Isobutylparaben

What it is

Isobutylparaben is the branched-chain counterpart of butylparaben. Like isopropylparaben, it lacked the toxicological dataset needed to set a safe maximum, and the EU prohibited it in 2014 alongside four other branched or long-chain parabens. It remains legal in some other markets.

Worth knowing

• Banned in the EU because safety could not be demonstrated

  As with isopropylparaben, the ban reflects an absence of adequate data rather than proven harm at the levels then in use.

  Matters most toPeople buying imported skincare; an EU-market product listing it would be non-compliant.

• Longer and branched paraben chains are more oestrogenically active in laboratory tests

  Oestrogen-receptor activity in the paraben family increases with chain length, which is the same reasoning behind the tighter 0.14% limit on propyl- and butylparaben. The absolute potency remains far below natural oestradiol.

  Matters most toPeople who avoid substances with any measurable hormonal activity.

Where the EU stands

Sources (2)

Every link goes to the original: a journal, a PubMed record or an EU document.

1. [1]
   Final amended report on the safety assessment of Methylparaben, Ethylparaben, Propylparaben, Isopropylparaben, Butylparaben, Isobutylparaben, and Benzylparaben as used in cosmetic products

   International Journal of Toxicology (Cosmetic Ingredient Review) · 2008 · doi:10.1080/10915810802548359

   The CIR expert panel judged parabens, including isobutylparaben, safe as used in cosmetics at then-current levels of up to 0.4% for a single ester and 0.8% for mixtures.

2. [2]
   Review of the safety of application of cosmetic products containing parabens

   Journal of Applied Toxicology · 2020 · doi:10.1002/jat.3917

   Concluded that individual paraben-containing cosmetics should not pose a hazard to human health, while advising against simultaneous use of very many such products.