Sunscreen chemicals should be engineered with great care. They are used in products intended for repeated application to large portions of the body. To offer effective protection from the sun’s rays, sunscreens must stick to the skin. So-called active ingredients – substances that filter out UVA and UVB radiation – are present in large concentrations.
Over the past decade dozens of studies have examined the potential health hazards of sunscreen chemicals. These include possible skin irritation or allergy, hormone disruption and skin damage that occurs when sunlight acts on sunscreen chemicals.
The federal Food and Drug Administration has not formally reviewed any of the recent studies in this category. Most sunscreen ingredients were already in use in 1978, when the FDA announced its intention to regulate sunscreen safety. Since then the agency has approved just one sun-filtering chemical – avobenzone,
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. Each may pose hazards to human health.
The most common sunscreens on the market contain chemical filters. These products typically include a combination of three to six of these active ingredients: oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate.
Nearly every chemical sunscreen contains avobenzone because it is the best agent for filtering skin-damaging UVA rays. However, avobenzone alone may break down when exposed to sunlight. Chemicals such as octocrylene must be added to the product to stabilize it. This practice has become more common in recent years.
Laboratory studies of several sunscreen chemicals indicate that they may mimic hormones and disrupt the hormone system (Krause 2012, Schlumpf 2001, 2004b, 2008). Some research on animals suggests that oxybenzone and two other sunscreen chemicals – 4-MBC and octinoxate – are toxic to reproductive systems or interfere with normal development. (See Table 1)
Experts caution that the unintentional exposure to and toxicity of active ingredients erodes the benefits of sunscreens (Krause 2012, Schlumpf 2010). But most conclude that more sensitive tests are needed to determine whether these ingredients pose risks to sunscreen users (Draelos 2010, Gilbert 2013).
The most problematic of the sunscreen chemicals used in the U.S. is oxybenzone, found in 80 percent of chemical sunscreens. EWG recommends that consumers avoid oxybenzone because it can penetrate the skin, cause allergic skin reactions and may disrupt hormones (Calafat 2008, Rodriguez 2006, Krause 2012). Preliminary investigations of human populations suggest a link between higher concentrations of oxybenzone and its metabolites in the body and increased risk of endometriosis and lower birthweight in daughters (Kunisue 2012, Wolff 2008).
Generally, chemical sunscreens deserve special scrutiny because most are known to permeate the skin to some degree. Two European studies have detected common sunscreen chemicals in mothers’ milk, indicating that the developing fetus and newborns may be exposed to these substances (Schlumpf 2008, Schlumpf 2010). A 2010 study by Margaret Schlumpf of the University of Zurich found at least one sunscreen chemical in 85 percent of milk samples. Four of the chemicals detected are commonly used in U.S. sunscreens.
The federal Centers for Disease Control and Prevention has detected oxybenzone in more than 96 percent of the U.S. population, based on a representative sampling of more than 2,500 Americans children and adults (Calafat 2008). Higher concentrations of oxybenzone were measured in samples collected from participants during the summer months.
The FDA is considering the approval of two sunscreen ingredients used in Europe – 4-methylbenzylidine camphor and 3-benzylidine camphor. Lab studies indicate they may disrupt the hormone system.
Products in EWG’s sunscreen database that utilize minerals to filter UV rays are made with zinc oxide and titanium dioxide, usually in the form of nanoparticles.
Though no ingredient is without hazard or completely effective, on balance our ratings favor these mineral sunscreens. They do not penetrate the skin, and they are stable in the presence of sunlight.
There are some exceptions. Mineral sunscreen could pose a risk of skin damage if manufacturers do not select forms that are coated with inert chemicals to reduce photoactivity. Nano-powders could potentially lodge in the lungs and reach the bloodstream, where they could damage internal organs. To date, no such problems have been reported. Still, 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.
Safer, more effective solutions may be on the horizon. The European sunscreen chemicals Mexoryl SX, Tinosorb S and Tinosorb M are promising UV filters not yet approved for use in the U.S.
This table summarizes human exposure and toxicity information for nine FDA-approved sunscreen chemicals and four ingredients now being considered by the FDA. We asked these questions:
|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|
|4-MBC||7||Pending FDA approval||Found in mothers’ milk; skin penetration in lab studies||Stimulates estrogen-dependent tumor cells; associated with reproductive disorders and behavioral changes in animals||Krause 2012, Janjua 2004, Janjua 2008, Klinubol 2008, Schlumpf 2004|
|3-BC||7||Pending FDA approval||Found in mothers’ milk; skin penetration in lab studies||Hormone-like activity; delays puberty and impairs reproduction in animals||Krause 2012, Durrer 2007, Schlumpf 2004|
|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||Relatively high rates of skin allergy||Klinubol 2008, Bryden 2006, Hayden 2005, Montenegro 2008|
|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|
|Tinosorb M||1||Pending FDA approval; offers good, stable UVA protection||Very limited skin penetration||No evidence of hormone disruption||Skin allergy is rare||Ashby 2001, Mavon 2007, Gonzalez-Perez 2007|
|Tinosorb S||0||Pending FDA approval; offers good, stable UVA protection||No evidence of hormone disruption||Ashby 2001|
|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|