The authors of a recent paper published in the Chemistry Central Journal state that metal ions such as iron and copper are among the key nutrients that must be provided by dietary sources. Numerous foodstuffs have been evaluated for their contributions to the recommended daily allowance both to guide for satisfactory intake and also to prevent over exposure. In the case of heavy metal ions, the focus is often on exposure to potentially toxic levels of ions such as lead and mercury. The aim of this study is to determine target hazard quotients (THQ) from literature reports giving empirical levels of metal ions in table wines using the reference upper safe limit value. Contributions to the THQ value were calculated for seven metal ions along with total values for each wine.
The THQ values were determined as ranges from previously reported ranges of metal ion concentrations and were frequently concerningly high. Apart from the wines selected from Italy, Brazil and Argentina, all other wines exhibited THQ values significantly greater than one, indicating levels of risk. The levels of vanadium, copper and manganese had the highest impact on THQ measures. Typical potential maximum THQ values ranged from 50 to 200 with Hungarian and Slovakian wines reaching 300. THQ values for a sample of red and white wines were high for both having values ranging from 30 to 80 for females based on a 250 mL glass per day.
The authors conclude that the THQ values calculated are concerning in that they are mainly above the safe level of THQ<1. It is notable that in the absence of upper safe limits, THQ values cannot be calculated for most metal ions, suggesting that further unaccountable risks are associated with intake of these wines.
Professor R Curtis Ellison comments: This paper has received a huge amount of media response within the first 24 hours of its on-line publication. Headlines include “Danger May Lurk in Some Foreign Wines” (LA Times), “Danger Lurking in Your Bottle of Red” (Times of London), “Researchers Question Health Benefits After Metal Found in Wine” (The Guardian), “Wine-drinkers Risking Parkinson’s With Every Glass” (In the News.Co.UK), and “Study: Many Wines Full of Dangerous Metals (FOX News), the latter adding “Researchers say if you’re the type of person who drinks a glass of wine either red or white every day, you may be damaging your health.”
Also being widely quoted is the authors’ statement in the Discussion of the paper: “The results from this study also question a popular belief about the health-giving properties of red wine: that drinking red wine daily protects you from heart attacks is often related to levels of anti-oxidants. However the finding of hazardous levels of metal ions which can be pro-oxidants leads to a major question mark over the protective benefits of red wine.”
The investigators took levels of metals that had been previously reported for wine from many countries, then incorporated the data into an equation to calculate the THQ (Target Hazard Quotients), devised by the US EPA in 1989 to provide an index of heavy metals in seafood. The equation includes concentration and estimated duration of exposure to heavy metals, sex, average adult body size, and other factors to calculate the THQ for the metals.
The data used were from the literature, and no standards were used to judge the accuracy of the measurements from the numerous sources. Further, whether the THQ has relevance for metals in wine has not been shown. Wine has so many other substances, including many anti-oxidants that may operate in opposition to any oxidation products from metals, that it may be premature to estimate harm from only one group of constituents.
The key problem with this paper, however, is that you cannot use levels of any single constituent or group of constituents in wine to determine the long-term net effects on health. Luckily, we have data from hundreds of prospective epidemiologic studies over more than 30 years to estimate such effects. And there has been a remarkable consistency in such reports: moderate consumption of any type of alcoholic beverage is associated with lower risk of coronary heart disease, ischemic stroke, and other types of cardiovascular diseases.
Article: Naughton DP, Petroczi A. Heavy metal ions in wines: meta-analysis of target hazard quotients reveal health risks. Chemistry Central Journal 2008;2:22 doi:10.1186/1752-153X-2-22. (On-line publication October 30, 2008).