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WHEN CERTAIN chemicals in a class known as phthalates, used to soften vinyl
plastic, were found to leach out of baby rattles and teethers several years
ago, it touched off a controversy that led to bans and voluntary recalls
in the toy industry. Regulators started reassessing the safety of these
chemicals, which some investigators suspect of causing cancer and birth
defects.
Now, researchers at the Centers for Disease Control and Prevention report
in the October issue of the journal Environmental Health Perspectives that
the average American may be exposed to other chemicals in the phthalate
family — substances shown to cause cancer, birth defects and adverse hormonal
effects in lab animals.
The researchers detected surprisingly higher levels of these plasticizers
than of toxins often tested for, such as lead or polychlorinated biphenyls
(PCBs) — and much higher than the other phthalates that had been most controversial
— in random urine samples taken of the American population. They concluded
that it was “critically important” to get further exposure data on these
chemicals, used in cosmetics, and a wide variety of other consumer products,
in order to assess health risks to people, especially “potentially susceptible
populations.”
Phthalates, chemicals that off-gas from plastic (familiarly associated
with “new car smell”) are used in scores of consumer products — everything
from perfumes and hair sprays to artificial leather and garden hoses, hair
sprays and lotions to shower curtains and vinyl flooring.
With up to 4 million tons of phthalates produced and widely used throughout
the world each year, industry representatives downplay any adverse effects
to human health.
NEW RESEARCH
The new study, done by CDC’s National Center for Environmental Health,
represents the first time researchers have measured the presence of phthalates
in humans. “It’s an important study,” says Mike Shelby, chief of the toxicology
laboratory at the National Institute of Environmental Health Sciences (NIEHS),
“because it shows for the first time how much of these compounds people
are really being exposed to.”
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Find
the phthalates |
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Di-ethyl phthalate:
Toothbrushes, auto parts, tools, toys, food packaging, insecticides, mosquito
repellents, aspirin and volatile components of cosmetics -- perfumes, nail
polishes and hair sprays. |
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Di-n-butyl phthalate:
Cellulose plastics, solvents for dyes, solvents for cosmetics (i.e., nail
polish), food wrap, perfumes, skin emollients, hair spray, insect repellents. |
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Benzyl butyl phthalate:
Plasticizers in adhesives, PVC flooring, wood finishes, biodegradable tampon
ejectors |
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| Sources: ATSDR,
CDC, Industry sources |
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The results, he says, show both that people are being exposed on a wide
scale and that “those with the highest levels are getting higher doses
than we thought.”
While the highest doses are at levels “much lower than where you’d see
toxic effects in rodents,” says Shelby, “it’s when those two start approaching
one another that you start to worry.”
More research is already underway on a bigger sampling of the population,
with more tests needed to better determine what health effects phthalates
might cause in people or developing fetuses.
Yet these preliminary findings add to concerns that “background” levels
of many chemicals in the environment — long thought to be in small enough
concentrations to have negligible effects on human health — could play
a crucial role in human development as well as in causing cancer, neurological,
immune system disorders and infertility, says Jim O’Hara, director of Health
Track, a new nonprofit group funded by the Pew Charitable Trusts trying
to build support for better “exposure” monitoring.
“What this study points to,” says O’Hara, “is that there’s a significant
gap in our knowledge of what levels people have of toxic substances.”
His views echo those of the Pew Environmental Health Commission, which
has charged that the nation faces an “environmental health gap.” In September
the commission called on Congress to mount a new program to effectively
track and monitor the chronic diseases that stem from environmental pollution
— everything from asthma and chronic respiratory diseases to birth defects
and developmental disorders to multiple sclerosis and Parkinson’s. While
“overt poisoning from environmental toxins has long been recognized, the
environmental links to a broad array of chronic diseases of uncertain cause
is unknown,” the Commission wrote.
CDC chemist John Brock, the lead researcher on the phthalate study, came
upon his discovery by accident. While he was looking for known carcinogens
such as PCBs in blood and urine, he discovered phthalates present at levels
1,000 times higher than PCBs.
Metabolites of diethyl phthalate (DEP), used in volatile components of
cosmetics like perfumes, nail polishes and hairsprays, were found at levels
about 70 times higher than metabolites of di-(2-ethylhexyl) phthalate (DEHP),
one of the chemicals banned in soft plastic toys, for example.
“Phthalates are everywhere in the lab, in the vials, the tubing, and the
syringes,” says NIEHS’s Shelby. “So we routinely shrugged them off as contaminants.”
But Brock was compelled by the question: What if they weren’t just contaminants,
but rather residues of chemical exposures in the environment from the widespread
use of phthalates from a variety of routes — through food and drink, skin
absorption or inhalation, for example?
“Everyone was looking for the needle in the haystack, when what they should
have been looking at was the hay,” says Brock. He went on to prove in ongoing
studies over the past few years that the “troublingly” high levels of phthalates
he detected in humans weren’t coming from soft plastic tubing but from
chemicals used in a wide range of products, ranging from nail polishes
and perfumes, hand lotions and soaps, to wood finishes.
By tracing the human metabolites of these chemicals — the breakdown products
in the human body — “we’ve been able to get really accurate numbers on
how average Americans are being exposed,” Brock says.
STUDY DETAILS
In the study, researchers measured the levels of seven phthalate metabolites
in urine samples taken from 289 people. The researchers are now following
up on an additional 1,000 subjects to better ascertain the sources of the
phthalates.
At this point, says Brock, it’s certainly not clear what health effects
the phthalates may have on the subjects. However, his biggest concern was
that “the highest levels of exposure were in women of child-bearing age.” |
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Reproductive biologist Earl Gray of the Environmental Protection Agency,
who studied the effects of phthalates on rodents, says that there’s ample
cause for concern as the chemicals are reproductive toxins, with two, DBP
and BzBP, particularly anti-androgenic, tending to block male hormones.
“The effects on rats were quite profound, creating malformed genitalia,
vaginal pouches, absent or undescended testes, and infertility,” says Gray.
The industry-sponsored Phthalate Esters Panel, while praising the study
for its use of the latest diagnostic chemical techniques, said the phthalate
levels uncovered in the CDC study are of “negligible” concern.
In a letter to CDC, the Panel’s toxicologist Raymond M. David suggested
using a formula that could take the new urine data and extrapolate “intake”
levels of the phthalates based on data from human volunteers in Britain.
With this formula, he found the “intake” exposures to be “at or below levels
that the EPA has determined to be safe for daily exposures.”
PROTECTING OUR HEALTH
Others, however, took the findings as a sign that the current regulatory
regime is not protecting public health. “This study reveals that exposures
are real, and that we’ve neglected the vital work of testing our own bodies
for pollutants in the environment,” says J. P. Myers, one of the co-authors
of the book “Our Stolen Future,” which proposed that hormone-disrupting
chemicals in the environment might be producing cancers and other ill effects.
“For a long time we’ve been depending on safety limits developed by engineers
and based on assumptions that are probably wrong.” |
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