Sunscreen makers offer mineral and non-mineral formulations, as well as products that combine mineral and non-mineral active ingredients. Mineral formulations incorporate zinc oxide or titanium dioxide in nano- and micro-sized particles that can be toxic if they penetrate the skin, but they offer strong and lasting UVA protection that is rare in non-mineral sunscreens. Most studies show that these ingredients do not penetrate skin to reach the bloodstream, but research continues. Sunscreens with these ingredients constituted 30 percent of the market in 2010.

The most common ingredients in non-mineral sunscreens are octisalate (found in 59 percent), oxybenzone (52 percent) and avobenzone (49 percent). Oxybenzone can trigger allergic reactions, is a potential hormone disrupter and penetrates the skin in relatively large amounts. Some experts caution that it should not be used on children.  Some 55 percent of sunscreens rated by EWG are non-mineral, and 15 percent combine both mineral and non-mineral active ingredients.

EWG reviewed the scientific literature on hazards and efficacy (UVB and UVA protection) for all active ingredients approved in the U.S. Though no ingredient is without hazard or perfectly effective, on balance our ratings tend to favor mineral sunscreens because of their low capacity to penetrate the skin and the strong and lasting UVA protection they offer.

Mexoryl SX (ecamsule) is another relatively low-risk, effective active ingredient that provides UVA protection, but it is sold in very few formulations. Tinosorb S and M appear to be both safe and effective but are not yet available in the U.S. For consumers who wish to avoid mineral products, sunscreens containing avobenzone are the best options (at the maximum allowable level of 3 percent for the best UVA protection). The potential hormone disrupters oxybenzone or 4-MBC appear to pose greater potential risks than other common sunscreens; EWG recommends against buying sunscreens that contain this compound.

Oxybenzone – experts caution against using it on children

Oxybenzone is found in more than half of the 814 beach and sport sunscreens in EWG’s 2012 database. Experts raise concerns about its use in sunscreens for children because of its ability to penetrate the skin and its association with allergic reactions and potential hormone disruption:

• “It would be prudent not to apply oxybenzone to large surface areas of skin for extended and repeated periods of time unless no alternative protection is available. There may be an additional concern for young children who have less well-developed processes of elimination and have a larger surface area per body weight than adults, with respect to systemic availability of a topically applied dose.” — Hayden C, Roberts M, Benson H. 1997. Systemic absorption of sunscreen after topical application. Lancet 350(Sep): 863-64.
• “…with respect to [oxybenzone], our data raise some concerns regarding the formulation of sunscreen products for specific application to children… whilst limited absorption across the skin was observed for the majority of the sunscreens tested, [oxybenzone] demonstrated sufficiently high penetration to warrant further investigation of its continued application.” — Jiang R, Roberts MS, Collins DM, Benson HAE. 1999. Absorption of sunscreens across human skin: an evaluation of commercial products for children and adults. British Journal of Clinical Pharmacology 48(4): 635-37.
• “It is evident that [oxybenzone] undergoes conjugation in the body to make it water soluble. However, we do not know at what age the ability to conjugate is fully developed, and therefore for children physical filters such as titanium dioxide and/or zinc oxide might still be considered a more appropriate sunscreen component.” — Gonzalez HG, Farbrot A, Larko O. 2002. Percutaneous absorption of benzophenone-3, a common component of topical sunscreens. Clinical and Experimental Dermatology 27(8): 691-94.

Zinc and titanium nanoparticles – effective in sunscreens, but avoid sprays and powders

Since 2007, EWG has highlighted zinc oxide and titanium dioxide as among the best of the available sunscreen ingredients for American consumers. In the 1980s, mineral sunscreens made with these minerals were thick and pasty white. Today, sunscreen makers use particles of between 20 and 200 nanometers in size to create lotions that are nearly clear.
Products with zinc and titanium, sometimes called “mineral filters,” tend to rate well in EWG’s guide because they block harmful UV radiation without penetrating healthy skin. Unlike other common sunscreen chemicals, zinc and titanium are not allergenic, do not break down in sunlight and do not disrupt the body’s natural hormones.  EWG’s review of more than a dozen in vivo and in vitro studies found little to no skin penetration for nanoparticle zinc oxide and titanium dioxide on healthy human, pig and rodent skins (EWG 2009).

EWG’s assessment of the comparative benefits of zinc and titanium sunscreens that might contain nanoparticles is not meant as an endorsement of all nanoscale products nor of the manufacturing processes. Studies suggest that nanomaterials are toxic to fish and other aquatic life in the environment and can damage organs if they are absorbed through the skin, lungs or gut and enter the bloodstream.

EWG urges consumers to avoid mineral-based sunscreens sold as powders or sprays because they could inhale nanoparticles, with unknown consequences. EWG urges manufacturers of mineral-based powder and spray products not to use nano-scale particles. Recent evidence suggests that people have likely ingested significant quantities of nanoscale titanium dioxide used as a whitener in food and toothpaste for more than a decade (Weir 2012).

Sunscreen chemicals: exposure and toxicity concerns

Sunscreens are used frequently over large portions of the body, which heightens the concerns over exposure.

A number of sunscreen chemicals are known to permeate the skin. Laboratory studies, tests on volunteers and human biomonitoring research have detected these chemicals in the general population. In the United States, the widely used chemical oxybenzone (or benzophenone-3) has been detected in 96 percent of the population (Calafat 2008, Wolff 2007). A recent European study detected four common sunscreen chemicals in mothers’ milk, indicating potential for exposure to the developing fetus and newborns (Schlumpf 2008). Indications of human exposure underscore the need for the FDA and other regulatory agencies to carefully review the toxicity of widely used sunscreen ingredients.

With this in mind, EWG evaluated US-approved sunscreen chemicals for both their ability to block UV radiation and for toxicity. The table below summarizes human exposure and toxicity information for 14 US-approved sunscreens and for three ingredients that are pending approval by the FDA. Ingredients are flagged for the following concerns:

• Human exposure – resulting from sunscreen chemicals penetrating skin and reaching sensitive organs or hormone receptors
• Hormone activity – that can affect the regulation of the reproductive, nervous, thyroid and immune systems, particularly if exposures occur during pregnancy or childhood.
• Other toxicity concerns — including sun-related skin allergy, effects on skin and breakdown products

No ingredient is without concerns; EWG’s rating system for sunscreens takes into account the range of concerns and differences in the weight of the evidence for each active ingredient.

• Four other ingredients approved in the United States are almost never used in sunscreens and are poorly studied: menthyl anthranilate, benzophenone-8, PABA and trolamine salicylate

Table references:

1 – Janjua 2004. 2 – Janjua 2008. 3 – Klinubol 2008. 4 – Schlumpf 2008. 5 – Seidlova-Wuttke 2006. 6 – Seidlova-Wuttke 2006. 7 – Schlumpf 2004. 8 – Schreurs 2005. 9 – Durrer 2007. 10 – Maerkel 2007. 11 – Faass 2009. 12 – Sarveiya 2004. 13 – Gonzalez 2006. 14 – Hayden 1997. 15 – Felix 1998. 16 – Calafat 2008. 17 – Wolff 2007. 18 – Wolff 2008. 19 – Schlumpf 2001. 20 – Schlumpf 2004. 21 – Schreurs 2007. 22 – Ma 2003. 23 – NTP 1992. 24 – Rodriguez 2006. 25 – Klammer 2007. 26 – Rachon 2006. 27 – Hayden 2005. 28 – Gomez 2005. 29 – McHugh 1997. 30 – Odio 1994. 31 – Vidal 2003. 32 – Berne 1998. 33 – Schauder 1997. 34 – SCCP 2007. 35 – Kurul 2001. 36 – Benech-Kieffer 2000. 37 – Molina-Molina 2008. 38 – Nohynek 2007. 39 – Gulson 2010. 40 – Sharma 2009. 41 – Sayes 2007. 42 – Wu 2009. 43 – Sadrieh 2010. 44 – IARC 2006. 45 – Takeda 2009. 46 – Shimizu 2009. 47 – Park 2009. 48 – Pan 2009. 49 – Montenegro 2008. 50 – Benech-Kieffer 2003. 51 – FDA 2006. 52 – Walters 1997. 53 – Shaw 2006. 54 – Mavon 2007. 55 – Ashby 2001. 56 – Gonzalez-Perez 2007. [click here for full reference list]