Chemical Substance Exposure of Some Cleaning Workers in Korea: Focusing on Inhalation Exposure

Abstract

This study aimed to prevent health damage caused by chemical exposure among cleaning workers who use cleaning agents and disinfectants in facility management and kitchen areas. We analyzed 5 years of measurement data (2016–2020) for cleaning workers across various industries in Korea, and conducted an exposure survey and health risk assessment for the two most frequently measured substances (i.e., 2-butoxyethanol and sodium hydroxide) and representative substances generated by their combined use (i.e., chlorine and chloroform). The findings indicate that when chlorine was generated by mixing hypochlorite-based disinfectants (e.g., bleach) with acidic cleaners containing substances such as nitric, hydrochloric, or citric acid, the risk index for chlorine gas (based on the 95th percentile exposure values) was 5.65 in the facility management cleaning industry, exceeding the acceptable threshold of 1. Because of the high usage and exposure frequency of cleaning and disinfecting agents and the common practice of mixing multiple products to enhance cleaning efficacy, it is necessary to manage hazardous risk factors by providing education on appropriate working methods, supplying personal protective equipment, and installing ventilation systems for these workers. Further research on the health risk assessment of combined chemical use is needed.

1. Introduction

Cleaning workers, classified as manual laborers, are tasked with maintaining cleanliness in various types of buildings (e.g., offices, apartments, and commercial spaces) using water and detergents. They are further categorized into: building interior cleaners, who clean inside and outside buildings; hospital cleaners, who clean and organize hospitals, and; kitchen cleaners, who are responsible for washing kitchens [1]. Professional cleaning is a common occupation worldwide [2]. According to the 2019 Employment Status Survey by Job Category in South Korea, there were 916,979 manual laborers. Among the six subcategories (i.e., construction- and mining-related; manufacturing-related; transportation-related; cleaning- and security-related; agriculture-, forestry-, and fisheries-related; and household-, food-, and sales-related manual labor), the cleaning- and security-related manual labor category had the highest number of workers (i.e., 318,952) [3]. Among them, there were 201,740 cleaning and environmental sanitation workers, including 142,252 female workers, indicating a high proportion of female workers. Considering their older age and lower wages, these workers are considered to be socially vulnerable.

In Korea, chemical substances that can harm human health are regulated by laws such as the Industrial Safety and Health Act and the Chemicals Control Act. The Safety Management Act for Consumer Chemical Products and Biocides plays a crucial role in preventing the inclusion of highly hazardous substances in chemical product manufacturing processes [4]. Despite these regulations, cases of health problems among cleaning workers who use cleaning agents and disinfectants in facility management and kitchen areas have been reported. Notably, in June 2020, a young female worker with no underlying health conditions died while cleaning and disinfecting a restaurant and kitchen. The bereaved family claimed that the accident occurred because she had mixed and used cleaning agents and oven cleaners at high concentrations to enhance cleaning power. Additionally, a facility management cleaning worker in a specific region was diagnosed with idiopathic pulmonary fibrosis, raising concerns regarding the health impacts of waxing agents used in cleaning tasks. However, evidence is insufficient to establish effective preventive policies. This incident spurred social interest in the hazards and risks associated with the cleaning agents and disinfectants used in cleaning processes [5].

Depending on their tasks and workplace, cleaning workers are exposed to various hazardous factors, including numerous cleaning agents, detergents, bleaches, and disinfectants. The toxicity and risks associated with chemical substances used by cleaning workers have been well documented in numerous previous studies. These studies revealed an increased prevalence of chronic obstructive pulmonary disease due to the use of cleaning agents [6], a contribution to the incidence of asthma [7,8,9,10,11,12,13], and an increase in skin diseases [14,15,16,17,18]. Furthermore, cleaning methods have been linked to musculoskeletal disorders in the neck, shoulders, elbows, and hands [19,20,21,22]. Specifically, the risk of asthma and respiratory symptoms is associated with the use of detergent enzymes [23], common cleaning chemicals [24], and certain products containing volatile organic compounds [25]. Cleaning agents are typically complex chemical mixtures designed to provide various aesthetic (e.g., fragrance) and functional (e.g., preservatives and biocides) properties to products [26]. According to existing surveys conducted by the Korea Occupational Safety and Health Agency (KOSHA), toilet bowl cleaners used for bathroom cleaning primarily contain strong acids such as hydrochloric acid, and cleaners used for removing stubborn stains mainly contain strong alkaline substances such as sodium hypochlorite and sodium hydroxide. Glass cleaners contain the irritant isopropyl alcohol; strippers include 2-butoxyethanol and sodium hydroxide; disinfectants contain deltamethrin, cyclohexane, and acetic acid, and specific adhesive products (e.g., SCOTCH GRIP 2262) contain tetrahydrofuran [1]. The main components of cleaning agents include surfactants, acidic and alkaline substances (e.g., sodium carbonate, potassium hydroxide, phosphoric acid, and acetic acid), solvents (alcohol and glycol ethers), additives (corrosion inhibitors and fragrances), and preservatives (e.g., formaldehyde). Disinfectants used for infection prevention, germ and microorganism elimination, and surface management include ethanol, chlorine, formaldehyde, hypochlorous acid, isopropanol, and quaternary ammonium compounds. Surface treatment products (e.g., floor polishes and waxes) contain plasticizers, glycol ethers, ethanolamines, and alkali salts [27].

Acids and alkalis in cleaning agents and disinfectants can cause corrosion or irritation to eyes and skin, sensitization, and various health effects such as neurotoxicity and reproductive toxicity due to organic solvents. The primary symptoms of chemical sensitivity include autonomic nervous, neurological, psychiatric, respiratory, gastrointestinal, sensory, circulatory, immune, urogenital, and gynecological symptoms [4].

Previous studies on the chemical exposure of cleaning workers primarily focused on general cleaning by domestic helpers, hospital interior cleaning, and surface cleaning using various products [28]. However, comprehensive health impact assessments on the use of cleaning agents in general building cleaning and food service facilities are lacking.

Therefore, it is necessary to assess the exposure status of cleaning agents and disinfectants used by cleaning workers in facility management and food service industries, where the likelihood of chemical exposure that could impact health is high. Health impact studies should be conducted to better understand and mitigate these risk factors.

2. Methodology

2.1. Data Analysis

To assess the chemical exposure levels of cleaning workers, we analyzed the 5-year measurement data (2016–2020) from the KOSHA, specific to different industry sectors in Korea. The analysis focused on 16,836 data points across six industry subcategories (KSIC 10th edition: 742, 561, 851, 852, 853, and 854). An additional selection process was conducted based on the main products, processes, and workplaces to extract data that likely represent the actual cleaning tasks performed by the workers.

In this study, the selected workplaces and the number of measurements were as follows. For the building and industrial facility cleaning and control service industry (hereafter referred to as “building cleaning industry”), data from 20 workplaces with 522 measurement cases were analyzed. In the restaurant industry, data from 31 workplaces with 195 measurement cases were analyzed. For the education-related industry (including elementary, secondary, and higher education institutions, special schools, foreign schools, and alternative schools, hereafter referred to as the “education industry”), data from one workplace with four measurement cases were analyzed. A total of 721 measurement cases were analyzed.

2.2. Air Sampling and Analytical Methods

An exposure survey targeting the building cleaning of buildings and food-preparation workplaces was conducted. Sampling involved collecting 77 air samples from six workplaces for 2-butoxyethanol, sodium hydroxide, chloroform, and chlorine. The sample collection methods included both personal and area sampling techniques [29,30,31,32]. The airflow rates for each sample were set according to the guidelines for work environment measurements and analysis techniques. During the use of cleaning agents, air quality was evaluated for chloroform, chlorine, and sodium hydroxide, among other organic solvents. The analysis of the target substances adhered to the KOSHA GUIDE principles, supplemented by guidelines from OSHA and NIOSH, as well as relevant academic research (

Table 1. Analysis method, detection limit, and quantitative limit for each measured substance.

Substance	Analysis Method	* LOD	** LOQ
2-Butoxyethanol	NIOSH method 1403	0.0027 mg/sample	0.0089 mg/sample
Sodium hydroxide	OSHA analytical method 121	0.0040 mg/sample	0.0133 mg/sample
Chloroform	OSHA analytical method 121	0.0022 μg/sample	0.0071 μg/sample
Chlorine	NIOSH method 6011	0.0181 μg/sample	0.0599 μg/sample

* LOD: Limit of detection. ** LOQ: Limit of quantification.

).

2.2.1. 2-Butoxyethanol

For the exposure assessment of 2-butoxyethanol, an activated coconut cell charcoal tube (SKC 226-01, front 100 mg, back 50 mg) was connected to an individual SKC sampling pump, and samples were collected for 360 min at a flow rate of 0.03 L/min, based on NOISH Method 1403 (2003) and referring to KOSHA GUIDE (A-119-2018) [29], which refers to some of the contents of OSHA Sampling and Analytical Method #53, and the samples were analyzed using GC-FID (Agilent7890B, Agilent, Santa Clara, CA, USA).

2.2.2. Sodium Hydroxide

To sample and analyze sodium hydroxide, a 3-stage cassette (SKC 225-3-01) equipped with an MCE filter (37 mm, 0.8 μm pore) was connected to an individual SKC sampling pump, referring to the KOSHA GUIDE (A-156-2018) [30] based on the OSHA Analytical Method 121 (2018), and samples were collected twice for 15 min at a flow rate of 1.5 L/min; the samples were analyzed using ICP-OES (Optima 7300DV, Perkin Elmer, Waltham, MA, USA).

2.2.3. Chloroform

Chloroform was collected at a flow rate of 0.2 L/min for 360 min by connecting an activated coconut cell charcoal tube (SKC 226-01, front 100 mg, back 50 mg) to an individual SKC sampling pump with reference to KOSHA GUIDE (A-28-2019) [31] based on the OSHA Analytical Method 121 (2018), and the samples were analyzed using GC-FID (Agilent7890B, Agilent, Santa Clara, CA, USA).

2.2.4. Chlorine

Chlorine was collected for 360 min at a flow rate of 0.8 L/min by connecting a cassette (SKC 225-9006) consisting of a prefilter (PTFE, 0.5 μm) and a silver membrane filter (silver membrane 25 mm, 0.45 μm) to an individual SKC sampling pump, referring to the KOSHA GUIDE (A-177-2019) [32] based on the NIOSH Method 6011, and the sample was analyzed using IC-CD (Aquion2, ThermoFisher, Gangnam-gu, Seoul, Republic of Korea).

2.3. Rish Assessment

Exposure concentrations (EC) of 2-butoxyethanol and chloroform were estimated using Equation (1) [29,31] as

$$\mathrm{EC}={\displaystyle \frac{\mathrm{Wf}+\mathrm{Wb}-\mathrm{Bf}-\mathrm{Bb}}{\mathrm{V} \times \mathrm{DE}}}\times {\displaystyle \frac{24.45}{\mathrm{MW}}}$$

(1)

EC is the concentration of the analyte (ppm), Wf is the amount of the layer in front of the sample (μg), Wb is the amount of the layer behind the sample (μg), Bf is the amount of the layer in front of the blank (μg), Bb is the amount of the layer behind the blank (μg), V is the amount of air collected (L), DE is the desorption efficiency, and MW is the molecular weight.

The exposure concentration of sodium hydroxide was estimated using Equation (2) [30], as

$$\mathrm{EC}={\displaystyle \frac{\mathrm{W}-\mathrm{B}}{\mathrm{V} \times \mathrm{R}}}\times \mathrm{F}$$

(2)

EC is the concentration of the analyte (mg/m³), W is the amount of sodium detected in the sample (μg), B is the amount of sodium detected in the blank (μg), V is the volume of air sampled (L), R is the recovery rate, and F is the conversion factor (converts the amount of elemental sodium to the amount of sodium hydroxide).

The exposure concentration of chlorine was estimated using Equation (3) [32], as

$$\mathrm{EC}={\displaystyle \frac{\mathrm{W}-\mathrm{B}}{\mathrm{V}}}$$

(3)

EC is the concentration of the analyte (mg/m³), W is the ${\mathrm{Cl}}^{-}$ concentration of the sample (μg), V is the ${\mathrm{Cl}}^{-}$ concentration of the blank (μg), and V is the air sampling volume (L).

The hazard quotient (HQ) can be obtained using Equation (4), according to exposure concentration (EC) and reference concentration (RFC).

$$\mathrm{HQ}={\displaystyle \frac{\mathrm{EC}}{\mathrm{RFC}}}$$

(4)

A risk assessment was conducted for the most frequently measured substances in workplace environments (i.e., sodium hydroxide) and representative substances generated by their combined use (i.e., chlorine). This assessment was based on quantitative risk assessment techniques from the United States Environmental Protection Agency (EPA) and European Chemicals Agency (ECHA) adapted to the conditions of Korean workplaces. Standardized methods were derived from previous risk assessments of workplace exposure to chemicals conducted by KOSHA [33].

3. Results

3.1. Analysis of 5-Year Work Environment Measurement Data for Korean Cleaning Workers (2016–2020)

3.1.1. Building Cleaning Industry

An analysis of the measurement data for harmful agents in the building cleaning industry is summarized in

Table 2. Number of measurements and measurement values for each harmful factor to be measured in the building cleaning business.

Classification	Substance	No. of Measurements	Unit	** OEL	Representative Value
					* AM	† SD	‡ GM	§ GSD
Organic Compound	2-Butoxyethanol	46	ppm	20	0.042	0.083	0.112	3.565
	Isopropyl alcohol	35	ppm	200	8.405	16.79	1.128	3.553
	Ethanolamine	45	ppm	3	0.001	0.003	0.010	5.318
	Mixed organic chemicals	50	-	1	0.002	0.004	0.031	3.511
Metal	Zinc oxide	20	mg/m3	0.05	0.001	0.001	0.031	2.126
	Iron oxide	2	mg/m3	5	0.003	0.003	0.057	2.390
Acid and Alkali	Sodium hydroxide	52	mg/m3	C2	0.045	0.049	0.176	2.426
	Potassium hydroxide	18	mg/m3	C2	0.008	0.010	0.081	2.524
	Hydrogen peroxide	9	ppm	1	0.001	0.002	0.034	2.728
	Hydrochloric acid	24	ppm	1	0.012	0.020	0.076	3.160
	Nitric acid	17	ppm	2	0.003	0.007	0.029	4.054
	Sulfuric acid	9	ppm	0.2	0.017	0.029	0.088	3.176
Dust	Other mineral dust	37	mg/m3	10	1.376	1.706	0.721	2.624
	Other dust	9	mg/m3	10	0.168	0.014	0.459	1.088
	Welding fume	2	mg/m3	5	0.239	0.012	0.537	1.052
	Metal working fluids	6	mg/m3	2	0.098	0.034	0.344	1.404

* AM: Arithmetic mean. ** OEL: Occupational exposure limit. † SD: Standard deviation. ‡ GM: Geometric mean. § GSD: Geometric standard deviation.

. All the 11 analyzed substances were organic compounds. The concentration of 2-butoxyethanol was 0.042 ± 0.083 ppm, that of isopropyl alcohol was 8.405 ± 16.79 ppm, and that of ethanolamine was 0.001 ± 0.003 ppm; the other organic compounds were not detected. Acids and alkalis were detected in all nine substances at the following concentrations: sodium hydroxide—0.045 ± 0.049 mg/m³, potassium hydroxide—0.008 ± 0.010 mg/m³, hydrogen peroxide—0.001 ± 0.002 ppm, hydrochloric acid—0.012 ± 0.020 ppm, nitric acid—0.003 ± 0.007 ppm, and sulfuric acid—0.017 ± 0.029 ppm. Phosphoric, acetic, and hydrofluoric acids were not detected. All measurement points related to harmful agents from welding and metal processing (i.e., metals, dust, and metal working fluids) were found to be applicable to the building cleaning industry.

3.1.2. Restaurant Industry

The analysis of the measurement data for harmful agents in the restaurant industry is summarized in

Table 3. Number of measurements and measurement values for each harmful factor to be measured in the restaurant industry.

Classification	Substance	No. of Measurements	Unit	** OEL	Representative Value
					* AM	† SD	‡ GM	§ GSD
Acid and Alkali	Sodium h-droxide	132	mg/m3	C2	0.095	0.110	0.236	2.510
	Potassium hydroxide	33	mg/m3	C2	0.041	0.054	0.151	2.729
	Hydrogen peroxide	2	ppm	1	0.014	0.000	0.157	1.010
	Hydrochloric acid	6	ppm	1	0.008	0.016	0.060	3.391

* AM: Arithmetic mean. ** OEL: Occupational exposure limit. † SD: Standard deviation. ‡ GM: Geometric mean. § GSD: Geometric standard deviation.

. Two organic compounds were measured (i.e., 2-butoxyethanol and isopropyl alcohol), both of which were undetectable. The measured concentration of sodium hydroxide was 0.045 ± 0.049 mg/m³, that of potassium hydroxide was 0.008 ± 0.010 mg/m³, that of hydrogen peroxide was 0.001 ± 0.002 ppm, and that of hydrochloric acid was 0.012 ± 0.020 ppm. Phosphoric acid was not detected.

3.1.3. Education Industry

In the education industry, measurements were conducted for sodium hydroxide and phosphoric acid among acids and alkalis. The sodium hydroxide concentration was 0.045 ± 0.049 mg/m³ and phosphoric acid was not detected. A summary of the measurement data of harmful agents in the educational industry is presented in

Table 4. Number of measurements and measurement values for each harmful factor to be measured in the education industry.

Classification	Substance	No. of Measurements	Unit	** OEL	Representative Value
					* AM	† SD	‡ GM	§ GSD
Acid and Alkali	Sodium hydroxide	2	mg/m3	C2	0.073	0.015	0.313	1.234

* AM: Arithmetic mean. ** OEL: Occupational exposure limit. † SD: Standard deviation. ‡ GM: Geometric mean. § GSD: Geometric standard deviation.

.

3.1.4. Comparison of Measurement Values across Industries

Sodium hydroxide and phosphoric acid were measured across all industries, and 2-butoxyethanol, isopropyl alcohol, potassium hydroxide, hydrogen peroxide, and hydrochloric acid were measured in both building cleaning and restaurant industries. For substances measured at least seven times in both industries (i.e., sodium hydroxide and potassium hydroxide), comparisons were made between the industries, and between each individual industry and the overall measurements. For sodium hydroxide, significant differences in measurement values were found between the building cleaning and restaurant industries, and between the building cleaning industry and the overall data (p < 0.001). However, no significant difference was observed between the restaurant industry and overall data (p = 0.237). Similarly, for potassium hydroxide, significant differences were found between the building cleaning and restaurant industries (p = 0.002), and between the building cleaning industry and the overall data (p = 0.003), but not between the restaurant industry and the overall data (p = 0.316). For sodium hydroxide, there were 132 restaurant samples and 52 building samples. For potassium hydroxide, there were 33 restaurant samples and 18 building samples. Because the restaurant samples make up 2/3 of the total samples, the “all industries” category is highly influenced by the restaurant results, which limits the evaluation of all industries. The comparison results are shown in Figure 1.

3.2. Risk Assessment

Through an exposure survey, two substances with the highest frequency of work environment measurements (i.e., 2-butoxyethanol and sodium hydroxide) along with chlorine and chloroform (i.e., representative substances generated by their combined use) were selected as target substances for risk assessment.

3.2.1. Derivation of Toxicity Reference Values

The selection criteria for toxicity data used to derive toxicity reference values were based on the ECHA (2008) and EPA (2010) guidelines. For workplace exposure, the toxicity reference value for 2-butoxyethanol was converted from the RfC of the EPA [34] of 0.33 ppm for Korean workers (using a correction factor of 4.2) [33]. This value was higher than the exposure limit set by the Korean Ministry of Employment and Labor (10 ppm); hence, it was reasonable to use the exposure limit as the reference value.

For sodium hydroxide, the toxicity reference value was set at 2 mg/m³ based on National Research Council (NRC) recommendations and domestic exposure limits. For chloroform, IPCS (1994) reported an adverse effect concentration of 10 mg/m³ (2 ppm) in workplace environments, which was adopted as the toxicity reference value. For chlorine, the chronic inhalation MRL of 5 × 10⁻⁵ ppm proposed by the Agency for Toxic Substances and Disease Registry (ATSDR) was converted to 2.1 × 10⁻⁴ ppm for Korean workers and selected as the toxicity reference value. Reference toxicity values for each compound are listed in

Table 5. Toxicity reference values for major chemical substances.

Substance	Source	Period	Route	Route	* PED	† UF	$‡ \mathbf{U}{\mathbf{F}}_{\mathbf{C}}$ (This Study)	RfC Work (This Study)
2-Butoxyethanol	EPA RfC	Chronic	rat, mouse	inhale	3.31 ppm	- *	4.2	10 ppm
Sodium hydroxide	NRC EEL	Acute	human (worker)	inhale	2 mg/m3	-	-	2 mg/m3
Chloroform	IPCS	Chronic	human (worker)	inhale	2 ppm	-	-	2 ppm
Chlorine	ATSDR MRL	Chronic	monkey	inhale	LOAEL 0.1 ppm	30	4.2	2.1 × 10−4 ppm

* PED: Toxicity endpoint. † UF: Uncertainty factor. ‡ ${\mathrm{UF}}_{\mathrm{C}}$: Correction uncertainty factor.

.

3.2.2. Carcinogenic Risk

For 2-butoxyethanol and chloroform, there is limited evidence from animal studies and insufficient evidence applicable to humans. The EPA does not recognize the toxicity reference values for the carcinogenic risk of these substances. Therefore, it was concluded that the carcinogenic risk could not be determined for the primary chemicals in cleaning agents, detergents, disinfectants, and their combined byproducts.

3.2.3. Non-Carcinogenic Risk

Using the measured concentrations of the four substances from the exposure surveys conducted in six different industries, we derived representative concentration values and the number of measurements for each substance per industry. The weighted average concentration of each substance was calculated based on a number of measurements. For 2-butoxyethanol and chloroform, all measurements were undetectable. The measured concentrations of sodium hydroxide were as follows: across all industries—1.85 × 10⁻² ± 5.96 × 10⁻² mg/m³; building cleaning industry—1.87 × 10⁻³ ± 4.07 × 10⁻³ mg/m³; restaurant industry—0.054 ± 0.100 mg/m³. The measured chlorine concentrations were as follows: across all industries—1.94 × 10⁻⁴ ± 4.22 × 10⁻⁴ ppm; building cleaning industry—2.58 × 10⁻⁴ ± 4.74 × 10⁻⁴ ppm; restaurant industry—non-detectable. The results of the exposure surveys for each substance are summarized in

Table 6. Exposure survey results for each substance subject to risk assessment.

Substance	Workplace	Industry	RW *	N	RO **	RI ***
						Building Cleaning Business	Restaurant Industry
Sodium hydroxide	A	Building cleaning business	1.04 × 10−2	3	1.85 × 10−2 ± 5.96 × 10−2	1.87 × 10−3 ± 4.07 × 10−3	0.054 ± 0.100
	B		1.90 × 10−4	4
	C		**** N.D	4
	D		**** N.D	6
	E	Restaurant industry	0.108	4
	F		0	4
Chlorine	A	Building cleaning business	0.001	3	1.94 × 10−4 ± 4.22 × 10−4	2.58 × 10−4 ± 4.74 × 10−4	**** N.D
	B		5.00 × 10−5	2
	C		**** N.D	4
	D		**** N.D	3
	E	Restaurant industry	**** N.D	2
	F		**** N.D	2

* RW: Representative measurement values for each workplace. ** RO: Representative overall measurement value. *** RI: Representative measurement values by industry. **** N.D.: Not detected. Workplace (A–D): Building cleaning industry work environment measurement workplace. Workplace (E, F): Restaurant industry work environment measurement workplace. Unit: Sodium hydroxide (mg/m³); chlorine (ppm).

.

Combining the derived toxicity reference exposure concentrations with the exposure survey results, we calculated the risk index for the median and 95th percentile concentration to determine the acceptability. This risk was unacceptable for chlorine. Specifically, when chlorine gas was generated by mixing hypochlorite-based disinfectants (e.g., bleach) and acidic cleaners (e.g., those containing nitric, hydrochloric, or citric acid), the risk index for the building cleaning industry at the 95th percentile exposure level was 5.65, exceeding the threshold of 1 and indicating unacceptable risk. The results of the risk index calculations and acceptability assessments are summarized in

Table 7. Risk index and acceptability determination results for each substance subject to risk assessment.

Substance	Division	* CTE			95th Percentile
		All Industries	Building Cleaning Business	Restaurant Industry	ALL Industries	Building Cleaning Business	Restaurant Industry
Sodium hydroxide	Exposure value	1.85 × 10−2	1.87 × 10−3	0.054	0.135	9.85 × 10−3	0.250
	Risk index	9.28 × 10−3	9.37 × 10−4	0.027	6.76 × 10−2	4.92 × 10−3	0.125
Chlorine	Exposure value	1.94 × 10−4	2.58 × 10−4	** N.D	1.02 × 10−3	1.19 × 10−3	** N.D
	Risk index	0.92	1.23	** N.D	4.86	5.65	** N.D

Exposure value unit: sodium hydroxide (mg/m³); other harmful factors (ppm); risk index unit (unitless). * CTE: central tendency estimates. ** N.D.: Not detected.

.

4. Observations

According to a study by Kang [35] on the working conditions of cleaning service workers, there were approximately 288,000 cleaning service workers in Korea. The sex distribution was 145,000 men (50.3%) and 143,000 women (49.7%). The proportion of female cleaning service workers was higher than the overall wage worker gender ratio (men: 57.6%, women: 42.4%). The average age of cleaning service workers was 59.7 years, which was higher than that of wage workers (40.8 years). Additionally, the average tenure of cleaning service workers was 2.9 years, which was lower than the overall average tenure of wage workers (5.4 years).

Approximately 66.3% of cleaning workers had an education level of middle school or below. This was significantly lower than the overall proportion of wage workers with the same educational level (15.2%). This indicates that the education level of cleaning service workers was notably lower than that of wage workers. Regarding the primary reasons for employment among cleaning workers, the “immediate need for income, such as living expenses” was the most common reason, cited by 57.3% of the respondents. This was followed by “satisfaction with working conditions (wages and working hours)” (20.5%) and “because it is a stable job” (11.2%). These findings suggest that cleaning workers considered their jobs a means of livelihood rather than desirable employment [35].

According to the classification of occupational injuries by sex and disease, the majority of cases involved injuries and poisoning, accounting for 78.7% of cases in men and 81.0% in women. The next most common category was musculoskeletal disorders, accounting for 7.6% of males and 9.6% of females. The most frequent types of occupational injuries were slips, which accounted for 37.8% of the cases, followed by falls (12.6%) and work-related diseases, including cerebrovascular and cardiovascular diseases (8.2%). Traffic accidents accounted for 5.6% of cases [20].

Cleaning workers frequently use chemical substances such as cleaning agents and disinfectants. According to Gapany-Gapanavicius et al. [36], mixing cleaning agents containing 10% hydrochloric acid with bleach-based disinfectants containing 5% NaOCl in a household setting can lead to respiratory issues. The authors reported that mixing these two substances for household cleaning purposes resulted in symptoms such as coughing, breathing difficulties, and irritation of the eyes and upper respiratory tract. This highlights the risks associated with the mixing of cleaning agents and the importance of effective ventilation during household cleaning.

In addition, throughout this study, he working environment, exposure to harmful agents, health status, and working conditions of cleaning workers were assessed using worker and manager questionnaires. The types and amounts of cleaning agents and disinfectants used were also investigated. A total of 100 cleaning agents were classified and manufacturers were requested to provide material safety data sheets to identify the ingredients of each product. Additional information was collected through online research. As a result, 21 substances with established exposure limits were identified, along with 12 substances that were subject to control. Additionally, 12 substances were measured at the workplace (i.e., monoethanolamine, 2-butoxyethanol, diethanolamine, sodium hydroxide, potassium hydroxide, ammonia, ethanolamine, hydrochloric acid, isopropyl alcohol, phosphoric acid, nitric acid, and xylene). Five substances required specific health examinations (i.e., 2-butoxyethanol, hydrochloric acid, isopropyl alcohol, nitric acid, and xylene) and two substances were recognized as carcinogens by the Ministry of Employment and Labor (i.e., 2-butoxyethanol and diethanolamine).

An inventory list was compiled and analyzed to identify the substances with respiratory effects in the products, which revealed that of the 100 products, 46 contained substances that affected the respiratory system. Examination of the ingredients and their hazards in the products used in the exposure survey revealed that the most frequently present substances were those causing severe eye damage/eye irritation, skin corrosion/skin irritation, and specific target organ toxicity (single exposure): Category 3 (respiratory tract irritation).

A risk assessment was conducted for the most common substances found in cleaning agents and disinfectants (i.e., sodium hydroxide) and the representative substances generated by their combined use (i.e., chlorine). This assessment revealed that chlorine posed an unacceptable level of risk. Chlorine gas can be generated when hypochlorite-based disinfectants such as bleach are mixed with acidic cleaners containing substances such as nitric, hydrochloric, or citric acid. Based on the 95th percentile exposure values, the risk index for chlorine gas in the building cleaning industry was 5.65, exceeding the threshold of 1 and indicating an unacceptable level of risk.

Domestic and international literature reviews have been conducted on the use of cleaning agents and disinfectants to understand the health impacts. Additionally, a work environment measurement survey and focus group interviews were conducted with facility management cleaning workers and kitchen staff to assess the health impacts. The findings indicate that cleaning workers typically earned relatively low wages and were older, and there was a higher proportion of women than men. The most commonly used product was bleach, which causes eye irritation, skin irritation from contact, respiratory symptoms (e.g., throat irritation and pain), and potentially asthma. Musculoskeletal disorders including wrist tendinitis, carpal tunnel syndrome, herniated discs, and knee arthritis were also prevalent. Wrist disorders were particularly common during washing tasks involving the handling of trays and containers.

Recent studies have been conducted on aircraft cleaning workers. The primary insecticide components identified during aircraft cleaning were permethrin and decamethrin. Worker exposure to permethrin was assessed using the ECETOC TRA (targeted risk assessment) tool, which utilizes toxicity values and various parameters. The derived no-effect level for human exposure to permethrin was 0.04 mg/m³ for inhalation (8 h) and 0.05 mg/kg per day for oral intake. The risk assessment for this substance revealed that the dermal and inhalation risks as well as the overall risk were approximately 33–41 times higher than safe exposure levels across all exposure routes. This indicates a significant risk of permethrin exposure among aircraft cleaning workers [37].

According to the study by Park et al. [38] on exposure assessment and work environment management for aircraft cleaning workers, the evaluation of five disinfectant and insecticide components (i.e., ethylenediaminetetraacetic acid, 1-methyl-2-pyrrolidone, pyrethrum, deltamethrin, and permethrin) showed that all were non-detectable (99 cases for ethylenediaminetetraacetic acid and 1-methyl-2-pyrrolidone, 41 cases for pyrethrum, 13 cases for deltamethrin, and 30 cases for permethrin). The cleaning agents included: ethylbenzene, xylene, benzene, toluene, ethanol (106 cases), and propylene glycol (11 cases). Benzene (exposure limit of 0.5 ppm) and propylene glycol were consistently undetectable. Ethanol (exposure limit of 1000 ppm) had a maximum concentration of 0.53 ppm, ethylbenzene (exposure limit of 100 ppm) had a maximum concentration of 0.085 ppm, toluene (exposure limit of 50 ppm) had a maximum concentration of 0.69 ppm, and xylene (exposure limit of 100 ppm) had a maximum concentration of 0.49 ppm. All measured values were <5% of the respective exposure limits.

Charles et al. [15] investigated the health impacts of cleaning workers by reviewing epidemiological studies from 1981 to 2005. Among the 35 studies examined (excluding case studies), the most frequent focus was respiratory diseases (17 studies). This was followed by studies on skin diseases (nine studies), musculoskeletal disorders (five studies), infections (three studies), and mental disorders (one study). Respiratory (e.g., asthma and reactive airway dysfunction syndrome) and skin diseases (including eczema, dermatitis, allergies, red and rough skin, itching, cracked skin, blisters, systemic reactions, and hypersensitivity) are primarily associated with the use of detergents, water, and rubber latex. Musculoskeletal disorders are linked to physical (e.g., awkward postures and prolonged standing) and psychological stressors (e.g., monotonous work and low promotion opportunities). Infections were mainly observed in hospital cleaning workers and were associated with broken glass in trashcans and uncapped needles. Mental disorders were associated with psychological stress and social stigma.

Vizcaya et al. [7] conducted a study on respiratory symptoms, history of asthma, workplace conditions, cleaning product use, and acute inhalation incidents using self-administered questionnaires. This study included 917 employees of 37 cleaning companies in Barcelona, and found that hydrochloric acid use was closely associated with asthma. The use of ammonia, degreasers, multipurpose products, and waxes has also been associated with asthma. Working in environments with high disinfection demands, stringent cleaning standards, and the use of cleaning products containing respiratory irritants increased the risk of asthma symptoms. This indicated that irritants played a significant role in cleaning-related asthma.

Dumas et al. [8] investigated the association between asthma and occupational exposure to cleaning products among hospital workers by referencing 179 hospital employees and 545 individuals in a French epidemiological study. The study found that 55% of male workers and 81% of female workers were exposed to cleaning and disinfection tasks weekly, with significant exposure to high-intensity ammonia. Among them, a subset of female workers showed a correlation with asthma. This study also identified risks associated with chlorine exposure, which can cause airway irritation and other respiratory issues.

In Korea, chemical substances that can harm human health are regulated by laws such as the Industrial Safety and Health Act and the Chemicals Control Act. The Safety Management Act for Consumer Chemical Products and Biocides plays a crucial role in preventing the inclusion of highly hazardous substances in chemical product manufacturing processes. However, cases of health damage among facility management and kitchen cleaning workers owing to the use of cleaning agents and disinfectants have also been reported. Recently, an incident occurred in which a young female worker with no underlying health conditions died while performing cleaning and disinfection tasks in restaurants and kitchens. This has raised concerns regarding the hazards and risks of the disinfectants and detergents used during cleaning operations. The present study identified temporary irritant risks associated with chlorine generation from cleaning agents and disinfectants. Further research is required to comprehensively understand the potentially fatal outcomes related to the use of cleaning agents and disinfectants by cleaning workers.

5. Conclusions

In this study, we analyzed 5 years’ worth of measurement data (2016–2020) from cleaning workers across various industries in Korea. We conducted a work environment measurement survey for the facility management of cleaning and kitchen cleaning workers. Based on the preliminary survey results, we performed a risk assessment of the most commonly found substances in cleaning agents (i.e., sodium hydroxide) and representative substances generated by their combined use (i.e., chlorine). The findings indicate that chlorine gas can be generated when bleach-based disinfectants (e.g., those containing hypochlorous acid) are mixed with acidic cleaners containing substances such as nitric, hydrochloric, and citric acid. Using the 95th percentile exposure values as a reference, the risk index for chlorine gas in the building cleaning industry was found to be 5.65, exceeding the threshold of 1 and indicating an unacceptable level of risk.

Research on occupations that use cleaning agents has primarily focused on hospitals and domestic cleaning. Epidemiological studies have predominantly focused on specific diseases (i.e., respiratory diseases, asthma, and skin diseases). In this study, we investigated the ingredients of cleaning agents and work patterns of general building and kitchen cleaning workers. We conducted a work environment survey and focus group interviews to assess the health impacts. The findings reveal that many cleaning agents contained substances that affect the respiratory system and cause eye damage/irritation and skin corrosion/irritation. There was also inadequate education and management regarding the storage and use of these cleaning agents. Moreover, cleaning workers typically earn low wages, are older, and comprise a high proportion of women. Most cleaning workers use cleaning agents and disinfectants such as bleach, the use of which often results in symptoms such as eye irritation, itchy skin from contact, respiratory symptoms (throat irritation and pain), and asthma.

Cleaning workers use cleaning products in much larger quantities and for longer periods than typical homemakers. Because of the nature of their work, which often involves short, intensive cleaning sessions, the stricter regulation of the chemical substances present in these products is needed to prevent occupational diseases. It is essential to manage hazardous risk factors in the workplace by educating workers, installing ventilation systems, and supplying personal protective equipment. Additionally, further research is needed to assess the risks associated not only with individual chemicals but also with the combined use of multiple chemicals contained in cleaning agents.