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Estrogen surrogates in sunscreens
The New Scientist has an interesting article on this subject at http://www.newscientist.com/dailynews/news.jsp?id=ns9999641 .
Text of the article follows my signature.
Howard Wallace, Certified Health Physicist
Phone: (425) 393-9059 The Boeing Company
Fax: (425) 393-3060 email: Howard.L.Wallace@Boeing.com
***************************************************
Sun block
Gender-bending chemicals that mimic oestrogen
are common in sunscreens, warn Swiss
researchers
Exclusive from New Scientist magazine
Gender-bending chemicals that mimic the effect of oestrogen
are common in sunscreens, warns a team of Swiss researchers
who have found that they trigger developmental abnormalities
in rats.
"We need to do more tests to see how they might be affecting
people," says Margaret Schlumpf from the Institute of
Pharmacology and Toxicology at the University of Zurich,
Switzerland.
Researchers know that chemicals which behave like oestrogen
can cause health problems. They can have a dramatic effect
on animals, for example turning fish into hermaphrodites.
Some researchers claim that hormonally active chemicals from
the urine of women taking the birth control pill are already
swamping the environment, and may be causing a decline in
sperm counts.
Uterine growth
Schlumpf and her colleagues tested six common UV screening
chemicals used in sunscreens, lipsticks and other cosmetics.
All five UVB screens -benzophenone-3, homosalate,
4-methyl-benzylidene camphor (4-MBC),
octyl-methoxycinnamate and octyl-dimethyl-PABA - behaved
like oestrogen in lab tests, making cancer cells grow more
rapidly.
Three caused developmental effects in animals. Only one
chemical - a UVA protector called
butyl-methoxydibenzoylmethane (B-MDM) - showed no
activity.
One of the most common sunscreen chemicals, 4-MBC, had a
particularly strong effect. When the team mixed it with olive oil
and applied it to rat skin, it doubled the rate of uterine growth
well before puberty. "That was scary, because we used
concentrations that are in the range allowed in sunscreens,"
Schlumpf says.
Nobody knows if doses are high enough to create problems for
people, says Schlumpf.
Low levels
"Evidence that they're a real health concern is still lacking,"
says Richard Sharpe from the Medical Research Council's
Reproductive Biology Unit in Edinburgh. But he adds, "It's not
good news that we are lathering ourselves with creams with
hormonal activity."
The Cosmetic Toiletry & Perfumery Association, which
represents sunscreen manufacturers in Britain, replies that the
levels found by Schlumpf are well below anything that would
cause an effect after a single application.
A study by the association, not yet published, shows no effect
from these chemicals in rats. But, it adds, "If levels are
increasing [in the environment] then we're aware something
would have to be done soon."
Breast milk
That day may be here since 4-MBC and other sunscreen
chemicals have been shown to accumulate in fish from lakes
where people swim.
More worryingly, they have been found in breast milk at levels
of nanograms per kilogram of fat - about the same as other
known environmental contaminants. Schlumpf worries that the
large amount of sunscreen used by bathers, especially
children, could dramatically increase this exposure.
Schlumpf says the other 25 or so chemicals used in
sunscreens should also be tested for hormonal activity, and
she will be looking more closely at 4-MBC to see if the
offspring of exposed rats develop health problems.
For the moment, she isn't advising people to ditch sunscreens
completely, but suggests that sunblocks like zinc oxide might
make a healthier alternative.
More at: Environmental Health Perspectives (vol 109, p 239)
Correspondence about this story should be directed to
letters@newscientist.com
1900 GMT, 18 April 2001
Nicola Jones
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