- NEW YORK, New York (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.
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- 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.
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- 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.
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- 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.
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- Most of the fish tested by the Virginia
researchers, including catfish, fish were contaminated with BDE-47, one
of the two main constituents of pentaBDE (Photo by Konrad Schmidt, courtesy
University of Minnesota)
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- Virginia researchers examined more than
1,000 fish from 332 different locations in the Roanoke and Dan River basins.
In total, 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.
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- 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.
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- "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."
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- More than half of the samples weighed
in with more BDE-47 than PCB-153, the most abundant of the PCB molecules.
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- Growing Problem
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- 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.
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- 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.
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- 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.
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- The levels of BDEs found in human breast
milk are rising (Photo courtesy Greenpeace) Levels of BDEs in the breast
milk of North American women has increased exponentially, from two to 200
parts per billion, over the last decade. These amounts are far above those
measured previously.
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- "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."
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- 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.
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- 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.
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- "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.
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- The Swiss government proposed a ban on
the use of sewage sluge on the nation's farmland last September, due to
concerns over chemicals like BDE (Photo by Ian Britton courtesy Freefoto.com)
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- Long term safety concerns have resulted
in reduced use of the penta product in some countries. 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.
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- In Japan, pentaBDE concentration in fish
has dropped because of voluntary reductions, according to Environment Canada's
Alaee.
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- 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.
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- Unknown Pathways
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- Scientists are still trying to determine
how the flame retardants enter the environment.
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- "We just don't know for sure,"
said Hale.
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- 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.
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- 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.
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- 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).
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- 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.
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- 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.
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- 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.
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- Revisiting Biosolids
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- 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.
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- 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.
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- "Sewage sludge contains everything
- literally - in the kitchen sink," said Hale.
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- This wastewater treatment plant in Englewood,
Colorado was recognized by the EPA last October for its efficient recycling
of sewage sludge as biosolids fertilizer (Photo courtesy EPA)
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- A recent EPA risk assessment of sewage
sludge concluded that biosolids containing limited amounts of heavy metals
and pathogens 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 or biosolids produced is now spread on land as a fertilizer.
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- 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.
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- 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 setting 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.
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- 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.
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- "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."
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- More information on bromine based flame
retardants such as pentaBDE is available through the Bromine Science and
Environmental Forum at: http://www.bsef.com/
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- http://ens-news.com/ens/jan2002/2002L-01-31-07.html
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