Are sunscreens harmful?
What are the components of sunscreens and how can they affect my health?
Are sunscreens safe for babies?
What are the impacts of sunscreen chemicals on the environment?
What do dermatologists recommend?
Skin cancer has been on the rise in the past decades, and is now the most common cancer in Canada. The good news is that it is largely preventable! Hence, increased awareness for sun protection and the use of sunscreens and sun protective clothing has increased worldwide. The Canadian Dermatology Association (CDA) recommends applying a generous amount of sunscreen to sufficiently cover the entire body (approximately one oz or 30 ml), and to repeat application regularly especially when sweating or swimming. It is also suggested to look for a sunscreen product that protects against both ultraviolet B and ultraviolet A, which are the two types of radiation emitted by the sun, with sun protection factor (SPF) values of 30 or higher. You can identify this by looking for a “Broad Spectrum” label or a CDA logo as shown on right.
Moreover, studies have shown that people tend to apply less sunscreen than what is recommended. “In fact, on average, people only apply 20% of the recommended amount”, explains Dr. Netchiporouk, a certified dermatologist at McGill University. Therefore, repeated application, every ~2 hours is suggested when exposed to sun, to compensate for underapplication each time.
Worldwide recommendations regarding sunscreen use have led to an increased availability and use of these products. Moreover, many cosmetic industries have incorporated sunscreen into their lines of products such as moisturizer, makeup, and lip balms. This has led to a considerable amount of sunscreen on our skin but also ending up in the oceans, lakes and other environments. The efficacy of protection by sunscreens has been widely accepted; but what about the risks?
Many researchers have been interested in studying the consequences of sunscreen use in animals, humans and the environment.
To understand the benefits and risks of sunscreen, we must first know what they are made of and how they work. "Two major types of sunscreens exist. The first is inorganic or mineral sunscreen, which acts like a shield: by deflecting ultraviolet radiations (UVR) away from the skin. Inorganic means that there are no carbon molecules. Only zink oxide and titatinum dioxide”, explains Dr. Litvinov the Director of Dermatology Research at McGill University. “The second type is organic/chemical sunscreen that is based on carbon molecules that absorb sun light and transform it into heat. These chemical substances can penetrate deeper into the skin and enter our blood circulation, though. These sunscreens are made with various chemicals such as oxybenzone, mexoryl/ecamsule or octocrylene."
Application of chemical sunscreen in addition to the use of cosmetic products containing UV filters, such as make-up, could result in a considerable amount of these chemicals directly in contact with the skin and can be absorbed into general blood circulation in the body.
A team of researchers from the US Food and Drug Administration (FDA) have examined this question. “Twenty four healthy adults participated to this study and were instructed to apply sunscreen to 75% of their body surface area for 4 days. The sunscreens were organic type and contained avobenzone, oxybenzone, octocrylene, and ecamsule. They found that blood levels of avobenzone, oxybenzone, octocrylene, and ecamsule exceed the threshold above which the FDA recommends", explains Dr. Netchiporouk. Moreover, other studies have shown the presence of UV filters such as oxybenzone in breast milk and urine; meaning that these sunscreens are in our bodies and might potentially affect our health.
According to Dr. Litvinov, “we should be careful when interpreting the meaning of these findings. Just because a sunscreen ingredient is found in blood, it does not mean it is necessarily harmful. The medical impact of these studies results remains unknown; hence, further studies are needed to completely understand the health consequences." According to the FDA, more safety and efficacy data on 12 organic (chemical) sunscreen ingredients (cinoxate, dioxybenzone, ensulizole, homosalate, meradimate, octinoxate, octisalate, octocrylene, padimate O, sulisobenzone, oxybenzone, and avobenzone) are needed before sunscreens with these compounds can be labelled as "safe and effective”. In fact, to date, only few studies have investigated the consequences of these ingredients in humans. "Some studies on specific cells of the immune system have shown that they behave differently when exposed to sunscreen chemicals. However, the meaning of these findings is unclear especially given that these studies were performed in test tubes and not in humans", highlights Dr. Litvinov. In some animals, like rats, these chemical filters have a negative impact on their reproductive behavior. In fact, animals exposed to very high concentrations of these ingredients had more difficulties to reproduce. Currently, there are no absolute data to support that sunscreen organic filters are toxic to humans or that they have an impact on the reproduction and fertility. Although more studies are needed, there are no urgent safety concerns. Overall, sunscreens are considered to be safe and to have greater benefit than potential risks. One existing risk of sunscreen, like any other product, is to develop an allergic reaction to it. However, this happens very rarely and can be readily diagnosed and treated by a certified dermatologist.
“If the knowledge that chemical sunscreens are readily absorbed by the body makes you uncomfortable, then consider physical/mineral sunscreens”, suggests Dr. Litvinov. The Food and Drug Administration (FDA) approved that there is sufficient information to consider zinc oxide and titanium dioxide sunscreens effective and safe for both humans and environment, in contrast to organic compounds that require additional studies. "Studies have shown that these minerals do not penetrate the skin, hence raising very few to no human health concerns. The only concern is potential risks of inhalation; thereby spray formulas are not recommended," suggests Dr. Netchiporouk. In addition, many like the fact that physical/inorganic sunscreens do not cause eye irritation. “Even though the texture of physical sunscreens is such that they leave a white residue on the face, the fact that they don’t irritate my eyes when I sweat during exercise is a big plus”, highlights Serge Rodrigue, a frequent sunscreen user.
Health Canada approves sunscreen use for babies older than 6 months of age. Before 6 months, the skin’s barrier is not considered mature, and small particles of chemicals might penetrate through the skin at a higher rate and potentially affect the baby's health, although this is theoretical and has not yet been proven. The real impact of sunscreen on child’s health is unknown and very limited studies were done in this age group. Therefore, at this age, sun protection should focus on avoiding peak sun exposure (10 a.m. to 2 p.m.), wearing protective clothing, hats, eye protection and staying in the shade, when possible.
Some of the organic chemicals that were found in water sources/supply around the world are oxybenzone, octinoxate, enzacamene, homosalate, octisalate, avobenzone and octocrylene. These compounds reach the aquatic environments after being washed off the skin directly in oceans, lakes, swimming pools or showers and more importantly, through waste products from cosmetics or sunscreen manufactures and industries. In fact, the highest quantity of organic filters in the water is reached in summer months and in more populated regions.
Every year, ~14,000 tons of sunscreen are estimated to affect coral reefs habitats. A team of scientific researchers was recently the first to investigate the concentration of organic filters in coral reefs in three locations in Hawaii. Octisalate, homosalate, octocrylene and oxybenzone were sunscreen ingredients frequently found in the corals revealing the abundance of these products in Hawaiian coral reef habitats. Unfortunately, common wastewater treatments fail to remove organic sunscreens that thereby accumulate and affect marine organisms such as the fish we eat. "These pollutants are toxic for corals and contribute to their whitening, also called bleaching, ultimately resulting in coral extinction, a damage exacerbated by the global climate change. Homosalate, oxybenzone, octocrylene, octisalate and avobenzone were found to reduce growth of coral species, whereas corals that were not exposed to these chemicals had normal growth", says Dr. Netchiporouk. In addition, chemical filters impede coral's adaptation to climate change. Similar findings were observed for flatworm and plankton. Furthermore, numerous studies worldwide have detected chemical filters in other marine species, including white fish, roach, perch, cod, rainbow trout, barb, chub, and mussels. Eating seafood that has been exposed to these chemicals may potentially be a concern for humans, but no studies have investigated the associated risk.
Zinc oxide and titanium dioxide are mineral ingredients of sunscreen that acts mainly as a physical barrier that reflects ultraviolet radiation. They are both commonly found in aquatic environment! Although their concentration increases in lakes during summer, this occurs for a short duration. "Caribbean corals that were exposed to high concentration of titanium dioxide eventually adapted and recovered from transient bleaching. Currently, it is considered that the overall risk of zinc oxide sunscreens to the environment is acceptably low. Hence, sunscreen formulation containing zinc oxide and titanium dioxide are favoured to protect the environment", says Dr. Litvinov.
To protect marine ecosystem, Hawaii recently prohibited the sale and distribution of sunscreen products containing oxybenzone or octinoxate. Considering current evidence on chemical filters effects on coral reefs and aquatic species, Palau government has also signed a law that restricts the sale and use of sunscreen and cosmetics that contain any of the listed 10 chemicals including oxybenzone, octocrylene and octinoxate. Similarly, Key West city commission in Florida voted in February 2019 for the prohibition of sunscreens containing oxybenzone and octinoxate.
Some countries have gone beyond and encouraged their population to use safer products for the environment. In an ecological water park in Mexico, visitors are encouraged to participate in a "Chemical-free sunscreen exchange program" which provides tourists with biodegradable sunscreens in exchange of their non-biodegradable products. Each year, over 100,000 sunscreens are exchanged with tourists. Such biodegradable sunscreens contain zinc oxide or titanium dioxide, both mineral UVR filters. Furthermore, in the U.S., the National Park Service warns the population about impacts of sunscreens on corals and encourages the use of formulas containing titanium oxide or zinc oxide.
"Recent studies suggest that organic filters (oxybenzone, octinoxate and others) are harmful to the environment and can be absorbed by the skin and moreover, enter our bloodstream in high concentration,” explains Dr. Litvinov. “Of course, further studies are needed to understand the health consequences. Until then, concerned individuals can continue to achieve effective sun protection using mineral/inorganic sunscreens containing zinc oxide or titanium dioxide, as these compounds are recognized as safe and effective and no additional data are required. They also don’t sting your eyes and less irritate the skin when applied. They do leave a white residue on the skin that I, personally, wear with pride demonstrating my sun protective behavior," highlights Dr. Litvinov. “We know for a fact that UV exposure can cause deleterious health consequences such as skin cancer and accelerated skin aging; whereas the adverse health effects of sunscreen in human are only hypothetical at this point. Sunscreen remains not only effective but also crucial" says Dr. Netchiporouk. More importantly, under-application should be avoided, as this would not provide an optimal protection against skin cancer.
According to Dr. Netchiporouk, sun protection is broad and sunscreen is only one piece of the puzzle. Hence, other important ways to protect us from the sun must be employed. These include:
Protective clothes: Thicker, heavier weight, lycra/polyester fabrics and dark coloured clothing have been shown to provide more protection. Athletic clothing as well as clothes that cover more skin are also recognize as a better protection. "A good protective clothing does not allow light to shine through" says Dr. Netchiporouk.
Sunglasses: Chronic sun exposure is also a risk factor for cataracts and other diseases of the eye. Darker sunglasses are not better as they could cause the pupil to dilate, hence increasing UV exposure. The best sunglasses are the ones that wrap around the face.
Hats: Broad-brimmed hats are recommended to decrease sunlight falling on the face and eyes.
Lip balm sunscreen: Lips are often forgotten, but they are as much exposed to the sun as the rest of the face, lower lip especially. Apply lip balm sunscreen generously over both lips and repeat frequently.