EPA scientists zero in on flame retardants in some home products and
pet food. There is concern about humans.
By Marla Cone, Los Angeles Times Staff Writer
August 16, 2007
Thyroid risks
click to enlarge
An epidemic of thyroid disease among pet cats could be caused by
toxic flame retardants that are widely found in household dust and
some pet food, government scientists reported Wednesday.
The often-lethal disease was rare in cats until the 1980s, when it
began appearing widely, particularly in California cats. That was at
the same time industry started using large volumes of brominated
flame retardants in consumer products, including furniture cushions,
electronics, mattresses and carpet padding.
Scientists from the Environmental Protection Agency noted a possible
connection between hyperthyroidism and flame retardants. The
chemicals -- known as polybrominated diphenyl ethers, or PBDEs --
mimic thyroid hormones, so experts have theorized that high exposure
in cats could cause overactive thyroids.
Cats that remain indoors and eat fish-flavored canned food were
found to be the most highly contaminated.
"We know there is an association between indoor living for cats and
hyperthyroidism," said Linda Birnbaum, a senior author of the study
and the EPA's director of experimental toxicology. "Our paper does
show cats are highly exposed and hyperthyroidism may be due to the
high PBDEs. More studies are needed to fully determine this."
A major unanswered question is whether cats are the proverbial
canaries in the coal mine, signaling health dangers for their
owners. Cats and human beings are the only mammals with a high rate
of hyperthyroidism.
So far, no link has been established between human endocrine
disorders and exposure to flame retardants. However, "there is
growing concern," the scientists wrote.
"It is clear that house cats may be able to serve as sentinels for
indoor exposure to PBDEs for humans who share their houses," said
Birnbaum, one of the world's leading experts on hormone-altering
chemicals.
Brominated flame retardants are ubiquitous outdoors and inside
homes. The chemicals have been building up in people and wildlife
over the last two decades, particularly in the United States, where
human concentrations have doubled every few years.
People in the United States have the highest PBDE levels in humans
worldwide, but U.S. cats are even more exposed -- some with levels
100 times greater, according to the study.
Twenty-three cats were tested in the EPA's study, including 11 with
hyperthyroidism. The researchers found that the cats with
hyperthyroidism had substantially higher levels of a PBDE compound.
Symptoms of the disease, which is a leading cause of cat death,
include weight loss, rapid heartbeat and irritability.
"Our results demonstrated that cats are being consistently exposed
to PBDEs, an endocrine-disrupting environmental contaminant," the
research team, led by Janice Dye and Marta Venier of the EPA's
National Health and Environmental Effects Research Laboratory in
North Carolina, wrote in their study published in the journal
Environmental Science & Technology. Because of this exposure, "cats
may be at increased risk for developing thyroid hyperplastic
changes."
Myrto Petreas, branch chief of environmental chemistry at the
California Department of Toxic Substances Control, said that the cat
study was small but that it reaffirmed health concerns not only for
cats but humans too, "especially children, anyone exposed to high
levels."
"PBDEs are in consumer products, so we get exposed while we use the
products in homes and during the lifetime of the products. We inhale
or ingest dust, mostly from hand-to-mouth transfer," said Petreas,
who did not participate in the study.
The risk to cats that eat dry food and live in homes with average
contamination is minimal, the study said, while "at the other
extreme, maximal PBDE exposure" occurs in cats that eat fish-
flavored canned food and live in houses with highly contaminated
dust.
Cats that eat canned food containing whitefish, salmon and other
seafood are exposed to PBDE levels up to 12 times higher than cats
that eat dry food, and five times more than cats that eat poultry or
beef canned foods, the study said. The chemicals build up in oceans
and other water bodies and magnify in food chains.
However, much of the exposure -- for cats as well as people -- comes
from dust, not food.
Cats, while sleeping, often come in direct and prolonged contact
with upholstery, carpeting and mattress materials that contain flame
retardants. In addition, they often sit on electronic equipment.
"Because of their meticulous grooming behavior, cats would
effectively ingest any volatilized PBDEs or PBDE-laden dust that
deposited on their fur during such activities," the scientists wrote.
Scientists say toddlers who crawl on floors and put objects in their
mouths also can be highly exposed to the chemical-tainted dust,
which has been found in most U.S. homes.
In people and cats with the highest levels, Petreas said, "it's
explained not by diet, but more contact with contaminated sofas,
computers and other consumer products."
Two pervasive PBDEs, used mostly in foam cushions, mattresses and
carpet padding, have been banned in the United States since 2004.
The ban was spurred by a California law.
However, other brominated flame retardants remain in widespread use.
In June, the California Assembly passed AB 706, written by
Assemblyman Mark Leno (D-San Francisco), which would prohibit
brominated and chlorinated flame retardants in furniture and
bedding. The bill, which now goes to the Senate Appropriations
Committee, does not ban their use in electronics.
California has the nation's strictest fire-retardant standards for
furnishings, so PBDE exposure is generally higher than elsewhere.
The cat epidemic showed up first in California and the Great Lakes
region -- the areas with the highest environmental levels of the
chemicals.
Susan J. DuBose >^..^<
www.PetGirlsPetsitting.com
www.Tx.SiameseRescue.org
www.shadowcats.net
"As Cleopatra lay in state,
Faithful Bast at her side did wait,
Purring welcomes of soft applause,
Ever guarding with sharpened claws."
Trajan Tennent
