As the Earth enters into its altered state in relation to the Sun many Northern hemisphere regions become ultraviolet radiation (UVR) "magnets". With this annual, albeit short-lived, repositioning of the Earth comes the annual positioning of products for solar lifestyles: sunscreen-bearing hair, skin, face and lip products. Do formulators and marketers ever give thought to the safety of these UVR protectants, which read and sound like the answers of a championship crossword puzzle for organic chemists?
One research group has taken the safety of these compounds beyond face value. In studies published in April of this year and December of last, researchers from the Institute of Pharmacology and Toxicology at the University of Zurich assessed the ability of several sunscreens to disrupt endocrine (hormone) function. In the test tube they found five of the six sunscreens to stimulate a breast cancer cell type that is turned on by estrogen-like chemicals. These included: benzophenone-3 (Bp-3), homosalate, 4-methyl-benzylidene camphor (4-MBC), octyl-methoxycinnamate (OMC), and octyl-dimethyl-PABA (the sixth sunscreen agent, butyl-methoxydibenzoylmethane , was without effect).
When willing, sexually immature female lab rats received one of the six chemicals in their diet (not a typical means of exposure but not atypical in the example of lip blocks and lip treatments, wherein licking of the lips is usually unavoidable) for four days (whopping doses, mind you) uterine weight increased with increasing doses of 4-MBC, OMC, and to a lesser extent by Bp-3. The other three compounds were orally inactive. Most interestingly, application of 4-MBC (in olive oil) to immature hairless rats also elicited increases in uterine weight at concentrations of five and 7.5 per cent.
Are these findings relevant and of concern to us humans? The London-based Cosmetic Toiletry & Perfumery Association asserts the concentrations investigated by the Swiss group far exceed those encountered by humans. One "antique", inorganic alternative to organic (that is, containing carbon) is titanium dioxide (known as "TiO2" its chemical symbol in cosmeceutical circles), a broad spectrum UVR screening agent.
A recent study suggests how effective TiO2 can be and underscores another, dark side of UVR immune suppression. Researchers from Leiden University in the Netherlands and the University of Edinburgh exposed the forearms of healthy humans with antibodies to HSV-1 (associated with oral herpes infection) to a precise dose of UVR from a sunlamp. Some of the subjects had a 9.5 per cent TiO2 sunscreen (SPF 10) applied to the forearm 10 minutes before "baking". UVR produced a significant reduction in immune function, which was completely blocked by application of TiO2.
So how relevant are these findings? Although this was a pilot study it did involve humans and revealed a functional change of biological and public health significance. TiO2 is cheap, effective, and does not appear to have any toxic effects of any significance. It may not be a sexy ingredient but it also would not be expected to be an endocrine disrupter, in the test tube, in animals or humans. A sexy complement to TiO2 would be green tea polyphenols, a member of a diverse subset of natural products with UVR protecting effects. Researchers from the University of Alabama in the USA recently showed that application of the most "bioactive" green tea polyphenol, EGCG (~1 mg/cm2 skin in 50 microliters of acetone), 20 minutes before exposure of human buttock skin to UVR, confers substantial protection against UVR-induced oxidative stress and inflammation. This was noted in both the epidermis and dermis.
Lessons To Be Learned
As noted by the authors of this last study, despite the prevalence of "green tea polyphenol"-containing cosmeceuticals, the question of effective dose remains unanswered. Does simply the inclusion of green tea polyphenols, and their labelling on the packaging, confer bioactivity and consumer-relevant efficacy? Most likely not. For a product to "work" a manufacturer/marketer has to work at it. Cosmeceuticals, by definition, are not a cosmeceutical and are thus an ineffective cosmetic until proven effective.
Anthony L. Almada, BSc, MSc, is the president and chief scientific officer of IMAGINutrition, Inc., in Aptos, California, USA. www.imaginutrition.com