher concentrations of arsenic (above 300 ppb) demonstrably increases the risks of various diseases. Below that level, our understanding of the risks gets fuzzier. Way below that (i.e. the around-10 ppb range), our understanding gets very fuzzy indeed, and we’re in the range where the science can’t inform us much further. Unfortunately, this is also the range where emotion and politics become bigger drivers for the decision-making. The apple juice controversy is a great example of the problem.

  2. Hi John – thanks for sharing. This is really interesting. I also see you have your own environmental health blog – I will start following it!

  3. Jim Birch says:

    Hmm. Apple juice isn’t a very good baseline fluid. Irrespective of arsenic, using apple juice for a primary H2O source is not a good idea – it has too much sugar with high fuctose. I’ll take my chances with water.