Flame retardants were found in U.S. supermarket food in larger than expected amounts, warranting further study given the possible ties to cancer, researchers reported Wednesday in Environmental Science & Technology, a peer-reviewed journal of the American Chemical Society.
"Our paper is the first U.S. market basket food survey for brominated flame retardants," study co-author Arnold Schecter said in a statement. Schecter is an environmental sciences professor at the University of Texas School of Public Health in Dallas.
The type of retardants found are technically known as polybrominated diphenyl ethers, or PBDEs, a chemical added to plastics, electronics, textiles and furniture foam to save lives by retarding flammability.
"We found PBDE contamination in all food containing animal fats," Schecter said of the study, which tested 32 food samples from well-known brands sold in three major supermarkets in Dallas. That's because PDBEs are easily absorbed by fatty tissues. Nonfat milk, on the other hand, had no detectable PBDE levels.
The highest levels were in fish, followed by meat and then dairy products.
"Although these findings are preliminary, they suggest that food is a major route of intake for PBDEs," Schecter added. Other study researchers included Linda Birnbaum, a U.S. Environmental Protection Agency scientist and president of the Society of Toxicology.
Ten times more in salmon sample
The Dallas levels were much higher than findings in the only two other similar studies done so far, one in Japan and the other in Spain.
The most contaminated sample in the Dallas study was a salmon filet at some 3,000 parts per trillion — compared with the highest level in the Spanish study of 340 ppt. Median meat levels in the Dallas study were twice the maximum found in Spain and Japan.
The large disparity was not accounted for in the study, but the Dallas researchers had earlier tested the breast milk of 47 Dallas women and found the highest PBDE levels in the world to date.
An industry group, the Bromine Science and Environmental Forum, criticized the study, saying it detected "levels so low that the authors elected to report them on a parts-per-trillion basis."
Scientists' understanding about the toxicity of retardants is limited but studies using rodents have associated the chemicals with cancer, endocrine disruption and brain impairment.
The Dallas study and others like it make clear that PBDEs are being released into the atmosphere and bodies of water, but exactly how remains a mystery.
Europe, U.S. moves
The concerns about PBDEs have led the European Union to ban two types — penta and octa. It is also weighing a ban on a third, deca-PBDEs.
In the United States, the two largest PBDE manufacturers, Albermarle and Greak Lakes Chemicals, in 2003 agreed to phase out penta and octa formulations by Jan. 1, 2005, as part of a voluntary accord with the EPA.
The researchers said they hoped the agreement would shift the trend. "If, as is anticipated, Deca-BDE becomes the only commercial PBDE manufactured in the United States beginning in 2005," they wrote, "we would expect to see a change in future PBDE patterns."
Schecter's next move is to do a larger study of foods from across the United States.
Funding for the Dallas study came from private non-profits as well as the EPA and the University of North Carolina.