Volume 79, Number 49
CENEAR 79 49 pp. 25-29
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A tempest in a teapot? yes, say manufacturers of organic sunscreens, who in March suddenly found themselves reacting to a report that certain sunscreens were potential endocrine disrupters.
For now, sunscreen makers have convinced regulators, formulators, and consumers that protection from UV-induced skin cancer, wrinkles, and aging outweighs any supposed risk to human growth and development. According to a European Union (EU) cosmetics advisory committee, currently approved sunscreens would have to be at least 100,000 times more potent than they are before any could have a hormonal effect on people.
And even the author of the study hauling sunscreens under the microscope says that, based on her tests, "no conclusions can be drawn with respect to risk of cancer or alterations of growth. Decisions on withdrawal of such compounds would be premature." Margaret Schlumpf is the head of the group responsible for the research paper [Environ. Health Perspect., 109, 239 (2001)] that set the stage for the controversy. She is an environmental toxicologist at the University of Zurich's Institute of Pharmacology & Toxicology (C&EN, May 14, page 26).
In vitro and in vivo tests suggested that two ingredients in particular--4-methylbenzylidene camphor (4-MBC) and octyl methoxycinnamate (OMC)--have estrogenic activity. The first is approved as a cosmetic ingredient in Europe; the second is an approved over-the-counter drug in the U.S. and is also approved for use in Europe and other parts of the world.
BUT THE SHOW ENDED with a report in June from the Scientific Committee for Cosmetic Products & Non-Food Products Intended for Consumers. The committee, a European Commission advisory body, questioned Schlumpf's experimental protocols and concluded that "organic sunscreen products allowed in the EU market today have no estrogenic effects." (The full report is available on the Web at http://europa.eu.int/comm/food/fs/sc/sccp/out145_en.html.)
Schlumpf tells C&EN that industry, regulators, and even journalists jumped to conclusions about her work. But she provides an epilogue: "We did not withdraw any statement on the estrogenicity of the UV filters." She says she is currently working on extended tests of 4-MBC--the sunscreen that showed greatest potential estrogenic activity in her earlier studies.
Schlumpf's work will continue to nag makers of sunscreens. But it is unlikely to have the effect that mad cow disease has had on producers of animal-derived cosmetic ingredients.
When word got around a few years ago that humans could get brain-destroying bovine spongiform encephalopathy disease by eating tainted meat, cosmetic makers replaced just about all animal-derived ingredients with vegetable-derived products--even though no evidence showed that animal-derived soaps or cosmetic products could pass along the disease. Too many people just feared a connection.
In the case of sunscreens, active ingredient makers and formulators say quick action means consumers can still get the protection they need against skin damage. Quick action has also preserved a huge market for sunscreens. Industry consultant Kline & Co. projects that 2001 sales of sunscreen active ingredients in the U.S. and Western Europe will be $100 million apiece and will grow about 4% annually through 2006.
In both cases, 80% of the market is organic sunscreens, while specialized versions of the inorganic pigments titanium dioxide and zinc oxide account for the balance. Organics have a greater share because they are generally less expensive than the inorganics and are easier to formulate with.
The largest organic sunscreen makers and distributors--BASF, Bayer's Haarmann & Reimer, Roche, Germany's Merck, and Ciba Specialty Chemicals--all contend that their UV filters are safe and pose no hazard for consumers.
Haarmann & Reimer thought so highly of 4-MBC that it considered applying to the Food & Drug Administration for listing in the U.S. Not anymore, though, says Karl A. Harris, cosmetic ingredients business unit director.
Ratan K. Chaudhuri, technical director for Merck's U.S. affiliate, EM Industries, says his company was initially concerned when Schlumpf published her paper. Merck supplies OMC, makes other organic filters, and markets microfine titanium dioxide under a partnership with the German TiO2 producer Sachtleben Chemie. "We funded studies through an independent lab and found no estrogenic activity for 4-MBC," he says.
However, Chaudhuri notes other problems with organic sunscreens. Some may irritate the skin of sensitive individuals. Others are not photostable. And a very small amount can sometimes penetrate the topmost layer of the skin, rendering the UV filter less effective. In response, says Chaudhuri, "we've developed a new 'nondelivery, delivery system' for sunscreens."
After searching for 10 years, Merck has found a technology to encapsulate organic sunscreen droplets and other ingredients in a polymer based on tetraethoxysilane to yield a water-based dispersion. "The active ingredient never touches the skin. And it has the effect and efficiency of unencapsulated sunscreens." Israeli firm Sol-Gel Technologies owns the technology, developed at Hebrew University of Jerusalem, to which Merck has exclusive rights.
Chaudhuri denies that Merck wants to use the encapsulation method to capitalize on any concern over hormonal activity. Schlumpf's studies, he says, "cannot be understood and cannot be confirmed." But the new Eusolex UV-Pearl line, the first of which encapsulates OMC, will allow formulators to make daily-wear sunscreens that "eliminate the irritation potential and keep the active ingredients on top of the skin."
Other producers also sing the safety of organic sunscreens. "Suppliers need to be sure the products they sell are safe," says Volker Schehlmann, BASF technical development manager. "And if Schlumpf's data are correct, the question is, what does it mean?" It means that the potency she reports for certain sunscreens is minimal compared to what we eat in our daily diet. Compared with vegetable sources of estrogen, the worst offending sunscreen is 2,200 times less potent, he says.
"That is probably the reason why no regulatory body in the U.S. or Europe saw a reason to take action," Schehlmann says. "The benefit of using sunscreen considerably outweighs any minimal risks at this time." And he points out that both OMC and 4-MBC are safe and have been around a long time.
While BASF defends its portfolio of organic sunscreens, it also has a portfolio of inorganic alternatives. The company is unique, he says, because it manufactures and supplies both types, which "act synergistically together."
For instance, BASF supplies microfine TiO2, under the Univul trade name, and zinc oxide, under the trade name of Z-Cote, that offers broad-spectrum UV-A and UV-B protection. A daily facial moisturizer in Procter & Gamble's Oil of Olay skin care line makes use of both Z-Cote and OMC, says Schehlmann.
Ralph Macchio, senior vice president of R&D at cosmetics manufacturer Coty, agrees with Schehlmann on the safety and benefits of sunscreens. "A tan is the body's reaction to damage," he says. With depletion of the ozone layer and greater outdoor exposure to UV light, he sees an even greater need for UV filters today than ever.
As a result, Coty has increased the number of products in its line that contain sunscreens. "It's gone from beach products to daily wear," says Macchio, "because more people are aware now that they can get a sunburn away from the beach."
And the Sun Protection Factor (SPF) index for all products containing sunscreens has been on the rise, he says. Where the typical SPF was 15 in the mid-1980s and 30 in the 1990s, some sunscreens today offer even higher protection, and "we now talk about antiaging and SPF because of the link between sun damage and aging."
Ciba Technical Marketing Manager Uli Osterwalder says his company takes Schlumpf's report seriously. "We've tested our newest UV filters, Thosorb M and S, in vitro and in vivo and found they have no endocrine disruption potential," he says. "We also distribute OMC. Any hazard from use of this UV filter is small. However, we do know that UV radiation is carcinogenic."
A PARTICULAR PROBLEM is skin exposure to UV-A light in the 320- to 400-nm range. Organic filters approved in the U.S. all protect against sunburn caused by UV-B light in the 290- to 320-nm range. Only Roche's avobenzone, sold as Parsol 1789, offers UV-A protection, Osterwalder says. So formulators must include either Roche's product or zinc oxide for any appreciable protection against UV-A, which can penetrate more deeply into the skin than UV-B and can also cause severe damage.
Ciba has petitioned FDA to approve its Tinosorb M sun filters for use in skin care products to give formulators another choice. Based on benzotriazole chemistry, Tinosorb M is a microscopic particle about 200 nm in diameter. The product not only acts as a water-dispersible UV absorber, but its particles can also scatter and reflect light. And like TiO2 and zinc oxide, it can boost the SPF index of a skin care formulation because it has UV-B blocking abilities as well.
Formulators that might have some concerns with organic filters, or that might want to use less of them, have alternatives. They can add ingredients that boost sun-filter performance, or they can blend organic with inorganic sunscreens or use inorganic sunscreens alone.
For those that want to boost SPF levels without using more sunscreen active ingredient--or use less sunscreen to get the same SPF levels--ISP has a solution. Developed under a personal care alliance with Rohm and Haas, ISP's Sunspheres can boost SPF by 50 to 70%, says Mary Davis, skin care business development director. The styrene acrylate copolymer hollow spheres refract light and thereby increase the chance that light will contact both organic and inorganic UV filters.
Croda's Crodafos CES, an emulsifying wax, also offers a boost to organic and inorganic sunscreens. Patrick Obukowho, personal care applications manager, says that because the product's blend of phosphate esters and fatty alcohol is such an effective system for delivering sunscreen actives to the surface of the skin, it can boost SPF values by 15 to 20%.
Gary J. Dee, care specialties business manager for Cognis, notes that a formulator's choice of emollients and other oil-based components can enhance or retard the effect of expensive sunscreens. "By understanding the carrier, you can get not only a more elegant and more efficient sunscreen, but also higher SPF," he says.
Understanding the spreading characteristics of emollients allows Cognis to help a customer to "tailor make" a sunscreen that allows the consumer to rub on a long-lasting film containing UV filters. And the feel of the sunscreen can be altered through choice of ingredients as well, in what Cognis calls its Cascading Emollients System.
Sam Naggiar, Cognis sun care project manager, explains that avobenzone, Roche's UV-A sunscreen, is a dry powder that may come out of solution, feel gritty, and irritate the skin if it is not dissolved in an appropriate carrier. Use of Cognis' dibutyl adipate, known as Cetiol B, overcomes that problem and, he adds, it is also an excellent solvent for all crystalline UV filters.
IT IS ALSO IMPORTANT to properly formulate and disperse inorganic sunscreens so that they are effective, says Julian P. Hewitt, sun care application team leader for Uniqema. Hewitt says the inorganics remain effective as long as the particles remain on the skin because they are photo-stable. (Some in the industry note that certain organic sunscreens are not photostable.)
Hewitt also contends that TiO2 and zinc oxide are unlikely to irritate "sensitive skin," and so are more often used in products for babies and young children. But while microfine grades of both zinc and TiO2 make good sunscreens, they often have a whitening effect on skin.
"Intensive work to develop a more transparent grade of TiO2 is nearing completion," he says. This new transparent TiO2, suitable especially for use in "prestige" cosmetics, will be commercially available next year. It will take advantage of Uniqema's development of a product with a "narrower particle size distribution." The company plans to reveal further details later this week at the Society of Cosmetic Chemists meeting in New York City.
Intensive work on organic sunscreen development is likely to continue in the months ahead, too. And Schlumpf and colleagues continue their investigations into the suspected estrogen activity of some organic sunscreens.
Manufacturers of organic sunscreens will continue to look closely at their products to assure themselves and the public of their safety. Some believe it is counterproductive to even discuss Schlumpf's research in public both because her findings are still so preliminary and because it may convince the public not to use a product that everyone agrees helps prevent skin cancer.
"There is no trend now to move away from sunscreens Margaret Schlumpf tested," BASF's Schehlmann says. "We have a long history of use for OMC and 4-MBC. And both have proved to be safe to use, and they remain widely accepted."
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