Analysis of patients with allergic patch test reactions to a plastics and glues series

Allergic contact dermatitis to phenol-formaldehyde resin at a single tertiary dermatology centre

BACKGROUND

Phenol-formaldehyde resin 2 (PFR2) has been shown to be a useful marker of contact allergy (CA) to various phenol-formaldehyde resins. These compounds are used in several industries as solids, powders, or semisolid resins, and are known to be sensitizing agents.

OBJECTIVES

The aims were to investigate contact allergy to PFR2 in a single tertiary dermatology centre, to examine associated simultaneous allergic reactions, and to identify cases of allergic contact dermatitis (ACD) to PFR2.

METHODS

A retrospective study was performed of patients patch tested to PFR2 between 1 January 2003 and 17 June 2020.

RESULTS

In all, 337 of 7922 patients were tested to PFR2 and 16 (4.7%) reacted. Of those 16 individuals, six (37.5%) had a relevant reaction (1.8% of total). Simultaneous allergic reactions were noted to colophonium in eight (50.0%) patients, Myroxylon pereirae in five (31.3%), and fragrance mix I (FMI) of three cases (18.8%).

CONCLUSION

Contact allergy to PFR2, even in a selected population of patients, is uncommon. However, patients exposed to plastics and glues, or who work with wood products should be routinely patch tested to a plastics and glues series containing PFR2. We recommend that all centres include PFR2 in their plastics and glues series.

Diaminodiphenylmethane Sensitization in north-eastern Italy from 1996 to 2012

BACKGROUND

4,4'-Diaminodiphenylmethane (DDM) is an aromatic amine used as a hardener, insulator and anticorrosive. Exposure implies risk of being sensitized and developing contact dermatitis.

OBJECTIVE

The aim of this study was to determine the occurrence of contact sensitization to DDM among patients with contact dermatitis and the role of occupational exposure.

PATIENTS AND METHODS

From 1996 to 2012, 24 056 consecutive patients with suspected allergic contact dermatitis were patch tested in north-eastern Italy. Individual characteristics were collected through a standardized questionnaire in eight departments of dermatology and occupational medicine.

RESULTS

The overall prevalence of DDM sensitization was 2.5% (n = 599) with a decreasing trend in considered years. Trieste area had the higher prevalence of sensitization (3.2%). Mechanics and chemical industry workers had a significant higher risk of being sensitized to DDM.

CONCLUSION

DDM sensitization is decreasing in years and is associated with some occupational exposures.

Hand/face/neck localized pattern: sticky problems--resins

Plastic resin systems have an increasingly diverse array of applications but also induce health hazards, the most common of which are allergic and irritant contact dermatitis. Contact urticaria, pigmentary changes, and photoallergic contact dermatitis may occasionally occur. Other health effects, especially respiratory and neurologic signs and symptoms, have also been reported. These resin systems include epoxies, the most frequent synthetic resin systems to cause contact dermatitis, (meth)acrylics, polyurethanes, phenol-formaldehydes, polyesters, amino resins (melamine-formaldehydes, urea-formaldehydes), polyvinyls, polystyrenes, polyolefins, polyamides and polycarbonates. Contact dermatitis usually occurs as a result of exposure to the monomers and additives in the occupational setting, although reports from consumers, using the raw materials or end products periodically surface. Resin- and additive-induced direct contact dermatitis usually presents on the hands, fingers, and forearms, while facial, eyelid, and neck involvement may occur through indirect contact, eg, via the hands, or from airborne exposure. Patch testing with commercially available materials, and in some cases the patient's own resins, is important for diagnosis. Industrial hygiene prevention techniques are essential to reduce contact dermatitis when handling these resin systems.

Contact sensitization to 4,4'-diaminodiphenylmethane and to isocyanates among general dermatology patients

BACKGROUND

Diisocyanates and 4,4'-diaminodiphenylmethane (MDA) are industrial sensitizers. Occupational asthma is a risk among workers exposed to diisocyanates. Exposure may also lead to contact sensitization and allergic contact dermatitis.

OBJECTIVE

The aim of this study was to determine the occurrence of contact sensitization to MDA and to diisocyanates among general dermatology patients.

PATIENTS AND METHODS

Patch testing with MDA was carried out in 1595 patients. Diphenylmethane-4,4'-diisocyanate (MDI) and toluene-2,4-diisocyanate (TDI) were tested in 1023 patients and isophorone diisocyanate (IPDI) and 1,6-hexamethylene diisocyanate (HDI) in 433 patients. The clinical data and sources of exposure are analysed.

RESULTS

MDA reactions were seen in 17 (1.1%) patients and MDI reactions in 4 patients. Six MDA-positive patients reacted to p-phenylenediamine and two to epoxy chemicals. 5/10 of the TDI reactions were seen concurrently with reactions to MDI, MDA, HDI, or to IPDI. IPDI reactions were seen in eight patients and HDI reactions in two patients. Possible sources of exposure were traced in most patients, although the association with the current dermatitis was not apparent in all cases.

CONCLUSION

(Di)isocyanates may induce contact sensitization with or without allergic contact dermatitis.

Contact allergy to the monomers in p-tert-butylphenol-formaldehyde resin

In many adhesive formulations p-tert-butylphenol-formaldehyde resin (PTBP-F-R) is used as a binder. Contact allergy to this resin is not rare. In patients hypersensitive to PTBP-F-R, and butylphenol derivatives therein, it is for diagnostic and preventive reasons necessary to know the nature of the primary sensitizing substances, as well as the cross-reaction patterns for these. The aim of this study was to investigate contact allergy to monomers in PTBP-F-R and potential cross-reacting substances. 12 patients hypersensitive to PTBP-F-R were patch tested with 2 monomers, the raw materials formaldehyde and p-tert-butylphenol, and 3 closely related substances. High pressure liquid chromatography (HPLC) was used to investigate the purity of the test substances. It was shown that the monomers 2-methylol p-tert-butylphenol and 2,6-dimethylol p-tert-butylphenol could elicit allergic reactions in humans hypersensitive to PTBP-F-R. No simultaneous reactions or cross-reactions were shown to formaldehyde, p-tert-butylphenol, p-tert-butylcatechol, 2(3)-tert-butyl-4-hydroxyanisole (BHA) or 3,5-di-tert-butyl-4-hydroxytoluene (BHT). It was also shown that low amounts of contaminants in the test substances, if not taken into account, could influence the conclusions drawn from the test results obtained.

Sensitizing capacity of some trimers in p-tert-butylphenol-formaldehyde resin

Contact allergy to p-tert-butylphenol formaldehyde resin (PTBP-F-R) is not rare. This resin consists of a large number of substances, most of which are still unknown. For diagnostic and preventive reasons the chemical identity of the sensitizers should be known, as well as their sensitizing capacities, cross-reaction patterns and presence in the environment. The aims of this study were to investigate the sensitizing capacities and potential cross-reacting patterns for 4-tert-butyl- 2,6-bis-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-phenol (XIII), 4-tert-butyl-2- (5 - tert - butyl - 2 - hydroxy-benzyloxymethyl) - 6 - (5 - tert - butyl - 2 - hydroxy - 3 - hydroxymethyl-benzyloxy methyl)-phenol (XIVa) and 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix(3)arene (XVIII) by the guinea pig maximization test. 4-tert-Butyl-2,6-bis-hydroxymethyl-phenol, 4-tert-butylbenzene-1,2-diol, 4-tert-butyl-2-hydroxymethyl-phenol, 4-tert-butyl-phenol, 4-tert-butyl-2-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-6-hydroxymethyl-phenol, 4-tert-butyl-2-[5-tert-butyl-3-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl) - 2 -hydroxy-benzyloxymethyl] - 6 - (5 - tert-butyl- 2 -hydroxy- 3 -hydroxymethyl-benzyloxymethyl)- phenol and were used as potential cross-reacting substances. In this study it is strongly indicated that the linear trimer XIII has a sensitizing capacity in the guinea pig which was significant when compared to the controls (p = 0.024). No cross-reactions were detected in animals induced with the linear trimer XIII. The linear trimer XIVa and the cyclic trimer XVIII failed to induce sensitization.

Occupational dermatoses in composite production

In a plant that produces fiber-resin composite by impregnation of cellulose fibers with phenol-formaldehyde and melamine-formaldehyde resins, a new technique was introduced that resulted in problems in the handling of uncured products. Many workers suffered dermatitis on areas of exposed skin. A primary investigation found that some workers had an occupationally related skin disease with contact allergy to work materials. We undertook a survey of occupational dermatoses, based on a questionnaire, clinical examination, and patch test with a standard series and a series of products and chemicals representing the work environment. Eighty-eight workers participated in the clinical investigation. In six workers, contact allergy to phenol-formaldehyde resin was seen, and in five workers, contact allergy to melamine-formaldehyde resin was noted. Two workers were allergic to both resins. Occupational dermatitis was diagnosed in nine of 88 (10.2%) workers. In this article, we discuss possible preventive measures for avoiding occupational dermatitis.

Simultaneous p-tert-butylphenol-formaldehyde resin and p-tert-butylcatechol contact allergies in man and sensitizing capacities of p-tert-butylphenol and p-tert-butylcatechol in guinea pigs

In patients who are hypersensitive to p-tert-butylphenol-formaldehyde resin (PTBP-F-R), it is necessary, for diagnostic, therapeutic, and preventive reasons, to know the identity of the primary sensitizing substances, their sensitizing capacities, and their crossreaction patterns. The aims of this study were to investigate the presence of a simultaneous p-tert-butylcatechol (PTBC) contact allergy in individuals who were hypersensitive to PTBP-F-R, to investigate the sensitizing capacity of PTBC and p-tert-butylphenol (PTBP) in guinea pigs, and to study any crossreaction patterns. In 294 dermatitis patients tested with PTBP-F-R and PTBC, there was a statistically significant over-representation of simultaneous test reactions. Use of the guinea pig maximization test demonstrated that PTBC is a strong sensitizer giving crossreactions to PTBP. PTBP, however, failed to induce sensitization.

Contact allergy to the monomers of p-tert-butylphenol-formaldehyde resin in the guinea pig

In patients hypersensitive to p-tert-butylphenol-formaldehyde resin (PTBP-F-R), and butylphenol derivatives therein, it is for diagnostic, therapeutic and preventive reasons necessary to know the identity of the primary sensitizing substances, their sensitizing capacities as well as their cross-reaction patterns. The monomers in PTBP-F-R, 2-methylol p-tert-butylphenol (2-MPTBP) and 2,6-dimethylol p-tert-butylphenol (2,6-MPTBP), have been shown to be contact sensitizers in man. The aim of this study was to investigate the sensitizing capacities of the monomers and establish cross-reacting patterns in the guinea pig with the guinea pig maximization test. 2,6-MPTBP was shown to be a strong sensitizer while it was indicated that 2-MPTBP was a sensitizer. Animals sensitized to 2,6-MPTBP showed cross-reactions to 2-MPTBP and p-tert-butylcatechol. No cross-reactions were shown to p-tert-butylphenol, tert-butyl 4-hydroxyanisole (BHA) and 3,5-di-tert-butyl 4-hydroxytoluene (BHT).