Decabromodiphenyl Ether (decaBDE) is one example of a polybrominated diphenyl ether (PBDE). PBDEs are commonly used as flame retardants, and are found in air, water, and soil samples all over the world. PBDEs are persistant in the environment, and have also been detected in human and animal blood and breast milk the world over. The amount of PBDEs in the environment has increased rapidly since the early 1990s, though some state and national governments have outlawed their production and use. Animal studies have shown that exposure to PBDEs during growth periods may lead to behavioral problems, liver effects, and the production of thyroid hormones. While current studies do not indicate problems to humans at this time and at current levels, the persistance of PBDEs and their accumulation over time is a concern to environmental groups and governments.