FS12.3 Occupational contact dermatitis to phenol formaldehyde resins

Abstract

Phenol formaldehyde resins were the first synthetic plastics to be used commercially, being patented as Bakelite in 1907.There are two main types of phenol formaldehyde resin [PFR], resols [phenol reacted with excess formaldehyde in alkaline conditions] and novolacs [formaldehyde reacting with excess phenol in acid conditions]. Novolac resins may require cross‐linking agents to cure them but resol can be hardened by heat alone. Usually sensitisation occurs when the resins are handled in partially condensed form. Modifications and additives to these resin systems increase the range of potential allergens. PFRs have electrical resistance and binding properties resulting in their widespread use in electrical appliances, glues, laminated floorboards, plywood, fibreglass including insulation, brake linings, clutch facings, grinding wheels, foundry sand moulds, abrasive cloths and papers, plastic moulds, telephones and steering wheels.Study aim: To analyse retrospectively the causes, occupations and investigations of patients demonstrated to have dermatitis from occupational contact with PFRs.Summary of Results: 27 dermatitis cases were identified (4 irritant and 23 allergic). The commonest causes were from contact with PFR used in fibreglass materials, in binders e.g. brakes, foundry sand, and from adhesives.Conclusions: Patients should be investigated for contact allergy by patch testing them with their own resins. PFR‐2 identified by M. Bruze was the best commercially available allergen to screen for contact allergy. Concomitant allergy to formaldehyde and PTBP formaldehyde resin is rare. The possibility of allergy to reactive diluents should be considered in those exposed to epoxy novolac systems.