Among the HD chemicals used, polyhexamethylene guanidine phosphate (PHMG) led in causing the household humidifier disinfectant poisoning tragedy (HHDT), followed by those containing oligo(2-(2-ethoxy)ethoxyethyl guanidinium (PGH), a mixture of methylchloroisothiazolinone (CMIT) and methylisothiazolinone (MIT), and benzalkonium chloride (BKC).2 PHMG was the leading cause of this HHDT, accounting for the majority of victims (n = 5,810) (PHMG brand users only; 48%, PHMG and other HD brand users; 100%).2

The purpose of this brief communication is to identify any neglect of KME’s legal obligations or failure of the Korea Disease Control and Prevention Agency’s (KDCPA) surveillance system to detect HD poisoning cases accumulated each year until 2011.

We examined government failures in the prevention and monitoring of chemical poisoning related to the HHDT in the following two categories. First, we reviewed the key points on HD risk prevention in the Toxic Chemicals Control Act (TCCA) under KME, which was enacted in 1991 and repealed in 2013. Second, we identified the government’s failure to update items that are commonly regulated or otherwise controlled in other countries for chemical risk prevention and chemical poisoning surveillance through a brief review of regulatory acts and documentation. The industry’s compliance with its legal obligations regarding the manufacture and marketing of raw HD chemicals or HD products is not reviewed.

In December 1996, a company submitted PHMG as an antimicrobial agent for use in carpets with documentations supporting the case for its polymer exemption under the TCCA (Table 1). In 1997, KME classified PHMG as non-hazardous and exempted it from hazard assessment based solely on these documents by a company (Table 2). This study briefly discusses several failures to take the necessary steps to protect the public from HD poisoning, which can be considered a dereliction of government duty.

Firstly, it appears that the KME did not fulfill its legal responsibilities to conduct a substantive technical review of the PHMG documentation submitted by the company to verify the accuracy of the information provided and to ensure compliance with the polymer exemption criteria (Tables 1 and 2). At that time, the enforcement decree of the TCCA required the chemical technical review team to assess the hazards of chemicals and the analytical results submitted by industry, as well as to conduct a comprehensive literature review for toxicity evaluation as part of the legal review process.4 This technical review was intended to certify the analytical results submitted by companies and to assess related domestic and foreign information, as outlined in Items 1, 2 and 3 of Article 7 of the Enforcement Decree of the TCCA.56 In the 1990s, under the Toxic Substances Control Act (TSCA), the US EPA chemical approval process required companies to submit a Pre-Manufacture Notification, followed by inspections, risk assessments and possible restrictions or bans on polymers that pose significant risks.7

If the KME had conducted a thorough technical review of the PHMG-related documentation, including a field investigation and re-analysis that the company submitted as required under the TCCA, the tragedy caused by PHMG could have been prevented to some extent.

Second, when the regulatory elements of the polymer exemption criteria were updated around 1993, the KME failed to introduce the exclusion of cationic polymers such as PHMG and PGH, which were being broadly regulated in other countries at the time. Not only can cationic polymers pose health risks such as skin and respiratory irritation, systemic toxicity, and potential damage to internal organs,8 ^, 9 their reactive nature can bind to negatively charged surfaces of aquatic organisms and disrupt their biological functions. PHMG and PGH contain positively charged guanidine groups that are cationic or soluble in water and cannot be exempted or otherwise classified as non-hazardous,10 even if they have a molecular weight greater than 1,000 g/mol.

Third the TCCA failed to include a provision requiring industry to submit updated hazard assessments when changing the use of a chemical after its initial approval, which is a conventional requirement in other countries throughout its enforcement period from 1991 to 2013. First approved in 1996 for use as an antimicrobial chemical in carpets, PHMG was freely allowed to be used as a HD without any need for a hazard assessment. There is no documentation of when and how PHMG was used as a chemical disinfectant in HD products since it was originally approved as a carpet disinfectant in 1995. By 1996, both the US11 and the European Union12 had introduced regulations requiring industry to submit updated hazard assessments when the use of a chemical was changed after its initial approval.

Finally, there was a severe deficiency in the national capacity for putting into place a poison control system with early sentinel case and epidemic detection, public warning, and toxicovigilance capabilities. Significant deficiencies and a lack of chemical poisoning surveillance systems help explain the inadequate response of the South Korean government to the HHDT for the nearly 17 years leading up to the end of 2011, resulting in the persistent accumulation of thousands of HD poisoning cases. Park et al.13 analyzed the role of nine Korean government organizations with at least a partial role in chemical poisoning detection during the period of widespread use of HD biocides and concluded that those agencies failed to contribute to the detection and prevention of the HHDT that had been growing in severity for over a decade.

A key strength of this short communication is its ability to highlight the critical need for regular updating of chemicals legislation to bring it into line with international standards, thereby reducing the health risks associated with chemicals.

In conclusion, the thousands of fatal and non-fatal cases of HD poisoning are directly linked to the failure of the authorities to fulfil their legal obligations to monitor the increasing incidence of HD chemical poisoning from the early 2000s to 2011.