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What is in your sunscreen?

Skin Conditions, General | November 7, 2016 | Author: Naturopath

general

What is in your sunscreen?

“If you love the great outdoors, you need a hardworking sunscreen”- Captions like this have attracted our attention probably a million times. There would hardly be anyone who has not fallen under the charm of sun protection products with their attractive labels, elegant look, amazing numbers and everlasting promises. Yes, protection from excessive sun exposure is essential, especially when statistics points that Australians have the second highest rate of skin cancer in the world. But do we really need ‘hardworking sunscreens’ to protect us from the sun? Let us take a look.

What are sunscreens? Are they really a necessity?

Sun protection products are topical (applied to skin) agents that shield us from the harmful ultraviolet rays (UVA and UVB) of the sun. They have varying degrees of sun protection factor (SPF), a measure that rates the product’s ability to block harmful UVB rays. Due to their capacity to delay sunburns, sunscreens are advocated for skin cancer prevention.

Although we have wholeheartedly embraced commercial sunscreens, a report published in 2016 by the Australian Institute of Health and Welfare (AIHW) confirms that melanoma skin cancer incidence has significantly increased in the past 30 years. This contradiction raises serious concerns regarding the effectiveness of sun protection formulas in preventing skin cancer.

Moreover, some epidemiological (population-based) data suggests that sunscreen use could be a risk rather than protective factor for skin cancer development.

This is not surprising given the fact that the product is loaded with several toxic chemicals. Nevertheless, we simply feel safe when we come across the words, ‘paraben-free’, ‘phthalate-free’, ‘hypoallergenic’ and so forth, on sunscreen labels. But, is there more to it than parabens and phthalates? Unfortunately, the answer is yes!

Common ingredients in sunscreens and their effects on human health

Sun protection agents are categorized into two, based on their mechanism of action- sunblocks and sunscreens.

Sunblocks, also known as physical blockers, are formulations that act as an opaque barrier between the skin and the UV rays, by reflecting or scattering them. Nowadays, sunblocks are typically known as physical or mineral sunscreens. They contain inorganic ingredients such as zinc oxide and titanium dioxide.

Sunscreens are chemical absorbers. They impart protection to the skin by absorbing UV rays. From a cosmetic perspective, chemical sunscreens are preferred as they are translucent and penetrate the skin without leaving any residues.

Ingredients that act as UVA filters

Chemical sunscreen ingredients are also referred to as ‘organic’ ingredients. This should not be confused with the term ‘natural’. In this context, organic simply means having carbon atoms, and is used to differentiate from inorganic mineral-based sunscreens that do not have carbon molecules.

The predominant organic ingredients that block UVA rays are benzophenones, avobenzone (Parasol 1789 or butyl methoxydibenzoylmethane) and ecamsule (Mexoryl SX).

Scientific evidence shows that these compounds exhibit toxicity.

According to the report published by National Toxicology Program (NTP is the United States Health Service program) in 2006, administration of benzophenone to laboratory animals through food for 2 years caused increased incidence of renal tubule adenoma, mononuclear leukemia and hepatocellular neoplasms. 

A photodegradation product of avobenzone, arylglyoxals, was demonstrated to have allergic effects when tested using lymph node assay. Ecamsule is relatively new to sunscreen industry.

It is widely used in sunscreens available in Australia and Europe. In the US, only a few ecamsule-based products at specific concentrations are approved by FDA (Food and Drug Administration) due to lack of sufficient safety data. 

Ingredients that act as UVB filters

PABA, cinnamates, salicylates and octocrylene are the ingredients that are often used in chemical sunscreens to absorb UVB rays. PABA fell out of favour from sunscreens when scientific studies proved that it sensitizes cells to UV damage and trigger allergic reactions. PABA-derivative, Padimate O, that is extensively used in sunscreens was shown to induce breaks in DNA strands when illuminated with sunlight. Administration of octyl-methoxycinnamate (octinoxate) to rats during gestation period, at doses close to those found in sunscreens, revealed impairment of reproductive and neurological development in the offspring. Yet another study demonstrated that five chemicals used in sunscreens, benzophenone-3, homosalate, 4-methyl-benzylidene camphor, octyl-methoxycinnamate and octyl-dimethyl-PABA, increases cell proliferation in MCF-7 breast cancer cells both in vitro and in vivo, thus indicating their endocrine activity(ability to act like hormones).

Inorganic ingredients

The most common inorganic filters used in sunscreens are zinc oxide (ZnO) and titatnium dioxide (TiO2). Currently, they are synthesized as nano-sized particles to achieve transparency. But their safety is debatable owing to the concern that they may get absorbed into the bloodstream due to their extremely small size11.

The safety of sunscreen ingredients is questionable due to three reasons (1) controversial scientific evidence on their potential to cross skin-blood barrier (2) their ability to act as endocrine disruptors (3) degradation of some of the ingredients into toxic metabolites following exposure to sun.

Sunscreens contain toxic chemicals. What are the alternatives?

Sunscreens contain toxic chemicals. What are the alternatives?When it comes to sunscreen safety, the most common reasoning is that they are applied to skin, not ingested. There is an ancient saying- “If you cannot eat it, you should not apply it on your skin”. Skin absorbs whatever we apply topically. From this prospect, the following natural products could be our best friends.

Carotenoids: These are fat-soluble yellow-orange pigments synthesized by plants, algae and photosynthetic bacteria. Some carotenoids are precursors for vitamin A synthesis. In humans, oral supplementation with β-carotene and carotenoid mix has been reported to protect from UV-induced erythema (redness of the skin).

Vitamin C and E: Vitamin C (L-Ascorbic acid) and vitamin E (α-tocopherol) possess powerful antioxidant capacity. They rejuvenate the skin by stimulating collagen production and protect it from photo-damage.

Silymarin: is a flavonoid compound present in milk thistle (Silybum marianum). Topical application of silymarin has been shown to suppress UVB-induced immune suppression and free radical generation in mice, thereby reducing skin cancer risk.

Reservatol: This polyphenolic compound is abundant in grapes, cranberries and peanut. A research study demonstrated that topical application of Calluna vulgaris (a perinneal plant) and red grape (Vitis vinifera) seed extracts to hairless mice, 30 minutes prior to UV irradiation, increased skin antioxidant enzyme levels and prevented damaging free radical production and apoptosis (an automated cell death process). Moreover, reservatol, when co-delivered with quercitin (a flavonoid present in fruits and vegetables) reduced oedema and leukocyte infiltration in precancerous/ cancerous skin lesions.

Plant oils: Oils extracted from plant sources such as Borage, Avacado, Aloe vera, Evening Primrose, Tea tree and Seasame are known to soothe the skin. Although they do not resist UV rays, they can possibly repair sun-damaged skin.

In case you plan to avoid sunscreens and go natural, follow these practical recommendations of Cancer Council of Australia:

  • Wear long sleeve clothing, pants and sun glasses to minimize overall exposure to sun.
  • Use broad brimmed hats (7.5 cm brim for broad-brimmed and 6 cm for bucket hats) as a part of your daily routine.
  • Use tinted films on cars and building glasses to reduce exposure to UV rays.  
  • Avoid sun exposure between 10 AM and 4 PM. This is particularly applicable for infants between 0-12 months.
  • Avoid the use of sunbeds or solariums as they significantly increase melanoma risk.
  • Regularly screen for skin cancer if you have a family history.

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References:

Australian Institute of Health and Welfare 2016. Australian Cancer Incidence and Mortality (ACIM) books: melanoma skin cancer. Canberra: AIHW. [Accessed September 2016]. http://www.aihw.gov.au/acim-books/

Wolf, P., Quehenberger, F., Mullegger, R., et al. (1998) Phenotypic markers, sunlight-related factors and sunscreen use in patients with cutaneous melanoma: an Austrian case-control study. Melanoma Res. 8, 370-378. http://www.ncbi.nlm.nih.gov/pubmed/9764814

Autier, P., Dore, J.F., Cattaruzza, M.S., et al. (1998) Sunscreen use, wearing clothes, and number of nevi in 6- to 7-year-old European children. European Organization for Research and Treatment of Cancer Melanoma Cooperative Group. J. Natl. Cancer Inst. 90, 1873-1880. http://www.ncbi.nlm.nih.gov/pubmed/9862624

(2006) Toxicology and carcinogenesis studies of benzophenone (CAS No. 119-61-9) in F344/N rats and B6C3F1 mice (feed studies). Natl. Toxicol. Program Tech Rep Ser, 1-264. http://www.ncbi.nlm.nih.gov/pubmed/16741556

Rhodes, M.C., Bucher, J.R., Peckham, J.C., et al. (2007) Carcinogenesis studies of benzophenone in rats and mice. Food Chem. Toxicol. 45, 843-851. http://www.ncbi.nlm.nih.gov/pubmed/17187913

Karlsson, I., Hillerstrom, L., Stenfeldt, A.L., et al. (2009) Photodegradation of dibenzoylmethanes: potential cause of photocontact allergy to sunscreens. Chem. Res. Toxicol. 22, 1881-1892. http://www.ncbi.nlm.nih.gov/pubmed/19856938

Osgood, P.J., Moss, S.H. and Davies, D.J. (1982) The sensitization of near-ultraviolet radiation killing of mammalian cells by the sunscreen agent para-aminobenzoic acid. J. Invest. Dermatol. 79, 354-357. http://www.ncbi.nlm.nih.gov/pubmed/6982950

McHugh, P.J. and Knowland, J. (1997) Characterization of DNA damage inflicted by free radicals from a mutagenic sunscreen ingredient and its location using an in vitro genetic reversion assay. Photochem. Photobiol. 66, 276-281. http://www.ncbi.nlm.nih.gov/pubmed/9277149

Axelstad, M., Boberg, J., Hougaard, K.S., et al. (2011) Effects of pre- and postnatal exposure to the UV-filter octyl methoxycinnamate (OMC) on the reproductive, auditory and neurological development of rat offspring. Toxicol. Appl. Pharmacol. 250, 278-290. http://www.ncbi.nlm.nih.gov/pubmed/21059369

Schlumpf, M., Cotton, B., Conscience, M., et al. (2001) In vitro and in vivo estrogenicity of UV screens. Environ. Health Perspect. 109, 239-244. http://www.ncbi.nlm.nih.gov/pubmed/11333184

Smijs, T.G. and Pavel, S. (2011) Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness. Nanotechnol. Sci. Appl. 4, 95-112. http://www.ncbi.nlm.nih.gov/pubmed/24198489

Heinrich, U., Gartner, C., Wiebusch, M., et al. (2003) Supplementation with beta-carotene or a similar amount of mixed carotenoids protects humans from UV-induced erythema. J. Nutr. 133, 98-101. http://www.ncbi.nlm.nih.gov/pubmed/12514275

Filip, A., Daicoviciu, D., Clichici, S., et al. (2011) Photoprotective effects of two natural products on ultraviolet B-induced oxidative stress and apoptosis in SKH-1 mouse skin. J. Med. Food. 14, 761-766. http://www.ncbi.nlm.nih.gov/pubmed/21470043

Caddeo, C., Nacher, A., Vassallo, A., et al. (2016) Effect of quercetin and resveratrol co-incorporated in liposomes against inflammatory/oxidative response associated with skin cancer. Int. J. Pharm. 513, 153-163. http://www.ncbi.nlm.nih.gov/pubmed/27609664

Katiyar, S.K. (2002) Treatment of silymarin, a plant flavonoid, prevents ultraviolet light-induced immune suppression and oxidative stress in mouse skin. Int. J. Oncol. 21, 1213-1222. http://www.ncbi.nlm.nih.gov/pubmed/12429970

Korac, R.R. and Khambholja, K.M. (2011) Potential of herbs in skin protection from ultraviolet radiation. Pharmacogn. Rev. 5, 164-173. http://www.ncbi.nlm.nih.gov/pubmed/22279374

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