Screening allergic reactions to resol resin based on phenol and formaldehyde in a clinic of occupational dermatology.

BACKGROUND

Allergic reactions to resol-type phenol formaldehyde resin [phenol formaldehyde resin 2 (PFR2)] are relatively common. It has been suggested that PFR2 should be included in baseline series. However, a recent international study found clinical relevance in only 25% of patients.

OBJECTIVES

To report the results of screening with PFR2 over a 5-year period (2012-2016), and to study the clinical relevance of allergic reactions to PFR2 over a 15-year period (2002-2016).

METHODS

At the Finnish Institute of Occupational Health, PFR2 was added to the baseline series in 2012. We had previously tested PFR2 in the plastic and glue series. We searched the patch test files for patients with allergic reactions to PFR2, and analysed their patch test results, occupation, exposure, and diagnosis.

RESULTS

During the screening period of 5 years, a total of 10 (1.6%) patients reacted positively to PFR2. Seven of these had occupational allergic contact dermatitis caused by phenol formaldehyde resin (PFR). In 3 patients, we found no exposure to PFR. Over the preceding 10 years, the clinical relevance of 10 additional allergic reactions to PFR2 was similarly high.

CONCLUSIONS

In an occupational dermatology clinic, 70% of PFR2 reactions were clinically relevant. Further studies in general dermatology clinics are needed.