Parabens

Parabens are one of the oldest and most-studied preservative families. "Clean beauty" marketing positioned them as endocrine disruptors, citing a 2004 study that found parabens in breast tumor tissue — but the study didn't establish causation, and subsequent research has been mostly reassuring. EU regulators have restricted some forms (isopropyl, isobutyl, phenyl) but considered others (methylparaben, ethylparaben) safe at regulated levels. The real issue with paraben replacements has been that MIT and other alternatives turned out to be worse sensitizers.