Methylparaben

What it is

Methylparaben is the methyl ester of 4-hydroxybenzoic acid, a compound that also occurs naturally in blueberries, carrots and other plants. It has been used as a cosmetic and food preservative since the 1920s, which makes it one of the most thoroughly studied preservatives in existence. Formulators like it because it is effective against moulds and yeasts, stable, odourless and cheap. In the EU it is a listed preservative with a 0.4% single-ester ceiling.

What it does well

• Very low rate of skin allergy despite decades of heavy use

  In the North American Contact Dermatitis Group series, paraben mix produced positives in about 1% of patch-tested patients, low for such a widely used substance. Dermatologists sometimes call this the 'paraben paradox': allergy shows up on patch testing far more often than it causes real-world dermatitis.

  Strong evidence

• The link to breast cancer has not held up

  The frequently cited 2004 study found parabens in breast tumour tissue but had no control tissue and did not test whether cosmetics were the source or whether parabens caused the tumours. The SCCS re-assessed methylparaben in 2023 including endocrine concerns and confirmed 0.4% as safe.

  Strong evidence

Worth knowing

• Weak oestrogen-like activity in laboratory tests

  Methylparaben binds oestrogen receptors in vitro, but its potency is several orders of magnitude below natural oestradiol and it is rapidly broken down by skin and liver esterases. The SCCS took this into account and still concluded 0.4% is safe.

  Matters most toPeople who want to minimise total exposure to substances with any hormonal activity.

• Combined exposure from many products at once

  A 2020 review concluded a single paraben-containing cosmetic poses no hazard, but advised against using very large numbers of paraben-containing products simultaneously. The EU already caps the total of all paraben esters at 0.8%.

  Matters most toPeople using many leave-on products daily who want to keep cumulative exposure down.

Where the EU stands

Sources (3)

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

1. [1]
   Opinion on methylparaben (CAS No. 99-76-3, EC No. 202-785-7) (SCCS/1652/23)

   SCCS (Scientific Committee on Consumer Safety), European Commission · 2023

   The SCCS concluded that methylparaben used as a preservative at up to 0.4% (as acid), or within an 0.8% ester mixture, is safe, having considered concerns about endocrine activity.

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 using a single paraben-containing cosmetic should not pose a hazard to human health, while cautioning against simultaneous use of very many such products.

3. [3]
   Contact dermatitis associated with preservatives: Retrospective analysis of North American Contact Dermatitis Group data, 1994 through 2016

   Journal of the American Academy of Dermatology · 2021 · doi:10.1016/j.jaad.2020.07.059

   Paraben mix produced positive patch tests in about 1% of patients, among the lowest rates of the preservatives studied.