Extremely high levels of flame retardants known as polybrominated diphenyl ether (PBDEs) were found in cats,
U.S. researchers reported in the August 15, 2007 issue of Environmental Science and Technology. Results suggested these toxins may be responsible for common feline hyperthyroidism.
Feline hyperthyroidism is the most common endocrine disorder in cats. PBDEs are persistent chemicals that are widely used as flame retardants in household products such as upholstered furniture, floor carpet, mattress and electronics such as computers and television among others.
The study by Janice A. Dye from U.S. Environmental Protection Agency and colleagues was designed to determine whether body burdens of PBDEs in hyperthyroid (HT) cats were higher than that of young or non-HT cats.
Dye and team tested PBDEs in 23 cats and found serum concentrations of PBDEs in young, old non-HT and HT cats were 4.3, 10.5 and 12.7 ng/ml, respectively. Overall, PBDEs in cats were 20 to 100 times greater than median levels in
U.S. adults, who are known to have the world's highest human PBDE levels.
The paper shows cat food and house dust are likely the sources of catís PBDEs. Early European studies found that children under the age of 4 years can have much higher levels of these compounds than adults.
The researchers conclude that "cats are highly exposed to PBDEs, hence, pet cats may serve as sentinels to better assess human exposure and adverse health outcomes related to low-level but chronic PBDE exposure."
Early studies by the Environmental Working Group found high levels of PBDEs in the milk of 20 first-time mothers in the
United States, which were on average 75 times the average found in recent European studies, according to an EWG report.
PBDEs are believed to have the ability to disrupt the body's thyroid hormone balance and disturb normal metabolism, according to the EWG. One condition caused by the toxins is hypothyroidism in adults, which can cause fatigue, depression, anxiety, unexplained weight gain, hair loss and low libido.
Studies show laboratory animals exposed to PBDEs before and after birth can have impaired brain development, damage their learning ability and memory and affect their behavior. A woman with high PBDEs may have low levels of T4 hormones, which could lower the IQ of her baby to as low as 70.
The researchers fear that children may pick up PBDEs in ways similar to cats as they inhale air with more dust and contact PBDEs-loaded floor carpet often.
Europe, three common forms of PBDEs have been banned. In the
U.S., no federal regulation to restrict use of these environmental pollutants and only
California has decided to ban PBDEs, according to the EWG.