Supplementary Note on Skin Sensitization with Simple Chemical Compounds

Abstract

The following observations may be recorded as an addendum to the note 1 in a past issue of this journal. Further experiments were carried out with dinitrochlorbenzene∗ (Cl:NO₂ :NO₂ = 1:2:4) which is known to be a frequent cause of trade eczema. 2 The reactions observed with this compound were rather stronger than those with nitroso-dimethylaniline. For instance, in one experiment lesions approximately 7 to 15 mm. in diameter were obtained after 18 intracutaneous injections on the back of 1/400 mg.† each, 2 a week for 9 weeks, when tested with the same concentration by intracutaneous injection on the side, one week after the last injection, and read on the following day. Reactions were noticed during the treatment, beginning with the third, fourth or later injections, and reaching a maximum after about 12 injections. Some sensitization appeared in practically all the guinea pigs injected, and the strongest reactions showed necrotic centers. In a second experiment the effects were weaker than in the above, although definite, when tested one week after the fourteenth injection. Another batch receiving 10 daily injections and tested a week later exhibited strong reactions with livid centers in 3 animals and weaker reactions in the remaining 2. Two similar experiments yielded less prominent but positive effects.

In cross tests with the 2 substances named a sharp specificity was evident since guinea pigs treated with dinitrochlorbenzene gave no distinct reaction to nitroso-dimethylaniline, and vice versa, as exemplified in Table I.