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               Estrogen surrogates in sunscreens

  • To: "'radsafe@list.vanderbilt.edu'
  • Subject: Estrogen surrogates in sunscreens
  • From: "Wallace, Howard L" <Howard.Wallace@PSS.BOEING.COM>
  • Date: Fri, 20 Apr 2001 11:45:32 -0700
  • 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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