Unfiltered wines and beers have been having a moment for a few years now, but despite the hype, filtration is still the norm. However, in some cases, that filtration process might be affecting a lot more than flavor. A new study in the ACS’ Journal of Agricultural and Food Chemistry posited that diatomaceous earth, a common filter actually increases the concentration of heavy metals in drinks.
The study by Benjamin W. Redan, Joseph E. Jablonski, Catherine Halverson, James Jaganathan, Md. Abdul Mabud, and Lauren S. Jackson was prompted by the Food and Drug Administration’s (FDA) discovery that some fruit juices, beers, and wines tested positive for unusually high amounts of heavy metals.
Mind you, these scientists weren’t talking about Slayer or the John Candy movie here. For the uninitiated, heavy metals are a set of chemical elements with some potentially toxic side effects (when consumed in specific forms via large or chronic doses). Members of this group include arsenic, lead, cadmium, and mercury.
Counter-intuitively, the report fingered one type of filter as the culprit. Diatomaceous earth (DE) is a naturally occurring rock that is often ground into a white powder and then employed as a filter.
The report stated that the team tested three different commercially available, food grade DE samples. All of the samples tested positive for arsenic, lead, and cadmium. Of greater concern was the conclusion that said substances were actually transferred from the DE to the beverage it was intended to purify.
When the researchers filtered beverages through the DE, they discovered that arsenic levels in the drinks increased and decreased in ratio to the amount of DE used. However, washing the DE or tweaking the ph level beforehand significantly decreased the heavy metal transfer.
However, there’s probably no need to rush to the fridge and toss all your filtered beverages just yet.
“Though the majority of wine samples in our analysis were under the proposed 10*g/L inorganic arsenic apple-juice limit, two samples contained total arsenic [18 and 11 ppb] above this threshold,” stated the study. “Regardless of these values, permissible levels of heavy-metal concentrations in beer and wine in the US have not been determined at this time. Still, metal limits have been suggested by other entities, such as the International Organisation of Vine and Wine. These data indicate that specific steps can be taken to limit heavy-metal transfer from DE filter aids to beer and wine.’”
Translated into English, the scientists are said: (A) There are no regulated limits on heavy metals in wine and beer. (B) The FDA does have a limit on heavy metals in apple juice which is ten parts per billion. (C) If you use the FDA’s apple juice limit, then only two of wine samples (and two retail available beers mentioned later) exceed the limit. (D) Moving forward, we need to create limits on wine and beer as well as use out knowledge to immediately reduce heavy metal transfers.
The report also noted that most of the retail drinks tested contained arsenic, but below the apple juice limit. The authors argue that effects of chronically consuming even these low doses warranted additional research.
Photo by Fabio Ingrosso [CC2.0]