“…Since the 1950s, PTBP‐FR has become commercially available and popular as a resin ingredient in adhesives, especially leather and rubber products (2). p ‐ tert ‐Butylphenol‐formaldehyde is a common sensitizer, and several cases of contact dermatitis due to PTBP‐FR have been reported in Japan (1, 3, 4). The patch test‐positive ratios for PTBP‐FR are not so high, reported as 2.3% (1984), 1.7% (1996) (5) and 2.2% (2000) (6) (Research Group of the Japanese Society for Contact Dermatitis).…”