Beer and Wine Could Be Contaminated with Arsenic Because of Filtering Process

The filtering process used to remove sediment from beer and wine could contaminate drinks with potentially dangerous heavy metals such as arsenic, scientists have warned.

Manufacturers often use filters such as diatomaceous earth (DE), a type of crumbly sedimentary rock, to give drinks clarity and make them last longer. According to the authors of a study published in the Journal of Agricultural Food Chemistry, this could contain heavy metals such as arsenic, lead and cadmium.

Exposure to large amounts of heavy metals can be toxic. However, as such substances occur in the air, water and soil, and in turn enter food, they can be hard to avoid.

Long-term exposure to arsenic has been linked to heart disease, and skin, bladder and lung cancers. Lead can cause developmental problems in children. Cadmium can irritate the stomach and cause diarrhea and vomiting, as well as cancer, kidney disease, and bone fragility.

Past reseach has shown heavy metals can find their way into alcohol, but the researchers wanted to answer how. They studied how three types of DE filter aids affected 20 types of ale and lager; and 20 types of red and white wine. They noted the amount of heavy metals transferred depended on the properties of the drink—including its pH—and the amount of filter used. They also tested whether washing a filter made a difference.

Beer and wine samples showed these drinks contain "a large range of heavy-metal concentrations" the scientists found, but below the safety limit except from in the case of two wines.

All of the DE filters tested contained arsenic, as well as lower levels of cadmium and lead. One DE caused levels of arsenic higher than that deemed safe by FDA for apple juice, which the authors used as a measure of a substance's safety. But when less DE was used, the levels of arsenic fell. The same result was seen when researchers washed the DE, or changed the pH of the wine or beer.

The results showed the amount of time the drink was filtered and the amount of DE used affected the transfer of arsenic.

The authors concluded: "The current study provides data showing that there are various factors that affect the transfer of heavy metals from filter aids to alcoholic beverages. These factors should be considered in designing beverage-filtration measures to mitigate heavy metal contamination."