Characteristics of the molecular weight of polyhexamethylene guanidine (PHMG) used as a household humidifier disinfectant

Dong Uk Park, Kee Won Yang, Jiwon Kim, Ju Hyun Park, So Yeon Lee, Kyung Ehi Zoh, Jung Hwan Kwon, Soyoung Park, Han Bin Oh

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


(1) Background: Household humidifier disinfectant (HD) brands containing polyhexam-ethylene 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–time-of-flight mass spectrometry (MALDI-TOF MS). The Mn, Mw, and MW distributions were compared among various HD products. (3) Re-sults: The mean Mn and Mw were 542.4 g/mol (range: 403.0–692.2 g/mol) and 560.7 g/mol (range: 424.0–714.70 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.

Original languageEnglish
Article number4490
Issue number15
Publication statusPublished - 2021 Aug 1

Bibliographical note

Funding Information:
Funding: This research was funded by the Special Commission on Social Disaster Investigation (grant no. 12198215600) and the Korea Environment Industry & Technology Institute (KEITI) through the Technology Development Project for Safety Management of Household Chemical Products Program, funded by the Korea Ministry of Environment (MOE) (2020002970001).

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Humidifier-disinfectant-associated lung injury (HDLI)
  • Molecular mass
  • Number-average molecular weight (M)
  • Oligomer
  • Polyhexamethylene guanidine (PHMG)
  • Polymerization
  • Weight-average molecular weight (M)

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery
  • Physical and Theoretical Chemistry
  • Organic Chemistry


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