Occupational allergic contact dermatitis and composition of acrylates in dentin bonding systems

Background Dentin-bonding systems contain sensitizing acrylates. They are increasingly used in dentistry, but only few cases of allergy have been encountered. Objective This study reports observations on eleven patients sensitized by acrylates in dentin-bonding compounds. Furthermore, the composition of dentin-bonding products was analysed and compared with the information given in the material safety data sheets. Methods Patch testing was performed to reveal allergic contact dermatitis, and chamber provocation tests to reveal possible respiratory sensitivity. Gas chromatography/mass spectrometry was used to analyse the chemical composition of the bonding products. Results The most common sensitizer in our material of eleven patients was 2-hydroxyethyl methacrylate (2-HEMA). Another putative sensitizer, BIS-GMA, used in dentin adhesives, did not cause sensitization. The typical allergic dermatitis localized to the fingertips (pulpitis). Seven of the eleven patients also developed paresthesia of the fingertips. One patient with positive patch test reactions to (meth)acrylates had pharyngitis hut no skin symptoms. One patient was sensitized because she had been patch tested with too high a concentration (undiluted) of dentin-bonding components. Material safety sheets gave inaccurate or wrong information about the contents. Conclusion Dentin-bonding acrylates are strong sensitizers, and even a single exposure may sensitize.     

Occupational allergic contact dermatitis from isophoronediamine (IPDA) in operative-clothing manufacture

Formaldehyde is a ubiquitous and potent sensitizer. Formaldehyde-sensitive patients may have long-lasting hand eczema (1). Contact dermatitis from formaldehyde is often chronic, probably because it is so difficult to avoid exposure to formaldehyde-containing products. An investigation in Denmark showed that 1/3 of all cosmetic products contained formaldehyde or formaldehyde-releasing preservatives (2). Formaldehyde can also be found in many houshold products. In recent years, the use of moistened baby toilet tissues has greatly increased.     

Occupational contact allergy to monomeric isocyanates

Background. The monomeric isocyanates diphenylmethane diisocyanate (MDI), 2,4‐toluene diisocyanate (TDI), isophorone diisocyanate (IPDI) and 1,6‐hexamethylene diisocyanate (HDI) are used in polyurethane products and sometimes cause contact allergy. Objectives. To describe patients with isocyanate contact allergy in an occupational dermatology clinic. Methods. Test files were screened for allergic reactions to isocyanates and 4,4′‐diaminodiphenylmethane (MDA). Patients with allergic reactions to some of the allergens were analysed for occupation, exposure, concomitant reactions to other allergens, and diagnosis. Results. Over a period of almost 13 years, 54 patients reacted to isocyanates (9 to IPDI, 12 to MDI, 6 to TDI, and 1 to HDI) or MDA (44 patients). The motor vehicle, electronics and paint industries, and painting and construction work, were among the most significant occupational fields. An in‐house polymeric MDI (PMDI) test substance was superior to commercial MDI preparations. About half of the occupational cases related to MDI products were diagnosed by testing MDA. The most prominent cause of IPDI allergy comprised polyurethane paint hardeners. Some of the IPDI reactions could be explained by cross‐allergy to isophoronediamine in epoxy products. Specific exposure to MDA was difficult to trace. Conclusions. MDA and PMDI test substances were significant in the diagnosis of MDI contact allergy.     

Contact allergy to epoxy (meth)acrylates

Background: Contact allergy to epoxy (meth)acrylates, 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (bis-GMA), 2,2-bis[4-(2-hydroxy-3-acryloxypropoxy)phenyl]-propane (bis-GA), 2,2-bis[4-(methacryl-oxyethoxy)phenyl] propane (bis-EMA), 2,2-bis[4-(methacryloxy)phenyl]-propane (bis-MA), and glycidyl methacrylate (GMA) is often manifested together with contact allergy to diglycidyl ether of bisphenol A (DGEBA) epoxy resin.
Objective: To analyse patterns of concomitant allergic reactions to the five epoxy (meth)acrylates in relation to exposure.
Methods: We reviewed the 1994–2008 patch test files at the Finnish Institute of Occupational Health (FIOH) for reactions to the five epoxy (meth)acrylates, and examined the patients' medical records for exposure.
Results: Twenty-four patients had an allergic reaction to at least one of the studied epoxy (meth)acrylates, but specific exposure was found only in five patients: two bis-GMA allergies from dental products, two bis-GA allergies from UV-curable printing inks, and one bis-GA allergy from an anaerobic glue. Only 25% of the patients were negative to DGEBA epoxy resin.
Conclusions: The great majority of allergic patch test reactions to bis-GMA, bis-GA, GMA and bis-EMA were not associated with specific exposure, and cross-allergy to DGEBA epoxy resin remained a probable explanation. However, independent reactions to bis-GA indicated specific exposure. Anaerobic sealants may induce sensitization not only to aliphatic (meth)acrylates but also to aromatic bis-GA.     

Occupational allergic contact dermatitis from 2-N-octyl-4-isothiazolin-3-one

2-N-octyl-4-isothiazolin-3-one (OIT) is an antimicrobial agent that is mainly used in industrial settings. The objective of the study was to find the significance of OIT contact allergy at our clinic of occupational dermatology. We looked through our patient material from 1991 for allergic reactions to OIT and analysed the clinical records. We found 8 patients with ordinary allergic reactions to OIT and 1 late reaction. 2 workers in the manufacture of paints had occupational allergic contact dermatitis from OIT in biocides. 2 patients were machinists and 3 were female farmers: in these cases, however, we could not find any exposure. A sewing machine operator had patch test reactions to 2 of her mattress textiles, and chemical analysis of them showed 40-50 parts per million OIT. In conclusion, OIT is a rare sensitizer, and its contact allergies occur mainly in paint manufacturing. It is infrequently used in metal-working fluids and possibly sensitizes machinists. Although it is also used in some biocides recommended for use in the textile industry, there are no previous reports of contact allergy in this field. Our sewing machine operator with OIT contact allergy had probably been sensitized from mattress textiles.     

Allergic contact dermatitis from salicyl alcohol and salicylaldehyde in aspen bark (Populus tremula)

Salicyl alcohol or 2-methylolphenol is a well-known allergen in phenol-formaldehyde resins and a strong sensitizer in guinea pigs. There is 1 previous report of allergic contact dermatitis from salicyl alcohol in aspen bark. We describe a second case with concomitant allergy to salicylaldehyde. An elk researcher who had handled leaves from various trees presented with eczema of the hands, face, flexures, trunk and extremities. Patch testing showed sensitivity to salicyl alcohol, salicylaldehyde, balsam of Peru (Myroxylon pereirae resin), aspen wood dust and an extract prepared from the bark of aspen (Populus tremula). Weaker reactions were observed to bark extracts of rowan (Sorbus aucuparia), tea-leaved willow (Salix phylicifolia) and goat willow (Salix caprea). We analysed salicyl alcohol and salicylaldehyde in the bark extracts and found the 2 chemicals in equal amounts, about 0.9 microg/mg in aspen bark and in lower concentrations in rowan and the willows. We did not find either of the chemicals in the test substance of balsam of Peru (Myroxylon pereirae). Besides salicyl alcohol, salicylaldehyde is also recommended to be used to screen for contact allergy to aspen. Both of these chemicals should be tested in forest workers in areas where aspen is growing.     

1,2-benzisothiazolin-3-one in disposable polyvinyl chloride gloves for medical use

BACKGROUND: Benzisothiazolinone is used as a slimicide in the manufacture of disposable powder-free polyvinyl chloride (PVC) gloves. We recently reported 6 patients from dentistry and health care probably sensitized to benzisothiazolinone in PVC gloves. OBJECTIVE: The study aimed to investigate how widely disposable PVC gloves for medical use on the Finnish market in 2006 contain benzisothiazolinone and to report new cases from 2 clinics in Helsinki. METHODS: 31 brands of disposable PVC gloves were analysed for their benzisothiazolinone content. We looked through the patient material of Helsinki University Central Hospital to find benzisothiazolinone allergic patients. We also described 3 previously unpublished benzisothiazolinone allergic patients from Finnish Institute of Occupational Health. RESULTS: 9 (30%) of the 31 glove brands contained 3-26 p.p.m. benzisothiazolinone. From the 2 clinics, we found 5 new benzisothiazolinone allergic patients who had used PVC gloves containing benzisothiazolinone. In addition, 3 patients had used disposable PVC gloves whose benzisothiazolinone content remained unknown. CONCLUSIONS: In Finland, benzisothiazolinone in powder-free PVC gloves has caused a small epidemic of allergic contact dermatitis in dental personnel and other health care workers. 1/3 of the disposable PVC gloves contained some benzisothiazolinone. A concentration of 20 p.p.m. benzisothiazolinone in a glove seems to be enough for sensitization.     

Antimicrobial allergy from polyvinyl chloride gloves

BACKGROUND: Contact allergy to plastic gloves is rare. Benzisothiazolinone is a biocide that is mainly used in industrial settings. We first suspected delayed-type contact allergy to benzisothiazolinone from polyvinyl chloride (PVC) gloves in 2004. We looked through our medical records from 1991 to 2005 to find similar cases. OBSERVATIONS: We found a total of 8 patients who are allergic to benzisothiazolinone and who had had exacerbations of their hand dermatitis while using PVC gloves. Patch testing revealed that 3 of them had weak allergic or doubtful reactions to the glove materials. Six of them had used Evercare Soft, Medi-Point, or Derma Grip PVC gloves, which in chemical analysis were shown to contain 9 to 32 ppm of benzisothiazolinone. Seven of the patients worked in dentistry or health care and 1 in farming. All of them had had hand dermatitis for many years. CONCLUSIONS: To our knowledge, there have been no previous reports of contact allergy to antimicrobial agents in plastic gloves. Benzisothiazolinone is widely used as a biocide in the manufacture of disposable PVC gloves. Small amounts of benzisothiazolinone in the gloves may sensitize those who already have hand dermatitis. We recommend that all patients with hand dermatitis while using PVC gloves should be patch tested with benzisothiazolinone.