There are generally two types of ingredients that are usually found in sunscreen that protect against UV rays: physical (or mineral) ingredients and chemical ingredients. While physical ingredients block, reflect and/or scatter the sun’s rays, chemical ingredients absorb them and transform them into heat.
Common Physical Ingredients:
- Titanium dioxide: Great for sensitive skin, it protects against both UVA and UVB rays (but not long UVA1 rays), it’s generally recognized as safe and effective by the FDA. While it can be used for children aged 6 months and above, powder and spray versions should be avoided, as there may be some risk of inhalation (the impacts are still being studied). It’s worth noting that some of these sunscreens may leave a white cast on skin (especially darker skin tones), but this varies from brand to brand
- Zinc oxide: Often found alongside titanium dioxide, it’s notably not as effective on its own as other ingredients on this list against sunburns. However, studies have shown that even with repeated use there is no evidence of skin absorption. It’s best to use to avoid sun damage to skin (instead of sunburns). There are also inhalation concerns with zinc oxide, so try to use liquid forms where possible.
Common Chemical Ingredients:
- Oxybenzone: Found in the majority of sunscreens in the United States, there have been some concerns about this ingredient. Specifically, some studies have found that this ingredient can be damaging to coral reefs (it’s actually banned in Hawaii), and as such, it is generally excluded from “green” products. There is also some evidence that the skin absorbs more of this chemical; while detrimental effects haven’t been proven, there are some linkages to lower birth weights when used by pregnant women. Additionally, many have reported skin irritation associated with oxybenzone.
- Octinoxate (Ethylhexyl Methoxycinnamate): Also found to be damaging to coral reefs (and as such, banned in Hawaii), it is especially potent for UVB protection. While no adverse effects have been proven, the chemical has been found in the milk of nursing mothers when they regularly used sunscreen with octinoxate. Additionally, animal studies have shown thyroid and behavioural alterations.
- Octisalate (Ethylhexyl Salicylate)/Octocrylene: Considered to be safer than the options above, there’s still some evidence of skin penetration in lab studies.
- Avobenzone (Butyl Methoxydibenzoylmethane): Provides full UVA protection but breaks down quickly in sunlight (up to 90% is destroyed within an hour of exposure). It can be stabilized with the addition of certain UVB blockers such as octocrylene. While there is a high rate of skin sensitivity associated with avobenzone, it has been shown to have very limited penetration of the skin, and there’s no evidence of hormone disruption
- Mexoryl SX and X: Developed by L’Oreal, these ingredients were only approved by the FDA in 2006Also used to block UVA rays, it’s often found with avobenzone, as together these ingredients are more stable. It’s water resistant, very stable in the sun, and generally not irritating to the skin. It also has been shown to have minimal skin penetration, and no found effects on hormones.
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