2-HEMA was the most important allergen in dentists and dental nurses, and MMA and EGDMA in dental technicians. Reactions to bis-GMA, DEGDA, TREGDA, EMA and EA were relevant in some patients.

The Technical Committee of Classification and Labelling dealing with harmonized classification of substances and classification criteria under Directive 67/548/EEC on behalf of the European Commission nominated an expert group on skin sensitization in order to investigate further the possibility for potency consideration of skin sensitizers for future development of the classification criteria. All substances and preparations should be classified on the basis of their intrinsic properties and should be labelled accordingly with the rules set up in the Directive 67/548/EEC. The classification should be the same under their full life cycle and in the case that there is no harmonized classification the substance or preparation should be self-classified by the manufacturer in accordance with the same criteria. The Directive does not apply to certain preparations in the finished state, such as medical products, cosmetics, food and feeding stuffs, which are subject to specific community legislation. The main questions that are answered in this report are whether it would be possible to give detailed guidance on how to grade allergen potency based on the existing methods, whether such grading could be translated into practical thresholds and whether these could be set for both induction and elicitation. Examples are given for substances falling into various potency groups for skin sensitization relating to results from the local lymph node assay, the guinea pig maximization test, the Buehler method and human experience.

In the logistic model, risk factors for the continuation of OHE were a long duration of hand eczema before diagnosis, respiratory atopy, skin atopy, and continuation in the same occupation. Those who ended up changing occupation due to their OHE had a better medical and economic prognosis.

To determine whether topical provocation could be used for the diagnosis of fixed drug eruption (FDE) instead of systemic provocation, we applied the suspected drug at various concentrations (1-10%) in either petrolatum, 94% ethanol or dimethyl sulphoxide (DMSO) as an open test on both clinically normal skin and on previous FDE lesions in 24 patients with established FDE due to phenazone salicylate, a sulphonamide, doxycycline, trimethoprim, chlormezanone, a barbiturate, or carbamazepine. In 18 of the 24 patients, local provocation of FDE was seen at sites or previous eruption but never on clinically normal skin. With some drugs, e.g. phenazone salicylate, positive provocation of FDE was seen with all the vehicles used; with sulphamethoxazole and trimethoprim, a positive result was seen only in DMSO. To study cross-reactions to other phenazone derivatives in patients with an FDE caused by phenazone salicylate, we applied topical phenazone, aminophenazone and propyphenazone to sites of previous FDE lesions in three patients. In all three, a positive reaction was seen with phenazone, but only one patient showed positive results with aminophenazone and propyphenazone. The present study suggests that topical provocation is useful with several drugs causing FDE. Testing should always be performed on sites of previous FDE, and the sensitivity of the open topical testing can be increased in certain cases by using a vehicle which increases penetration of the drug.

Our data show that MI used alone also potentially induces contact allergy. Careful monitoring is needed to determine whether or not this antimicrobial is safe to use in cosmetics.

Out of 923 female dental nurses in the Helsinki district, 799 were interviewed using a computer-assisted telephone interview. A structured questionnaire was used to inquire about skin, respiratory symptoms, atopy, work history and methods, and exposure at work. The 328 nurses, who reported work-related dermatitis on their hands, forearms or face, were invited to an interview by an occupational physician; 245 nurses participated. 31 nurses had previously been diagnosed with an occupational skin disease (OSD). 133 nurses with a suspected OSD were selected for further clinical examinations with prick and patch testing. Among the 107 nurses examined, 22 new cases of OSD were diagnosed. There were altogether 29 cases of allergic contact dermatitis, 15 of contact urticaria, 12 of irritant contact dermatitis, and 1 case of onychomycosis. Rubber chemicals and natural rubber latex (NRL) in protective gloves, as well as dental-restorative plastic materials [(meth)acrylates], were the most common causes of allergy. 42% of the OSD cases in the studied population had been missing from the statistics (Finnish Register of Occupational Diseases). Plastic gloves or NRL gloves with a low-protein content are recommended for dental work. Skin exposure to (meth)acrylates should be avoided.

Topical provocation with the causative agent was performed in 30 patients with fixed drug eruption (FDE). The epicutaneous open test method was used on inactive sites of old FDE lesions. Drugs at 10% in the vehicles petrolatum, alcohol and dimethylsulfoxide (DMSO) were used as test preparations. Positive reactions were always seen with phenazone salicylate (16 patients) and carbamazepine patients (3 patients), and in an individual case from chlormezanone. Both positive and negative reactions were seen with trimethoprim (3 and 2, respectively), doxycycline (2 and 1) and sulfadiazine (1 and 1). Control tests on unaffected skin with drug preparations and pure vehicles remained negative. The present results confirm our previous observation that topical provocation is a reliable test method in FDE caused by phenazone salicylate. The present study also shows that topical provocation may be useful in FDE caused by carbamazepine. In FDE caused by trimethoprim, doxycycline and sulfonamides, a positive, but not a negative, skin reaction is informative.

Exposure to wood dusts may cause various skin and mucosal symptoms. Allergic dermatoses, caused by wood dusts, diagnosed at the Finnish Institute of Occupational Health during 1976-1999 are reported here. 16 had allergic contact dermatitis and, 2 had contact urticaria. 9 men (3 cabinet makers, 3 joiners, 1 carpenter, 1 knifemaker and 1 machinist) were mainly exposed to tropical hardwoods. 1 man had dermatitis caused by western red cedar. 5 patients, 3 men and 2 women, were exposed to Finnish pine or spruce dusts, and 1 man to aspen. 7 also had rhinitis, 4 asthma or dyspnoea and 3 conjunctivitis. On patch testing, 10 men reacted to 9 different wood dusts, including teak (5), palisander (3), jacaranda (2), mahogany (2), walnut (2) and obeche (1). Reactions to wood allergens, including lapachol (2), deoxylapachol (1), (R)-3,4-dimethoxydahlbergione (2), 2,6-dimethoxy-1,4-benzoquinone (1), mansonone A (2) and salicyl alcohol (1), were noted in 4 cases. All but 1 of 5 patients exposed to pine or spruce dusts reacted to the sawdusts, all 5 to colophonium, 3 to abietic acid, 2 to tall oil resin, 3 to wood tar mix and 4 to other wood gum resins. Of the 2 CU patients, 1 was prick and RAST positive to obeche, 1 reacted with urticarial dermatitis to punah wood dust on chamber exposure. Occupational allergic dermatoses are mainly caused by the dusts of hardwoods, mostly due to Type IV allergy, but may also be caused by softwood dusts. Patch tests can be done with wood dusts, but should be confirmed by patch testing with wood allergens if possible.