“…Under the influence of light, heat and oxygen they form oxidation products such as hydroperoxides, peroxides, epoxides and ketones, which apparently occur or are formed regularly in preparations containing abietic acid-or dehydroabietic acidic. Important allergens such as 15-hydroperoxyabietic acid (Karlberg and Gäfvert 1996;Karlberg et al 1988 a, b), 13,14--epoxyabietic acid ), 7-oxodehydroabietic acid (Sadhra et al 1996(Sadhra et al , 1997, 15-hydroperoxydehydroabietic acid (Shao et al 1995) and dehydroabietic acid peroxides (Gäfvert et al 1992) occur among these oxidation products (see also Section 5.4.1; Figure 2; Gäfvert 1994;Gäfvert et al 1992;Hausen et al 1989Hausen et al , 1993Karlberg 1988Karlberg , 1991Karlberg and Gäfvert 1996;Karlberg et al 1988 c;Khan and Saeed 1994). No allergenic effect for the pimaric acid type of resin acids (Figure 1) was found (Ehrin and Karlberg 1990).…”