Yong-Hwa Kim

Nationwide Study of Humidifier Disinfectant Lung Injury in South Korea, 1994-2011. Incidence and Dose-Response Relationships.

RATIONALE Humidifier disinfectant lung injury is an acute lung disease attributed to recurrent inhalation of certain disinfectant aerosols emitted from room humidifiers. An outbreak of this toxic lung injury occurred in South Korea from 1995 until all humidifier disinfectant products were recalled from the consumer market by the government in 2011. OBJECTIVES A nationwide study was conducted to ascertain and classify all potential cases of humidifier disinfectant lung injury in Korea and to assess dose-response relationships. METHODS By several mechanisms, clinicians and the general public were invited to report all suspected cases of humidifier disinfectant lung injury to public health officials in South Korea. A committee was convened to define diagnostic criteria based on pathologic, radiologic, and clinical findings for index cases, combined with assessment of environmental exposure to humidifier disinfectants. Clinical review and environmental assessments were performed and later combined to determine overall likelihood of disease for each study participant, classified as definite, probable, possible, or unlikely. Survival time from exposure to onset of symptoms was analyzed to assess dose-response relationships. Three broad categories of risk factors were examined: (1) biological susceptibility, (2) temporal cycle of exposure and recovery, and (3) spatial conditions and density of disinfectant. MEASUREMENTS AND MAIN RESULTS Of 374 possible cases identified and reviewed, 329 were unanimously classified by the diagnostic committee, as follows: 117 definite, 34 probable, 38 possible and 140 unlikely cases. A total of 62 individuals with definite or probable disease died. Risk factors examined for polyhexamethyleneguanidine phosphate exposure that were found to be significant in shortening survival included age 4 years or younger at onset, use of disinfectant for 7 days per week, airborne density of 800 μg/m(3) or more of disinfectant, and daily exposure 11 or more hours in duration. CONCLUSIONS Dose-response analysis indicated that development of humidifier disinfectant lung injury and death were associated strongly with recurrent, intense, acute exposure without sufficient recovery time between exposures, more so than long-term cumulative exposure. These findings may explain some reversible or clinically unapparent cases among coexposed family members.

Ecological health and causal assessment of fish communities experiencing multiple stressors in Gap Stream, South Korea

Habitat evaluation, water chemistry, fish community data, and a chemical exposure biomarker were used to evaluate the effects of multiple stressors on fish community structure and identify the probable cause(s) of fish community degradation in the Gap Stream, South Korea during May-October 2000. Downstream of a wastewater outfall, there was a decline in the Index of Biotic Integrity of the fish community due to a decrease in the number of native species, an increase in the percentage of tolerant species, and an increase in external deformities and lesions. Five candidate causes of fish community degradation were identified including habitat alteration, chemicals including metals and polycyclic aromatic hydrocarbons (PAHs), low dissolved oxygen, and nutrient enrichment. The results of our causal analysis suggest that chemical contamination, habitat alteration, and nutrient enrichment were the principal probable causes responsible for the degradation of the fish community in the Gap Stream below the municipal wastewater treatment plant.

Development and Evaluation of an aquatic ecological risk assessment system (KORECORisk) for the management of industrial complexes

ABSTRACT KORea ECOlogical Risk assessment (KORECORisk) was developed to support decision making for the ecological risk-based management of chemicals in industrial complexes in South Korea. The system is based on a geographical information system and consists of a release rate estimation module, an exposure estimation module, and an ecological risk assessment module. For release rate and exposure estimation, the chemical use data from the national chemical inventory database and a dynamic multimedia fate model, respectively, were used. The ecological risk was assessed by calculating the risk quotient. A case study was presented to demonstrate an application of KORECORisk to setting a risk-based priority among the 6 major industrial complexes or among the chemicals used in the individual industrial complexes. Furthermore, a more detailed assessment was performed to demonstrate and evaluate a potential use of KORECORisk for the management of individual complexes. With 3 phthalates (1,2-benzenedicarboxylic acid dibutyl ester; 1,2-benzenedicarboxylic acid dimethyl ester; and 1,2-dibenzenedicarboxylic acid dioctyl ester) as model chemicals, KORECORisk provided prediction in time and space that are of sufficient resolution required for the aquatic risk assessment but with varying uncertainty. The uncertainty associated with the use of KORECORisk appeared to vary widely (from <10 to 103) with the chemical. Within the range of the chemicals tested, the release rate estimation appeared to introduce larger uncertainty than the exposure estimation. A more accurate chemical use inventory would improve the accuracy of not only the chemical release estimation but the exposure estimation module by reducing the influence of the unidentified sources. The release estimation module should be modified to provide temporal variation with a time resolution relevant to the exposure duration for which toxic effects could occur.