The Trouble With Oxybenzone and Other Sunscreen Chemicals

Sunscreen is a unique body care product: consumers are directed to apply a thick coat over large areas of the body and reapply frequently. Thus, ingredients in sunscreen should not be irritating or cause skin allergy, and should be able to withstand powerful UV radiation without losing their effectiveness or forming potentially harmful breakdown products. Sunscreens commonly include ingredients that act as “penetration enhancers” and help the product adhere to skin. As a result, many sunscreen chemicals are absorbed into the body and can be measured in blood, breast milk and urine samples.

Active ingredients in sunscreens come in two forms, mineral and chemical filters. Each uses a different mechanism for protecting skin and maintaining stability in sunlight. The most common sunscreens on the market contain chemical filters. These products typically include a combination of two to six of these active ingredients: oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate. Mineral sunscreens use zinc oxide and/or titanium dioxide. A handful of products combine zinc oxide with chemical filters.

Lab studies indicate that some chemical UV filters may mimic hormones or cause skin allergies, which raises important questions about unintended effects on human health from frequent sunscreen application. The most worrisome is oxybenzone, added to nearly 70 percent of the non-mineral sunscreens in EWG’s 2016 sunscreen database.

The Centers for Disease Control and Prevention has detected oxybenzone in more than 96 percent of the American population, based on a representative sampling of children and adults (Calafat 2008). Participants who reported using sunscreen have higher oxybenzone exposures (Zamoiski 2015). Oxybenzone can cause allergic skin reactions and may disrupt hormones (Rodriguez 2006, Krause 2012).

Americans’ exposures to oxybenzone appear to be increasing over the past decade, based on analysis of CDC’s multi-year NHANES study (Han 2012). Investigators at UC Berkeley recently reported a dramatic drop in teen girls’ exposure to oxybenzone and other ingredients of concern in cosmetics when they switched from their usual products to replacements that did not contain those chemicals (Harley 2016).

EWG recommends that consumers avoid sunscreens with oxybenzone. But other chemical filters show similar indications of hormone disruption or skin allergy. Two European studies have detected oxybenzone and other sunscreen filters in mothers’ milk, indicating that the developing fetus and newborns may be exposed to these substances (Schlumpf 2008, Schlumpf 2010). A 2010 study of Swiss mothers by Margaret Schlumpf of the University of Zurich found at least one sunscreen chemical in 85 percent of milk samples.

Experts caution that the unintentional exposure to and toxicity of active ingredients erode the benefits of sunscreens (Krause 2012, Schlumpf 2010). But most conclude that more sensitive tests are needed to determine whether sunscreen chemical ingredients pose risks to users (Draelos 2010, Gilbert 2013).

Active ingredient toxicity

This table outlines human exposure and toxicity information for nine FDA-approved sunscreen chemicals. We asked these questions:

  • Will the chemical penetrate skin and reach living tissues?
  • Will it disrupt the hormone system?
  • Can it affect the reproductive and thyroid systems and, in the case of fetal or childhood exposure, permanently alter reproductive development or behavior?
  • Can it cause a skin allergy?
  • What if it is inhaled?
  • Other toxicity concerns?
Chemical EWG Hazard Score Use in U.S. sunscreens Skin Penetration Hormone disruption Skin Allergy Other concerns References
UV filters with higher toxicity concerns
Oxybenzone 8 Widespread Detected in nearly every American; found in mother’s milk; 1-to-9% skin penetration in lab studies Acts like estrogen in the body; alters sperm production in animals; associated with endometriosis in women Relatively high rates of skin allergy Janjua 2004, Janjua 2008, Sarveiya 2004, Gonzalez 2006, Rodriguez 2006, Krause 2012
Octinoxate (Octylmethoxycinnamate) 6 Widespread Found in mothers’ milk; less than 1% skin penetration in human and laboratory studies Hormone-like activity; reproductive system, thyroid and behavioral alterations in animal studies Moderate rates of skin allergy Krause 2012, Sarveiya 2004, Rodriguez, 2006, Klinubol 2008
UV filters with moderate toxicity concerns
Homosalate 4 Widespread Found in mothers’ milk; skin penetration less than 1% in human and laboratory studies Disrupts estrogen, androgen and progesterone Toxic breakdown products Krause 2012, Sarveiya 2004, SCCNFP 2006
Octisalate 3 Widespread; stabilizes avobenzone Skin penetration in lab studies Rarely reported skin allergy Walters 1997, Shaw 2006 Singh 2007
Octocrylene 3 Widespread Found in mothers’ milk; skin penetration in lab studies Relatively high rates of skin allergy Krause 2012, Bryden 2006, Hayden 2005
UV filters with lower toxicity concerns
Titanium Dioxide 2 (topical use), 6 (powder or spray) Widespread No finding of skin penetration No evidence of hormone disruption None Inhalation concerns Gamer 2006, Nohynek 2007, Wu 2009, Sadrieh 2010, Takeda 2009, Shimizu 2009, Park 2009, IARC 2006b
Zinc Oxide 2 (topical use), 4 (powder or spray) Widespread; excellent UVA protection Less than 0.01% skin penetration in human volunteers No evidence of hormone disruption None Inhalation concerns Gulson 2012, Sayes 2007, Nohynek 2007, SCCS 2012
Avobenzone 2 Widespread; best UVA protection of chemical filters Very limited skin penetration No evidence of hormone disruption Breakdown product causes relatively high rates of skin allergy Unstable in sunshine, must be mixed with stabilizers Klinubol 2008, Bryden 2006, Hayden 2005, Montenegro 2008, Nash 2014
Mexoryl SX 2 Uncommon; pending FDA approval; offers good, stable UVA protection Less than 0.16% penetrated the skin of human volunteers No evidence of hormone disruption Skin allergy is rare Benech-Kieffer 2003, Fourtanier2008
6 other ingredients approved in the U.S. are rarely used in sunscreens: benzophenone-4, benzophenone-8, menthyl anthranilate, PABA, Padimate O, and trolamine salicylate


Hormone disruption

In addition to oxybenzone, other chemical filters appear to be endocrine disruptors. Nine researchers from Denmark and Switzerland reviewed the available evidence on hormone disruption for three common UV filters (oxybenzone, homosalate and octinoxate), three uncommon UV filters (Benzophenone-2, PABA and OD-PABA), and two European ingredients (3-BC and 4-MBC) (Krause 2012). They report that a large number of studies in animals and cells have shown that the chemicals affect reproduction and development by altering reproductive and thyroid hormones, although the evidence was mixed for some studies. Animal studies find lower sperm counts and sperm abnormalities after exposure to oxybenzone and octinoxate, delayed puberty after exposure to octinoxate and altered estrous cycling for female mice exposed to oxybenzone. Recently Danish researchers reported that eight of 13 chemical sunscreen ingredients allowed in the U.S. affected calcium signaling of male sperm cells in laboratory tests, which the researchers suggest could reduce male fertility (Endocrine Society 2016).

It is difficult to know the implications to human health from exposure to a mixture of hormone-disrupting ingredients in sunscreen. Intentional dosing studies in people are rare. One research group has applied a mixture of three hormone-disrupting sunscreen ingredients to human volunteers and reported alterations in inhibin B and testosterone, male sex hormones and thyroid hormones (Janjua 2004, 2008). The researchers concluded these differences were normal variation and not attributed to sunscreen exposure, but critics argue that the exposures were too short to be conclusive (Krause 2012). A Swiss survey for the ingredient octinoxate suggest that young children might have short-term exposures that put them at risk for thyroid disruption on days they use sunscreen (Manová 2015).

Preliminary investigations by a team of researchers at the NIH and SUNY Albany suggest a link between higher concentrations of oxybenzone and related benzophenones and increased risk of a variety of reproductive effects. Specifically:

Men with higher benzophenone-2 (BP-2) levels in bodies had poorer sperm quality, no association was found for other benzophenones (Louis 2015),

Male exposures to BP-2 and 4-hydroxyoxybenzone were associated with longer time to partner’s conception (Buck Louis 2014),

Male and female BP-2 levels were associated with greater odds of a female baby, and male’s 4-hydroxybenzophenone exposure was associated with an increased odds of a male baby (Bae 2016),

Female exposures to oxybenzone and related chemicals was linked to increased risk of endometriosis (Kunisue 2012).

Mineral sunscreens

Mineral sunscreens are made with zinc oxide and titanium dioxide, usually in the form of nanoparticles.

Mineral sunscreens usually rate better than chemical sunscreens for safety in the EWG database. However, it is important that manufacturers use forms of minerals that are coated with inert chemicals to reduce photoactivity. If they don’t, users could suffer skin damage. To date, no such problems have been reported.

The FDA should set guidelines and place restrictions on zinc and titanium sunscreens to minimize the risks to sunscreen users and maximize these products’ sun protection. Our detailed analysis of nanoparticles in sunscreens is here.

Inactive ingredients

FDA must also take a close look at the so-called inactive ingredients in sunscreens. These typically make up half to nearly all of a sunscreen product.

One ingredient in particular is a cause for concern: methylisothiazolinone, or MI, a preservative. This year, EWG has found MI listed on the labels of 66 sunscreens and 39 SPF-rated daily moisturizers. MI is used alone or in mixtures with a related chemical preservative called methylchloroisothiazolinone, or MCI.

The American Contact Dermatitis Society named MI its “allergen of the year” in 2013.

Laboratory studies indicate that MI is a skin sensitizer or allergen. Over the past several years, physicians have reported serious cases of serious skin allergy, most notably in children exposed to MI from baby wipes and other products meant to be left on the skin (Chang 2014). In a study published in 2014, researchers at Baylor University surveyed the ingredients in 152 children’s body care products labeled “hypoallergenic” and found MI in 30 of them (Schlichte 2014).

In 2015, researchers from 15 clinics in the U.S. and Canada reported an increase in MI allergy in patients. The researchers concluded that they had documented “the beginning of the epidemic of sensitivity to methyliosthiazolinones in North America” (Warshaw 2015).

That MI has become relatively common in sunscreen is a matter of concern because sunscreen users are likely to be exposed to significant concentrations of this chemical. The products that contain MI are intended to be applied to large portions of the body and to be reapplied often.

In March 2015, the European Scientific Committee on Consumer Safety concluded that no concentration of MI could be considered safe in leave-on cosmetic products (EU SCCS 2014).

MI is allowed in U.S. products. Last September, the Cosmetics Ingredient Review expert panel – an independent, cosmetics-industry-funded body the American cosmetics industry pays to advise it on the safety of cosmetics ingredients – told the industry that MI was safe for use in body care products as long as manufacturers come up with formulations that wouldn’t cause allergic reactions (CIR 2014). Since FDA has little legal power to regulate cosmetics ingredient safety, it has authorized the cosmetics industry to police itself through this CIR panel. The body’s recommendations are not legally binding on any company. In several decades, it has declared only 11 ingredients or chemical groups to be unsafe (CIR 2012).

EWG recommends that the FDA launch a more thorough investigation of the safety of all ingredients currently in sunscreens to ensure that none of them damage skin or cause other toxic effects in consumers.


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About the ratings

EWG provides information on sunscreen products from the published scientific literature, to supplement incomplete data available from companies and the government. The ratings indicate both efficacy and the relative level of concern posed by exposure to the ingredients in this product - not the product itself - compared to other sunscreens. The ratings reflect potential health hazards but do not account for the level of exposure or individual susceptibility, factors which determine actual health risks, if any. Methodology | Privacy Policy | Terms & Conditions

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