POPs in the butter.

With negotiations under way for a United Nations treaty to control the global release of persistent organic pollutants, or POPs (SN: 12/16/00, p. 389), chemists are looking for common items to survey for these long-lived, largely fat-soluble compounds. Scientists in England have decided to look no further than the kitchen table. They've found that butter could do the job.

Olga I. Kalantzi and Kevin C. Jones of Lancaster University and their colleagues reasoned that grazing cows would concentrate ambient POPs in the fat of their milk, and that making butter would further concentrate that POPs-bearing fat. So, the scientists measured tiny traces of polychlorinated biphenyls (PCBs) and several other nearly ubiquitous POPs in butter from 23 countries around the globe.

Overall, PCBs varied up to 60-fold between countries, with the highest amounts in Czech butter, the scientists report in the March 15 ENVIRONMENTAL SCIENCE & TECHNOLOGY. Other POPs varied even more dramatically. In India's butter, the concentration of hexachlorocyclohexane, a constituent of the pesticide lindane (SN: 3/15/97, p. 157), was roughly 223,000 picograms per gram--almost 1,000 times as much as in Australia's butter.

Noting that several factors can affect how much pollution a cow picks up and passes on in milk, Jones' team argues that butter nevertheless looks useful for monitoring trends in POPs.