title: The fate of two isothiazolinone biocides, 5-chloro-2-methylisothiazol-3(2H)-one (CMI) and 2-methylisothiazol-3(2H)-one (MI), in liquid air fresheners and assessment of inhalation exposure.
abstract: There exist public concerns regarding the two most widely used isothiazolinones (5-chloro-2-methylisothiazol-3(2H)-one (CMI) and 2-methylisothiazol-3(2H)-one (MI)) in various consumer products because they cause allergic responses in dermatitis and are potentially harmful when inhaled. Hydrolysis and photolysis tests for CMI and MI at pH 4, 7, and 9 were performed to evaluate their stability. While MI did not degrade under the test conditions, CMI slightly degraded at pH 9 via hydrolysis and at pH 4 via photolysis. To better understand human exposure to MI and CMI during the use of consumer products, the vaporization rates of MI and CMI from two commercial air fresheners were quantified in a custom-made chamber. The evaporation of MI was almost negligible over 7 d, whereas a significant amount of CMI evaporated over the same period. Because the volume of air freshener decreases over time due to evaporation of water, the MI concentration in the product increased by a factor of 1.8-2.2. The air concentration of CMI was predicted using a ConsExpo model using a fixed weight fraction (model 1) and a new model that reflects changes in the concentrations of active ingredients and the product volume over time (model 2). The concentration determined using model 1 reached a steady-state value of 0.032 µg L(-1), whereas that predicted using model 2 increased consistently. Inhalation exposure was also assessed using two exposure scenarios: a room and a car. Both calculated values of margin of exposure were much higher than 300, indicating a negligible inhalation risk.
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors.forename: Seon-Kyung
authors.initials: SK
authors.lastname: Park
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea. Electronic address: junghwankwon@korea.ac.kr.
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Kwon
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004202:Disinfectants / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D006795:Household Products / Q000032:analysis*; D006801:Humans; D006868:Hydrolysis; D019570:Inhalation Exposure / Q000032:analysis*; D008962:Models, Theoretical; D010782:Photolysis; D018570:Risk Assessment; D013844:Thiazoles / Q000032:analysis*; D014835:Volatilization; D014867:Water / Q000737:chemistry
chemical_list: D004202:Disinfectants; D013844:Thiazoles; D014867:Water
keywords: Consumer products; Evaporation; Isothiazolinones; Mass transfer; Risk assessment