Biphenyl-4,4'-diol

Endpoint summary

Description of key information

A number of reports are available and indicate that biphenyl-4,4'-diol may be a cause of rubber allergy in a small number of cases. Based on the human data, a recent review concludes that the substance has 'insignificant' or 'questionable' potential as a contact allergen. However more recent animal data (mouse LLNA) show a positive response and inidcate that biphenyl-4,4'-diol is a potential skin sensitiser.

Additional information

A number patch tests in humans are available, relating to the substance as a latex additive.

Holness & Nethercott (1996) report a reaction incidence in a small proportion (1%) of 311 subjects challenged with biphenyl-4,4'-diol. The tested concentration of was relatively low (0.1%) therefore the positive response can be concluded to be reliable, although the incidence of affected individuals is very low. The sensitising potential can be presumed to be weak and the confounding issue of pre-existing dermatitis has to be addressed before concluding any biological significance for the healthy human population in regard to delayed contact hypersensitivity induced by the substance.

Masmoudi & Lachapelle (1987) investigated the cause of acquired allergic contact dermatitis to neoprene gloves in one individual. Reactions were assessed following challenge with a series of standard allergens and also with sections of the rubber used in the neoprene gloves. A positive response indicating sensitisation was seen following challenge with 4,4'-dihydroxydiphenyl

Cronin (1980) presents a review of a large number of patients presenting with dermal allergy indicates that exposure to rubber (or chemical additives used in rubber) to be a relatively frequent cause of allergy. Positive responses to rubber of up to ~10% are reported; however none of the case histories implicate biphenyl-4,4'-diol as the cause of rubber chemical sensitisation.

Estlander et al (1986) identified 542 cases of occupational allergic contact dermatitis over a period of ten years (1974 -1983), of which 63 cases were of rubber glove allergy. Two of these individuals (~3% of the cohort) showed positive responses to challenge with 0.2% 4,4-dihydroxyphenyl, indicating that 4,4-dihydroxyphenyl may be responsible for a small proportion of the reported cases of rubber allergy.

In a recent attempt to rank chemical allergens, Schlede et al (2008) conclude that biphenyl-4,4'-diol is a contact allergen with insignificant or questionable contact allergenic potential, based on human case reports with no correlating animal data.

The reports of skin sensitisation in humans exposed to biphenyl-4,4'-diol as a rubber additive indicate at most a weak sensitisation potential, but should also be considered in light of the more recent animal data (mouse LLNA) which shows a positive response for this substance. The weight of evidence of the human and animal data therefore indicate skin sensitising potential for biphenyl-4,4'-diol.