Is homosalate safe?

What the evidence says

Homosalate is a chemical UV filter allowed in sunscreens sold in Canada, at concentrations up to 15%. Health Canada classifies it as a drug ingredient and, after reviewing the same data as the FDA, has not found a new safety concern that would pull it from the market — it says approved sunscreens are safe when used as directed. That said, homosalate is absorbed through the skin into the bloodstream with regular sunscreen use, and this is why both Health Canada and the FDA asked manufacturers for more safety data rather than simply confirming it as fully cleared.

Lab and animal studies have found homosalate can act somewhat like estrogen and interact with thyroid cells in a dish or in rodents, but a 2017 rat study covering pregnancy, nursing, and early life found no effect on thyroid function or puberty, and rat uterus tests have not shown real estrogenic effects in the body. Human data are limited to small pharmacokinetic studies showing the chemical is absorbed and cleared within about a day, without reported harm. Europe has taken a more cautious stance, capping homosalate at 0.5% (versus 15% allowed in Canada and the US) over reproductive toxicity signals seen in an animal study, so the story differs by region.

In Canada, homosalate remains permitted at higher concentrations, and Health Canada's position is that the protective benefit of sunscreen against sunburn and skin cancer outweighs these theoretical concerns. Bottom line for parents: using an approved Canadian sunscreen containing homosalate as directed is considered safe by Health Canada, and the bigger, well-proven risk is unprotected sun exposure. If you want to avoid chemical filters altogether, mineral sunscreens with zinc oxide or titanium dioxide are the alternative Health Canada also approves.