This article looks at some sunscreen agents commonly in use:
Octyl Methoxycinnamate and other cinnamates cause photo and contact allergy and do not effectively block UVA. We must ask, what is the point of using a sunscreen agent that causes allergy in the presence of sunlight?
Benzophenones/oxybenzone/benzoylmethanes do absorb some UVA radiation but have been found to cause photo/contact allergy and most significantly, they tend to imitate and therefore exacerbate existing skin disease (including acne).
Titanium dioxide effectively blocks out UVA radiation and therefore protects against skin cancer. Although this is also a photon scattering agent (UV reflector), it does absorb UV radiation which produces free radicals in the presence of water. Many manufacturers use different methods to “coat” the particles, making them less reactive.
Salicylates commonly cause photo allergy.
PABA (Paramino benzoic acid) is part of the B group of vitamins. Taken internally, it can help prevent UV damage. Used externally, it causes phototoxicity and sensitisation. PABA generates free radicals when exposed to sunlight, predisposing the skin to cancer. It does not effectively block UVA radiation. It is banned as a sunscreen agent.
Zinc oxide effectively blocks out UVA radiation, has the benefit of being inert on the skin (it does not absorb UV radiation) and has skin healing properties. It does, however, contain large particles and can form a paste when applied to the skin. The finer the zinc particles, the less visible they are on the skin. Micronized superfine zinc is the best choice for minimizing the “paste-effect” without resorting to nanoparticles.
Iron oxide is found naturally in mineral clays. Due to the large particle size, iron oxide also acts as a UV reflector and is inert in the sun (does not produce free radicals). Natural mineral clays also contain varying proportions of other UV protectors such as titania.
It must also be noted that this discussion of the active constituents in sunscreens is academic without paying respect to the ingredients in the carrier or base formulation. Do they cause free radical damage themselves and in particular, how well do they stand up to sun exposure?
There are instances of people using sunscreens who have reacted to the excipients (base materials/carriers) included in the formulation, such as preservatives, fragrances and emulsifiers, which have caused contact allergies. So there is cause for concern not only about the active ingredients in sunscreens, but about the inert ingredients as well. Ed note: I don’t know about anyone else but standard sunscreens make my eyes sting and water particularly after swimming in the surf. I worked out that for me, it is probably the product fragrance that is causing this effect. In any case, it has been a long time since I have used a conventional sunscreen as I prefer to stick to zinc oxide based products, including GOOD DAY SUNSHINE Sunscreen from Kasia Organics.
There are a number of base ingredients to look for such as antioxidant vitamins C and E at effective concentrations. Vitamins C and E (tocopherol) are known to protect against skin cancer, particularly when applied topically as they prevent free radical damage from UV radiation. Certified organic shea butter, sesame and avocado oils have natural UV protective qualities, primarily due to their vitamin A and E content. Shea butter also protects against burning (UVB radiation) and is an excellent emollient, softening the skin and preventing the formation of wrinkles. Aloe vera, a plant which has been shown to prevent DNA damage to the skin following sun exposure and its use in treating burns of all descriptions is well-known and an excellent inclusion as a base ingredient. Antioxidant medicinal strength herbal extracts of ginkgo biloba, green tea and pomegranate are also excellent for their ability to protect against DNA damage from UV radiation.
Reference: by Tess Dingle ND