With the weather warming up, we’re all eager to spend more time outdoors. Though it’s best to use sunscreen year round (hopefully you’ve been doing that!), these sunny months make it all the more necessary to protect yourself while you enjoy the rays.
Sunscreen. It’s necessary to reduce our risk of skin cancer, and also to protect the skin from photodamage, which can increase the appearance of fine lines, wrinkles, hyperpigmentation, sagging and bagging, and all the other icky signs of aging.
7 Potentially Damaging Chemicals in Sunscreen
A completely safe, natural ingredient has been found to act as a physical barrier between your skin and the sun: zinc oxide. Knowing that such an ingredient exists, you wonder why most sunscreens on the shelves continue to contain chemical ingredients that range from questionably unsafe to verifiably harmful.
If you’re shopping for sunscreen, watch out for these ingredients:
Oxybenzone (also called “benzophenone-3” or “BP-3”) is an organic compound used as an ingredient in sunscreens because it absorbs UVB and UVA rays. You’ll find this ingredient in many sunscreens today, including regular lotion sunscreens and makeup foundations with an SPF. It easily dissolves into lotions and creams, so you have a nice product that disappears on your face and then protects from the sun.
Many people are concerned with this ingredient, though, for three reasons:
Widespread Exposure: A study by the Centers for Disease Control and Prevention found evidence of widespread exposure to oxybenzone. After analyzing urine samples from over 2,500 people, researchers found BP-3 in over 96 percent of them, concluding that exposure was prevalent in the general population during 2003-2004. Females were more likely than males to have concentrations above the 95th percentile, likely as a result of personal care product use, the researchers said.
Photosensitizer: Some laboratory studies have shown that oxybenzone penetrates the skin, then increases the production of DNA-damaging free radicals when exposed to light, which suggests it may have the potential to encourage changes in the skin that could lead to cancer. More studies need to be done, but early studies have raised concerns.
Hormone Disruptor: Animal studies have indicated that oxybenzone may disrupt the hormone system, causing weak estrogenic activity.
The Environmental Working Group (EWG) gives this ingredient a hazard score of “8” (out of 10), and notes that it has relatively high rates of skin allergy.
Octinoxate is reportedly the most widely used UVB-blocking agent in the skin care industry because it is less irritating than other sunscreen ingredients. Also called octyl methoxycinnamate, it’s an organic compound formed from methoxycinnamic acid and 2-ethylhexanol.
A clear liquid, it’s insoluble in water and is used in sunscreens and other cosmetics to protect from skin damage. It absorbs ultraviolet radiation in the UVB range, and is permitted by the FDA in skin care formulations at 7.5 percent.
Three concerns with this ingredient:
Instability: When it’s exposed to sunlight, it is changed to a less UV-absorbent form, which would seem to compromise its effectiveness. According to a 2005 study, researchers exposed various chemical sunscreen ingredients, including octinoxate, to UV rays. The results showed that the exposure reduced octinoxate’s ability to protect from UV rays. In a 2008 scientific article, the authors write, “Upon exposure to sunlight, octinoxate degrades into a photoproduct with less UV-absorbing ability.”
Increased free radicals: In the aforementioned study, exposure to UV rays produced free radicals in the films that persisted even after exposure had ended. That means that this ingredient could be increasing the damage to skin from UV rays, and that the damage could continue even after skin is out of the sun. Some manufacturers combine sunscreen ingredients with other antioxidants in an effort to quench this free-radical damage, but so far we don’t have enough studies to know if that’s helping. A 2005 study, for example, looked at exactly what several chemical sunscreens did in the skin to reduce sunburn. The authors concluded: “These findings suggest that sunscreens may prevent redness partly by UV absorption and partly by inhibition of the skin’s inflammatory response. As such, sunscreens might promote instead of protect against melanoma.”
Disrupt hormones: A 2004 animal study found the chemical to have estrogenic activity. Whether or not these same effects would be seen in humans is not yet clear.
The EWG gives this one a hazard rating of “6,” and notes that it’s been found in mothers’ milk, with widespread human exposure.
PABA is a natural chemical found in the vitamin folic acid and also in several foods, including grains, eggs, milk, and meat. Since it is a natural ingredient with a broad range of uses, one would think PABA would be safe for use as a sunscreen. Unfortunately, some studies have raised concerns that it may not be safe to use topically.
PABA was introduced to sunscreens in the 1970s because of its natural ability to absorb UV rays—the ones that cause sunburn. Most sunscreens today, however, don’t use PABA. Like oxybenzone, it was found to increase sensitivity to allergic reactions.
Most sunscreens today, however, don’t use PABA. Like oxybenzone, it was found to increase sensitivity to allergic reactions.
More concerning, however, were studies that showed PABA might damage DNA. In the later 1990s, University of Oxford researcher Dr. John Knowland reported on studies that showed when the chemical sunscreen was exposed to sunlight, it broke down, releasing free radicals that could damage DNA. Results such as these raised the concern that PABA could actually encourage the formation of cancerous cells in the skin.
This is an organic compound made from salicylic acid and “3,3,5-trimethylcyclohexanol,” and is said to absorb ultraviolet rays to protect the skin from sun damage, particularly short-wave UVB rays, which are associated with the DNA damage that can increase risk of skin cancer.
Again, the concern with this one is that it has a mild hormone-disrupting activity. Studies have found that human breast cancer cells, when exposed to homosalate, grew and multiplied 3.5 times more than normal. The estrogenic activity of the chemical has also been observed in human placental tissues, raising concerns about pregnant women who may be exposed to the chemical.
Animal studies have also shown that homosalate may enhance the amount of pesticides we absorb through the skin. Mice that wore a sunscreen containing homosalate along with the common insect repellant DEET, for example, were found to absorb more of the herbicide than mice who didn’t wear the sunscreen.
The EWG gives this one a hazard rating of “4,” and notes that it disrupts estrogen, androgen, and progesterone.
Octocrylene is made by combining diphenylcyanoacrylate with 2-ethylhexanol, creating a clear and colorless oily liquid. Like homosalate, it absorbs UVB and short-wave UVA rays, protecting the skin while also adding a moisturizing property to the formula. It combines well with avobenzone, and is often seen in sunscreen products paired up with this ingredient. It’s also easily combined with other oils, and formulators use it to help keep ingredients more thoroughly mixed in their products.
One of the concerns with this one is that like octinoxate, it acts as a photosensitizer, actually increasing the production of free radicals when skin is exposed to the sun. Free radicals damage skin, increasing the risk of premature aging and skin cancer.
According to a 2006 study, for example, researchers found that octocrylene, octylmethoxycinnamate, and oxybenzone, when left on the skin for about 20 minutes, resulted in an increased generation of free radicals. After 60 minutes, the sunscreens raised that level higher than that produced by the skin alone when exposed to UV radiation. In other words, after the sunscreen is on the skin for an hour, it can cause more damage than if you were wearing no sunscreen at all.
The EWG gives this one a hazard rating of “3,” and notes that it has rather high rates of causing skin allergies. A 2014 study, for example, recommended that this ingredient not be used in sunscreens for children, because of the risk of causing contact dermatitis. It’s also been found to have widespread exposure in the U.S. population.
This one is similar to homosalate, as it’s made by combining an ester of salicylic acid with 2-ethylhexanol. It may be called “octyl salicylate” or “2-ethylhexyl salicylate.” Like other chemical sunscreens, it absorbs UV light, protecting the skin, and because it’s made with a fatty alcohol, it also has an emollient property, which manufacturers like because it makes the formula more water resistant.
Though it absorbs UVB rays within a certain range, octisalate is thought to be a weak sunscreen and doesn’t protect at all from UVA rays. Because of that, it’s rarely used alone. Instead, it’s typically combined with other chemical sunscreens, like avobenzone, on which it’s said to have a stabilizing effect. The chemical degrades fairly quickly, though, when exposed to sunlight, so is unlikely to add much protection, particularly after you’ve had the product on for awhile.
Octisalate is also called a “penetration enhancer,” meaning that it can increase the amount of other ingredients passing into the skin. That means if there are other potentially hazardous ingredients in the formula (such as preservatives or fragrances), it can usher these ingredients much more deeply into the skin and potentially into the body.
The EWG gives this one a hazard rating of “3,” and notes that exposure to it is widespread.
Considered the safest of all of these options, avobenzone is still a chemical sunscreen, and lacks the stability of many of the other ingredients, meaning that it can break down into unknown chemicals once it’s applied to skin.
A synthetic dibenzoylmethane derivative, avobenzone absorbs UV rays over a wide wavelength, and is considered an effective broad-spectrum sunscreen. Since it’s one of the few that can protect against both UVA and UVB rays, it’s found in a great many sunscreen products, as well as in other products meant to protect from UV rays, like makeup and lip care products.
The EWG gives this one a low hazard rating of only 2. It has no evidence of causing hormone disruption, and doesn’t penetrate the skin very deeply. The problem is that it is not very stable, and once exposed to UV rays, it breaks down and degrades, compromising its ability to protect the skin. One study found that after 2 hours of sunlight exposure, avobenzone lost 85 percent of its ability to absorb UVA rays.
Avobenzone was also found to react with octinoxate, leading to the destruction of both chemicals and loss of skin protection. Manufacturers address the issue by combining the chemical with octocrylene and oxybenzone, which help enhance the stability of avobenzone. Studies have shown various rates of degradation even after these chemicals are added, however.
Another concern: studies have found that the chemical “presented a pronounced phototoxicity” when applied to skin and exposed to UV rays, meaning that it increased skin irritation and damage. Later studies suggested that the levels of the chemical would have to be higher than what is usually found in sunscreen products to cause this type of damage, because avobenzone typically doesn’t absorb far into skin, but again, this depends on the formulation, and whether its paired with other penetration-enhancers.
A 2009 study also found that avobenzone could damage key building blocks in the skin like thymidine, tryptophan, and tyrosine. Other research has suggested it can produce free radicals and cause DNA and protein damage. Manufacturers blend it with free radical scavengers to try to counteract this action.
Finally, avobenzone is considered one of the most common UV filters to cause allergic reactions and contact dermatitis.
Isn’t It Best to Avoid Harmful Chemicals in Sunscreen?
There is more research that needs to be done to determine exactly what the dangers are when it comes to chemicals in sunscreen, but we just don’t feel comfortable using them with what we know so far.
EWG – The Trouble With Sunscreen Chemicals
Environmental Health Perspectives – Concentrations of the Sunscreen Agent Benzophenone-3 in Residents of the United States
Free Radical Biology and Medicine – Sunscreen Enhancement of UV-Induced Reactive Oxygen Species in the Skin
Skin Cancer Foundation – Guide to Sunscreens
Photochemistry and Photobiology – Unexpected Photolysis of the Sunscreen Octinoxate in the Presence of the Sunscreen Avobenzone
Journal of the European Academy of Dermatology and Venereology – Sunscreens – What's Important to Know
Melanoma Research – Sunscreen Ingredients Inhibit Inducible Nitric Oxide Synthase
Toxicology – Endocrine Activity and Developmental Toxicity of Cosmetic UV Filters — An Update
EWG – PABA
Photochemistry and Photobiology – Photoaddition of p-Aminobenzoic Acid to Thymine and Thymidine
Safe Cosmetics – Homosalate
Free Radical Biology and Medicine – Sunscreen Enhancement of UV-Induced Reactive Oxygen Species in the Skin
Actas Dermo-Sifiliográficas – Sun Protection in Children: Realities and Challenges
Wisderm – Avobenzone
Toxicology in Vitro – Skin Phototoxicity of Cosmetic Formulations Containing Photounstable and Photostable UV-Filters and Vitamin A Palmitate
Photochemistry and Photobiology – A Blocked Diketo Form of Avobenzone: Photostability, Photosensitizing Properties and Triplet Quenching by a Triazine-Derived UVB-Filter