A new study from Kingston University in London claims that wines sourced from several different parts of the world may contain potentially hazardous levels of heavy metal ions, which could contribute to diseases such as Parkinson's when consumed regularly over a lifetime. While the results have received a great deal of attention in the media, some members of the scientific community remain skeptical.
According to the study, published in Chemistry Central Journal, 13 out of 16 wines examined for potentially high levels of heavy metals, including iron, copper, lead, mercury, vanadium and manganese, had levels above recommended safe limits, as set by the United States Environmental Protection Agency. A target hazard quotient (THQ) exceeding one could cause health effects over a lifetime of consumption, according to an EPA risk-estimation formula comparing the time a person is exposed to a toxin and its established reference dose. The formula was developed by the EPA for Superfund sites and has been used to assess the risk of exposure to chemicals in seafoods.
The researchers found that wines from Hungary and Slovakia had THQ levels greater than 350. Wines from Austria, France, Germany, Portugal and Spain showed levels of more than 100 and wines from the Czech Republic, Greece, Jordan, Macedonia and Serbia contained below 100, but still above one. Wines from Argentina, Brazil and Italy contained acceptable levels of heavy metal ions.
Neither the study nor its two authors, Declan Naughton, a professor of biomolecular sciences and Andrea Petróczi, a sport and exercise scientist, provided elaboration into what kind of wines—grape, region, vintage, etc.—were examined. They also did not conduct all of the tests themselves, relying on heavy metal amounts determined by prior research, where necessary.
The heavy metals being examined in the study occur naturally in many types of foods. Indeed, the body uses low levels of some of the metals, such as iron, copper and manganese to good use, but others, such as mercury and lead have no known health benefit. Typically, the ions from the metals will pass from soil to plant. Pollutants in the environment, such as fungicides and pesticides, could also be contributors.
"Excess intake of metal ions is credited with pathological events such as Parkinson's disease," Naughton said in a statement. "In addition to neurological problems, these ions are also believed to enhance oxidative damage, a key component of chronic inflammatory disease, which is a suggested initiator of cancer."
It is important to note that THQ is a determination of long-term risk, the study added, and a typical 18-year-old would have to drink 8.5 ounces (one to two glasses) of the tested wines for more than 17,000 days before reaching a level of concern. This model also assumes that the same individual will live to be more than 80 years old.
Nonetheless, Naughton believes the results are applicable to the average consumer. "In the U.K., levels of many chemicals are labelled on bottled drinking water but not on wines," he said. "Levels of metal ions should appear on wine labels, along with the introduction of further steps to remove key hazardous metal ions during wine production."
Naughton added that the study is not meant to scare wine drinkers into abstaining, but rather "with a view to drawing this finding to the attention of scientific and medical researchers," he said.
It seems to be working. Dr. Curtis Ellison, an epidemiologist at Boston University said that the study contains several limitations. Notable is the fact that the researchers used a THQ standard normally applied to heavy metal measurements in seafood products, not agriculture, and therefore may lack relevance. A second concern is the fact that the data on heavy metal ions in wines was pulled from several different research texts and "no standards were used to judge the accuracy of the measurements from the numerous sources," he said.
"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," he said.
Several scientists and the U.K.'s National Health Service said it was too soon to mandate warning labels for wines, and that further research was needed. A spokesman for the U.S. Alcohol and Tobacco Tax and Trade Bureau (TTB) said the agency tests wines for heavy metals if it believes there may be a safety hazard. The TTB uses a mass spectrometer to measure metals in wines—not the THQ estimation formula. The agency forwards elevated levels to the Food and Drug Administration to determine if they're dangerous. The spokesman added that they have yet to detect any serious safety problems.
The Liquor Control Board of Ontario (LCBO), which controls all wine sales in the Canadian province, tests all its products for heavy metals and other contaminants. According to George Soleas, vice president of quality assurance, in the last 10 years, the LCBO has rejected only a handful of products, be it beer, wine or spirits, due to potentially harmful levels of metal. For potentially high levels of lead for example, of more than 8,000 products tested, only eight have ever been rejected.
"We buy wines from Slovakia, Hungary and the Czech Republic, as well as the usual suspects from the Old World—France, Italy, Greece," said Soleas, who has degrees in clinical biochemistry and enology. "We buy from 68 countries, and rarely find dangerously high levels of metals. Maybe if we find arsenic with lead, then it's due to the use of the two in combination in the 1980s and '90s when it was an approved fungicide. You still get remnants of it, but it hasn't been used for 10 to 15 years. It's rare and we reject it."
Soleas said he found the study results to be "wishy-washy" based on his experience testing wines for heavy metals and expressed disappointment in both the way the results were published and the extended coverage in the press. The levels of heavy metals the scientists found, he added, are actually lower than what is allowable in tested water reservoirs across the western world.
"Drinking water is sometimes higher in metals than these wines," Soleas said. "I'm not trying to minimize the fact that contaminants get into wine, but they are targeting the wrong contaminants. Most people will drink two glass of wine a night, but eight glasses of water per day, and if they take a multivitamin tablet they get two milligrams of manganese on top of that, so how is the metal obtained from wine going to kill anyone?"
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