Isopropylparaben is a chemical compound belonging to the paraben chemical family, the isobutyl ester of p-hydroxybenzoic acid.

It occurs as a white powder, poorly soluble in water.

What it is used for and where

It is a preservative used in food, pharmaceuticals, cosmetics and more.

It is used as a preservative against:

• fungi
• yeasts
• moulds

Like all members of the paraben family, it can give rise to allergies.

In a 2020 study, six parabens were compared in a cytotoxicity test with two in vitro toxicological methods and the results classified Isopropylparaben as positive (1).

Parabens

Parabens are preservative chemical compounds that have been the subject of attention in the scientific literature as possible endocrine disruptors (particularly propylparaben and butylparaben), i.e. with the possibility of damaging the hormone-producing glands in our bodies, particularly in the breasts. The 2004 study by Darbre et al. showed that parabens remain in our bodies as intact esters (2). Following this study, some of the scientific literature in 2005 and 2006 cast doubt on Darbre's conclusions and claimed they were limited. However, both the US FDA and the European SCCP authorised in 2006 the use of a single paraben in cosmetic products at a concentration of 0.4% and the use of total parabens at a concentration of 0.8% (3). However, there is no shortage of studies that consider the restrictions unnecessary: M. G. Kirchhof et al. in 2013 found that parabens are among the safest and most well-tolerated preservatives and that current data do not support drastic regulations or personal exposure restrictions (4). Darbre in 2014 published a further study in which he showed how parabens can cause DNA damage (5).

Isopropylparaben  studies

Typical optimal commercial product characteristics Isopropylparaben

• Molecular Formula C₁₀H₁₂O₃
• Molecular Weight 180.203 g/mol
• Exact Mass
• UNII  A6EOX47QK0
• CAS  4191-73-5
• DSSTox Substance ID  
• IUPAC  propan-2-yl 4-hydroxybenzoate
• InChI=1S/C10H12O3/c1-7(2)13-10(12)8-3-5-9(11)6-4-8/h3-7,11H,1-2H3 
• InChl Key      CMHMMKSPYOOVGI-UHFFFAOYSA-N
• SMILES   CC(C)OC(=O)C1=CC=C(C=C1)O
• EC Number: 224-069-3
• PubChem Substance ID 329748175
• MDL number MFCD00016468
• Beilstein Registry Number 2641564
• ChEBI   179285

Synonyms: 

• Isopropyl 4-hydroxybenzoate
• p-Oxybenzoesaureisopropylester
• Benzoic acid, 4-hydroxy-, 1-methylethyl ester
• 1-Methylethyl 4-hydroxybenzoate
• Isopropyl-4-hydroxybenzoate
• Isopropyl p-hydroxybenzoate
• isopropyl paraben
• propan-2-yl 4-hydroxybenzoate
• p-Hydroxybenzoic acid isopropyl ester
• Isopropylhydroxybenzoate
• 4-Hydroxybenzoic Acid Isopropyl Ester
• 4-Hydroxybenzoic acid, 1-methylethyl ester
• methylethyl 4-hydroxybenzoate

References_______________________________________________

(1) Chrz J, Hošíková B, Svobodová L, Očadlíková D, Kolářová H, Dvořáková M, Kejlová K, Malina L, Jírová G, Vlková A, Mannerström M. Comparison of methods used for evaluation of mutagenicity/genotoxicity of model chemicals - parabens. Physiol Res. 2020 Dec 31;69(Suppl 4):S661-S679. doi: 10.33549/physiolres.934615. 

(2) Darbre PD, Aljarrah A, Miller WR, Coldham NG, Sauer MJ, Pope GS. Concentrations of parabens in human breast tumours. J Appl Toxicol. 2004 Jan-Feb;24(1):5-13. doi: 10.1002/jat.958.

(3) https://www.fda.gov/cosmetics/cosmetic-ingredients/parabens-cosmetics

Cosmetic Ingredient Review Expert Panel. Final amended report on the safety assessment of Methylparaben, Ethylparaben, Propylparaben, Isopropylparaben, Butylparaben, Isobutylparaben, and Benzylparaben as used in cosmetic products. Int J Toxicol. 2008;27(Suppl 4):1-82.

(4) Kirchhof MG, de Gannes GC. The health controversies of parabens. Skin Therapy Lett. 2013 Feb;18(2):5-7.

(5) Darbre PD, Harvey PW. Parabens can enable hallmarks and characteristics of cancer in human breast epithelial cells: a review of the literature with reference to new exposure data and regulatory status. J Appl Toxicol. 2014 Sep;34(9):925-38. doi: 10.1002/jat.3027.