4-Methylbenzylidene camphor

4-Methylbenzylidene camphor is an ultraviolet light blocker used in cosmetics and sunscreen preparations that also has estrogenic activities.{20419,20420} It has estrogenic activity in fish and in mammals, binding competitively to estrogen receptors and stimulating transactivation.{20419} In addition to reducing receptor sensitivity to estradiol, 4-MBC directs dose-dependent changes in the expression of estrogen receptor subtypes, progesterone receptor, and androgen receptor.{20419,20420} This results in changes in reproductive organ and brain development in both males and females.{20419,20420} When applied topically, it is absorbed systemically and can be detected in urine.{20421}