The Oxy humidifier sterilizer scandal in South Korea caused 239 deaths and 1,528 cases of lung disease. The products containing the toxic substances PHMG and PHG were on the market for 17 years, highlighting problems with corporate ethics and risk assessment systems.
The Oxy humidifier sterilizer scandal is the worst disaster in South Korea’s history, causing 239 deaths and 1,528 lung diseases. The specific culprits were PHMG and PHG, toxic substances that are listed as pesticide ingredients in the United States. Shockingly, the toxic substances were on the market for 17 years until 2011, when the Korean Centers for Disease Control and Prevention became aware of the outbreak and began investigating. Not only were victims outraged, but so were non-victims, leading to a boycott of the company’s products. What’s even more shocking is that Oxy’s products were already commonplace in our daily lives. We had been living without realizing the toxic substances around us.
Should the public be expected to live with the presence or absence of toxic substances on the conscience of companies? Of course not. Under current law, toxic substances undergo many tests before they can be sold on the market. These tests are collectively known as risk assessments. Only products with a certain level of risk are allowed on the market. PHMG and PHG were already listed as toxic substances in the United States and had to be risk assessed before they could be used in sanitizers. In the wake of the Oxy incident, many people criticized the company for selling a toxic substance without a risk assessment. The shocking truth is that the toxic substance was risk assessed, and the conclusion was ‘no risk’.
To better understand the Oxy case, it’s important to understand the steps involved in a risk assessment. Before we do that, we need to clarify the terms “harm” and “hazard” as they are used in toxicology. The slightest difference in one letter can mean a lot.
“Excessive accumulation of heavy metals is hazardous” versus ‘excessive accumulation of heavy metals is harmful’ is a clear distinction. We all know that “hazardous” and “harmful” are toxic terms that imply danger. To understand the difference between hazard and harm, let’s take a look at their dictionary meanings. Hazard refers to the inherent dangers of a chemical, such as its toxicity, that adversely affect human health or the environment. Risk refers to the hazardousness of the situation to which a hazardous substance may be exposed.
The dictionary explanation still doesn’t quite capture the difference between the two words. Hazard refers to the degree to which the substance itself is dangerous, whereas risk refers to the degree to which human exposure to the substance is dangerous. Hazard is influenced by the toxicity of the substance itself and factors related to the exposure of the person using the substance. Factors related to the latter include the likelihood of exposure, duration of exposure, frequency of exposure, and intensity of exposure. This is why the toxicity of a substance from a human perspective is the basis for assessing its risk. No matter how hazardous the substance itself is, it will not harm humans if they are not exposed to it in their lifetime. This is why the assessment of toxicity to humans is called a risk assessment rather than a hazard assessment.
Risk assessment consists of four main steps. They are hazard identification, dose-response assessment, exposure assessment, and risk determination. Hazard identification means identifying the kinds of diseases and health effects that can occur. There are several ways to categorize toxicity, but the most common is the acute toxicity assessment. This is characterized by a toxicity metric called the LD50, which is a relative measure of the magnitude of toxicity. LD50 is the dose that kills 50% of the test group when administered to experimental animals. Acute toxicity assessments provide six levels of toxicity, ranging from ‘practically non-toxic’ to ‘extremely toxic’.
Dose-response assessment is the relationship between the exposure dose of a hazardous substance and the toxic response through animal clinical trials. Hazardous substances without a threshold at low doses are carcinogenic, while those with a threshold and toxicity at higher doses are non-carcinogenic. The distinction between non-carcinogenic and carcinogenic substances determines how the reference exposure is calculated. The third step, exposure assessment, means estimating the amount of hazardous substance to which a person is actually exposed. The effects of the location, volume, and timing of emissions, as well as the properties of the substance itself, such as mobility, degradability, and the pathway of absorption of the hazardous substance by humans, are all taken into account. Information on lifespan, body weight, and average duration of exposure are then quantified and presented to determine exposure factors. This leads to the final calculation of the chemical intake.
As you can see, risk assessment is a fairly systematic process. However, in the Oxy case, the first step in the risk assessment process, hazard identification, was problematic. SK chemicals intentionally misrepresented the toxicity of PHMB in its material safety data sheet (MSDS) dated March 6, 1997, which stated that PHMB is a hazardous substance under the Occupational Safety and Health Act and is a severe eye irritant. However, the very next day, on March 7, SK filed a patent claiming that PHMB is not regulated by the OSHA and is a mild ocular irritant. In other words, the patent misrepresented its toxicity.
The second step, dose-response evaluation, was also problematic. In this step, which involves clinical testing on animals, the results of an inhalation toxicity assessment on 15 laboratory rats were manipulated. Professor Cho Mo Cho of Seoul National University, a leading authority in the field of toxicology, was paid to analyze the data from only two rats that survived the inhalation toxicity test.
No matter how systematic a risk assessment methodology is, it is up to humans to make it work. Almost all of the problems with toxic substances are not caused by problems with risk assessments, but by humans not following them. The cost of ignoring legally mandated risk assessments in favor of self-interest has been enormous. Risk assessment is more important because it has a direct relationship with life. In particular, the nature of toxic substances is such that their effects are not immediately apparent, but often accumulate in the body. Because the effects don’t show up right away, people can be exposed for a long time without knowing exactly what caused their illness. This makes it difficult for victims to prove that the harm was caused by the product. Even if they do manage to prove the damage and receive financial compensation, they are left with a toxic body.
Even now, people live in fear that there are products on the market that are being marketed under false pretenses. In the end, human conscience and ethics cannot be entrusted with the safety of the entire population. The risk assessment system can only work if there is an institutional mechanism to control human greed and corporations. Professionals involved in risk assessment need to clarify their professional ethics, and each individual in a company needs to clarify their professional ethics. One alternative is to publish all experimental data related to the risk assessment process. This would provide transparency and ensure reliability of the assessment. The introduction of institutional mechanisms is urgently needed to ensure the proper functioning of the risk assessment system.
