butter
© Gary Porter / Milwaukee Journal Sentinel / MCTFlame retardants were found in a box of butter.

Flame retardant chemicals that are known to be harmful to health have been found in a package of butter sampled in a Dallas grocery story, according to a study published Tuesday. This is the first reported case of food contamination that is thought to have resulted from the chemicals used in the food packaging.

The chemicals are polybrominated diphenyl ethers -- or PBDEs. The chemicals are commonly found in electronic devices, fabrics and insulation. PBDEs are known to be harmful to animals and are suspected of disrupting human thyroid hormones. U.S. manufacturers have agreed to phase out a particularly harmful type of chemical called deca-BDE.

Ten samples of butter were purchased in Dallas grocery stores as part of a routine investigation intended to help scientists improve estimates for the amounts of PBDEs people consume in food. The contaminated sample of butter contained PBDEs that were 135 times the average amount found in the other nine samples and was particularly high in the dangerous deca-BDE. The butter's paper wrapper had levels more than 16 times greater than in the butter itself.

The authors of the report, from the University of Texas School of Public Health in Dallas, said they don't know how and where the butter was contaminated. But they called for more random screening of food products. "This suggests that screening for toxic chemicals in food can reveal their presence in U.S. food, and illustrates a potential route of exposure."

The study appears online in the journal Environmental Health Perspectives.