After years of carefree Slip, Slop, Slapping, beach goers and reef lovers have recently discovered that their chemical sunscreen was somehow poisoning their favourite aquatic playgrounds. To protect its coral reefs and the economy depending on them, the state of Hawaii was recently first in history to ban oxybenzone and octinoxate; two chemical UV-filters widely used in sunscreen formulation. Scientific studies have demonstrated the deadly toxicity of these two compounds on corals and other marine organisms. My question is, if chemical sunscreens are detrimental to coral reefs, how come we allow these products on our skin? After reading this, you will probably think Hawaii’s initiative is also doing a favour to its people...
Have you ever felt clueless reading the ingredients listed on the back of your sunscreen? The toxicity of chemical sunscreens has been published worldwide, with scientific reports going back to the late 90’s! The more informed I get on the topic, the more clueless I am on the reasons why these compounds were ever approved on the market... Oxybenzone and octinoxate are used in 97% of sunscreens and 70% of cosmetics on the market. Like most chemicals, they become problematic once they are absorbed through the skin and enter the bloodstream via the application of sunscreens and other personal care products.
Oxybenzone (aka Benzophenone-3) is a photo-toxicant, especially in the presence of ultraviolet light. This means that the greater the light intensity, especially in the UV and near-UV spectrum, new forms of toxicity manifest, and usually in a dose-dependent manner of both oxybenzone and light. It is directly absorbed through the skin and can be detected in urine within 30 minutes of application [1,2]. Oxybenzone can also contaminate semen , placenta and breast milk of marine mammals and humans [4,5]and is even linked to Hirschsprung’s disease, a development abnormality in humans in cases of prenatal exposure to oxybenzone . That explains why it is not recommended to use oxybenzone-based products during pregnancy, breast-feeding, or on children under the age of 2. I personally believe this is enough reason to avoid oxybenzone all around.
The most common pathological reaction to octinoxate is contact dermatitis and photo-allergic reactions [7-13].When seating on the skin, it is degraded by sunlight into toxic by-product. Once in the body, octinoxate can cause toxicity to a number of different organ systems.It is a fat-soluble chemical, which means that some of it that is absorbed by the body will be metabolized and excreted in urine, but much of it will be stored either in fat tissue or lipid-rich tissue such as the placenta [14,15]. In sunscreen formulations, octinoxate can react with avobenzone (another chemical filter) reducing the overall sun protection factor of the product, leading to photo-instability and an increase risk of sunburn .
The list of scientific studies linking these two ingredients to health drawbacks is very long. To further read about it, I recommend reading full reports on www.haereticus-lab.organd www.ewg.org. If you are now looking to avoid these ingredients, there are safer alternatives with mineral-based sunscreens that use zinc oxide and/or titanium dioxide as UV-filters. P4O sunscreen is formulated using zinc oxide and is 100% natural and biodegradable.
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2. Gonzalez, G., A. Farbrot, and O. Larkö, Percutaneous absorption of benzophenone‐3, a common component of topical sunscreens.Clinical and experimental dermatology, 2002. 27(8): p. 691-694.
3. Zhang, T., et al., Benzophenone-type UV filters in urine and blood from children, adults, and pregnant women in China: partitioning between blood and urine as well as maternal and fetal cord blood.Science of the Total Environment, 2013. 461: p. 49-55.
4. Rodríguez-Gómez, R., et al., Determination of benzophenone-UV filters in human milk samples using ultrasound-assisted extraction and clean-up with dispersive sorbents followed by UHPLC–MS/MS analysis.Talanta, 2015. 134: p. 657-664.
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6. Huo, W., et al., The relationship between prenatal exposure to BP-3 and Hirschsprung's disease.Chemosphere, 2016. 144: p. 1091-1097.
7. Collaris, E.J. and J. Frank, Photoallergic contact dermatitis caused by ultraviolet filters in different sunscreens.International journal of dermatology, 2008. 47: p. 35-37.
8. Schmidt, T., J. Ring, and D. Abeck, Photoallergic contact dermatitis due to combined UVB (4-methylbenzylidene camphor/octyl methoxycinnamate) and UVA (benzophenone-3/butyl methoxydibenzoylmethane) absorber sensitization.Dermatology, 1998. 196(3): p. 354-357.
9. Rodríguez, E., et al., Causal agents of photoallergic contact dermatitis diagnosed in the national institute of dermatology of Colombia.Photodermatology, photoimmunology & photomedicine, 2006. 22(4): p. 189-192.
10. Ang, P., S.K. Ng, and C.L. Goh, Sunscreen allergy in Singapore.American Journal of Contact Dermatitis, 1998. 9(1): p. 42-44.
11. Schauder, S. and H. Ippen, Contact and photocontact sensitivity to sunscreens: Review of a 15‐year experience and of the literature.Contact dermatitis, 1997. 37(5): p. 221-232.
12. Cook, N. and S. Freeman, Report of 19 cases of photoallergic contact dermatitis to sunscreens seen at the Skin and Cancer Foundation.Australasian journal of dermatology, 2001. 42(4): p. 257-259.
13. Warshaw, E.M., et al., Patch test reactions associated with sunscreen products and the importance of testing to an expanded series: retrospective analysis of North American Contact Dermatitis Group data, 2001 to 2010.Dermatitis, 2013. 24(4): p. 176-182.
14. Schlumpf, M., et al., Exposure patterns of UV filters, fragrances, parabens, phthalates, organochlor pesticides, PBDEs, and PCBs in human milk: correlation of UV filters with use of cosmetics.Chemosphere, 2010. 81(10): p. 1171-1183.
15. Alonso, M.B., et al., Toxic heritage: Maternal transfer of pyrethroid insecticides and sunscreen agents in dolphins from Brazil.Environmental pollution, 2015. 207: p. 391-402.
16. Benvenuti. How does octinoxate degrade avobenzone?2012; Available from: https://http://www.futurederm.com/how-does-octinoxate-degrade-avobenzone/.