Sunscreen: Everything you need to know

When it comes to fighting back against the harmful effects of the sun’s UV rays, a layer of SPF is arguably the single most important step in a skin-care regimen. Though we have all become a little more knowledgeable about protecting our skin from the sun, not many people truly understand what to look for in a sunscreen and how hard it works for our skin. So, we sat down with our research team, dermatologists and cosmetic chemists to answer your burning questions.

Do I really need to use sunscreen?

Yes. Skin cancer occurs when skin cells are damaged, for example, by overexposure to ultraviolet (UV) radiation from the sun.

Approximately, two in three Australians will be diagnosed with skin cancer by the time they are 70. Australia has the highest cancer rate for men and women combined, at 468.0 people per 100,000.

Ultraviolet (UV) radiation is a proven human carcinogen. On average, a person’s risk for melanoma doubles if he or she has had more than five sunburns.

The Skin Cancer Foundation states that about 90% of non-melanoma skin cancers are associated with exposure to ultraviolet (UV) radiation from the sun.

The vast majority of melanomas are caused by the sun. In fact, one UK study found that about 86 percent of melanomas can be attributed to exposure to ultraviolet (UV) radiation from the sun.

Is sunscreen safe?

Yes. The safety of sunscreens has been studied by research scientists for years, and the evidence that sunscreens are safe and effective is overwhelming. Dermatologists recommend it. Scientific studies support wearing it on a regular basis to protect against skin cancer. You can read more about sunscreen regulations by country here. There have been some concerns raised that we will look at in detail below.

Should I be worried about nanoparticles in sunscreens?

No. Some sunscreens contain nanoparticles to prevent sunscreen forming a visible layer on the skin. A nanoparticle is a tiny particle ranging from 1 to 100 nanometres in size.

The nanoparticles in sunscreens do not pose a threat to your health. In 2017, TGA published a review of the scientific evidence related to titanium oxide and zinc oxide nanoparticles in sunscreens. The evidence suggests that these nanoparticles are highly unlikely to cause harm because they remain on the surface of the skin, which is made-up of dead skin cells. New research supports the conclusion of their review. In a 2018 study by the University of South Australia, researchers asked volunteers to apply sunscreen over five consecutive days. The researchers found that nanoparticles remained on the surface of volunteers’ skin and did not cause any damage to their skin cells.

The TGA found no evidence that these nanoparticles reach viable skin cells. Instead the particles remain on the surface and outer layer of skin.

Is it true that chemical sunscreen gets into your bloodstream? Should I stop using sunscreen?

In February 2019, the FDA (US Food and Drug Administration) proposed new rules aimed at improving sunscreen safety and asked the sunscreen industry for additional evidence on the safety of 12 common chemical sunscreen ingredients. In theory, if manufacturers don't submit this data by November 2019, all sunscreens that contain these 12 chemicals could be pulled from the market (notwithstanding that manufacturers will ask for an extension on this deadline, which may be granted if they show that they are committed to conducting the safety studies).

The FDA has deemed physical filters, titanium dioxide and zinc oxide as generally regarded as safe and efficient (GRASE) but still hasn't come to a conclusion on the common chemical sunscreen filters such as avobenzone, octinoxate, oxybenzone, octocrylene, etc. Hence the reason for this study.

The recent JAMA study (6 May 2019) was understaken to find out what is the maximum plasma concentration of active ingredients of various types of sunscreen formulations under maximal use conditions.

24 volunteers were divided into four groups that each received a different sunscreen formulation (a lotion, a cream or one of two different sunscreen sprays). The study protocol required application (2 mg/cm2) 4 times a day to 75% of body surface area for 4 days. The participants stayed in the laboratory for up to seven days and weren't actually exposed to sunlight. They each had 30 blood samples taken over the course of their stay. The researchers then examined blood levels for four common sunscreen ingredients: avobenzone, oxybenzone, octocrylene and ecamsule. They wanted to see whether the blood concentrations of these chemicals surpassed 0.5 nanograms per milliliter, a threshold set by the FDA in 2016. The FDA says that any medication that is absorbed into the blood at levels that exceed this threshold need to undergo additional safety studies.

The results revealed that within just one day of sunscreen application, all four chemicals were found in people's blood at levels exceeding the threshold. The study also showed the blood levels of these chemicals increased in subsequent days as the sunscreen was reapplied, suggesting that the chemicals may accumulate in the blood over time. These levels were high enough to warrant further testing on the substances' safety.

The demonstration of systemic absorption of chemical sunscreens is not unknown. The new findings show that is well above the FDA guideline. This does not automatically mean these ingredients are toxic or harmful. What the findings do mean is that further studies need to be undertaken to determine whether systemic absorption

of sunscreen poses risks to human health.

It is important to note that the findings, is just a starting point, and does not mean that people should stop using sunscreen, especially given the very serious and well-known risks of sun exposure we mentioned earlier. Testing under actual use conditions will also need to be carried out, as most users apply less sunscreen than the recommended amount, often without reapplication. It is unrealistic to assume that one would apply sunscreen to 75% of their body every 4 hours, and stay out of the sun.

What we do know with absolute certainty is that ultraviolet (UV) radiation is a proven human carcinogen and that the sun does cause skin cancer and melanoma. Cancer Council Australia research published in the Australian and New Zealand Journal of Public Health in 2015 showed that in 2010, Australians prevented more than 1,700 cases of melanoma and 14,000 cases of non-melanoma skin cancer thanks to regular sunscreen use over the previous decade. So we know sunscreen saves lives.

If you are worried about chemical sunscreens, a physical (mineral) sunscreen is a good alternative. Ingredients such as titanium dioxide and zinc oxide are GRAS (generally regarded as safe) and should be used as part of a larger program of photoprotection that includes seeking shade, and wearing protective clothing, hats, and sunglasses.

How do I read the Sunscreen ingredient list?

The ingredients list on sunscreens is a scary place for even the most dedicated sun-protectant enthusiast.

Simply put, sunscreens contain both Active ingredients and Inactive ingredients.

The Active ingredients are your sunscreen ingredients, which are either physical blockers or chemical blockers. And, yes! Products can contain both.

The Inactive ingredients the base can either be a lotion or gel, for example. This is not to say they don’t do anything. Inactive ingredients include ones that help preserve, emulsify, moisturize, condition and smooth out the sunscreen.

What is the difference between a physical and chemical sunscreen?

Contrary to popular belief, both physical and chemical sunscreens don’t protect our skin by reflecting and scattering UV energy. Instead they attenuate the UV energy, absorbing it and turning it into less harmful energy.

Physical sunscreen

Also known as inorganic sunscreen ingredients. Titanium dioxide and zinc oxide provide UV protection primarily via absorption of UV radiation and some reflection or scattering of UV rays.

The minerals titanium dioxide and zinc oxide are the main active ingredients in physical blocks.

• Offers protection against both UVA and UVB rays and is naturally broad spectrum

• Less irritating and a better option for sensitive skin

• Easily tolerated around the eye area

• Appeals to the clean beauty market

• More suitable to for those who suffer from hyperpigmentation or melasma.

• One of the disadvantages of Physical sunscreen is that it can be difficult to fully blend into the ski, and leaves an unsightly white cast. However, these sunscreens have come a long way from older formulations that sat on your skin in a greasy, white layer. Today's zinc and titanium dioxide formulas are micronized so they can sink into the skin, while still offering the same protection.

• Titanium Dioxide is not biodegradable and has been found to react in warm seawater to form hydrogen peroxide which is harmful to sea life.

Zinc oxide offers better UVA protection (UVA1 and 2) than titanium dioxide (UVA2)

• There is no risk of physical filters entering the bloodstream.

• The TGA found no evidence that these nanoparticles reach viable skin cells. Instead the particles remain on the surface and outer layer of skin.

Chemical sunscreen

Also known as organic sunscreen ingredients. Chemical filters absorb ultraviolet (UV) radiation, convert it to heat and dissipate it through the skin. Chemical sunscreen absorbs into the skin and then absorbs UV rays, converts the rays into heat, and releases them from the body.

The most common chemical sunscreens include oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate. Newer filters include Bemotrizinol and Bisoctrizole.

• Cosmetically elegant. Absorbs quickly into the skin without leaving a white cast.

• Thinner consistency that makes application a breeze.

• Suited to those to play a lot of sport or sweat a lot and need a water-resistant formulation.

• Depending on the formula, could be pore-clogging

• Recent studies confirm that at least 4 of the common chemical filters absorbs into the bloodstream (read more above). Further research is needed to ensure safety of a number of chemical sunscreen ingredients.

• Increased chance of irritation and stinging (especially for those who have dry skin with a damaged moisture barrier) due to the multiple ingredients combined in order to achieve broad-spectrum UVA and UVB protection

• The protection it offers gets used up more quickly when in direct UV light, so reapplication must be more frequent

• Increased chance of redness for rosacea-prone skin types because it changes UV rays into heat which can exacerbate flushing

• Newer ingredients like Tinosorb provide substantial broad-spectrum protection from both UVA and UVB rays. Available as Tinosorb M and Tinosorb S, these ingredients work to absorb, scatter and reflect the sun’s UV rays.

• Tinosorb S (also called Bemotrizinol) is capable of absorbing UVA and UVB rays, resulting in broad UV spectrum protection for the skin. One of the benefits of Tinosorb S is that it is a photostable compound. When combined with other sunscreen ingredients, it helps to avert molecule degradation caused by the photons present in the sun’s UV rays. This photostability enhances the sunscreen’s effectiveness in protecting the skin.