Sun Block has Endocrine Disruptor Chemicals
New Scientist 18apr01
[Environmental Health Perspectives Abstract below]
Gender-bending chemicals that mimic oestrogen are common in sunscreens, warn Swiss researchers
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 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."
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.
Environmental Health Perspectives v.109, n.3, Mar01
Margret Schlumpf, Beata Cotton, Marianne Conscience, Vreni Haller, Beate Steinmann, and Walter Lichtensteiger
Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
Ultraviolet (UV) screens are increasingly used as a result of growing concern about UV radiation and skin cancer; they are also added to cosmetics and other products for light stability. Recent data on bioaccumulation in wildlife and humans point to a need for in-depth analyses of systemic toxicology, in particular with respect to reproduction and ontogeny. We examined six frequently used UVA and UVB screens for estrogenicity in vitro and in vivo. In MCF-7 breast cancer cells, five out of six chemicals, that is, benzophenone-3 (Bp-3), homosalate (HMS), 4-methyl-benzylidene camphor (4-MBC), octyl-methoxycinnamate (OMC), and octyl-dimethyl-PABA (OD-PABA), increased cell proliferation with median effective concentrations (EC50) values between 1.56 and 3.73 µM, whereas butyl-methoxydibenzoylmethane (B-MDM) was inactive. Further evidence for estrogenic activity was the induction of pS2 protein in MCF-7 cells and the blockade of the proliferative effect of 4-MBC by the estrogen antagonist ICI 182,780. In the uterotrophic assay using immature Long-Evans rats that received the chemicals for 4 days in powdered feed, uterine weight was dose-dependently increased by 4-MBC (ED50 309mg/kg/day), OMC (ED50 935 mg/kg/day), and weakly by Bp-3 (active at 1,525 mg/kg/day). Three compounds were inactive by the oral route in the doses tested. Dermal application of 4-MBC to immature hairless (hr/hr) rats also increased uterine weight at concentrations of 5 and 7.5% in olive oil. Our findings indicate that UV screens should be tested for endocrine activity, in view of possible long-term effects in humans and wildlife. Key words: benzophenone-3, estrogenic activity, MCF-7 cell proliferation, 4-methylbenzylidene camphor, octylmethoxycinnamate, pS2 protein, rat, uterotrophic assay, UV screens. Environ Health Perspect 109:239-244 (2001). [Online 28 February 2001]
Address correspondence to M. Schlumpf, Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland. Telephone: +41-1-635 5971. Fax: +41-1-635 6857. E-mail: email@example.com
Preliminary reports were presented at the 9th Annual Meeting of SETAC-Europe, Leipzig, Germany, 25-29 May 1999, and at the Third SETAC World Congress, Brighton, U.K., 21-25 May 2000.
We wish to thank A. Soto and C. Sonnenschein for their valuable help in establishing the MCF-7 cell system, and J. Ashby and M. Prins for their advice on the uterotrophic assay.
This investigation was supported by the Swiss Environmental Protection Agency (Bundesamt für Umwelt, Wald und Landschaft), grants FE/ BUWAL/1999.H.03 and FE/BUWAL/2000.H.04.
Received 22 August 2000; accepted 13 October 2000.
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