Usability of a spot test for isothiazolinones

Isothiazolinones Common in Children's Toy Slime

BACKGROUND

Contact dermatitis to homemade slime has been frequently reported, with isothiazolinones as a likely sensitizer. Little is known on the presence of these preservatives in commercial, store-bought slime products.

OBJECTIVES

The aims of the study were to review the literature on "slime dermatitis" and to assess for the presence of isothiazolinones in commercially available slime products and homemade slime components.

METHODS

An experimental, colorimetric spot test was used to verify the presence of isothiazolinones in 38 slime products of the 16 best-selling commercial slime kits, 1 finished homemade slime, and 4 common components of homemade slime. High-performance liquid chromatography with UV detection was performed on 8 commercial slime products.

RESULTS

According to the spot test, 27 (71%) of the 38 commercial slime products contained isothiazolinones. High-performance liquid chromatography with UV detection analyses indicated, however, that false-positives and false-negatives readily occur: isothiazolinone content was correctly identified in only 4 (50%) of the 8 samples.

CONCLUSIONS

This study is the first to demonstrate the presence of isothiazolinones in commercial slime toys. Although the colorimetric spot test may have some utility as a screening assay, it is far from specific and likely not sensitive enough to reliably identify methylisothiazolinone.

Isothiazolinone Detection in Dish Soap and Personal Care Products: Comparison of Lovibond Isothiazolinone Test Kit and Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry

BACKGROUND

Isothiazolinones are commonly used preservatives, which may cause allergic contact dermatitis. The Lovibond Isothiazolinone Test Kit (LITK) has been reported to successfully identify clinically relevant, occult isothiazolinones in patient personal care products.

OBJECTIVE

The aim of the study was to analyze dish soaps and personal care products that do not declare isothiazolinones ("no-ISO") for the presence of isothiazolinones via 2 methods: LITK and ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS).

METHODS

No-ISO dish soaps (n = 9), a convenience sample of patient products (n = 6), and controls (positive [isothiazolinone declared], n = 5; negative, n = 2) were tested with LITK (X3) and UHPLC-MS/MS.

RESULTS

Several no-ISO dish soaps and personal products were positive for isothiazolinones (LITK, n = 12; UHPLC-MS/MS, n = 3). Ultrahigh-performance liquid chromatography-tandem mass spectrometry specifically identified methylisothiazolinone alone in 1 no-ISO dish soap, methylchloroisothiazolinone in another, and both in a third. Using UHPLC-MS/MS as the criterion standard, we observed the accuracy of LITK for 9 dish soaps was poor (sensitivity, 66.7%; specificity, 20%) and very poor for 6 personal care products (sensitivity, 0%; specificity, 0%).

CONCLUSIONS

Personal products may contain undeclared isothiazolinones. The current study found that LITK had poor accuracy for testing dish soap and personal care products. Clinicians should be aware of these factors when managing patients with contact allergy to isothiazolinones.