Flame Retardant Chemical Found in Fish, Humans
By Pat Hemminger
NEW YORK, New York, January 31, 2002 (ENS) - Freshwater fish in Virginia have been found to contain the highest reported levels in the world of a common but controversial flame retardant, penta bromo diphenyl ether. The chemical, which is showing up in animals and humans around the globe, has been linked in laboratory animal studies to behavioral problems, but little is known about its effects on humans.
Penta bromo diphenyl ether (pentaBDE) has also been found in sewage sludge spread on land across the United States, renewing concerns about the long term safety of the U.S. biosolids program.
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, and with their transport throughout the body.
One carp from the Hyco River contained more than 47 parts per million of BDE-47, the highest known amount to be recorded in any fish so far.
"Flame retardants are a current use chemical. Basically what we're doing is pumping more and more of the chemical into the environment and building up the levels," said Robert Hale from the Virginia Institute of Marine Science (VIMS), the main author of a report on the study published in the December 2001 issue of "Environmental Science and Technology."
More than half of the samples weighed in with more BDE-47 than PCB-153, the most abundant of the PCB molecules.
BDEs have been found worldwide in fish, wildlife and people. Research to date, though limited, suggests that these chemicals can cause harmful effects similar to those caused by PCBs.
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. The effects are similar to those seen in connection with PCBs, the researchers said.
BDE chemicals are persistent and bioaccumulative, meaning that they do not readily break down in the environment, and they accumulate in the tissues of animals. Like other persistent organic pollutants (POPs), BDEs get into humans mainly through food.
"It's a concern for a regulatory body if you have anything like that, that's increasing so much and your toxicology base is very limited," said Jake Ryan, a senior researcher with Health Canada who collected the North American breast milk data. "It may be innocuous and that's OK - but if it isn't then it's a real problem. You need to have a better handle on it."
One of the major concerns about BDEs in breast milk is the exposure of infants. Though the Swedish study using mice used massive amounts of BDEs, far greater than the estimated daily intake of human adults or infants, the fact that these chemicals accumulate in the body over time could potentially lead to harmful levels of the toxins in people who are frequently exposed, or particularly vulnerable - such as infants.
While current environmental levels of BDE are not considered dangerous, studies show that these levels are increasing. Researchers in Canada have studied the historical trends of BDEs in lake trout by comparing 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," said Mehan Alaee, an Environment Canada scientist who heads the federal BDE research team. "BDEs increased 300-400 times from 1978 to 1998," he noted.
In Japan, pentaBDE concentration in fish has dropped because of voluntary reductions, according to Environment Canada's Alaee.
But demand for the chemical continues to increase in the United States, which accounts for 98 percent of worldwide penta 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," said Hale.
PentaBDE is added to polyurethane cushions, such as those found in vehicles and household furniture, to delay ignition and slow down fires. Hale suggested the chemical could seep into the environment, ending up in storm sewers, when discarded cushions disintegrate.
PentaBDE can constitute up to 30 percent of the weight of fire protected upholstery, so this route could easily account for the levels being seen in the environment, Hale suggested.
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 the flame retardant's use. Particularly in residential fires, pentaBDE can slow down a fire, allowing residents time to escape and reducing property damage, says the Brominated Flame Retardants Industry Panel (BFRIP).
A BDE treated sofa, for example, would be slower to ignite and could increase escape time by a factor of 15, the industry group says.
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, a member of the BFRIP panel and the head of regulatory affairs for Great Lakes Chemical, agrees that more and better research into pentaBDE may be needed. The Swedish toxicological study indicating pentaBDE produced permanent damage in mice "was not done using the generally accepted method," he said.
The discovery of significant amounts of BDEs in biosolids, a mixture of sewage sludge used as fertilizer, concerns some scientists and environmentalists because of the potential for more of these chemicals entering the food supply.
The Virginia Marine Institute's Hale and his colleagues were measuring the levels of nonophenols and PCBs in U.S. biosolids when they came across the BDEs.
"Sewage sludge contains everything - literally - in the kitchen sink," said Hale.
In Europe, several countries are reevaluating the use of biosolids as fertilizers. 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.
Concerns over pollutants and pathogens entering the food supply have led to a reevaluation of the risks associated with biosolids in the U.S. as well. In 1999, the EPA proposed limiting the amount of dioxin allowed in biosolids to 300 parts per trillion. Some critics consider that limit to be too high, and final action on the controversial rule was recently extended to March 2002.
A National Academy of Sciences review, "Risks from Toxicants and Pathogens in Biosolid Fertilizers," is scheduled for release this spring. The Virginia team's BDE data have been given to the National Academy of Sciences committee, Hale noted.
"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," said Hale. "Both nonophenols and brominated flame retardants were not on the considered list and both of them have environmental legitimacy."
More information on bromine based flame retardants such as pentaBDE is available through the Bromine Science and Environmental Forum at: http://www.bsef.com/