The most widely used sunscreen ingredient, known for its low potential to sensitize skin or act as a phototallergen. Estrogenic effects noted in laboratory animals at concentrations close to those experienced by sunscreen users.

Associated with photoallergic reactions. This chemical absorbs through the skin in significant amounts. It contaminates the bodies of 97% of Americans according to Centers for Disease Control research.

Octisalate is a weak UVB absorber with a generally good safety profile among sunscreen ingredients. It is a penetration enhancer, which may increase the amount of other ingredients passing through skin.

Sunlight causes this unstable ingredient to break down into unknown chemicals, especially in the presence of another active, Octinoxate. Primarily a UVA-absorbing agent.

Titanium has a long history of use in sunscreen; little absorption and no adverse health effects are reported. An estimated 70% of sunscreens with TiO2 contain nano-size particles. Significant data gaps remain.

Octocrylene may be used in combination with other UV absorbers to achieve higher SPF formulas. It produces oxygen radicals when exposed to UV light.

An estimated 30% of sunscreens with zinc oxide contain nanoparticles. Micronized zinc offers improved sun protection. However little is known regarding toxicological effects of micronized zinc oxide especially the nano-size particles.

A UVB protector. Research indicates it is a weak hormone disruptor, forms toxic metabolites, and can enhance the penetration of a toxic herbicide.

An estimated 70% of sunscreens with TiO2 contain nano-size particles. Micronized titanium offers greater sun protection than conventional titanium. However little is known regarding potential health effects of micronized TiO2--especially the nano-size fraction.

Known to produce free radicals when exposed to sunlight, leading to damage of DNA, this UVB protector may have the potential to cause cancer.

An estimated 30% of sunscreens with zinc oxide contain nano-size particles. Micronized zinc offers greater sun protection than conventional zinc. However little is known regarding potential health effects of micronized zinc oxide--especially the nano-size fraction.

A moderately effective UVA protector not permitted for use in Europe or Japan. 1 study found that it produces damaging reactive oxygen species when exposed to sunlight.

A derivative of the once-popular PABA sunscreen ingredient, research shows this chemical releases free radicals, damages DNA, has estrogenic activity, and still causes allergic reactions in some people.

Can cause skin and eye irritation. Does not penetrate the skin to a large degree, but enhances the ability of other chemicals to penetrate.

Not an approved active ingredient in the U.S., Tinosorb S may be added to sunscreens to boost their efficacy. Few studies exist on the toxicology of this chemical. It is photostable and not estrogenic.

FDA approved use of this UVA-absorbing agent in 2006. 2 hours of sunlight can degrade as much as 40% of this active ingredient. Low skin penetration.

Not an approved active ingredient in the U.S., but found in some products. Provides UVB and partial UVA protection.

An estimated 70% of sunscreens with TiO2 contain nano-size particles. Micronized titanium offers greater sun protection than conventional titanium. However little is known regarding potential health effects of micronized TiO2--especially the nano-size fraction.

A UV filter not approved as an active ingredient for sunscreen in the U.S., but listed as an inactive ingredient in some products. European researchers cite concerns over thyroid toxicity, hormone disruption, and recommend the chemical not be used in sunscreen.

Not an approved active ingredient in the U.S., but found in some products.

Though approved as a sunscreen active ingredient in the U.S., this UVB absorber is no longer in common use.