Good data (and good conclusions) on (not much) arsenic in CA wines

Short: A new article in the American Journal of Enology and Viticulture publishes data showing that California wines contain honest-to-goodness insignificant amounts of arsenic. Even if you can’t call the authors completely disinterested, they’ve published their data openly in an excellent scientific journal (and that’s a lot better than you can say for the arsenic fearmongers).


At the risk of bringing up what must surely be everyone’s least favorite wine story from 2015, I’m writing once again about arsenic in wine. I hope you’ll agree with me that, given the reason, it’s justified. A group of reasonably trustworthy researchers has published a scholarly research article demonstrating that California wines don’t have an arsenic problem, and while their work won’t put the arsenic-wine baby to bed once and for all, it goes a long way in the right direction.

My denigration of the perpetrators a year before the scandal broke is here, and my response to the scandal itself is here.

Two problems have lain at the bottom of all of the talk about arsenic in wine. One is that no one – not the US government, not the World Health Organization, and not expert toxicologists talking amongst themselves in the peer-reviewed toxicology literature – is sure how much arsenic is too much arsenic. The other is that the people talking about arsenic in wine haven’t been transparent with their data. This article doesn’t help with the first problem, but it does help with the second.

In short, two independent wine testing labs ran arsenic stats for 28 wines named in the arsenic-related lawsuit brought against California wineries, plus 73 other California wines bought essentially at random* from stores in Pennsylvania and New York. The results:

Wine category                               Mean arsenic concentration                      Standard deviation

Reds                                                6.75 µg/L**                                                    7.33 µg/L

Whites                                           10.9 µg/L                                                         11.0 µg/L

Rosés                                             27.2 µg/L                                                        16.9 µg/L

The first and most important thing to observe about these numbers is that they’re all dramatically lower than the 100 µg/L guideline Health Canada has set for wine and even more dramatically lower than the 200 µg/L the International Organization of Vine and Wine (OIV) has set for its members (of which the United States is not one, but which includes nearly every other significant winemaking country around the globe). (The United States hasn’t regulated arsenic in wine.) Even the wine with the highest concentration of arsenic in this study clocked in at 68.4 µg/L. Yes. Some of these numbers are higher than the 10 µg/L the US Environmental Protection Agency allows in drinking water. But do you drink wine the same way you drink drinking water? Compare wine to food, not to water.

The second thing to note is that, generally speaking, cheaper wines had higher arsenic concentrations. That’s both interesting and not unexpected. (Higher concentrations in rosés and whites than reds, incidentally, isn’t a factor of price. The white >> red phenomenon has been observed in other studies and is assumed to have something to do with processing, though we’re unsure what.)

The third thing to know is that the wines cited in the lawsuit had higher arsenic concentrations (25.6 µg/L) than the random wines (7.42 µg/L), but even the lawsuit-associated wines were still dramatically lower than the 100 µg/L guideline. The wines in the lawsuit were cheaper, generally speaking, than the average wines.

And the fourth thing to note, once again, is that you don’t need to be worried about arsenic poisoning from wine. These researchers did something I think is silly and calculated “average daily” arsenic exposure from average wine consumption data rather than calculating exposure for a heavy-imbiber. To generalize just a bit from their data, the average American drinking two five-ounce glasses of Californian wine a week, every week, will get no more than 10% of the arsenic in her diet from wine, even if she’s drinking the cheap stuff. Arsenic is naturally present in the environment. It’s in water, rice, meat, beer, and bread. If you smoke, you’re getting arsenic in tobacco.

I’m not willing to call this research “unbiased.” Research is never unbiased; scientists can’t escape having a point of view any more than you or I, and it colors the scientific process from the questions they ask to the methods they choose, the way they read their instruments, and the conclusions they draw even if they’re trying in all earnestness to be objective. The labs behind this paper have also run tests and provided evidence for the wine industry in the past, and it’s presumably in the authors’ best interest to conclude in the wine industry’s favor. For that matter, it’s also in the best interest of the publishers of the journal, the American Society for Enology and Viticulture, to side with California’s wineries. All of that said, everyone’s long-term reputations here are best-served by being fair and transparent and there’s every good reason to think that they’re doing just that. And that’s a lot more than can be said for the arsenic fearmongers BeverageGrades.

*The researchers used a “convenience sample,” which in this case means that instead of trying to devise some strategy for obtaining a “representative” sample, they used what they could find. Convenience samples are sometimes a real problem in research (when a psychologist uses the freshmen in his psych 101 class to represent the American public, for example), but here this strategy makes a lot of sense: these are wines you’re going to commonly find as a consumer.

**µg/L = micrograms of arsenic per liter of wine

4 thoughts on “Good data (and good conclusions) on (not much) arsenic in CA wines

  1. Maybe the most clearly written story about this foolishness, though I always get flummoxed with the standard deviation symbol.

    And can we blame the Pennsylvania state store system for most of the arsenic?

    • Thanks, Curmudgeon. I appreciate that. The reason I included the standard deviation numbers here is just to show folks who might have been wondering how the general range of actual arsenic concentrations played out beyond the averages alone. The bottom line remains: some wines have a little more, some have so little as to be undetectable, and none have enough to raise alarm.

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