Homosalate

Homosalate is an FDA-approved sunscreen active ingredient that provides primarily UVB protection, stopping where the UVA range begins. It’s internationally approved for use in sunscreens, up to a maximum concentration of 15%. Since the UVA-protecting range of homosalate is very narrow, it’s not used alone in sunscreens, but is often used with UVA filters such as avobenzone, where it can help improve stability. It’s considered non-sensitizing and is most often seen in sunscreens rated SPF 30 and greater. Interestingly, since homosalate is a salicylate ingredient just like salicylic acid, part of how it works to reduce signs of UV-triggered redness is from its calming benefit. Some researchers speculate that this could mean people stay out in the sun longer since they won’t see their skin turn colour, but since homosalate is never used alone and the redness-producing damage it offsets is a benefit, it’s not considered a valid concern. Other studies have shown that homosalate suppresses the formation of a type of free radical known as singlet oxygen which is formed when skin is exposed to UV light. Turning to safety, studies have shown that homosalate has low penetration into skin, is not an endocrine disruptor, and is unlikely to provoke an allergic reaction on skin. In vitro studies on breast cancer cells have shown that homosalate has cytotoxic effects; however, this does not apply to how sunscreen is used on skin, and the amounts shown to provoke this effect are much greater than what could be absorbed into the body from topical application. Despite an impressive safety profile, this sunscreen active is one of several currently undergoing further safety and toxicology testing under the purview of the United States Food and Drug Administration (FDA). This testing is to gain a better understanding of the systemic absorption, metabolism, and elimination of these sunscreen actives when small amounts enter the body via topical use. It’s important to know that the presence of this or other sunscreen actives in the body does not mean your health is at risk. It is anticipated that the additional testing being done will reaffirm the safety of these ingredients; however, those who remain concerned can choose sunscreens with mineral actives (titanium dioxide and zinc oxide) which are not included in the FDA’s new call for additional testing.