Patch test clinic experience of potential cross-reactivity of isothiazolinones

Severe Allergic Contact Dermatitis From Octylisothiazolinone in Over-Ear Headphones: A Case Series

BACKGROUND

Octylisothiazolinone (OIT; CAS 26530-20-1) is used as a biocide in leather products.

OBJECTIVES

To report several cases of allergic contact dermatitis (ACD) from the use of headphones containing OIT, and to highlight the strong allergic potential of this preservative.

PATIENTS AND METHODS

Four patients with ACD from headphones were patched tested using the European baseline, cosmetic, rubber, plastics/glues and acrylates series. Patients were also tested to different parts of their own headphones ('as is'). Chemical analyses of the headphones was additionally performed with Ultra Performance Liquid Chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

All patients had developed localised ACD to the contact sites of the headphones, except for one patient who developed 'angioedema-like' dermatitis. All patients were shown to have been primarily sensitised to OIT. UPLC-MS/MS analysis confirmed OIT in the leather ear pads of the headphones.

CONCLUSIONS

OIT is a relevant and strong sensitizer in leather, and may cause severe ACD. Safer use concentrations (limits) of OIT, as well as product labelling in the leather industry, may be required to ensure a better protection of consumers.

Increasing non-cosmetic exposure and sensitization to isothiazolinones require action for prevention: Review

Frequent use of methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and MI in cosmetic products has been the main cause of widespread sensitization and allergic contact dermatitis to these preservatives (biocides). Their use in non-cosmetic products is also an important source of sensitization. Less is known about sensitization rates and use of benzisothiazolinone (BIT), octylisothiazolinone (OIT), and dichlorooctylisothiazolinone (DCOIT), which have never been permitted in cosmetic products in Europe. BIT and OIT have occasionally been routinely patch-tested. These preservatives are often used together in chemical products and articles. In this study, we review the occurrence of contact allergy to MI, BIT, OIT, and DCOIT over time, based on concomitant patch testing in large studies, and case reports. We review EU legislations, and we discuss the role of industry, regulators, and dermatology in prevention of sensitization and protection of health. The frequency of contact allergy to MI, BIT, and OIT has increased. The frequency of contact allergy to DCOIT is not known because it has seldom been patch-tested. Label information on isothiazolinones in chemical products and articles, irrespective of concentration, is required for assessment of relevance, information to patients, and avoidance of exposure and allergic contact dermatitis.

Analysis of Contact Allergens in Polyvinyl Chloride Examination Gloves in the United States

Background: Polyvinyl chloride (PVC) gloves are recommended as a safe alternative for patients with rubber accelerator allergy. However, allergic contact dermatitis to other chemicals in PVC gloves has been reported. Objective: To analyze single-use PVC medical examination gloves in the United States for the presence of potential contact allergens. Methods: Using liquid chromatography-mass spectrometry, 20 unique PVC gloves were analyzed in triplicate for 6 chemicals: benzisothiazolinone, bisphenol A, mono(2-ethylhexyl) maleate, tricresyl phosphate, triphenyl phosphate, and triphenyl phosphite. Results: All 20 PVC gloves contained detectable quantities of benzisothiazolinone (range, 0.001-1.48 parts per million [ppm]), bisphenol A (0.01-0.11 ppm), triphenyl phosphate (0.01-2.11 ppm), and triphenyl phosphite (0.001-0.22 ppm). Eighteen (90%) gloves contained mono(2-ethylhexyl) maleate (0.001-0.14 ppm) and 3 (15%) contained tricresyl phosphate (0.001-0.002 ppm). Conclusions: Known allergens were present in all 20 PVC gloves. However, the detected levels were mostly low and their relationship with sensitization and elicitation thresholds requires further study.

Sensitization to isothiazolinones in the Spanish Contact Dermatitis Registry (REIDAC): 2019-2021 epidemiological situation

BACKGROUND

Current frequency and risk factors for sensitization to methylisothiazolinone (MI), methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), benzisothiazolinone (BIT) and octylisothiazolinone (OIT) in Spain are not well known.

OBJECTIVES

To study the frequency of sensitization, risk factors and simultaneous sensitization between the four isothiazolinones.

MATERIALS AND METHODS

We analysed all 2019-2021 consecutive patients patch-tested with MI (0.2% aq.), MCI/MI (0.02% aq.), BIT (0.1% pet.) and OIT (0.1% pet) within the Spanish Contact Dermatitis Registry (REIDAC).

RESULTS

A total of 2511 patients were analysed. Frequencies of sensitization were: any isothiazolinone 15.7%, MI 6.8%, MCI/MI 4.8%, BIT 3.5% and OIT 0.5%. MI and MCI/MI sensitization was associated with being occupationally active, hand dermatitis, detergents and age over 40. BIT sensitization was associated with leg dermatitis and age over 40. About one in nine MI-positive patients were positive to BIT, whereas one in five BIT-positive patients were positive to MI.

CONCLUSIONS

Sensitization to MI, MCI/MI and BIT is still common in Spain, while sensitization to OIT is rare. Currently, sensitization to MI and MCI/MI seems to be occupationally related. Although its origin is unknown, sensitization to BIT is more frequent in patients aged over 40 years. Simultaneous sensitization between MI and BIT is uncommon.

North American Contact Dermatitis Group Patch Test Results: 2019-2020

Background: Patch testing is an important diagnostic tool for assessment of allergic contact dermatitis (ACD). Objective: This study documents the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2019, to December 31, 2020. Methods: At 13 centers in North America, patients were tested in a standardized manner with a screening series of 80 allergens, and, as indicated, supplemental allergens. Results: Overall, 4121 patients were tested; 2871 (69.7%) had at least 1 positive/allergic patch test reaction and 2095 patients (51.2%) had a primary diagnosis of ACD. The most commonly positive allergens were nickel (18.2%), methylisothiazolinone (MI) (13.8%), fragrance mix (FM) I (12.8%), hydroperoxides of linalool (HPL) (11.1%), and benzisothiazolinone (BIT) (10.4%). Compared with that of 2017-2018, prevalence of top 20 allergens statistically increased for FM I, HPL, BIT, propolis, and hydroperoxides of limonene (3.5%). For the first time, MI positivity did not increase between reporting periods. Approximately one-fifth of patients (20.3%) had ≥1 clinically relevant reaction(s) to allergens/substances not on the NACDG series. Conclusions: The epidemic of MI contact allergy in North America may have reached a plateau. Patch testing using a robust screening series, and supplemental allergens as indicated, is necessary for comprehensive evaluation of ACD.

Trends in preservative allergy: Benzisothiazolinone emerges from the pack

BACKGROUND

Preservatives are used widely in cosmetic, household, and industrial products to prevent microbial growth and spoiling of the products. There has been a recent epidemic of contact allergy to methylisothiazolinone (MI).

OBJECTIVES

To establish emerging trends in preservative contact allergy as MI is replaced.

METHODS

We performed a retrospective study on consecutively patch-tested patients at our center from January 2011 to December 2019.

RESULTS

A total of 7846 consecutively patch-tested patients were included who were patch tested between January 2011 and December 2019. The prevalence of allergy to MI fell from a peak of 9.39% in 2013 to 1.98% in 2019. MI/methylchloroisothiazolinone (MCI) followed a similar trend, with a peak prevalence of 7.85% in 2014 and falling to 1.39% in 2018. The prevalence of contact allergy to benzisothiazolinone (BIT) has increased steadily increased in 2014 from 0.26% (confidence interval [CI] 0.03-0.93) to 3.42% (CI 2.43-4.66) in 2019.

CONCLUSIONS

Our data show a significant increase in the prevalence of contact allergy to BIT over the last 6 years, probably as a consequence of increased use in household products. It is essential to continue to look for emerging trends in contact allergy to enable prompt preventative measures to be taken.

Evolution of methylisothiazolinone sensitization: a Belgian multicentric study from 2014 to 2019

BACKGROUND

In the 2010s an epidemic of allergic contact dermatitis to methylisothiazolinone occurred in Europe. European authorities banned the use of methylisothiazolinone in leave-on cosmetics in 2017 and limited its use in rinse-off products in 2018.

OBJECTIVES

To investigate the sensitization rate to methylisothiazolinone in Belgium between January 2014 and December 2019, and to assess co-sensitizations to octylisothiazolinone and benzisothiazolinone in methylisothiazolinone -sensitized patients.

METHODS

A retrospective study of patch test results with methylisothiazolinone, octylisothiazolinone and benzisothiazolinone observed in patients attending five Belgian hospitals.

RESULTS

Overall, 560 of 10.029 patients (5.58%) had a positive patch test reaction to methylisothiazolinone, and its sensitization rate decreased from 7.9% in 2014 to 3.1% in 2019. Rinse-off cosmetics, paints and detergents were the most prevalent sensitization sources in recent years. Simultaneous reactions readily occurred to octylisothiazolinone, and, surprisingly, and increasingly, also to benzisothiazolinone.

CONCLUSIONS

Contact allergy to methylisothiazolinone in Belgium has reached a pre-epidemic level, reflecting the impact of recent regulatory measures. Leave-on cosmetics, in contrast to rinse-off products, have almost disappeared as sensitization sources in Europe. Paints and detergents also remain problematic. The remarkably high number of patients (co-) sensitized to benzisothiazolinone should be a focus of future research. This article is protected by copyright. All rights reserved.

Amended Safety Assessment of Methylchloroisothiazolinone and Methylisothiazolinone as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) reassessed the safety of the mixture Methylchloroisothiazolinone (MCI)/Methylisothiazolinone (MI), which functions as a preservative in cosmetic products. The Panel reviewed relevant animal and human data provided in this safety assessment, and data from the previously published safety assessment of this mixture, and concluded that MCI/MI is safe in cosmetics when formulated to be nonsensitizing, based on the results of a quantitative risk assessment or similar methodology; however, at no point should concentrations exceed 7.5 ppm in leave-on products or 15 ppm in rinse-off products.

In vivo demonstration of immunologic cross-reactivity to octylisothiazolinone in patients primarily and strongly sensitized to methylisothiazolinone

BACKGROUND

Notwithstanding that concomitant exposure to different isothiazolinone derivatives may result in concomitant sensitization, clinical and animal studies have suggested cross-reactivity between these derivatives, notably between methylisothiazolinone (MI) and octylisothiazolinone (OIT).

OBJECTIVE

To investigate if patients sensitized to MI show cross-reactions to OIT and/or to benzisothiazolinone (BIT) by applying the concept of the re-test method.

PATIENTS AND METHODS

From March to October 2019 consecutive patients were patch tested with MI 0.2% aqueous in duplicate at the two lower corners of both shoulder blades. Patients sensitized to MI, but not to OIT 0.1% petrolatum (pet.) nor to BIT 0.1% pet., were re-tested, 2 months later, with the latter two derivatives at the skin sites where the MI reactions had fully disappeared.

RESULTS

Of 116 patients, 15 (13%) were sensitized to MI, eight of these not sensitized to BIT nor to OIT. Of these, seven patients, all (very) strongly sensitized to MI, were re-tested: five patients showed positive patch test reactions to OIT 0.1% pet.; one patient to OIT 0.1% pet. and BIT 0.1% pet.; and one other patient showed no reactions.

CONCLUSION

This study suggests that patients primarily and strongly sensitized to MI may show immunologic cross-reactions to OIT, and to a far lesser extent to BIT.

Isothiazolinone derivatives and allergic contact dermatitis: a review and update

Allergic contact dermatitis (ACD) from isothiazolinones has frequently been described in the literature. Following an epidemic of sensitization to methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) in the 1980s, and more recently to MI, the Scientific Committee on Consumer Safety of the European Commission banned their use in leave-on products, while restricting that in rinse-off cosmetics. Despite a decreasing prevalence of ACD from MCI/MI and MI, cases caused by occupational exposure and non-cosmetic isothiazolinone sources are on the rise. Moreover, sensitization to newer and lesser known isothiazolinones has been reported. This paper reviews the epidemiology of contact allergy to different isothiazolinones, clinical presentation of isothiazolinone-induced ACD, most relevant sensitization sources and potential cross-reactions between isothiazolinone derivatives. It also provides an update on recent legislative measures.

Patterns of concomitant allergic reactions in patients suggest cross-sensitization between octylisothiazolinone and methylisothiazolinone

BACKGROUND

Recent animal tests have indicated cross-reactivity between methylisothiazolinone (MI), octylisothiazolinone (OIT), and benzisothiazolinone (BIT).

OBJECTIVES

To retrospectively analyse concomitant reactions to different isothiazolinones in patients in an occupational dermatology clinic during the ongoing MI contact allergy epidemic.

METHODS

We searched patch test files (January 2012 to February 2017) for patients with allergic reactions to OIT, BIT, and MI, and analysed their patch test results, occupations, exposure, and diagnoses.

RESULTS

We found 61 (9.4%) allergic reactions to MI, 19 (2.9%) reactions to OIT and 9 (1.4%) reactions to BIT in a total of 647 consecutively tested patients. Seventeen (89%) of the OIT-positive patients had concomitant reactions to MI, whereas only 3 (33%) BIT-positive patients had allergic reactions to MI. The MI reactions in OIT-positive patients were almost exclusively extreme reactions (+++). Exposure to OIT was identified in 26% of the OIT-positive patients, and 56% of the BIT-positive patients had been exposed to BIT.

CONCLUSIONS

Allergic reactions to OIT were strongly associated with extreme reactions to MI, which suggests cross-sensitization. In contrast, BIT reactions were mostly independent.