potential danger in some sunscreens

[Guest guest]

i haven't seen anything in this group about this

topic, so...

``...

Out of the frying pan...

NewScientist 21 Apr 01

Protecting yourself against the Sun

may expose you to a hidden risk

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.

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. " Evidence that they're a real health

concern is still lacking, " says 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. "

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.

Further reading:

More at: Environmental Health Perspectives (vol 109, p 239)

Nicola From New Scientist magazine, vol 170 issue 2287,

21/04/2001, page 5

....''