Butter has been used previously to measure human dietary exposure to chemicals, she noted, but never before to monitor air pollutant levels. Consumption of the trace amounts of pollutants found in butter has shown no effect on human health, Jones said.
The study, a collaboration between Greenpeace Research Laboratories (who collected the samples) and the University of Lancaster (who conducted the measurements), evaluated butter samples from 23 countries. The researchers found that European and North American butter had the highest PCB levels. Lower contaminant levels were found in samples from the Southern Hemisphere, including Australian and New Zealand butters. PCB levels ranged from 110 to 3,330 picograms per gram of butter. A picogram is a trillionth of a gram, far smaller than the microgram levels that might cause a person harm, Jones noted.
Persistent organic pollutants, or POPs, are chemical substances that linger in the environment, bioaccumulate through the food chain, and pose a risk to human health and the environment, according to the United Nations Environment Programme, an international organization created to control the pollutants. The U.N. group calls for the reduction and eventual elimination of POP emissions.
In December, the U.N. officials announced that 122 countries, including the U.S., have negotiated a treaty to eliminate 12 specific persistent organic pollutants. Eight pesticides (aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex and toxaphene) are on the list, in addition to PCBs, dioxins, furans and hexachlorobenzene - an industrial chemical used to make synthetic rubber, ammunition and fireworks.
"With suitable controls, safeguards and further research," the researchers conclude, "we think that butter could be used to monitor the regional and global distribution of [POPs] and the
Contact: Beverly Hassell
American Chemical Society