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 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.
This table outlines human exposure and toxicity information for nine FDA-approved sunscreen chemicals. 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|
|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|
|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|
Nearly every chemical sunscreen in the United States contains avobenzone because it is the best available agent for filtering skin-damaging UVA rays. However, avobenzone alone may break down when exposed to sunlight and must be stabilized with other chemicals such as octocrylene.
Laboratory studies of several sunscreen chemicals indicate that they may mimic hormones and disrupt the hormone system (Krause 2012, Schlumpf 2001, 2004, 2008). Some research on animals suggests that oxybenzone and other sunscreen chemicals can be toxic to reproductive systems or interfere with normal development. (See Table 1) Another sunscreen chemical, 4-methylbenzidyl camphor, used in Europe and under petition for use in the United States is also a hormone disruptor.
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 sunscreen chemicals ingredients pose risks to sunscreen users (Draelos 2010, Gilbert 2013). Generally, chemical sunscreens deserve special scrutiny because most are known to permeate the skin to some degree.
Two European studies have detected 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.
The most problematic of the sunscreen chemicals used in the U.S. is oxybenzone, found in nearly every chemical sunscreen. EWG recommends that consumers avoid this chemical 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).
The federal Centers for Disease Control and Prevention has detected oxybenzone in more than 96 percent of the American population, based on a representative sampling of more than 2,500 children and adults (Calafat 2008). Researchers found higher concentrations of oxybenzone in samples collected from participants during the summer months, and concluded that sunscreen use may explain this seasonal difference.
Mineral sunscreens are made with zinc oxide and titanium dioxide, usually in the form of nanoparticles.
Mineral sunscreen usually rate better than chemical sunscreens for safety in our 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.
New sunscreen chemicals may be on the horizon. The chemicals Mexoryl SX and Mexoryl SL, developed by the French company LaRoche-Posay Laboratoire Dermatologique, and Tinosorb S and Tinosorb M, developed by the German chemical giant BASF, are promising UVA filters. The FDA is considering the manufacturers’ applications to market them in the U.S.
The FDA is also considering the approval of another European sunscreen ingredient 4-methylbenzylidine camphor that may disrupt the hormone system, according to laboratory studies. Europe recently deemed another sunscreen chemical and hormone disruptor, 3-Benzylidene camphor (Mexoryl SD), to be unsafe in sunscreens (SCCS 2013b). EWG recommends that FDA launch a more thorough investigation of the safety of ingredients currently in use, and those proposed for inclusion in U.S. sunscreens to ensure that none of them damage skin or cause other toxic effects in consumers.
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