It is pretty easy to just ignore important information when we see products on the shelf at Target or CVS with pretty packaging and we think “this can’t be a health threat?  Otherwise, these stores wouldn’t be allowed to sell them…”; however FDA approval is very loose with regulations in self care products.  If a product or ingredient doesn’t have direct evidence, for example, of causing cancer or threatening people’s lives, the chances are good it will be approved for production.  

There are several ingredients specifically in sunscreen that, through studies, have shown evidence that they are harmful to our health.  The three most common UV filters that have been proven to be the most harmful (especially because they penetrate into the skin immediately upon application) are oxybenzone, octinoxate, and homosalate.

Oxybenzone is the most concerning ingredient.  Studies have shown a correlation in the following: lower testosterone levels in young boys, birth weights in babies whose mothers had been exposed, and increased risk of endometriosis and breast cancer being that it acts as an endocrine disruptor. The National Toxicology Program found equivocal evidence of carcinogenicity in rats after observing increases in thyroid tumors and uterine hyperplasia in females with high exposure to oxybenzone (NTP 2020).

Octinoxate (Octyl methoxycinnamate) is the second most concerning ingredient.  Animal studies have shown the chemical has hormone effects on the metabolic system and affects thyroid hormone production (Seidlova-Wuttke 2006), with some evidence for other endocrine targets, including androgen and progesterone signaling (Krause 2012). Octinoxate can also cause allergic reactions after exposure to ultraviolet light (Rodriguez 2006).  It has also been proven that it can be harmful to marine life. 

Homosalate has been found to penetrate the skin, disrupt hormones and produce toxic breakdown byproducts over time (Krause 2012, Sarveiya 2004, SCCNFP 2006, Matta 2020).  It is recommended that this ingredient be used at 1.5% and not to exceed 10%.  The FDA allows sunscreens to use up to 15% in their formulas.  

It has only been recently (as in the last decade) that consumers are digging deeper into what is in their self care products. FDA-approved sunscreen chemicals, often referred to as active ingredients, provide ultraviolet, or UV, protection and have been used in sunscreen formulations for years and years.  The best ingredients to look for are titanium dioxide and zinc oxide- they are proven safe and effective by the 2019 FDA classification, they do not absorb into the skin, and they do not cause hormone disruption or other health concerns.  You may have a little white residue on your skin but worth the trade off!

NTP, Toxicology and Carcinogenesis Studies of 2-Hydroxy-4-methoxybenzophenone Administered in Feed to Sprague Dawley (Hsd:Sprague Dawley SD) Rats and B6C3F1/N Mice. 2020. Available at
Seidlová-Wuttke et al., Comparison of effects of estradiol (E2) with those of octylmethoxycinnamate (OMC) and 4-methylbenzylidene camphor (4MBC) – 2 filters of UV light – on several uterine, vaginal and bone parameters. Toxicology and Applied Pharmacology, February 2006, 210(3):246-54.
Krause et al., Sunscreens: Are They Beneficial for Health? An Overview of Endocrine Disrupting Properties of UV-Filters. International Journal of Andrology, 2012, 35:424-436
Rodriguez et al., Causal Agents of Photoallergic Contact Dermatitis Diagnosed in the National Institute of Dermatology of Colombia. Photodermatology, Photoimmunology & Photomedicine, 2006, 22(4):189-192.
SCCNFP, Opinion Concerning Homosalate. 2006.
Sarveiya et al., Liquid Chromatographic Assay for Common Sunscreen Agents: Application to In Vivo Assessment of Skin Penetration and Systemic Absorption in Human Volunteers. Journal of Chromatography B-Analytical Technologies in the Biomedical and Life Sciences, 2004, 803(2): 225-231
M.K. Matta et al., Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients A Randomized Clinical Trial. Journal of the American Medical Association, 2020, 323(3):256-267
Written by Allyson Welch

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