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The trouble with ingredients in sunscreens

Sunscreen products are intended to be applied to the body every day, over the course of a lifetime. The companies that make and sell sunscreen ingredients and products should test them thoroughly for potential short-term and long-term health effects. This includes toxicity testing for irritation and skin allergies, as well as testing for skin absorption and the potential to cause cancer, disrupt the hormone system and impact reproduction and development.

In 2021, the Food and Drug Administration, which oversees sunscreen safety, proposed its latest update to regulations for these products. The agency reviewed 16 ingredients and reported that only two, zinc oxide and titanium dioxide, are “generally recognized as safe and effective”, or GRASE, based on the available information. A GRASE designation means the ingredient is widely recognized as safe and effective by experts.

Citing data showing safety issues, the FDA proposed that two rarely used sunscreen ingredients, aminobenzoic acid and trolamine salicylate, are not GRASE.

The FDA proposed that 12 other ingredients are not GRASE due to insufficient data: Avobenzone, cinoxate, dioxybenzone, ensulizole, homosalate, meradimate, octinoxate, octisalate, octocrylene, oxybenzone, padimate O, and sulisobenzone.

While these twelve ingredients may not be GRASE, they will still be allowed to be used in products on the U.S. market until the FDA finalizes its 2021 proposal.

In the meantime, the FDA has requested additional safety data of these ingredients because of health concerns and studies by the agency that show these ingredients can be absorbed through the skin. In recent years, studies have also raised concerns about endocrine-disrupting effects of three ingredients: homosalate, avobenzone and oxybenzone.

In 2021 the European Commission published final opinions on the safety of three non-mineral ultraviolet, or UV, filters, oxybenzone, homosalate and octocrylene. It found that two of these filters – homosalate and octocrylene –  are not safe in the amounts at which they’re currently used. As a result, the commission proposed limiting the allowed concentrations of these filters in sunscreens.

But the  U.S has different standards, as sunscreen manufacturers are legally allowed to use these two chemicals at concentrations higher than the European limits. That’s why hundreds of U.S.-made sunscreens have such high levels of the substances.

The ingredients oxybenzone, octinoxate, octisalate, octocrylene, homosalate and avobenzone are all systemically absorbed into the body after use, according to studies published by the FDA. These studies also reported that the ingredients could be detected on the skin and in the blood weeks after they had last been used.

Other studies have reported sunscreen ingredients were detected in breast milk, urine and blood plasma samples.

Absorption from skin application is not the only way sunscreen ingredients end up in the body. It’s also possible for sunscreen users to inhale ingredients in sunscreen sprays and ingest some of the ingredients they apply to their lips, so the ingredients should not be harmful to the lungs or internal organs.

This constant exposure to sunscreen chemicals raises concerns, especially because there is not enough safety data for most ingredients.

Active ingredient toxicity

This table outlines human exposure and hazard information for eight common FDA-approved sunscreen chemicals, often referred to as active ingredients because they provide UV protection. Sunscreen products typically include a combination of active ingredients, except for those formulated with zinc oxide.

Table 1. Summary of health concerns associated with sunscreen active ingredients.

Chemical FDA 2019 proposed classification as safe and effective Skin penetration Hormone disruption Skin allergy or other concerns
Oxybenzone No + + +
Octinoxate (Octyl methoxycinnamate) No + + +
Homosalate No + + +
Octisalate No +
Octocrylene No + +
Avobenzone No + + +
Titanium dioxide Yes + Inhalation concerns
Zinc oxide Yes + Inhalation concerns

+ = evidence; – = no or weak evidence

Specific ingredient concerns


The most worrisome sunscreen active ingredient is oxybenzone, according to publicly available scientific research. It is readily absorbed through the skin and the Centers for Disease Control and Prevention found higher levels of oxybenzone in those who report applying sunscreen. It causes allergic skin reactions, behaves like a hormone disruptor and may be more harmful to children as they are more susceptible to the effects of chemicals.

In an evaluation of CDC-collected exposure data for American children, researchers found that adolescent boys with higher oxybenzone measurements had lower total testosterone levels.

A 2017 systematic review of 23 studies reported that there was evidence of associations between oxybenzone exposure and adverse reproductive outcomes, including  birth outcomes. According to the latest proposed FDA sunscreens monograph, the agency needs further data to determine whether oxybenzone can be considered safe and effective, since:

[The] available literature … indicat[es] that oxybenzone is absorbed through the skin to a greater extent than previously understood and can lead to significant systemic exposure. … The significant systemic availability of oxybenzone … is a concern, among other reasons, because of questions raised in the published literature regarding the potential for endocrine activity.

Four studies published in 2020, after the FDA released its draft proposal, support previous findings that oxybenzone can act as an endocrine disruptor and may increase the risk of breast cancer and endometriosis. In addition, the National Toxicology Program found equivocal evidence of carcinogenicity in rats after observing increases in thyroid tumors and enlargement of the uterus in female rats with high exposure to oxybenzone.

Investigators at the University of California at Berkeley reported a dramatic drop in teen girls’ exposure to oxybenzone in cosmetics when they switched from their usual products to replacements that did not contain this chemical – suggesting sunscreen products are a significant source of exposure to oxybenzone.

Recently, the European Commission reported current human exposure levels to oxybenzone were unsafe and proposed a concentration restriction of 2.2 percent, lower than the limited amount allowed in U.S. sunscreens, which is up to 6 percent. Several countries, and one U.S. state, ban the sale of sunscreens that contain this ingredient, because it may harm aquatic life.

Due to the health concerns associated with oxybenzone, EWG recommends consumers avoid sunscreens with oxybenzone.

Octinoxate, or octyl methoxycinnamate

Octinoxate is a non-mineral UV filter. It is readily absorbed into the skin and continues to be absorbed after the sunscreen has been applied. According to the FDA’s 2020 study, it has been found in blood samples at levels 16 times above the proposed FDA safety threshold.

Animal studies have reported octinoxate has hormone effects on the metabolic system and affects thyroid hormone production, with some evidence for other endocrine targets, including androgen and progesterone signaling. Octinoxate can also cause allergic reactions.

Several countries, and one U.S. state, ban the sale of sunscreens that contain this ingredient, because it may harm aquatic life.


Homosalate is a non-mineral UV filter widely used in U.S. sunscreens. The FDA has proposed that there are insufficient data to evaluate whether it is safe and effective to use in sunscreens. Homosalate can penetrate the skin and disrupt hormones.

A recent European Commission opinion reported that homosalate has a recommended maximum concentration of 1.4 percent, because of concerns for potential hormone disruption. The FDA allows U.S. sunscreen manufacturers to use it in concentrations up to 15 percent.


Octisalate, a non-mineral UV filter, readily absorbs through the skin at levels 10 times the FDA’s cutoff for systemic exposure. This cutoff, 0.5 nanograms per milliliter, is the maximum concentration that may be found in blood before there are potential safety concerns. The FDA has requested additional safety tests when a sunscreen is absorbed above this level.

The FDA 2019 proposed update suggests there is insufficient data to determine whether octisalate can be classified as safe and effective to use in sunscreens. A case report showed that the chemical has been linked to allergic contact dermatitis.


Octocrylene readily absorbs through the skin at levels about 14 times the FDA’s cutoff for systemic exposure. But the agency suggested there is not enough data to determine whether the chemical be classified as GRASE.

Octocrylene has been linked to aquatic toxicity, with the potential to harm coral health. It is often contaminated with benzophenone, which is a carcinogen. According to one study, benzophenones levels can increase in products over time.

The European Commission recently concluded there is some evidence of octocrylene’s hormone-disrupting potential but current use concentrations up to 10 percent are considered safe.


Avobenzone is a widely used non-mineral filter that provides protection from ultraviolet A, or UVA, rays and is often used with other non-mineral active ingredients in products offering broad spectrum protection. In one study, avobenzone was detected on average in samples at levels nine times above the FDA’s cutoff for systemic exposure.

Because avobenzone is not stable, it must be paired with other ingredients that act as stabilizers to prevent it from breaking down in the sun. Breakdown products of avobenzone have been shown to cause allergic reactions. Avobenzone can disrupt the endocrine system and has been shown to block the effects of testosterone in cellular studies.

Titanium dioxide and zinc oxide

Mineral sunscreens are made with titanium dioxide and zinc oxide, usually in the form of nanoparticles. The FDA in 2021 proposed that both titanium dioxide and zinc oxide be classified as GRASE. Evidence suggests that few, if any, zinc or titanium particles penetrate the skin to reach living tissues.

Because of the potential of exposure through inhalation, the International Agency for Research on Cancer has classified titanium dioxide as possibly causing cancer in humans. For this reason, powdered or spray formulations containing titanium dioxide are a concern. Zinc oxide is also a cause for inhalation concerns when used in spray and powder products

In general, mineral sunscreens tend to rate better than chemical sunscreens in EWG’s sunscreen guide. But to improve their stability when exposed to sunlight and prevent these chemicals from breaking down, manufacturers use forms of minerals coated with other inert chemicals.

To lower the risks to sunscreen users and maximize these products’ sun protection, EWG supports stronger guidelines and restrictions on the types of zinc and titanium used in sunscreens, including nanoparticles, which we have analyzed in detail.

Other active ingredients

Mexoryl SX, an uncommon active ingredient in the U.S., was approved by the FDA to be used in one specific sunscreen formulation in 2006. This ingredient offers strong UVA protection and public research provides no evidence of hormone disruption and rare incidence of skin allergy. But the FDA’s analysis showed there wasn’t enough data to classify the ingredient as safe and effective.

Aminobenzoic acid, or PABA, and trolamine salicylate are active ingredients that are no longer commonly used in U.S. sunscreens. The FDA’s 2019 proposal concluded that the risks of these chemicals outweigh their benefits and proposed classifying them as unsafe, not GRASE.

Inactive ingredients

EWG continues to urge the FDA to also look closely at the so-called inactive ingredients in sunscreens, which typically make up half to 70 percent of these products. Like cosmetic ingredients, these inactive sunscreen ingredients are generally unregulated.

EWG recommends the FDA launch a thorough investigation of the safety of all sunscreen ingredients to ensure none of them damages skin or harms health in other ways.