Patch testing with 2.0% (0.60 mg/cm2) formaldehyde instead of 1.0% (0.30 mg/cm2) detects significantly more contact allergy

The new Italian SIDAPA Baseline Series for patch testing (2023): an update according to the new regulatory pathway for contact allergens

Allergic contact dermatitis (ACD) is a common inflammatory skin disease caused by delayed hypersensitivity to chemical and biotic contact allergens. ACD significantly affects the patients' quality of life negatively impacting both occupational and non-occupational settings. Patch testing is the gold standard diagnostic in vivo test to precise the ACD etiology and to correctly perform prevention. According to the Italian Medicines Agency (AIFA) legislative decree no. 178 of 29th May 1991, allergens are defined as medicines and therefore they are subject to strict regulation. In 2017, AIFA (decree no. 2130/2017) started a procedure to regulate contact allergens on the Italian market and actually the contact allergens temporarily authorized are reported in AIFA decree no. 98/2022, valid until November 2023. The availability on the market of contact allergens to diagnose ACD and continuous updating on the basis of new epidemiological trends are mandatory, jointly with the continuous update of the baseline and integrative series for patch testing. For this reason, the scientific community represented in Italy by the Skin Allergies Study Group of SIDeMaST (Italian Society of Dermatology and Venereology) and SIDAPA (Italian Society of Allergological, Occupational and Environmental Dermatology) are constantly working, in close relationship with the European scientific communities with large expertise in this important sector of the modern Dermatology. Herein, we report the setting up of regulatory legislation by AIFA and the new Italian Adult Baseline Series for patch testing.

Contact allergy to and allergic contact dermatitis from formaldehyde and -releasers: A clinical review and update

This review aims to provide a clinically useful update regarding the role of formaldehyde (FA) and its five main releasers (FRs) quaternium-15, diazolidinyl urea, DMDM hydantoin, imidazolidinyl urea and 2-bromo-2-nitropropane-1,3-diol (bronopol) in contact allergy and allergic contact dermatitis. These ubiquitous preservatives are still often, and sometimes undeclared, present in cosmetics, pharmaceuticals, medical devices, household detergents and chemical (industrial) products. In Europe, the use of free FA and quaternium-15 in cosmetics is forbidden and contact allergy rates have been found to be stable to decreasing. However, FA/FRs still readily provoke localized (e.g., facial/hand), airborne and generalized dermatitis, and may also complicate atopic and stasis dermatitis, or result in nummular dermatitis. Seborrheic-, rosacea- and impetigo-like dermatitis have recently been reported. For a correct diagnosis, FA 2% aq. (0.60 mg/cm² ) should be used, and particularly the FRs bronopol 0.5% pet. and diazolidinyl urea 2% should be patch tested separately in a baseline series. If sensitization to FA occurs, both FA and FRs should preferably be avoided, except perhaps for bronopol in case it tests negatively. If a patient reacts to one or more FRs (such as bronopol, or diazolidinyl/imidazolidinyl urea), but not to FA, then the specific FR(s) should be avoided. This article is protected by copyright. All rights reserved.

Contact dermatitis associated with preservatives: Retrospective analysis of North American Contact Dermatitis Group data, 1994 through 2016

BACKGROUND

Preservatives are often necessary components of commercial products. Large-scale North American studies on preservative allergy are limited.

OBJECTIVE

To evaluate demographics, positive patch test reactions (PPTRs), clinical relevance, and trends for preservatives tested by the North American Contact Dermatitis Group.

METHODS

We conducted a retrospective cross-sectional analysis of North American Contact Dermatitis Group patch testing results of preservatives from 1994 through 2016.

RESULTS

A total of 50,799 patients were tested; 11,338 (22.3%) had a PPTR to at least 1 preservative. The most frequent reactions were to methylisothiazolinone 0.2% aqueous (aq) (12.2%), formaldehyde 2% aq (7.8%), formaldehyde 1% aq (7.8%), quaternium-15 2% petrolatum (pet) (7.7%), and methyldibromo glutaronitrile/phenoxyethanol 2% pet (5.1%). Paraben mix 12% pet (1%), iodopropynyl butylcarbamate 0.1% pet (0.4%), benzyl alcohol 1% pet (0.3%), and phenoxyethanol 1% pet (0.2%) had the lowest PPTRs. Linear regression analysis of preservatives tested showed that only methylchloroisothiazolinone/methylisothiazolinone 0.01% aq (parameter estimate, 0.42; 95% CI, 0.17-0.66; P < .005) had a significant increase in PPTRs over time.

LIMITATIONS

Collected variables are dependent on clinical judgment. Results may be prone to referral selection bias.

CONCLUSIONS

This large North American study provides insight on preservative PPTRs and trends from 1994 through 2016.

The European baseline series: Criteria for allergen inclusion (with reference to formaldehyde releasers)

Existing criteria for inclusion in the European baseline series are summarized. Additional criteria are developed to aid decision making where the current criteria do not yield an unequivocal result. These include a consideration of whether an allergen (hapten) is better placed in a special series and the frequency with which an allergen cross-reacts with existing markers in the baseline series.

Allergic Contact Dermatitis

Allergic contact dermatitis is common, resulting in considerable morbidity. Diagnosis is based on a thorough history, physical examination, and patch testing. Several commercially available panels of patch testing are currently used. Allergens are found in a wide variety of daily products, occupational exposures, and foods. The mainstay of treatment is avoidance of the allergen, and databases like Contact Allergen Management Program and Contact Allergen Replacement Database help patients to select products that do not contain allergens to which they are sensitized. Topical corticosteroids can be used to treat exacerbations, but should be avoided in long-term treatment.

Comparison of Nickel Sulfate 2.5% and Nickel Sulfate 5% for Detecting Nickel Contact Allergy

BACKGROUND

Nickel is among the most common contact allergens found on patch testing worldwide and, because of its ubiquitous nature in our environment, often has important implications for allergen avoidance strategies. In both North America and Europe, nickel positivity is found in approximately 20% of patients who undergo patch testing. Whereas in North America, nickel sulfate is typically tested at a concentration of 2.5%, in Europe, it is tested at a 5% concentration.

OBJECTIVE

The primary objective was to assess the differences in patch test positivity to nickel sulfate 2.5% and 5%.

METHODS

We investigated 205 consecutive patients between September 2017 and February 2018 who were tested to nickel sulfate at concentrations of both 2.5% and 5%.

RESULTS

Among the 205 patients tested, 33% were positive (+, ++, or +++) to at least 1 concentration of nickel sulfate, 20% were positive to nickel sulfate 2.5%, and 31% were positive to nickel sulfate 5% (χ1(N = 205) = 16.1, P = 0.0001). Patients were 6.5 times more likely to have a positive reaction to nickel sulfate 5% than 2.5% (odds ratio 95% confidence interval, 2.3-25.6).

CONCLUSIONS

Given our findings, we propose an additional evaluation of nickel sulfate 5% as a standard allergen for patch testing in North America.

North American Contact Dermatitis Group Patch Test Results: 2015-2016

BACKGROUND

Patch testing is an important diagnostic tool for the assessment of allergic contact dermatitis (ACD).

OBJECTIVE

This study documents the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2015, to February 28, 2017.

METHODS

At 13 centers in North America, patients were tested in a standardized manner with a screening series of 70 allergens. Data were manually verified and entered into a central database. Descriptive frequencies were calculated, and trends were analyzed using χ test.

RESULTS

A total of 5597 patients were tested. There were 3725 patients (66.6%) who had at least 1 positive reaction, and 2798 patients (50.2%) were ultimately determined to have a primary diagnosis of ACD. A total of 572 patients (10.2%) had occupationally related skin disease. There were 10,983 positive allergic reactions. Nickel remained the most commonly detected allergen (17.5%). Methylisothiazolinone, which was added to the screening series for the 2013-2014 cycle, had the second highest positive reaction rate of allergens tested (13.4%). Compared with the previous reporting periods (2013-2014) and (2005-2014), positive reaction rates for the top 35 screening allergens statistically increased for only 1 allergen: hydroxyethyl methacrylate (3.4%; risk ratios, 1.24 [confidence interval, 1.00-1.54] and 1.46 [confidence interval, 1.23-1.73]). Three newly added allergen preparations-ammonium persulfate (1.7%), chlorhexidine (0.8%), and hydroquinone (0.3%)-all had a reaction rate of less than 2%. Twenty-three percent of the tested patients had at least 1 relevant allergic reaction to an allergen not on the NACDG series; 12% of these were occupationally related. T.R.U.E. Test (SmartPractice Denmark, Hillerød, Denmark) would have hypothetically missed one quarter to almost 40% of reactions detected by the NACDG screening series.

CONCLUSIONS

These results confirm that the epidemic of sensitivity to methylisothiazolinone has continued in North America. Patch testing with allergens beyond a screening tray is necessary for a complete evaluation of occupational and nonoccupational ACD.

Skincare products containing low concentrations of formaldehyde detected by the chromotropic acid method cannot be safely used in formaldehyde-allergic patients

BACKGROUND

Formaldehyde is a well-known contact sensitizer. Formaldehyde releasers are widely used preservatives in skincare products. It has been found that formaldehyde at concentrations allowed by the European Cosmetics Directive can cause allergic contact dermatitis. However, we still lack information on whether formaldehyde at low concentrations affects dermatitis in formaldehyde-allergic individuals.

OBJECTIVES

To study the effects of low concentrations of formaldehyde on irritant contact dermatitis in formaldehyde-allergic individuals.

METHODS

Fifteen formaldehyde-allergic individuals and a control group of 12 individuals without contact allergy to formaldehyde and formaldehyde releasers were included in the study. The individuals performed the repeated open application test (ROAT) during 4 weeks with four different moisturizers releasing formaldehyde in concentrations that had been determined as > 40, 20-40, 2·5-10 and 0 p.p.m. by the chromotropic acid (CA) spot test. Dimethyloldimethylhydantoin was used as a formaldehyde releaser in the moisturizers. The ROAT was performed on areas of experimentally induced sodium lauryl sulfate dermatitis. The study was double blind, controlled and randomized.

RESULTS

Nine of the 15 formaldehyde-allergic individuals had reappearance or worsening of dermatitis on the areas that were treated with moisturizers containing formaldehyde. No such reactions were observed in the control group (P < 0·001) or for the moisturizers without formaldehyde in the formaldehyde-allergic individuals (P < 0·001).

CONCLUSIONS

Our results demonstrate that the low concentrations of formaldehyde often found in skincare products by the CA method are sufficient to worsen an existing dermatitis in formaldehyde-allergic individuals.