Metabolite analysis of 14C-labeled chloromethylisothiazolinone/methylisothiazolinone for toxicological consideration of inhaled isothiazolinone biocides in lungs.

5-Chloro-2-methyl-4-isothiazolin-3-one (CMIT) and 2-methyl-4-isothiazolin-3-one (MIT) used as preservatives in various products, including humidifier disinfectants, presents substantial health hazards. This research delves into the toxicological assessments of CMIT/MIT in the respiratory system using animal models. Through the synthesis of radiolabeled [14C]CMIT and [14C]MIT, we investigated the biological uptake and in vivo behaviors of CMIT/MIT in the respiratory tissues following intratracheal exposure. Quantitative whole-body autoradiography (QWBA) revealed significant persistence of CMIT/MIT in lung tissue. In addition, radio high-performance liquid chromatography (radio-HPLC) with tandem mass spectrometry (LC-MS/MS) was employed for metabolite profiling and identification. Notably, around 28% of the radiolabel was retained in tissue after the extraction step, suggesting covalent binding of CMIT/MIT and their metabolites with pulmonary biomolecules. This observation demonstrates the propensity of the electrophilic isothiazolinone ring in CMIT/MIT to undergo chemical interactions with biothiols in proteins and enzymes, fostering irreversible alterations of biomolecules. Such accumulations of transformations could result in direct toxicity at both cellular and organ levels. Additionally, the detection of metabolites, including a MIT dimer conjugated with glutathione (GSH), as analyzed by mass spectrometry indicates the possible reduction of cellular GSH levels and subsequent oxidative stress. This investigation offers an in-depth insight into the toxic mechanisms of CMIT/MIT, underlying their capability to engage in complex formations with biomacromolecules and induce pronounced respiratory toxicity. These results highlight the imperative for stringent safety assessments of these chemicals, advocating for improved public health and safety measures in the use of chemicals.

Association of exposure to indoor molds and dampness with allergic diseases at water-damaged dwellings in Korea.

This study aims to characterize levels of molds, bacteria, and environmental pollutants, identify the associations between indoor mold and dampness exposures and childhood allergic diseases, including asthma, allergic rhinitis, atopic dermatitis, using three different exposure assessment tools. A total of 50 children with their parents who registered in Seoul and Gyeonggi-do in Korea participated in this study. We collated the information on demographic and housing characteristics, environmental conditions, and lifestyle factors using the Korean version of the International Study of Asthma and Allergies in Childhood questionnaire. We also collected environmental monitoring samples of airborne molds and bacteria, total volatile organic compounds, formaldehyde, and particulate matter less than 10 µm. We evaluated and determined water damage, hidden dampness, and mold growth in dwellings using an infrared (IR) thermal camera and field inspection. Univariate and multivariate regression analyses were performed to evaluate the associations between prevalent allergic diseases and exposure to indoor mold and dampness. Indoor mold and bacterial levels were related to the presence of water damage in dwellings, and the mean levels of indoor molds (93.4 ± 73.5 CFU/m3) and bacteria (221.5 ± 124.2 CFU/m3) in water-damaged homes were significantly higher than those for molds (82.0 ± 58.7 CFU/m3) and for bacteria (152.7 ± 82.1 CFU/m3) in non-damaged dwellings (p < 0.05). The crude odds ratios (ORs) of atopic dermatitis were associated with < 6th floor (OR = 3.80), and higher indoor mold (OR = 6.42) and bacterial levels (OR = 6.00). The crude ORs of allergic diseases, defined as a group of cases who ever suffered from two out of three allergic diseases, e.g., asthma and allergic rhinitis, and allergic rhinitis were also increased by 3.8 and 9.3 times as large, respectively, with water damage (+) determined by IR camera (p < 0.05). The adjusted OR of allergic rhinitis was significantly elevated by 10.4 times in the water-damaged dwellings after adjusting age, sex, and secondhand smoke. Therefore, a longitudinal study is needed to characterize dominant mold species using DNA/RNA-based sequencing techniques and identify a causal relationship between mold exposure and allergic diseases in the future.

Bioaccumulation and in vivo fate of toxic benzylalkyldimethylammonium chloride in rats via the radiotracer analysis.

Benzylalkyldimethylammonium chloride (BAC), a quaternary ammonium compound (QAC), is utilized in industrial and biomedical applications for antimicrobial purposes. Since the coronavirus disease (COVID-19) outbreak, various types of BAC-containing household chemicals have been produced. BACs have several adverse effects; however, their biological uptake, translocation, and excretion in animal models (essential for better understanding in vivo behavior and toxicological impact) remain unclear. In this study, we performed the first biodistribution and whole-body imaging studies of BAC in male Sprague Dawley rats, using two different administration routes. Quantitative whole-body autoradiography (QWBA) data obtained for intranasal 14C-labeled BAC ([14C]C12-BAC) exposure showed substantial uptake values for the respiratory organs (e.g. 346 ng g-1 of lung at 3 h post administration) and the radiotracer was transported to other internal organs. The amount of radiotracer in the heart, adrenal gland, and pancreas were 198, 1410, and 186 ng g-1 tissue respectively at 168 h following exposure. Autoradiograms obtained after intravenous injection also showed high accumulation and slow excretion in these organs. The cumulative excretion analysis revealed that approximately 6.4% of the administered radioactivity remained in rats after a week. The results indicated that continuous inhalation exposure to BAC leads to potential toxic effects in extrapulmonary organs and the respiratory tract. Thus, the radiolabeling method utilized may help assess various synthetic QACs in living subjects.

Biodistribution and respiratory toxicity of chloromethylisothiazolinone/methylisothiazolinone following intranasal and intratracheal administration.

A variety of isothiazolinone-containing small molecules have been registered and used as chemical additives in many household products. However, their biodistribution and potential harmful effects on human health, especially respiratory effects, were not yet identified in sufficient detail. The purpose of this study was to investigate whether a biocide comprising a mixture of chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) could reach the lungs and induce lung injury when exposure occurs by two administration routes involving the respiratory tract: intratracheal and intranasal instillation. To investigate the biodistribution of CMIT/MIT, we quantified the uptake of 14C-labeled CMIT/MIT in experimental animals for up to seven days after intratracheal and intranasal instillation. In the toxicity study, lung injury was assessed in mice using total inflammatory cell count in bronchoalveolar lavage fluid (BALF) and lung histopathology. The results of the biodistribution study indicated that CMIT/MIT were rapidly distributed throughout the respiratory tract. Using quantitative whole-body autoradiogram analysis, we confirmed that following intranasal exposure, CMIT/MIT reached the lungs via the respiratory tract (nose-trachea-lung). After 5 min post intratracheal and intranasal instillation, the amount of radiotracer ([14C]CMIT/MIT) in the lungs was 2720 ng g-1 and 752 ng g-1 tissue, respectively, and lung damage was observed. A higher amount of the radiotracer resulted in higher toxicity. Both intratracheal and intranasal instillation of CMIT/MIT increased inflammatory cell counts in the BALF and induced injuries in the alveoli. The frequency and the severity scores of injuries caused by intratracheal instillation were approximately-four to five times higher than those induced by intranasal instillation. Therefore, we concluded that CMIT/MIT could reach the lungs following nasal and intratracheal exposure and cause lung injuries, and the extent of injury was dependent on the exposure dose.

Multi-layer relationships between psychological symptoms and life adaptation among humidifier disinfectant survivors.

In April 2011, the Korea Centers for Disease Control and Prevention (CDC) announced the results of an epidemiological investigation that an unknown cause of lung disease that occurred throughout Korea was caused by humidifier disinfectants. The unprecedented social catastrophe caused by humidifier disinfectants, a household chemical, has so far reported 1,784 deaths and 5,984 survivors in South Korea. This study was designed to investigate the multi-layer relationships between psychological symptoms and adaptive functioning in survivors of the Humidifier disinfectants in South Korea caused by chemical toxic substances. Specifically, this study aimed to explore how psychological symptoms affect actual interpersonal relationships and job adjustment with two variable sets, six internalizing and externalizing subscales, and three adaptation subscales. A total of 224 survivors recruited from a program to support humidifier disinfectant survivors by the government participated in this study. This research was approved by the Institutional Review Board of one of the Universities in South Korea. The age range of the participants was 18-73 years (M = 42.23, SD = 10.90), 37.1% (n = 83) were male, and 62.9% (n = 141) were female. The participants responded to the Adult Self-Report (ASR) of the Achenbach System of Empirically Based Assessment (ASEBA). A Canonical Correlation Analysis (CCA) generated three unique patterns in the relationships between psychological symptoms and adaptive functions. Humidifier disinfectant survivors in the first pattern were more vulnerable to psychological symptoms and showed maladaptive functioning in life. Survivors in the second pattern showed intrusive behaviors and appeared to be adaptive in relationships with friends. Finally, survivors in the third pattern showed aggressive behaviors and reported poor partner relationships while showing good relationships with friends. The practical implications of the interventions are also discussed.

Exploring Socio-Demographic Factors Affecting Psychological Symptoms in Humidifier Disinfectant Survivors.

This study aimed to compare the psychological symptoms of humidifier disinfectant survivors to the general population and explore socio-demographic factors influencing survivors' psychological symptoms. A one-way Multivariate Analysis of Covariance (MANCOVA) and a series of two-way MANCOVA were conducted with a sample of 228 humidifier disinfectant survivors and 228 controls. The results demonstrated that the survivor group displayed higher anxious/depressed symptoms, withdrawn symptoms, somatic complaints, thought problems, attention problems, aggressive behavior and rule-breaking behavior than the general group. Moreover, among the socio-demographic factors, the two-way interaction effects of group × family economic status and group × number of friends were found to be statistically significant. The limitations and implications of this study are discussed.

Characteristics of Exposure to Chloromethylisothiazolinone (CMIT) and Methylisothiazolinone (MIT) among Humidifier Disinfectant-Associated Lung Injury (HDLI) Patients in South Korea.

This study aimed to quantify both chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) dissolved in different product brands and to characterize the exposure to these chemicals among humidifier disinfectant-associated lung injury (HDLI) patients. Both CMIT and MIT dissolved in different humidifier disinfectant (HD) products were quantified using gas chromatography-mass spectrometry. The inhalation level of CMIT and MIT was estimated based on HD-associated factors as reported by HDLI patients. A total of eleven HD products marketed until the end of 2011 were found to contain CMIT and/or MIT. The level of combined CMIT and/or MIT dissolved in these HD products ranged from 12 to 353 ppm. The level varied among HD products and the year of manufacture. The average inhalation levels were estimated to be 7.5, 4.1, and 3.2 µg/m3 for the definite, probable, and possible groups, respectively. If probable and possible groups were collapsed together, the inhalation level of the collapsed group was significantly different from that of the definite group (p < 0.001). All HDLI patients responded as having used HD not only while sleeping, but also as having a humidifier treated with HD within close proximity every day in insufficiently ventilated spaces. These HD use characteristics of patients may be directly/indirectly linked to the HDLI development.

Experimental determination of indoor air concentration of 5-chloro-2-methylisothiazol-3(2H)-one/ 2-methylisothiazol-3(2H)-one (CMIT/MIT) emitted by the use of humidifier disinfectant.

A mixture of 5-chloro-2-methylisothiazol-3(2H)-one/2-methylisothiazol-3(2H)-one (CMIT/MIT) had been used as an active ingredient in humidifier disinfectants (HDs). Owing to its high reactivity, the atmospheric concentration of CMIT/MIT, following its use in HD, would be lower than expected assuming that it is removed by ventilation only. In order to evaluate the exposure concentration of CMIT/MIT used as an HD, room-scale chamber studies were conducted under plausible use of three different HD doses at air change rates (ACR) of 0.3, 0.5, and 1.0 h-1. Atmospheric CMIT/MIT was sampled using two serial impingers containing deionized water after the attainment of steady state. Water samples in which CMIT/MIT was dissolved were concentrated using a cosolvent evaporation method with efficiencies of 35.5 and 77.9% for CMIT and MIT, respectively. The estimated air concentration, assuming that all the CMIT/MIT is absorbed in deionized water, increased linearly with increasing emission rate, but was independent of the ACR. This indicates that the removal rate of CMIT/MIT via chemical reactions is more than the removal rate by ventilation. Further investigations on homogeneous and heterogeneous chemical reactions of CMIT/MIT under ambient conditions are necessary to understand the actual exposure concentration of the mixture in HD.

Early-life exposure to humidifier disinfectant determines the prognosis of lung function in children.

BACKGROUND: Use of humidifier disinfectants (HD) at home leads to chemical airborne exposure, causing HD associated lung injury (HDLI) with high mortality. However, the lung function in children diagnosed with HDLI is not well studied. We investigated the effect of HD exposure on lung function, prognosis, and exposure characteristics associated with the lung function phenotype in children. METHODS: Eighty-one children diagnosed with HDLI in a nationwide cohort were tested for spirometry and diffusing capacity of the lung for carbon monoxide (DLco) from July 2013 and followed up with at five time points over 2 years. The results were compared with 122 children without HD exposure as controls. Home investigation and questionnaire analysis were conducted to assess HD inhalation exposure. RESULTS: HDLI survivor's mean percent of predicted forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and corrected DLco were significantly lower compared with the control group. On longitudinal assessment, FVC was within the normal range, but flattened, and spirometry showed a predominantly restrictive pattern. Corrected DLco did not normalize above 80% despite increasing age. The persistently low phenotype of lung function was associated with initial exposure age, especially less than 12 months of age. Higher density HD exposure during sleep and close distance between the bed and the humidifier were significantly associated with persistently low corrected DLco. CONCLUSIONS: HD exposure affects prolonged decrement in lung function, especially DLco, particularly among children who are exposed within the first year of life. These results suggested that early-life HD exposure determines long-term prognosis of lung function in children.

Humidifier disinfectant and use characteristics associated with lung injury in Korea.

Since around the year 2000, hundreds of people in Korea have developed humidifier disinfectant-associated lung injury (HDLI). We collected all HD exposure-related information from the field investigations into the locations in which the 1199 registered patients had used HD. Among the people who registered, 38% (1st round = 214, 2nd = 73, 3rd = 166) were confirmed as HDLI patients. Children aged under eight years old made up the highest proportion of HDLI cases (N = 279, 62%), followed by pregnant women (N = 31, 7%). One hundred thirty-three (29%) of the confirmed HDLI patients died. Fifty-seven percent of HDLI patients (N = 259) developed HDLI after <1 year of HD use. The number of HDLI patients who used only the Oxy Saksak HD brand was found to be 176 (39%), followed by the brands Cefu (N = 27, 6%) and Aekyung (N = 22, 5%). HD products containing only polyhexamethylene guanidine phosphate (PHMG-P) were the most frequently used among HDLI patients (N = 234, 52%), followed by oligo (2-(2-ethoxy)ethoxyethyl) guanidinium (PGH) (N = 27, 6%) and a mixture of chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) (N = 26, 6%). The average PHMG-P inhalation level estimated from the patient group classified as suffering lung injury definitely associated with HD use was 145.1 µg/m3 (N = 91, SD = 395.1 µg/m3 ), higher than levels estimated from both the probable and possible HDLI patient groups. In conclusion, HD exposure-related variables, including type of HD brand and estimated inhalation HD level, were associated with the risk of HDLI.

Association of high-level humidifier disinfectant exposure with lung injury in preschool children.

BACKGROUND: Children aged ≤6years reportedly account for 52% of victims of humidifier disinfectant-associated lung injuries. OBJECTIVES: To evaluate the association of humidifier disinfectants with lung injury risk among children aged ≤6years. METHODS: Patients with humidifier disinfectant-associated lung injuries (n=214) who were clinically evaluated to have a definite (n=108), probable (n=49), or possible (n=57) association with humidifier disinfectants as well as control patients (n=123) with lung injury deemed unlikely to be associated with humidifier disinfectant use were evaluated to determine factors associated with increased risk of humidifier disinfectant-associated lung injury using unconditional multiple logistic regression analysis. RESULTS: For estimated airborne humidifier disinfectant concentrations, risk of humidifier disinfectant-associated lung injury increased ≥two-fold in a dose-dependent manner in the highest quartile (Q4, 135-1443µg/m3) compared with that in the lowest quartile (Q1, ≤33µg/m3). Registered patients using more than two humidifier disinfectant brands were at an increased risk of humidifier disinfectant-associated lung injury (adjusted OR, 2.2; 95% confidence interval, 1.3-3.8) compared with those using only one brand. With respect to the duration of humidifier disinfectant use, risk of humidifier disinfectant-associated lung injury increased ≥two-fold in the lowest quartile (≤5months) compared with that in the highest quartile (≥14months; adjusted OR 0.3; 95% confidence interval, 0.2-0.6). CONCLUSIONS: Younger children are more vulnerable to HDLI when exposed to HD chemicals within short period in early life.

Types of household humidifier disinfectant and associated risk of lung injury (HDLI) in South Korea.

From 2002 through 2015, hundreds of people died of fatal lung injuries associated with the use of humidifier disinfectants (HDs) in Korea. Several chemical disinfectants used for household humidifiers were later clinically confirmed to cause HD-associated lung injury (HDLI). The aim of this study is to evaluate the registered lung disease cases and to compare the distribution of HDLI patients, including deaths, by HD use characteristics including types of HD and HD brands categorized by age group. A total of 530 registered were clinically examined through two rounds of investigations conducted from July 2013 until April 2015. Information on HD use was obtained from a structured questionnaire and home investigations. Approximately one-half of the patients (n=221) were clinically confirmed to be associated with the use of HDs. Pregnant women (n=35, 16%) and pre-school children≤6years old (n=128, 58%) accounted for most of the HD-associated lung injury patients (n=163, 74%). Sixty-seven percent of HDLI patients developed HDLI after less than one year of HD use. HD products containing polyhexamethylene guanidine phosphate (PHMG) were the most frequently used among confirmed HDLI patients (n=123, 55.7%), followed by oligo (2-(2-ethoxy) ethoxyethyl guanidinium (PGH) (n=24, 10.9%) and a mixture of chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) (n=3, 1.4%). Other HDs did not appear to be linked to HDLI. The majority of the HDLI patients (n=85, 38.5%) was found to use only Oxy Saksak® products containing PHMG. The development of HDLI was clinically found to be associated with the use of several HD products containing PHMG and PGH, and to lesser extent, CMIT/MIT.

Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment.

It has frequently been reported that exposure to artificial light at night (ALAN) may cause negative health effects, such as breast cancer, circadian phase disruption and sleep disorders. Here, we reviewed the literature assessing the effects of human exposure to ALAN in order to list the health effects of various aspects of ALAN. Several electronic databases were searched for articles, published through August 2014, related to assessing the effects of exposure to ALAN on human health; these also included the details of experiments on such exposure. A total of 85 articles were included in the review. Several observational studies showed that outdoor ALAN levels are a risk factor for breast cancer and reported that indoor light intensity and individual lighting habits were relevant to this risk. Exposure to artificial bright light during the nighttime suppresses melatonin secretion, increases sleep onset latency (SOL) and increases alertness. Circadian misalignment caused by chronic ALAN exposure may have negative effects on the psychological, cardiovascular and/or metabolic functions. ALAN also causes circadian phase disruption, which increases with longer duration of exposure and with exposure later in the evening. It has also been reported that shorter wavelengths of light preferentially disturb melatonin secretion and cause circadian phase shifts, even if the light is not bright. This literature review may be helpful to understand the health effects of ALAN exposure and suggests that it is necessary to consider various characteristics of artificial light, beyond mere intensity.

Occupational Exposure to Diesel Particulate Matter in Municipal Household Waste Workers.

OBJECTIVE: The purposes of this study were to determine the following: 1) the exposure levels of municipal household waste (MHW) workers to diesel particulate matter (DPM) using elemental carbon (EC), organic carbon (OC), total carbon (TC), black carbon (BC), and fine particulate matter (PM 2.5) as indicators; 2) the correlations among the indicators; 3) the optimal indicator for DPM; and 4) factors that influence personal exposure to DPM. METHODS: A total of 72 workers in five MHW collection companies were assessed over a period of 7 days from June to September 2014. Respirable EC/OC samples were quantified using the thermal optical transmittance method. BC and PM 2.5 were measured using real-time monitors, an aethalometer and a laser photometer. All results were statistically analyzed for occupational and environmental variables to identify the exposure determinants of DPM. RESULTS: The geometric mean of EC, OC, TC, BC and PM 2.5 concentrations were 4.8, 39.6, 44.8, 9.1 and 62.0 µg/m3, respectively. EC concentrations were significantly correlated with the concentrations of OC, TC and BC, but not with those of PM 2.5. The exposures of the MHW collectors to EC, OC, and TC were higher than those of the drivers (p<0.05). Workers of trucks meeting Euro 3 emission standard had higher exposures to EC, OC, TC and PM 2.5 than those working on Euro 4 trucks (p<0.05). Multiple regression analysis revealed that the job task, European engine emission standard, and average driving speed were the most influential factors in determining worker exposure. CONCLUSIONS: We assessed MHW workers' exposure to DPM using parallel sampling of five possible indicators. Of these five indicators, EC was shown to be the most useful indicator of DPM exposure for MHW workers, and the job task, European emission standard, and average driving speed were the main determinants of EC exposure.

Estimating Benzene Exposure Level over Time and by Industry Type through a Review of Literature on Korea.

The major purpose of this study is to construct a retrospective exposure assessment for benzene through a review of literature on Korea. Airborne benzene measurements reported in 34 articles were reviewed. A total of 15,729 individual measurements were compiled. Weighted arithmetic means [AM(w)] and their variance calculated across studies were summarized according to 5-year period intervals (prior to the 1970s through the 2010s) and industry type. Industries were classified according to Korea Standard Industrial Classification (KSIC) using information provided in the literature. We estimated quantitative retrospective exposure to benzene for each cell in the matrix through a combination of time and KSIC. Analysis of the AM(w) indicated reductions in exposure levels over time, regardless of industry, with mean levels prior to the 1980-1984 period of 50.4 ppm (n = 2,289), which dropped to 2.8 ppm (n = 305) in the 1990-1994 period, and to 0.1 ppm (n = 294) in the 1995-1999 period. There has been no improvement since the 2000s, when the AM(w) of 4.3 ppm (n = 6,211) for the 2005-2009 period and 4.5 ppm (n = 3,358) for the 2010-2013 period were estimated. A comparison by industry found no consistent patterns in the measurement results. Our estimated benzene measurements can be used to determine not only the possibility of retrospective exposure to benzene, but also to estimate the level of quantitative or semiquantitative retrospective exposure to benzene.

Blood levels of cadmium and lead in residents near abandoned metal mine areas in Korea.

We analyzed national data on blood lead levels (BLL) and blood cadmium levels (BCL) in residents living near 38 abandoned metal mining areas (n = 5,682, 18-96 years old) in Korea that were collected by the first Health Effect Surveillance for Residents in Abandoned Metal mines (HESRAM) from 2008 to 2011. The geometric mean BCL and BLL were 1.60 µg/L (95 % CI = 1.57-1.62 µg/L) and 2.87 µg/dL (95 % CI = 2.84-2.90 µg/dL), respectively, notably higher than levels in the general population in Korea and other countries. We found significantly higher BLL and BCL levels in people living within 2 km of an abandoned metal mine (n = 3,165, BCL = 1.87 µg/L, BLL = 2.91 µg/dL) compared to people living more than 2 km away (n = 2,517, BCL = 1.31 µg/L, BLL = 2.82 µg/dL; P < 0.0001) and to the general population values reported in the literature.

Polycyclic aromatic hydrocarbons exposure in residents living near a cement factory with kilns.

PURPOSE: This study was performed to investigate polycyclic aromatic hydrocarbons (PAHs) exposure in the area around a cement factory with kilns using waste, including refuse plastic fuel. METHODS: Atmospheric total suspended particulates (TSPs) for each of an exposed area and a non-exposed area were collected. Similarly, urine samples were collected from 330 subjects in the exposed area and 126 subjects in the non-exposed area. Gas chromatography with mass spectrometry was used to analyze PAHs in the collected TSP samples and the PAH metabolites, urinary 2-naphthol (2-NAP) and 1-hydroxypyrene (1-OHP), of the residents. The concentrations of urinary 2-NAP and 1-OHP were adjusted by creatinine concentrations. RESULTS: The atmospheric concentrations of PAHs, including naphthalene and pyrene, were higher in the exposed area than those in the non-exposed area. The geometric means (GMs) of the urinary 2-NAP concentrations in the exposed and non-exposed groups without work experience were 4.06 and 1.55 µg/g creatinine, respectively. The GMs of the urinary 1-OHP concentrations were 0.26 and 0.14 µg/g creatinine, respectively. The results showed that the concentrations of PAH metabolites were significantly higher in the exposed group than those in the non-exposed group (p < 0.001). Multiple linear regression analysis with the log-transformed urinary 2-NAP and 1-OHP concentrations and other variables indicated a strong correlation of residence in the exposed area and smoking with an increase in the urinary 2-NAP and 1-OHP concentrations. CONCLUSIONS: In addition to the known risk factors, this study indicated that living near a cement factory with kilns is also a risk factor for PAH exposure.

Characteristics of particulate matter generated while handling municipal household waste.

OBJECTIVES: This study was conducted to assess the size characteristics of particulate matter (PM) generated during waste collection and sorting, and to assess the effect of the type of waste-handling activity on levels of coarse and fine PM. METHODS: A portable aerosol spectrometer calibrated to 1.2 //min was used to monitor PM generated during four types of waste-handling activities. The types of PM measured included inhalable particulate matter (IPM), PM10, respirable particulate matter (RPM), PM2.5 and PM1. Twenty-eight data sets with 3,071 subsets recorded every 6 sec were categorized according to occupational and environmen¬tal classifications, including type of waste-handling activity. An ANOVA was used to compare PM levels characterized by size. Significant variables with p-values <0.25 were included in a multiple regression model for predicting levels of each PM. RESULTS: The average levels of PM10 and PM2.5 greatly exceeded the air-quality levels enforced by the Korean Ministry of the Environment. The highest PM2.5 fine-particle levels monitored were during waste-transfer work, while the highest IPM and PM10 coarse-particle levels monitored were during waste-sorting work. The type of waste-collection activity was the only factor that significantly affected both PM25 and IPM, accounting for 36% (p=0.0034) and 40% (p=0.0049), respectively, of the observed variations. None of the factors affected PM10 or RPM levels. CONCLUSIONS: Waste-collection and Waste-transfer work may be associated with the generation of high levels of fine PM, which can be influenced by environ Workmental conditions such as traffic levels and the type of waste transport vehicle.

Airborne bacteria and fungi associated with waste-handling work.

BACKGROUND: Municipal workers handling household waste are potentially exposed to a variety of toxic and pathogenic substances, in particular airborne bacteria, gram-negative bacteria (GNB), and fungi. However, relatively little is known about the conditions under which exposure is facilitated. METHODS: This study assessed levels of airborne bacteria, GNB, and fungi, and examined these in relation to the type of waste-handling activity (collection, transfer, transport, and sorting at the waste preprocessing plant), as well as a variety of other environmental and occupational factors. Airborne microorganisms were sampled using an Andersen single-stage sampler equipped with agar plates containing the appropriate nutritional medium and then cultured to determine airborne levels. Samples were taken during collection, transfer, transport, and sorting of household waste. Multiple regression analysis was used to identify environmental and occupational factors that significantly affect airborne microorganism levels during waste-handling activities. RESULTS: The "type of waste-handling activity" was the only factor that significantly affected airborne levels of bacteria and GNB, accounting for 38% (P = 0.029) and 50% (P = 0.0002) of the variation observed in bacteria and GNB levels, respectively. In terms of fungi, the type of waste-handling activity (R2 = 0.76) and whether collection had also occurred on the day prior to sampling (P < 0.0001, R2 = 0.78) explained most of the observed variation. Given that the type of waste-handling activity was significantly correlated with levels of bacteria, GNB, and fungi, we suggest that various engineering, administrative, and regulatory measures should be considered to reduce the occupational exposure to airborne microorganisms in the waste-handling industry.

An assessment of dust, endotoxin, and microorganism exposure during waste collection and sorting.

This study was conducted to assess inhalation exposure to dust, endotoxin, and microorganisms (including viable bacteria, Gram-negative bacteria [GNB], and fungi) during waste collection and sorting; to identify factors affecting this exposure; and to estimate the gastrointestinal exposure to microorganisms. A total of 48 or 49 workers involved in collecting and sorting waste from households or the street were studied. Each worker carried two personal samplers in which filters were placed in the breathing zone for estimation of inhalation exposure. To assess the possibility of gastrointestinal exposure, microorganisms on the workers' faces were collected before and after work and compared with those collected from office workers. Inhalation exposure levels were categorized according to job title, waste type handled, and working conditions and were compared using analysis of variance. Multiple regression models were developed to identify those factors that substantially affected inhalation exposure. The average exposure level to total dust was 0.9 mg/m3 (range = 0.05 to 4.51 mg/m3), and the average exposure to endotoxin was 1123 EU/m3. The average respective exposure levels to bacteria, GNB, and fungi each exceeded 10(4) colony forming units (CFU)/m3. The multiple regression models found several factors that significantly explained the variation in levels of inhalation exposure to endotoxin and microorganisms; namely, sex (dust, bacteria, and GNB), job title (GNB and fungi), collection day (dust, bacteria, and GNB), temperature (endotoxin and GNB), humidity (endotoxin and fungi), and region (endotoxin) were significantly associated with exposure to these agents. In addition, the workers' faces were highly contaminated with microorganisms. In conclusion, inhalation exposure to endotoxin and microorganisms was high during waste collection and sorting, which may place workers at risk of developing various health problems, including respiratory complaints.