Do You Know What Chemicals Are in Your Sunscreen?

May 7th 2016

While it is certain sun damage to your skin is hazardous due to aging and cancer risks, protecting yourself safely with sunscreen is not as straightforward as you might think. Choosing brands with safer ingredients such as mineral blocks and avobenzone is a good idea, and some formulations feature more cosmetically appealing finishes to prevent that white-smeared sun block look.

Chemical filters

The most commonly used chemical UVA filters are oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate. Most commercial sunscreens use some combination of these, some as few as two, while others use all six.

According to the Environmental Working Group, two of these chemicals, oxybenzone and octinoxate, have extremely high toxicity scores. These scores are judged on factors such as skin penetration and presence in lactating mothers' milk, as well as possible physical effects. Both of these chemicals have hormone-mimicking effects that can affect the reproductive systems. They also carry moderate to high risks of skin reactions.

Of the common chemical filters, avobenzone carries the lowest toxicity risk and is the most effective UVA filter. Unfortunately, it is unstable and degrades in sunlight, so it needs to be mixed with stabilizing chemicals that carry their own toxicity risks. Because of its instability, it is also more prone to causing allergic reactions.

Mineral Blocks

Alternatives to chemical blocks include mineral blocks such as titanium dioxide and zinc oxide. These are relatively low in toxicity when used topically in creams or ointments, though sprays and powders containing these ingredients offer a risk of inhalation. Because these substances provide a physical block to the sun's rays, they are very effective at preventing damage. However, creams and other applications of this type remain visible on the skin, which may not be acceptable to some people. The physical nature of the particles can also block pores and the residue can be difficult to remove. Mineral blocks are occasionally used in conjunction with chemical filters to create particular levels of protection, but this is rare as it can increase costs.


In common with most cosmetics and medicines, fillers or inactive ingredients make up more than half of the bulk of sunscreen, providing a base for the active ingredients and preserving and enhancing them. Some of these chemicals, however, bring their own risks. For example, methylisothiazolinone, an extremely common preservative in sunscreens, has been implicated as a skin sensitizer, leading to higher rates of allergic reaction. Another family of preservatives, the parabens, has been blamed for a range of allergic reactions and hormone disruptions and is associated with developmental and reproductive issues. This is the same set of chemicals that has been implicated in rising breast cancer figures thanks to its almost ubiquitous use in deodorants.

Retinyl palmitate, or vitamin A palmitate, is often used to add anti-aging properties and to protect from UV damage. However, it breaks down quickly in the sun to form damaging free radicals, and FDA studies on mice suggest it can speed the development of skin tumors and other surface malignant cells when used before sun exposure.


In the quest to reduce the risks of skin cancer while still gaining the benefit of sunshine on the skin, a good sunscreen is your best friend. But it is important to be aware of the various chemicals used to produce the necessary protective effects and to consider what they may do to the skin in turn.

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