Chemical filter sunscreens were developed for their ease of use and inexpensive ingredients. These products typically include a combination of two to six of the following active ingredients: oxybenzone, octinoxate, avobenzone, homosalate, octocrylene and octisalate. Many of these sunscreens are ineffective and studies have shown in addition to hormone disruption, skin penetration, skin allergies, cell damage and other concerns.
Chemical sunscreens absorb UV radiation. This means UVA rays, the type responsible for more serious damage, reach deeper layers of skin. Most chemical UV filters protect from UVA or UVB rays, not both.
A study by the Centers for Disease Control and Prevention (CDC) found evidence of widespread exposure to oxybenzone. After analyzing urine samples from over 2,500 people, researchers found oxybenzone 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.
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.
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.
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.”
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."
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.
Hawaii signed the first bill in the U.S. to ban the sale of sunscreen chemicals that are toxic to coral reefs and marine life
Environmental researchers have published studies showing how oxybenzone and octinoxate, which accumulate in the water from bathers or from wastewater discharges, can damage coral reefs through bleaching and harming the corals’ DNA. In some instances, the corals can die.
A February 2016 study in the Archives of Environmental Contamination and Toxicology examining the impact of oxybenzone in corals in Hawaii and the U.S. Virgin Islands concluded that the sunscreen ingredient “poses a hazard to coral reef conservation and threatens the resiliency of coral reefs to climate change.’’
A team of researchers and students are planting branches clipped from a coral nursery off Key Biscayne.
Last year Hawaii banned the sale or distribution of any sunscreens containing oxybenzone and octinoxate, a measure that will go into effect on Jan. 1, 2021. It was the first state in the nation to implement such a ban.
Avobenzone 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 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. Avobenzone’s instability issues tend to become even worse when it is mixed in a formula with one or both of the mineral active sunscreen ingredients. 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. 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.
Avobenzone is considered one of the most common UV filters to cause allergic reactions and contact dermatitis.
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. Like homosalate, it absorbs UVB and short-wave UVA rays. It combines well with avobenzone, and is often seen in sunscreen products paired up with this ingredient.
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.
Similar to homosalate, 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.
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.
Palau is set to become the first country to impose a widespread ban on the sale and use of sunscreen and skincare products that contain a list of ten different chemicals
Palau is a collection of hundreds of coral and volcanic islands about 890 km east of the Philippines and is heavily reliant on tourism revenue. Scientists have been raising concerns about the impacts of sunscreen products on marine life for many years. The banned sunscreens are defined as skin-care products sold for topical use containing any of the following ingredients:
- oxybenzone (benzophenone-3)
- octinoxate (octyl methoxycinnamate)
- 4-methyl-benzylidene camphor
- methyl paraben
- ethyl paraben
- butyl paraben
- benzyl paraben
EWG has been publishing a list of the most common active sunscreen filters for many years. While many of these filters cause skin rashes and hormonal changes, most sunscreen manufacturers have yet to change their formulations, rather choosing to eliminate these hazardous filters just before their banned and replace them with other hazardous filters, rather than reformulating to safe sunscreens.