A lifesaving chemical which is used to make upholstery flame-resistant, pentaBDE (penta bromo diphenyl ether), has turned up in water supplies and even in breast milk.
Freshwater fish in Virginia have been found to contain the highest reported levels in the world. It?s showing up in animals and humans around the globe. PentaBDE has also been found in sewage sludge that is spread on farmland across the United States.
It?s been linked to behavioral problems in laboratory animals, but little is known about its effects on humans. In one Swedish study, 10 day old mice that were given large doses of the two major chemicals in commercial pentaBDE showed permanent disturbances in their behavior, memory and learning.
Some of the compounds in pentaBDE, including its BDE molecules, are similar in structure to PCBs (polychlorinated biphenyls), industrial chemicals which are classified as probable carcinogens. PCBs are known to cause birth defects, neurological damage and thyroid imbalances. Their use was banned in the U.S. in 1976. The chemical structure of BDEs also resembles thyroxin, a thyroid hormone. Initial studies indicate that BDEs could interfere with the metabolism of thyroid hormones.
Virginia researchers examined more than 1,000 fish from 332 different locations in the Roanoke and Dan River basins. 33 species of fish were tested, including striped bass, catfish and carp. The scientists found that 89 percent of the fish were contaminated with BDE-47, one of the two main constituents of pentaBDE. One carp from the Hyco River contained more than 47 parts per billion of BDE-47, the highest known amount to be recorded in any fish so far.
BDE chemicals do not readily break down in the environment, and they accumulate in the tissues of animals. They get into humans mainly through food. Levels of BDEs in the breast milk of North American women over the last decade has increased from two to 200 parts per billion. One of the major concerns is the exposure of infants to BDEs in breast milk.
Researchers in Canada have compared amounts of the chemical in archived trout samples with trout caught in recent years. ?We found that trends are rapidly rising in lake trout from Lake Ontario,? says Mehan Alaee, an Environment scientist. ?BDEs increased 300-400 times from 1978 to 1998,? he says.
The European Commission approved a ban on pentaBDE, effective in July 2003, and the European parliament has recently proposed extending that ban to include other BDEs. In Japan, pentaBDE concentration in fish has dropped because of voluntary reductions. But demand for the chemical continues to increase in the United States, which accounts for 98 percent of worldwide use. Production of pentaBDE doubled to 8,500 tons between 1992 and 1999.
Scientists are still trying to determine how the flame retardants enter the environment. ?We just don?t know for sure,? says Robert Hale of the Virginia Institute of Marine Science. PentaBDE is added to polyurethane cushions, such as those found in vehicles and household furniture, to delay ignition and slow down fires. Hale thinks the chemical could seep into the environment, ending up in storm sewers, when discarded cushions disintegrate.
Environmental regulators will have to weigh the potential environmental and human health effects of pentaBDE against its known life saving properties, when deciding whether to restrict its use. In residential fires, pentaBDE can slow down a fire, allowing residents time to escape and reducing property damage. A BDE treated sofa, for example, would be slower to ignite and could increase escape time by a factor of 15.
Under a pilot program of the U.S. Environmental Protection Agency, the main U.S. manufacturer of pentaBDE, Great Lakes Chemical, is now voluntarily testing whether children?s exposure to PBDEs presents a risk. Bob Campbell, of Great Lakes Chemical, says the Swedish toxicological study indicating pentaBDE produced permanent damage in mice ?was not done using the generally accepted method.?
The discovery of significant amounts of BDEs in sewage sludge used as fertilizer concerns scientists because of the potential for more of these chemicals entering the food supply. ?Sewage sludge contains everything – literally – in the kitchen sink,? says Hale.
The original EPA risk assessment of sewage sludge concluded that it was safe to apply to land. However, the assessment did not consider BDEs. In the U.S., 60 percent, or about four million tons a year, of the sewage sludge is now spread on land as a fertilizer. In Europe, several countries are reevaluating its use as a fertilizer. In September 2001, Swiss authorities proposed banning the disposal of sewage sludge on agricultural land by 2005. In 1999, the Swedish Farmers Association issued a temporary ban on spreading sewage sludge on farmland because of concern over potentially hazardous chemicals, including BDEs, in the sludge.
Robert Hale says, ?Our major point on the whole sludge issue is that the EPA has done a risk assessment on a number of chemicals but they?ve left more chemicals out than they?ve considered.?
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