Levels of flame-retardant compounds in wildlife are declining in northern countries, suggesting that curbs on the chemicals are working, according to two new studies.
The studies published in the most recent edition of the journal Environmental Toxicology and Chemistry examine concentrations of polybrominated diphenyl ether (PBDEs) and hexabromocyclododecanes (HBCDs) over 20 years in Canada and Norway.
While use of those chemicals is uncommon in those countries, the compounds have been found in the environment and in the bodies of animals migrating north.
A study examining data on Lake Ontario trout between 1979 and 2004 found that PBDE concentrations increased until the mid-1990s, then leveled off or fell. HBCD levels also fell, although not as quickly.
The second study focused on PBDE and HBCD in seabird eggs in northern Norway between 1983 to 2003 and produced findings that echoed the Canadian research. PBDE concentrations increased until 1993, then fell through 2003. But HBCD levels increased in the Norway study, which the researchers were unable to explain.
Researchers credited the decline to government policies aimed at reducing PBDEs, which studies suggest can cause cancer. Within the past year, studies have found undescended testicles in babies whose mothers had high levels of the chemicals, decreased sperm quality in men and effects on thyroid function.
Some countries and several U.S. states have limited or banned the most common types of the chemicals, but older furniture or carpet containing the compounds are still in use and still for sale in some places.
The two studies are important for understanding how to prioritize chemical regulations, the researchers wrote. The studies also provide a window into how replacement chemicals are interacting in the environment.
Click here to read the Canadian study.
Click here to read the Norwegian study.