Ultraviolet Protection with Cosmeceutical Ingredients

The sun, our source of vital light and warmth, has a love/hate relationship with the inhabitants of Earth. The sun helps our bodies produce vitamin D, an essential nutrient, as well as triggering various light-controlled functions. Unfortunately, the sun can also inflict sunburn, ultraviolet (UV) damage, wrinkles and sun spots. Research on the dangers of the sun has only been prevalent in the past decade or so, leaving many people playing catch-up and trying to undo years of skin damage.

With the growing amount of research on the possible perils of sun exposure, the demand from consumers for products that contain sun protection continues to rise. And increasingly, the trend is for formulas with ingredients that naturally provide SPF. "Many people are turning to natural personal care to avoid the potential health risks posed by synthetic ingredients, especially those that are absorbed deep into the skin, acting at a cellular level, like sunscreen," said Celeste Lutrario, vice president of research and development, Burt’s Bees. Companies are looking to eliminate popular but potentially harmful ingredients from their sunblock formulas, such as parabens and phthalates, chemical preservatives that have possible carcinogenic effects; pore-clogging petroleum and mineral oil; and metoxycinnate and benzophenones, which can generate free radicals and are known skin irritants. An in vitro study from Copenhagen University Hospital, Denmark, found that three chemical ultraviolet absorbers, benzophenone-3 (BP-3), octyl-methoxycinnamate (OMC) and 3-(4-methylbenzylidene) camphor (4-MBC) possess endocrine-disrupting effects in animals.¹ For four days, 32 volunteers were exposed to whole-body topical applications of 2 mg/cm² of a sunscreen formulation at 10 percent (w/w) of each ingredient. Blood and urine concentrations were measured over the course of those days. Results showed all three sunscreens were undetectable in plasma and urine before the first application, but one to two hours after the first application, all three were detectable. The maximum median plasma concentrations were 187 ng/mL BP-3, 16 ng/mL 4-MBC and 7 ng/mL OMC for females and 238 ng/mL BP-3, 18 ng/mL 4-MBC and 16 ng/mL of OMC for men. A similar study from Buenos Aires supported the theory that OMC is an endocrine disruptor with estrogenic activity.² This in vitro study examined OMC’s effects on the hypothalamic release of luteinizing-hormone releasing hormone (LHRH), as well as on the amino acid neurotransmitter system in immature rats of 15 (prepubertal) and 30 (peripubertal) days of age. OMC decreased the LHRH release significantly in male and female rats of both ages. In male rats, OMC increased the release of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter; in the female ones, OMC diminished the excitatory amino acid aspartate (ASP) and glutamate (GLU) without modifications in the hypothalamic GABA release. Researchers concluded the inhibitory effect of OMC on LHRH release appears to be related to its action on the inhibitory and excitatory amino acid neurotransmitters in male and female rats.

Natural Sun Blockers

Two of the most popular SPF ingredients to replace potentially dangerous chemical sunblocks are titanium dioxide and zinc oxide, oxidized versions of naturally occurring metals. They are not absorbed into the skin, but instead act as reflective sun blocks when applied, protecting against UVA and UVB rays, and are ideal for those with sensitive skin. Incidentally, these ingredients are the "only two natural ingredients FDA recognizes as sun protectants," Lutrario said. A study from sunSmart Inc., New York, assessed the suitability of microfine zinc oxide as a broad-spectrum photoprotective agent by examining properties generally considered important in sunscreens: attenuation spectrum, sun protection factor (SPF) contribution, photostability and photoreactivity.³ Results showed zinc oxide attenuates throughout the UVR spectrum, including long-wavelength UVA; is photostable and does not react with organic sunscreens under irradiation; and is an effective and safe sunblock that provides broad-spectrum UV protection.

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