The most widely used sunscreen ingredient, known for its low potential to sensitize skin or act as a phototallergen. Estrogenic effects are noted in laboratory animals as well as disruption of thyroid hormone and brain signaling.

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 dioxide has a long history of use in sunscreen and other products. It appears safe for use on skin, due to low penetration but inhalation is a concern. Some titanium sunscreens contain nano-size particles may have greater toxicity to body tissues and environment.

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

Sunscreens with micronized zinc oxide may contain nanoparticles. Micronized zinc offers improved sun protection compared to conventional (larger) particles. Micronized zinc particles do not penetrate healthy skin but may be more toxic to living cells and the environment. Inhalation of powders and sprays is a concern.

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

Sunscreens with micronized titanium dioxide may contain nanoparticles. Micronized TiO2 offers greater sun protection than conventional (larger) particles. These small particles do not penetrate skin but may be more toxic to living cells and the environment. Inhalation of powders and sprays is a concern.

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

Nano zinc oxide offers greater sun protection than larger zinc particles. Comparatively little is known regarding potential health effects of nanoparticles. They do not penetrate healthy skin, thus appear to pose a low health risk in lotions. Inhalation of powders and sprays is a concern.

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.

Nano TiO2 offers greater sun protection than larger titanium particles. Comparatively little is known regarding potential health effects of nanoparticles. They do not penetrate healthy skin, thus appear to pose a low health risk in lotions. Inhalation of powders and sprays is a concern.

Zinc has a long history of use in sunscreen and other skin care products; little absorption and no adverse health effects are reported. Some sunscreens with zinc contain nanoparticles which do not penetrate skin but may pose toxicity concerns if inhaled or in the environment.

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.

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 approved for use in United States sunscreens. Concerns about hormone disruption.

Not an approved sunscreen 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.