Review of Inhalation Health Risks Involving Chloromethylisothiazolinone (CMIT) and Methylisothiazolinone (MIT) Used as Disinfectants in Household Humidifiers

Abstract

The association between lung injury and exposure to humidifier disinfectant (HD) containing a mixture of chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) has been controversial in South Korea. This study conducts a literature review in order to evaluate the likelihood of CMIT/MIT reaching the lower part of the respiratory tract and causing lung injury. A literature review focused on the inhalation risk of HD containing a mixture of CMIT and MIT. The major contents included the physicochemical properties of CMIT and MIT contained in HDs and methodological reviews on substance analysis, toxicity tests and clinical cases. HD products marketed in South Korea have been reported to contain approximately 1–2% CMIT and 0.2–0.6% MIT along with magnesium nitrate (20–25%), magnesium chloride (0.2–1.0%), and water (70–75%). The types of CMIT and MIT dispersed into the air and deposited in the respiratory tract are assumed to be either gaseous substances or nanoparticles mixed with magnesium salts. The result of the literature review including clinical cases of lung injury among CMIT/MIT HD product users, demonstrated that these chemicals likely reach the lower respiratory tract and accordingly cause lung injury. A number of humidifier disinfectant-associated lung injury cases with clinical evidence should be prioritized in risk assessment of HD containing CMIT and MIT, even though there might be insufficient evidence in all related areas, including inhalation exposure assessment studies, animal testing, and epidemiological studies.

Alveoli‐Like Multifunctional Scaffolds for Optical and Electrochemical In Situ Monitoring of Cellular Responses from Type II Pneumocytes

“…Due to this, the alveoli are easily exposed to potentially hazardous materials and air pollution. Alveolar diseases are caused by the inhalation of noxious chemical components, such as cigarette smoke, [ 1 ] humidifier disinfectants, [ 2 ] and airborne microplastics. [ 3 ] As lower respiratory tract infections, chronic obstructive pulmonary disease, lung cancer, and tuberculosis are among the ten most common causes of death worldwide.…”

Effects of stabilizer magnesium nirate on CMIT/MIT-induced respiratory toxicity

“…Chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT), which are major components of HDs, are associated with fatal health effects such as lung injury [ 2 ]. Patients who were exposed to only a CMIT/MIT-containing HD product showed progressive respiratory difficulty, similar to humidifier disinfectant-associated lung injury (HDLI) caused by exposure to polyhexamethylene guanidine phosphate (PHMG-P) or oligo(2-(2-ethoxy)ethoxyethyl guanidinium chloride (PGH) [ 3 ]. Commercial products of CMIT/MIT are a 3:1 ratio mixture and have been widely used in water-based industrial products and cosmetics as preservatives.…”

“…Commercial products of CMIT/MIT are a 3:1 ratio mixture and have been widely used in water-based industrial products and cosmetics as preservatives. Until now, various types of isothiazolinone-containing products have been registered and used as chemical additives in shampoos, hair rinses, disposable hand disinfectants, cosmetics, and many more products [ 3 , 4 ] (see also United States Environmental Protection Agency, USEPA 1998). Despite the safety concerns becoming much essential with the frequent usage of various types of isothiazolinone-containing products, the potentially harmful effects on human health, especially respiratory effects, were not yet identified in sufficient detail.…”

“…CMIT/MIT does not exist alone in HD products but is mixed with a significant amount of magnesium nitrate (22.6%), which is added as a stabilizer [ 3 ]. Magnesium nitrate is commonly used as a laboratory chemical, intermediate, and fertilizer.…”

Mechanism of 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) in controlling microbial problems in aircraft fuel systems

“… 17 Since organic compounds containing sulfur, nitrogen, oxygen, un-saturated bonds and aromatic planar cycles are considered effective corrosion inhibitors, 18 while their synthetic raw materials are inexpensive, the synthesis process is relatively mature, and safety is somewhat guaranteed. 19 Therefore, this topic is of some significance for research.…”