The Facts

• Methylparaben is a benzene ring compound with a hydroxyl and methyl ester group attached at the para or 1,4 positions. Methylparaben has a molecular formula of C8H8O3 and a structural formula of CH3(C6H4(OH)COO). It has a molecular weight of 152.15 g/mol and is registered under the CAS number 99-76-3 in the U.S. and E218 in the European Union. It is commercially synthesized through the esterification of para-hydroxybenzoic acid with methanol and is also known as methyl p-hydroxybenzoate, 4-(Methoxycarbonyl)phenol and 4-Hydroxybenzoic acid methyl ester. Methylparaben is sold under the trade names of Danisol M, Maseptol, Moldex, Nipagin, Paridol, Preserval, Solbrol and Tegosept M.
  
  

Antimicrobial Mechanism

• Though an exact mode of action has not been established between parabens and their antimicrobial properties, research indicates that a variety of mechanisms act upon cell membranes to cause microbial destruction. In 1972 researchers Furr and Russell discovered that, in the presence of parabens, the bacteria Serratia marcescens began leaking intracellular RNA. Later research conducted by Freese et al. in 1973 concluded that parabens inhibit serine uptake and disrupt cellular metabolism by preventing the oxidation of alpha-glycerol phosphate and nicotinamide adenine dinucleotide in the bacteria Bacillus subtilis. From these observations it was postulated that parabens interrupt both the electron transport and membrane transport systems of a microbial cell.
  
  

Applications

• Methylparaben can be found in a wide variety of preserved foods, pharmaceuticals, cosmetics and hair and skin care products. In cosmetic emulsions and consumer goods, methylparaben is combined with other preservatives such as phenoxyethanol, DMDM hydantoin and the antimicrobial formaldehyde releaser diazolidinyl urea. Such combinations are sold under the trade names of Germaben and Liquapar.
  
  

Related Compounds

• Other species in the paraben chemical family include ethylparaben, propylparaben, isopropylparaben, butylparaben, isobutylparaben and benzylparaben. Of these related compounds ethyl, propyl and butylparaben are the most commonly used in industry; normally in conjunction with methylparaben to increase antimicrobial activity and preservation length.
  
  

Controversy

• Methylparaben has been rated safe for consumer use at a daily limit of 10 mg per kilogram of body weight. Recently, however, claims have been made that methylparaben acts as a skin irritant and weak estrogenic agent, the latter of which is tenuously linked to breast cancer. Dr. Leslie Baumann, founder and chief of the Department of Cosmetic Dermatology at the University of Miami, notes that alternative preservatives in skin care applications usually cause more irritation than methylparaben. As of October 2007, no causal link between breast cancer and methylparaben has been found.