R.L. Nixon, A. Ross, A. Palmer
Natural rubber is both elastic and plastic, depending on the temperature. The process of polymerisation (vulcanisation) involves reacting rubber isomers with sulphur to produce a polymer with increased elasticity and reduced plasticity. The addition of accelerators speeds the vulcanisation process, such as thiurams, carbamates, thiazoles and thioureas.
In a recent review of causes of occupational skin disease from our clinic since its inception in 1993, we reported that the most common occupational allergens were thiurams, chromate, p-phenylenediamine (hair dye), ammonium persulphate (hairdressing bleach), epoxy resin, diaminotoluene sulphate (hair dye) and preservatives, in that order (1). However, we now report a declining rate of allergy to thiurams in our clinic population from 1993 to 2017. It appears that there has been a changing pattern of accelerator allergy, with more reactions to carbamates in recent times. Manufacturing advances to reduce the content of natural rubber latex protein may also have led to lower levels of thiurams. In addition, the more widespread use of powder-free gloves is likely to have been associated with lower levels of accelerators, as the gloves undergo more washing and/or chlorination.
However, the most significant advance in this area has been the advent of accelerator-free gloves, such as the Ansell Micro-Touch NitraFree glove. It is likely that we will continue to see fewer cases of contact allergy to rubber accelerators.
1. Cahill, JL, Williams JD, Matheson MC, Palmer AM, Burgess JA, Dharmage SC,Nixon RL. Occupational skin disease in Victoria, Australia. Australas J Dermatol 2016; 57: 108–114.