Axel Rothe

When should a substance be designated as sensitizing for the skin (`Sh’) or for the airways (`Sa’)?

In the List of MAK and BAT Values compounds are designated with `Sa’ (`sensitizing for the airways’) or `Sh’ (`sensitizing for the skin’) if, according to scientific evidence, they are allergens. Mainly based on suggestions by a WHO working group and based on our own experience, extended criteria have been elaborated by the working group `skin and allergy’ of the Commission of the Deutsche Forschungsgemeinschaft for the Investigation of Health Hazards of Chemical Compounds in the Work Area, which are presented in this article. They serve as guidelines for deciding which substances have to be labelled `Sa’ and `Sh’, respectively, for the prevention of sensitization and subsequent allergic diseases in workers. Although in some special cases their strict application may not be deemed necessary or possible, the proposed new criteria should be used to make the procedure of classification of substances: 1) more rational, 2) more consistent, 3) more comprehensible, and 4) more transparent. This paper informs readers working scientifically or administratively in this field and invites a critical discussion of the issue.

Contact dermatitis from N-(α-chlorobenzylidene)phenylhydrazine

N‐(α‐chlorobenzylidene) phenylhydrazine (AC) is both a strong irritant and a powerful sensitizer. 5 out of 6 people at risk fell ill after only once coming into contact with this halogenated hydrazine derivative. As in the first report concerning this problem the compound was used to train chemistry students.

Patch testing with zinc dibenzyldithiocarbamate. A multicentre study of the Information Network of Departments of Dermatology and the German Contact Dermatitis Research Group

While a list of allergens in protective rubber gloves was being compiled (1), a representative of a large European glove manufacturer indicated that the 2 dithiocarbamates currently tested in standard series and in rubber series, i.e. zinc diethyldithiocarbamate (ZDEC) and zinc dibutyldithiocarbamate (ZDBC), did not represent the full spectrum of dithiocarbamates currently used in glove production. Zinc dibenzyldithiocarbamate (ZBEC, CAS-No. 14726-36-4, Fig. 1) was said to be used as a vulcanizing agent even more frequently than ZDEC or ZDBC. Based on this information, ZBEC was patch tested in unselected, consecutive patients in addition to the standard series in 16 departments of dermatology, all members of the Information Network of Departments of Dermatology (IVDK; http://www.ivdk.org) and the German Contact Dermatitis Research Group (DKG). The objective of this study was to determine the frequency of sensitization to ZBEC and to investigate cross-reactions to other dithiocarbamates.

Contact dermatitis from chemicals used in the production of photographic emulsions

Contact allergy to alkanolamine borate (AAB) in metal working fluids (MWF) has been reported a few times before. This is a further report on delayed hypersensitivity to AAB. A dermatitis developed on the back of the hands and lower arms in a machinist daily exposed to 2 MWF. When patch tested, he reacted to these 2 MWF. Additional patch testing with the ingredients of both MWF yielded positive test reactions to AAB and to 2 other, not chemically related ingredients. Both MWF, to which he reacted, contained AAB, but he reacted only to one of them. Further patch testing was performed with 2 AAB from 2 MWF to which he had not been exposed and also with raw materials used for synthesis of AAB. A positive reaction to only one AAB was obtained. AAB are used as corrosion inhibitors in MWF. Amino borate and boramine are concepts synonymous with AAB. AAB are obtained as condensation products of boric acid and ethanolamines. Due to synthesis variations in type of participating substances, their concentrations, and other physical-chemical factors, various chemicals may be formed. In fact, thin-layer chromatography investigations of the 4 patch tested AAB have revealed that each AAB consists of many substances, which are partly different for the various AAB. This study shows that it is not possible to use one particular AAB for tracing contact allergy to any AAB and that the allergen(s) in AAB is/are not identified.