Jeff Glorfeld
Jeff Glorfeld is a former senior editor of The Age newspaper in Australia, and is now a freelance journalist based in California, US.
Health officials around the world are on the lookout for contaminants in food and beverages, and studies from as far afield as Finland, Italy and Chile have found evidence of lead, cadmium, mercury and arsenic in products such as bottled water, carbonated beverages and fruit juices. In the US, the Food and Drug Administration (FDA) is trying to protect the public from health hazards caused by exposure to the heavy metals arsenic, lead and cadmium in food and beverages.
Elevated amounts of these contaminants – above the allowable limits set by the FDA – have been reported in some fruit juices, wines and beers, but researchers were at a loss as to how the metals are ending up in the finished products.
But FDA-led researchers believe they have found a likely culprit: diatomaceous earth, a commonly used filtration material.
More importantly, they believe they have also found ways to limit the contamination, according to their report, published in the Journal of Agricultural and Food Chemistry.
The advocacy publication Consumer Reports says children are particularly vulnerable to the harmful effects of heavy metals.
“Exposure to these metals early on can affect their whole life trajectory,” wrote Jennifer Lowry, from the American Academy of Pediatrics’ Council on Environmental Health, in a recent report on contamination in fruit juices.
Diatomaceous earth is one of the most commonly used filter aids for processing some fermented alcoholic beverages. It increases clarity and extends the shelf life of products.
The new report says previous experiments found that use of food-grade filter aids for processing apple and grape juices can change the final concentrations of inorganic arsenic, lead and cadmium, but it was not clear whether the same is true for fermented alcoholic beverages, which can have substantial differences in their physical and chemical properties.
Researchers, led by Benjamin Redan and Lauren Jackson, from the FDA’s Chicago facilities, say their study builds on previous work to identify factors affecting the transfer of heavy metals from three types of food-grade diatomaceous earth filter aids to ale and lager beer, and to red and white wine.
Wines from the US, Australia, Argentina, Spain, Italy, South Africa, Germany, France and Italy were tested.
Beers were tested from the US, Australia, Scotland, Britain, Barbados, Germany, the Czech Republic, Ireland, Jamaica, Belgium and Holland.
The scientists found that all three types of diatomaceous earth contained arsenic, as well as smaller amounts of lead and cadmium.
When used to filter beer or wine in the lab, one of the diatomaceous earth samples increased arsenic significantly, rising above the safe limit of 10 parts per billion (ppb) proposed by the FDA for apple juice.
But the amount of arsenic transferred to the drinks decreased when the beverage was exposed to less diatomaceous earth, the pH of the liquid was altered, or the diatomaceous earth was washed beforehand.
The researchers also measured levels of the heavy metals in commercial beer and wine samples. Although they detected arsenic in the beverages, levels were below 10 ppb, with the exception of two wine samples that contained 18 and 11 ppb of arsenic.
The report says analyses of beer and wine market samples indicated a large range of heavy-metal concentrations, but it points out that the nature of the processing steps used in the production of the commercial samples, including the type and quantity of filter aids, are not known.
