A study published in the peer-reviewed journal <em>Environmental Health Perspectives</em> (EHP) reports one of the worst cases of food contamination with polybrominated diphenyl ether (PBDE) flame retardants in the United States. The incident also marks the first time food contamination has been thought to result from PBDEs in food packaging.

One of 10 samples of butter purchased at five Dallas grocery stores contained high concentrations of deca-BDE, a PBDE compound widely used in electronics as well as in textiles, wire and cable insulation, and automobile and airplane components. Animal studies have linked consumption of deca-BDE with thyroid hormone changes in adult rodents and neurobehavioural changes in young rodents.

PBDE levels in the contaminated butter were more than 135 times higher than the average of the other nine samples; levels of BDE-209, the main component of deca-BDE, were more than 900 times higher.

The contamination came to light during a routine investigation intended to help scientists improve estimates of the amount of PBDEs and other persistent organic pollutants people inadvertently consume in food. Scientists have detected low levels of these compounds in many fat-rich foods including fish such as salmon, meat, poultry, eggs, and dairy products.

Further investigation revealed the butter's paper wrapper had PBDE levels more than 16 times greater than levels in the butter itself. It is unclear whether the paper was contaminated before or after it reached the butter packaging plant, according to lead author Arnold Schecter of the University of Texas School of Public Health. The source of the contamination also is unclear.

US manufacturers have agreed to end all uses of deca-BDE by 2014, and the European Union phased it out in 2008. However, chemicals don't vanish from the environment just because they're phased out, Schecter says, and products containing deca-BDE often are used for many years. 

The authors of the paper agree their research underscores the need for a regulatory programme that samples American food for persistent organic pollutants such as PBDEs