Characteristics of Exposure to Chloromethylisothiazolinone (CMIT) and Methylisothiazolinone (MIT) among Humidifier Disinfectant-Associated Lung Injury (HDLI) Patients in South Korea.

Dong-Uk Park,Ju-Hyun Park,Seung-Hun Ryu,Jung-Hwan Kwon,Jiwon Kim,Seon-Kyung Park,Han Bin Oh,Sungkyoon Kim,Kyung Ehi Zoh,So-Yeon Lee,Jihoon Park,Soyoung Park

doi:10.3390/molecules25225284

Abstract

This study aimed to quantify both chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) dissolved in different product brands and to characterize the exposure to these chemicals among humidifier disinfectant-associated lung injury (HDLI) patients. Both CMIT and MIT dissolved in different humidifier disinfectant (HD) products were quantified using gas chromatography–mass spectrometry. The inhalation level of CMIT and MIT was estimated based on HD-associated factors as reported by HDLI patients. A total of eleven HD products marketed until the end of 2011 were found to contain CMIT and/or MIT. The level of combined CMIT and/or MIT dissolved in these HD products ranged from 12 to 353 ppm. The level varied among HD products and the year of manufacture. The average inhalation levels were estimated to be 7.5, 4.1, and 3.2 μg/m3 for the definite, probable, and possible groups, respectively. If probable and possible groups were collapsed together, the inhalation level of the collapsed group was significantly different from that of the definite group (p < 0.001). All HDLI patients responded as having used HD not only while sleeping, but also as having a humidifier treated with HD within close proximity every day in insufficiently ventilated spaces. These HD use characteristics of patients may be directly/indirectly linked to the HDLI development.

Highlights

A number of studies have demonstrated that chemicals added to a household humidifier as a disinfectant to suppress microbial growth have caused fatal lung injury, including interstitial pneumonitis and widespread lung fibrosis in children, pregnant women, and even adults
A total of 453 (38%) among the 1199 people who registered with the HLIIDC program from 2013 to 2017 were clinically evaluated as to whether their lung injury was associated with the use of humidifier disinfectant (HD)
Cases related to HD containing only a mixture of CMIT and MIT (n = 26) was obtained from only people who registered with the HLIIDC program before the end of 2017 (n = 1199)

Summary

Introduction

A number of studies have demonstrated that chemicals added to a household humidifier as a disinfectant to suppress microbial growth have caused fatal lung injury, including interstitial pneumonitis and widespread lung fibrosis in children, pregnant women, and even adults. These specific lung injuries have been collectively named humidifier disinfectant-associated lung injury (HDLI) [1,2,3]. The use of a CMIT/MIT mixture is currently banned in Korea for cosmetics, except for rinse-off products with a permitted concentration of up to 0.0015% [16] These chemicals were first used as disinfectants in household humidifiers in South Korea. Lung injury patients have been reported among people who used HD

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