A team of researchers led by Mehmet Coelhan of the Weihenstephan research centre at the Technical University of Munich, Germany, has found that brewers might unwittingly be adding arsenic to beer. In research presented at the 245th ACS National Meeting & Exposition in New Orleans, US, Coelhan suggests that the material used to filter beers might add arsenic at the same time as it removes yeast.
A 2008 paper found that levels of arsenic in Italian beer were up to two and a half times the legal limit of 10μg/l in the US and Europe. To investigate where that might have come from, Coelhan's team, whose work at the Weihenstephan research centre focuses on beer related research and carries out a lot of analysis for the brewing industry, analysed nearly 360 samples of beer for heavy metals and found that some had levels over that 10μg/l threshold. However, when the team analysed the water, malt and hops used, they couldn't make the amount of arsenic in those ingredients add up to the level of arsenic in the beers, suggesting that the answer lies in Kieselguhr, the material used to filter the beers after fermentation.
Coelhan's team found that there could be large amounts of 'extractable arsenic' in Kieselguhr, which is a diatomaceous rock made from fossilised algae. Once powdered it is used by brewers to remove yeast and sediment from beer. Some of the kieselguhr that Coelhan analysed released arsenic at up to 12μg/l.