This 2001 study tested whether Tinosorb M-active and Tinosorb S could mimic hormones in the body. Neither ingredient showed estrogenic or androgenic activity in lab tests or in rats, suggesting they don't act like estrogen or testosterone in your system.
Researchers used lab binding assays to see if these sunscreen filters could attach to estrogen and androgen receptors, plus tested them in immature rats to check for hormone-like effects.
Funding not disclosed in abstract