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Sunscreen – Long Term Safety?

Skin Conditions | January 29, 2018 | Author: Naturopath

Skin conditions

Sunscreen – Long Term Safety?

Sunscreen has been a cornerstone of sun safety since it became the the “slop” in Slip Slop Slap. But is it safe to use long-term? We explore chemical ingredients, the truth about natural sunscreens, and long-term risks of blocking UV rays.

Sunscreen is a unique skin care product in that it's applied liberally all over the body and repeatedly reapplied. Its ingredients come in contact with not just the skin but also the internal environment – any applied to the lips may be “eaten”, inhaled particles interact with the lungs and respiratory tracts, and some chemicals may move into circulation due to “penetration enhancers” found in many sunscreen formulations. A recent survey found that 17% of adult Australians are worried about those chemicals impacting their health.

Here's a quick 101 of the nasties commonly found in commercial sunscreen formulations:

Proven Harmful Ingredients in Sunscreens

Oxybenzone – Used to absorb UV rays. Oxybenzone is highly penetratable through the skin and has been found in breast milk. It acts as a oestrogen in the body, throwing hormone levels out of whack in both men and women, and has been associated with endometritis. It is also highly hazardous to aquatic life with long-lasting effects, and many environmental agencies recommend use of “eco friendly” sunscreens that do not contain oxybenzone before swimming in natural water [1].

Octinoxate or Octylmethoxycinnamate – Another UV absorbing agent. Studies have shown that octinoxate also penetrates through the skin and acts as a hormone disruptor. It has been been linked to thyroid and reproductive issues in animal studies [2]. Environmentally, it may lead to coral bleaching.

Proven Harmful Ingredients in SunscreensMethylisothiazolinone – A preservative and common allergen that may trigger contact dermatitis, particularly in children [2].

Dioxybenzone – Used to make sunscreen “waterproof”. Dioxybenzone frequently causes skin irritation, allergic reactions, respiratory irritation. Swimming in chlorinated pools can break down the dioxybenzone, reducing UV filtering and increasing its toxic actions [3][9]. Like oxybenzone, it is toxic to aquatic life.

Parabens – Used as preservatives in many cosmetic products, parabens may be linked to oestrogen-associated cancers. They have been found in breast cancer tumours and are suspected to accelerate the growth of cancer cells [4].

No studies have yet concluded that long-term sunscreen use will lead to the negative side effects of these chemicals, and many dermatologists argue that the risk of skin cancer far outweighs the risk of the more common mild negative reactions. Speak to a qualified practitioner for personalised advice.
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Natural Sunscreen & Nanoparticles

Natural sunscreens offer an alternative, with fewer irritating ingredients and more environmentally friendly formulations. While conventional sunscreens use a combination of UV absorbing chemicals,  natural alternatives generally contain minerals that block and reflect UV rays from the skin such as zinc oxide and titanium dioxide. No commercial sunscreen is entirely chemical-free, so be sure to always check the ingredients label for known irritants.

The major failing of natural sunscreens is that the UV-reflective minerals are quite large and sit on top of the skin rather than penetrating into the dermis like commercial formulas. This leads to three problems:

  • Sun-blocking minerals are easily rubbed off
  • UV radiation can penetrate between the mineral particles
  • Many natural products leave a white residue

Natural Sunscreen & NanoparticlesTo get address these issues, some products use nanoparticle minerals that sit deeper within the skin, providing more protection and a more transparent appearance.

Nanosized zinc oxide is the strongest of the two most common nanoparticles, followed by nanosized titanium dioxide – they both block UV rays and don't break down in the sun.

Nanoparticles are unlikely to penetrate through the skin in healthy people, but they can aggregate in the deepest layers of the skin and hair follicles where they may cause toxic oxidative stress. Many manufacturers coat the nanoparticles with silicon to reduce their oxidative effects, or include antioxidants like vitamin C serum or rosehip oil to quench oxidative damage cause by nanoparticles.
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While research is still in its early stages, the oxidative effects of nanoparticles in sunscreens appear to be mild and contained to the skin. No links to hormone disruption or cancer have been found [5]. Natural sunscreen are also generally considered eco-friendly, especially compared to conventional products.

Vitamin D

Vitamin D is a pro-hormone with roles in bone health, DNA synthesis, cell differentiation, immune reactions, mood stability and cognitive health. It truly is an essential nutrient – its actions are necessary for the most fundamental body functions.

 The majority of vitamin D in the body is produced in a chemical reaction between UVB rays activating cells within the epidermis of the skin – the same dangerous UVB rays that sunscreens block. Australia has a high rate of vitamin D deficiency and some researchers believe this is because of our sunscreen use – however, there are a number of factors affecting vitamin D synthesis including amount of time spent outdoors. Sunscreen has been shown to reduce the production of vitamin D in strict laboratory settings, but studies have concluded that regular sunscreen use in a real-life setting does not compromise vitamin D levels [6].

For most healthy people to maintain adequate vitamins D levels, 5 – 15 minutes of direct sunlight exposure to arms, face, hands and legs without sunscreen  is recommended, three times a week [7]. It may take more sunlight exposure than this to correct a deficiency and many people find they need to take a vitamin D supplement in addition to increased time outdoors.
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CAUTION: Speak to a practitioner for personal advice as any UV exposure can increase the risk of skin cancer.

Who Shouldn't Use Sunscreen

Frequent use of sunscreen on babies under the age of 6 month is not recommended as their sensitive skin is very reactive. All babies under the age of twelve month have more sensitive skin than adults and easily suffer from burns – the Cancer Council of Australia recommends babies are protected from direct sunlight as much as possible, especially during days with a UV level of 3 or more [8].

How To Use Sunscreen Long-TermHow To Use Sunscreen Long-Term

  • Use sunscreen as protection against incidental sun exposure rather than a way to extend your time in the sun. Don't assume that sunscreen is enough protection when in the sun for long periods of time, such as at an outdoor event, mowing the lawn, or swimming.
  • Reapply sunscreen within two hours or immediately after swimming.
  • Do NOT apply more sunscreen if you experience redness, itchiness or soreness. These reactions may be from the sun or from the sunscreen itself – either way, applying more sunscreen won't help. Get out of the sun, find some shade or go indoors immediately.
  • Use sunscreen in combination with other sun-safety techniques. Sunscreen has never been intended as a sole protector against sunburn or skin cancer. [8]

Natural Sun Safety

Sun safety doesn't end with sunscreen. Combine sunscreen use with these essential sun-safety tools for maximum protection against sun burn, irritation, and skin cancer:

  • Wear a wide-brimmed hat, a long-sleeved shirt and sunglasses with certified UV protection whenever possible
  • Stay out of direct sunlight between 10am and 4pm
  • Check the UV rating before attending outdoor events and plan accordingly
  • Seek shade whenever possible
  • Remember that snow, water and clouds reflect and multiply UV radiation
  • UV radiation increases by 10% for every 1,000 metre increase in altitude [8]  Australia’s best online discount chemist


[1] National Center for Biotechnology Information. PubChem Compound Database (2018) Oxybenzone.

[2] National Center for Biotechnology Information. PubChem Compound Database (2018) Octinoxate.

[3] Carbonell, R. & Lauder, S. (2012) Tests raise questions over nano-free sunscreen. ABC News.

[4] Pan, S., et al. (2016) Parabens and Human Epidermal Growth Factor Receptor Ligand Cross-Talk in Breast Cancer Cells. Environ Health Prespect., 124:5, 563 – 569.

[5] Smijs, T. G. & Pavel, S. (2011) Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness. Nanotechnol Sci Appl., 4, 95 – 112.

[6] Vanchinathan, V. & Lim, H. W. (2012) A Dermatologist's Perspective on Vitamin D. Mayo Clin Proc., 87:4, 372 – 380.

[7] Johnson, L. E. (2016) Vitamin D. Merck Manual Database,,-dependency,-and-toxicity/vitamin-d 

[8] Cancer Council Australia (2017) Sunscreen FAQS.

[9] Sherwood, V. F., et al. (2012) Altered UV absorbance and cytotoxicity of chlorinated sunscreen agents. Cutan Ocul Toxicol., 31:4, 273 – 279.

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