{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T07:18:57Z","timestamp":1773213537294,"version":"3.50.1"},"reference-count":30,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2021,7,26]],"date-time":"2021-07-26T00:00:00Z","timestamp":1627257600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Special Commission on Social Disaster Investigation","award":["12198215600"],"award-info":[{"award-number":["12198215600"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>(1) Background: Household humidifier disinfectant (HD) brands containing polyhexamethylene guanidine (PHMG) have been found to cause the most HD-associated lung injuries (HDLIs) in the Republic of Korea. Nevertheless, no study has attempted to characterize the potential association of the health effects, including HDLI, with the physicochemical properties of PHMG dissolved in different HD brands. This study aimed to characterize the molecular weight (MW) distribution, the number-average molecular weight (Mn), the weight-average molecular weight (Mw), and the structural types of PHMG used in HD products. (2) Methods: Quantitative measurements were made using matrix-assisted laser desorption\/ionization\u2013time-of-flight mass spectrometry (MALDI-TOF MS). The Mn, Mw, and MW distributions were compared among various HD products. (3) Results: The mean Mn and Mw were 542.4 g\/mol (range: 403.0\u2013692.2 g\/mol) and 560.7 g\/mol (range: 424.0\u2013714.70 g\/mol), respectively. The degree of PHMG oligomerization ranged from 3 to 7. The MW distribution of PHMG indicated oligomeric compounds regardless of the HD brands. (4) Conclusions: Based on the molecular weight distribution, the average molecular weight of PHMG, and the degree of polymerization, the PHMG collected from HDLI victims could be regarded as an oligomer. PHMG, as used in household humidifiers, should not be exempted from toxic chemical registration as a polymer. Further study is necessary to examine the association of PHMG oligomeric compounds and respiratory health effects, including HDLI.<\/jats:p>","DOI":"10.3390\/molecules26154490","type":"journal-article","created":{"date-parts":[[2021,7,26]],"date-time":"2021-07-26T04:19:30Z","timestamp":1627273170000},"page":"4490","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Characteristics of the Molecular Weight of Polyhexamethylene Guanidine (PHMG) Used as a Household Humidifier Disinfectant"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3847-7392","authenticated-orcid":false,"given":"Dong-Uk","family":"Park","sequence":"first","affiliation":[{"name":"Department of Environmental Health, Korea National Open University, Seoul 03087, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kee Won","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Sogang University, Seoul 04107, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiwon","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Environmental Health, Korea National Open University, Seoul 03087, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ju-Hyun","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Statistics, Dongguk University, Seoul 04620, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"So-Yeon","family":"Lee","sequence":"additional","affiliation":[{"name":"Humidifier Disinfectant Health Center, Department of Pediatrics, Asan Medical Center, College of Medicine, University of Ulsan, Seoul 05505, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2821-070X","authenticated-orcid":false,"given":"Kyung Ehi","family":"Zoh","sequence":"additional","affiliation":[{"name":"Department of Environmental Health Sciences, Graduate School of Public Health, Seoul National University, Seoul 08826, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6341-7562","authenticated-orcid":false,"given":"Jung-Hwan","family":"Kwon","sequence":"additional","affiliation":[{"name":"Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Soyoung","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, School of Medicine, Sungkyunkwan University, Seoul 03181, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7919-0393","authenticated-orcid":false,"given":"Han Bin","family":"Oh","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Sogang University, Seoul 04107, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Yang, H.-J., Kim, H.-J., Yu, J., Lee, E., Jung, Y.-H., Kim, H.-Y., Seo, J.-H., Kwon, G.-Y., Park, J.-H., and Gwack, J. 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