Trends in formaldehyde and formaldehyde-releaser contact allergies as compared with market exposure in Thailand.

BACKGROUND: Formaldehyde and formaldehyde releasers (FRs) are common preservatives in cosmetics and household products. Their contact allergy trends are decreasing in Europe and America, but trend data for Asia are limited. OBJECTIVES: The first objective was to determine the prevalences of and trends in contact allergies to formaldehyde and FRs. The second objective was to establish how often formaldehyde and FRs were mentioned on the labels of products sold in the Thai market. METHODS: Twenty years of data on patch test results for formaldehyde and FRs were reviewed. Their frequency of mention on the labels of 5855 products was analysed. RESULTS: The trends in contact allergy to formaldehyde and FRs were decreasing. The overall prevalence of formaldehyde contact allergy was 2.5%. The most common FR to cause contact allergy was quaternium-15. Formaldehyde and FRs were identified as ingredients in 10.2% of the products surveyed. Dimethylol dimethyl hydantoin was the most common FR (5.2%). The highest use of formaldehyde and FRs (15.5%) was in hair care products. CONCLUSION: Although contact allergy trends in Thailand were decreasing, the proportion of products with FRs remained high. Comprehensive and universal legislation is needed to control the presence of formaldehyde and FRs.

The Value of Patch Testing With Shoe Material Samples in Patients Suspected of Shoe Allergic Contact Dermatitis.

BACKGROUND: Patch testing is the standard diagnostic tool for shoe allergic contact dermatitis (ACD). As shoe materials change over time, utilizing commercial allergen series might be ineffective. However, because testing with patients' shoe samples is laborious, its value is questioned. OBJECTIVE: The aim of this study was to ascertain the benefits of patch testing with patients' shoes by comparing the frequencies of patch-test positivity of shoes and shoe-related allergens in baseline series for suspected shoe ACD patients. METHODS: A retrospective study was conducted of patients with clinically suspected shoe ACD who underwent patch testing with baseline series and shoe samples 2000 to 2019. RESULTS: Almost half of the cohort (77 of 178; 43.3%) was diagnosed with shoe ACD. Of those 77, 48 (62.3%) were positive to shoe-related allergens from the baseline series, whereas 53 (68.8%) were positive to their shoe materials. The prevalence of tests positive to shoe material but negative to shoe-related allergens was 29 of 77 (37.7%). The most common shoe-related allergens were potassium dichromate (7.9%), carba mix (6.8%), and mercapto mix (6.7%). CONCLUSIONS: Patch testing with shoe materials increased the diagnostic yield by 37.7 percent. To diagnose shoe ACD, testing of shoe materials may compensate for unknown, scarce, or novel allergens not in the baseline series.

Methylchloroisothiazolinone and/or methylisothiazolinone in cosmetic products-A market survey.

BACKGROUND: There was a global epidemic of methylchloroisothiazolinone (MCI) and/or methylisothiazolinone (MI) contact allergy from 2009 to 2015. In response, the Thai Ministry of Public Health regulated the use of MCI/MI in cosmetics. OBJECTIVE: To survey the presence of MCI/MI and MI alone, as labelled on cosmetics sold on the Thai market, before and after the ministerial directive. METHODS: The presence of MCI and/or MI in leave-on and rinse-off cosmetics sold on the market, based on the labelling of ingredients in 3445 products, was analysed. RESULTS: Before the implementation date, most leave-on products contained MCI/MI. After the regulations came into force, the only leave-on cosmetic subcategories that complied with the law were facial skin-care, sunscreen and make-up products. MCI/MI and MI alone were found on the labels of both leave-on and rinse-off products, the presence of each varying between product subcategories. CONCLUSIONS: Despite the ministerial regulations restricting their use, MCI and/or MI are still found in cosmetics sold on the Thai market. Dermatologists should be aware of this situation, and counsel patients to avoid products containing MCI and/or MI.

Contact sensitizers in commercial hair dye products sold in Thailand.

BACKGROUND: Hair dyes are known to contain potent contact allergens for which sensitization rates have increased over the last decade. OBJECTIVE: To examine the type and frequency of potent contact sensitizers labelled on hair dyes sold in metropolitan Bangkok, Thailand. METHODS: During the 2013-2014 study period, labelled ingredient information from home use and professional hair dye products was collected. RESULTS: Two hundred and fifty-two hair dye products were evaluated. One hundred and forty-nine products from 48 brands were domestically produced in Thailand, and 103 products were from 23 multinational brands produced in countries other than Thailand. Two hundred and fourteen of 252 (84.9%) hair dye products were found to contain strong skin sensitizers, with 118 (46.8%) being found in domestically produced products, and 96 (38.1%) being found in multinational brand products. Thirty-eight hair dye products (15.1%) were free of potent skin sensitizers. The number of domestically produced products (31, 20.8%) that were free of potent skin sensitizers was significantly higher (p = 0.002) than the number of multinational brand products (7, 6.8%). CONCLUSIONS: p-Phenylenediamine was the most prevalent potent sensitizer found among domestically produced hair dyes available on the market. Our findings indicate regional differences in hair dye allergen exposure.

Cosmetic preservative labelling on the Thai market.

BACKGROUND: Preservatives are added to cosmetics and other consumer products to prevent microbial growth and product degradation. Many cosmetic preservatives are skin sensitizers and frequent causes of contact dermatitis. The use of preservatives may vary by country and/or region, according to legislation, and may be reflected in differences in the prevalence rates of preservative allergy worldwide. OBJECTIVE: To examine the type and frequency of preservative use in cosmetics sold in Thai markets in metropolitan Bangkok, Thailand. METHODS: Preservatives contained in 1000 different cosmetics sold in Thai markets were documented and analysed, based on the labelling of ingredients. RESULTS: Most of the cosmetic and skincare products sold in Thai markets were international brands, with only a small proportion of cosmetic products being produced in Thailand. International brand cosmetics were more likely to contain non-formaldehyde-releasing preservatives than domestically produced brands. Isothiazolinone-based preservatives, which are responsible for the current increase in the prevalence of contact allergy, were found at a significant frequency in domestically produced, leave-on cosmetic products. CONCLUSION: Preservatives in cosmetics were significantly different according to source of production and type of cosmetics.