Sunscreens with UV Filters that Mimic Estrogen
Skin cancers are a direct result of overexposure to the UV rays in sunlight. Both basal cell and squamous cell cancers (the most common types of skin cancer) tend to be found on sun-exposed parts of the body, and their occurrence is typically correlated to lifetime sun exposure. The risk of melanoma, a more serious but less common type of skin cancer, also has some relation to sun exposure. Skin cancer has also been linked to exposure to artificial sources of UV rays, such as using a tanning bed. Due to the high possibility of skin cancer due to overexposure of UV rays, a commitment to sun protection when outside and avoiding the most intense sun during the day, is one of the most important things we can do for prevention of skin cancers.
When choosing a sunscreen, it is important to select broad spectrum sunscreens without harmful chemicals. In a study of six common sunscreen chemicals, five of them exerted significant estrogenic activity, as measured by the increase in proliferation rates of human breast cancer cells (MCF-7 cells) grown in vitro. These chemicals were 3-(4-methylbenzylidene)-camphor (4-MBC), octyl-methoxycinnamate (OMC), octyl-dimethyl-PABA (OD-PABA), bexophenome-3 (Bp-3) and homosalate (HMS). The results for 4-MBC have been replicated in other laboratories.
The current body of evidence suggests that zinc oxide macroparticles are safest and most efficacious for blocking the harmful rays of the sun, both UVA and UVB.