Contribution of Patch Tests with Occupational Handled Products in the Diagnosis of Occupational Contact Dermatitis: A 10-year Review

Introduction

Allergic contact dermatitis (ACD) is a common occupational disease. Its diagnosis is essentially based on interrogation and patch tests. However, commercially available batteries are sometimes not appropriate for the working conditions and the handled products, which must then be tested. In Tunisia, no previous study has focused on the contribution of patch tests with handled products in the workplace. The objective of this study is to establish the sociodemographic and occupational profile of the patients benefiting from patch tests with handled products in the workplace to identify the characteristics of these products as well as to evaluate the relevance of their positivity and their contributions in terms of aetiological diagnosis of occupational ACD.

Methods

This is a retrospective descriptive epidemiological study conducted for a period of 10 years from January 1^st, 2006, to December 31, 2015, among patients exercising a professional activity and consulting the Dermato-Allergology Unit of the Occupational Medicine ward of the University Hospital Farhat Hached of Sousse for the exploration of ACD.

Results

During the study period, 113 patients received patch tests of handled products in the workplace with a prevalence of 7.3% of patch-tested patients during the same period. The mean age was 35.79 ± 9.45 years with a male predominance (sex ratio = 1.35). The most represented activity sectors were the health sector in 30.1% and the textile sector in 21.2%. The majority of patients were professionally active (61.9% of the study population) with an average professional seniority of 10.28 ± 8.49 months. In total, 138 patch tests with handled products were carried out of which 46 tests were positive (33.3%). After the analytical study, variables independently significantly associated with the positivity of patch tests with handled products in the workplace were the male gender and the working in the plastics industry. An occupational disease was declared to the National Health Insurance Fund for 8 patients, i.e., 7.1% of cases.

Conclusion

Patch tests with handled products in the workplace can provide strong arguments for the professional origin of the ACD.

Multiyear Group and Medical Center Patch Test Frequency Data: Confounding Variables

Patch test frequency data have been extensively published by research groups, such as the International Contact Dermatitis Research Group, North American Contact Dermatitis Group, Dermato-Allergology Study and Research Group, and European Environmental Contact Dermatitis Research Group. As this knowledge accumulation is widely applied in clinical and public health settings, we describe confounding factors to consider when using such data for medical policy considerations. These concepts can also be used in individual reports of new allergens or series of cases. Some of these confounders may have been reported in current literature (until October 2020), whereas others have not been mentioned/considered in most group publications.

Epidemics of Dermatitis

Allergic contact dermatitis (ACD) remains a globally prevalent disease for both children and adults. The silent ACD epidemic continues to be fueled by the introduction of novel allergens in industrial and household products and the continued presence of known allergens. In 1997, Allan Dillarstone noted a sinusoidal pattern to epidemics when allergenic preservatives were replaced by alternative chemicals within the market, which then similarly increased in allergenicity. A call for public health vigilance and prevention initiatives is needed to intervene in the ACD epidemic.

Nickel: Intrinsic Skin Sensitization Potency and Relation to Prevalence of Contact Allergy

Nickel remains the most commonly identified contact allergen. However, it has proven difficult to demonstrate significant skin-sensitizing activity for nickel in toxicology tests, which typically have indicated a weak skin sensitization potential. Information indicates that in vivo assays are not predictive of dermal sensitization hazard or potency for nickel due to a human-specific mechanistic route for nickel sensitization that animals lack. A similar rationale will apply to in vitro alternatives-although these currently have limited ability to determine intrinsic potency. Generally, in silico methods are not designed for metal allergens and cannot contribute to the analysis. For ethical reasons, human experimental work has been limited, with a single study suggesting moderate potency. Accordingly, it seems reasonable to conclude that the high frequency of contact allergy to nickel in humans is a function of both its intermediate potency coupled with a high level of dermal exposure, particularly to damaged/inflamed skin.

Patch Testing With a New Composition of the Mercapto Mix-A Multicenter Study from the International Contact Dermatitis Research Group

BACKGROUND

Mercaptobenzothiazole compounds are associated with allergic contact dermatitis caused by rubber products. Several screening substances have been used for patch testing.

OBJECTIVE

To compare the frequency of positive test reactions to a mercapto mix containing a higher concentration of 2-mercaptobenzothiazole with reactions to the combination of 2-mercaptobenzothiazole 2.0% and mercapto mix 2.0%.

METHODS

There were 7103 dermatitis patients in 12 International Contact Dermatitis Research Group dermatology departments who were patch tested with 2-mercaptobenzothiazole 2.0% petrolatum (pet.), mercapto mix 2.0% pet., and mercapto mix 3.5% pet.

RESULTS

Contact allergy to the 3 test preparations varied among the 12 centers: 2-mercaptobenzothiazole 2.0% pet. (0-2.4%), mercapto mix 2.0% pet. (0-4.9%), and mercapto mix 3.5% pet. (0-1.4%). 2-Mercaptobenzothiazole 2.0% and mercapto mix 2.0% detected a few more positive patients compared with mercapto mix 3.5%, but the difference was statistically insignificant (mercapto mix 2.0% pet., P = 1.0; 2-mercapto-benzothiazole 2.0% pet., P = 0.66).

CONCLUSIONS

Mercapto mix 3.5% pet. is not better than 2-mercaptobenzothiazole 2.0% and mercapto mix 2.0% by a difference that is significant. By using only 1 test preparation (mercapto mix 3.5%), an additional hapten could be tested. No cases of suspected/proven patch test sensitization were registered.

Methylchloroisothiazolinone and/or Methylisothiazolinone Contact Allergies in Thailand

BACKGROUND

Methylchloroisothiazolinone, in combination with methylisothiazolinone (MCI/MI), and MI alone are common preservatives. The incidences of MCI/MI and MI-alone contact allergies have risen markedly worldwide, leading to changes in their use in products.

OBJECTIVES

The aim of the study was to determine the incidences of positive patch test reactions and factors associated with MCI and/or MI contact allergies during the recent decade in Thailand.

METHODS

Medical records of patients who underwent patch testing at Siriraj Hospital from 2009 to 2018 were retrospectively reviewed. The incidences of positive reactions, histories, and clinical data of MCI/MI and MI-alone contact allergy patients were analyzed.

RESULTS

Of 2789 patients undergoing patch testing, most were female (76.1%). The mean ± SD age was 42.7 ± 15.7 years. Positive reactions to MCI/MI increased from 2009 to 2016 before declining. The MCI/MI contact allergy was most common in females, middle-aged patients, and those with metal allergy histories, with the hands and arms being the predominant sites. However, MI-alone contact allergy was more common in males and mainly at the trunk. Its incidence significantly declined for the last 5 years.

CONCLUSIONS

The incidences of MCI/MI and MI-alone contact allergies began to decline because the Food and Drug Administration Thailand regulations restricted their use. The risk factors for the allergies reported in this study provide important information for patient care.

Hand eczema

Hand eczema is an inflammation of the skin; the cause is often multifactorial. Initial management includes avoiding causative irritants or allergens (e.g., by wearing impermeable gloves) and applying emollients and potent topical glucocorticoids.