Exposures to humidifier disinfectant and various health conditions in Korean based on personal exposure assessment data of claimants for compensation.

BACKGROUND: Humidifier disinfectants (HDs) were commonly used household chemicals to prevent microbial growth in a humidifier water tank in South Korea. A growing body of evidence has indicated that its airborne exposure can induce severe lung injury. However, there has been low awareness of other health outcomes in HD users. This study aimed to evaluate health conditions appealed by claimants for compensation in relation with an increased exposure to HD. METHODS: From survey data of personal HD exposure assessment of claimants for compensation in Korea, we included a total of 4,179 subjects [cases in each dataset were defined by nine reported health conditions, i.e., pneumonia, asthma, cardiovascular disease, respiratory disease, otorhinolaryngologic disease, brain disease (including cerebrovascular disease), dermatological disease, lung cancer, and all cancers]. HD exposures was considered as the following exposure criteria: exposure duration, exposure proximity, exposure direction, chemical type, cumulative exposure time, indoor air concentration, and cumulative exposure level. Logistic regression models were used to evaluate the associations between HD exposure and health conditions. RESULTS: After adjusting for sociodemographic and health behavioral factors and other chemical exposures (households, environmental, and occupational exposures), an increase in cumulative HD exposure time was significantly associated with risks of all nine diseases (all p-trends < 0.05). An increase in HD exposure duration was associated with asthma, respiratory disease, otorhinolaryngologic disease, dermatological disease, all cancers, and lung cancer (p-trends < 0.05). Indoor HD concentration was associated with only pneumonia (p-trend = 0.015). CONCLUSIONS: Our findings suggest that cumulative exposures to airborne HD might potentially increase the risk of various reported health outcomes.

Environmental exposures to lead, cadmium, and mercury and pterygium in Korean adults.

Pterygium, one of the most common eye disorders, is an abnormal fibrovascular proliferation extending from the conjunctiva to the cornea. The mechanism of development in pterygium has not been fully elucidated; however, oxidative stress is suggested to be one of the major causes. Heavy metals such as lead (Pb), cadmium (Cd), and mercury (Hg) enter the human body and induce oxidative stress. However, no study has investigated the association of these heavy metals with pterygium. Therefore, this study aimed to evaluate the associations of environmental exposures to Pb, Cd, and Hg with pterygium in the Korean general adults. We analyzed data from 6,587 adults (≥ 20 years of age) who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2011. Pterygium was diagnosed as the presence of a wing-shaped fibrovascular growth. The exposures of Pb, Cd, and Hg were estimated by measuring blood concentrations. The prevalence of pterygium in this study population was 4.0% (348 subjects). After adjusting for potential confounders, the Pb level in blood was found to have a significant dose-dependent association with pterygium (p for trend = 0.001), and its highest quintile (vs. the lowest) had an odds ratio (OR) of 2.22 (95% CI: 1.30, 3.78) for pterygium. The Hg level in blood in the second quintile (vs. the lowest) had an OR of 1.64 (95% CI: 1.04, 2.59) for pterygium. In conclusion, this study suggests that environmental exposures to Pb and Hg in the Korean general adults may be related to the development of pterygium.

Long-term exposure to ambient air pollutants and hearing loss in Korean adults.

BACKGROUND: Hearing loss is the most prevalent sensory deficit globally, and its prevalence has been growing at a rapid pace, mainly due to aging population. Although there is plentiful evidence that exposure to air pollutants contributes to oxidative stress and free radical formation in inner ear is linked to hearing impairment, there is little awareness of the contribution of air pollution to hearing loss. OBJECTIVE: To evaluate the associations between long-term exposures to air pollution and hearing loss in Korean adults, while controlling for sociodemographic and clinical factors and occupational, recreational, and firearm noise exposures. METHODS: We analyzed data from 15,051 adults in the Korean National Health and Nutrition Examination Survey V (2010-2012). Ambient air pollutant concentrations for participant residing in administrative division and local/town units were collected for current-to-3 years prior to the audiometric examination. Pure-tone average (PTA) of hearing thresholds at speech-frequency (0.5, 1, 2, 4kHz) and high-frequency (3, 4, 6kHz) were computed, and hearing loss was defined as PTA >25dB in either ear. RESULTS: Ambient PM10 was significantly associated with the increased risk of hearing loss at speech-frequency and high-frequency (current year and prior year 3), while CO was significantly associated with the increased risk of hearing loss at speech-frequency (prior year 2 and 3) and high-frequency (prior year 2), when air pollution was assessed at local/town (finer unit). After additional adjustment for regional socioeconomic status and population density (a proxy for traffic noise), NO2 became significantly associated with hearing loss at speech-frequency. When air pollution was assessed at administrative division (larger unit), PM10 and CO became stronger and SO2 became significant in hearing loss at speech-frequency. CONCLUSION: Our results suggest that long-term exposures to environmental PM10, NO2, CO, and SO2 at the levels currently observed in the general population may be risk factors affecting hearing loss.

Long-term exposure to ambient air pollutants and age-related macular degeneration in middle-aged and older adults.

Absract In developed countries, age-related macular degeneration (AMD) is a leading cause of irreversible blindness in adults. The key pathways of AMD are suggested to be excessive oxidative stress and inflammation in the central retina. Because air pollution has been found capable of inducing oxidative stress and inflammation, it may play a role in development of AMD. This study investigated the association between ambient air pollution and AMD in 15,115 middle-aged and older adults (≥40 years) from Korean National Health and Nutrition Examination Survey 2008-2012. After controlling for important confounders, ambient NO2 and CO in current-to-5 prior years and PM10 in 2-to-5 prior years were significantly associated with higher prevalence of early AMD, while O3 in current-to-5 prior years was significantly associated with lower prevalence of early AMD. When modeled air pollution within administrative division units, its ORs with an IQR increase in NO2, CO, and O3 at current year were 1.24 (95% CI: 1.05-1.46), 1.22 (95% CI: 1.09-1.38), and 0.80 (95% CI: 0.70-0.92), respectively. Overall, results from air pollution at local/town units were consistent with those at administrative division units. Long-term exposures to ambient air pollution may play a role in the risk of AMD in middle-aged and older adults.

Humidifier Disinfectant Consumption and Humidifier Disinfectant-Associated Lung Injury in South Korea: A Nationwide Population-Based Study.

Humidifier disinfectant (HD) is a household biocidal product used in humidifier water tanks to prevent the growth of microorganisms. In 2011, a series of lung injury cases of unknown causes emerged in children and pregnant women who had used HD in Korea. This study investigated changes in the nationwide number of cases of humidifier disinfectant-associated lung injury (HDLI) in concordance with nationwide HD consumption using data covering the entire Korean population. More than 25 kinds of HD products were sold between 1994 and 2011. The number of diagnosed HDLI, assessed by S27.3 (other injuries of lungs) of the Korea National Health Insurance Service (NHIS) data, sharply increased by 2005, subsequently decreased after 2005, and almost disappeared after 2011 in concordance with the annual number of HD sales. The number of self-reported HDLIs, assessed using data from all suspected HDLI cases registered in the Korea Ministry of Environment, changed with the annual number of HD sales, with a delay pattern, potentially induced by the late awareness of lung injury diseases. The present study suggests that changes in the nationwide annual consumption of HD products were consistent with changes in the annual number of HDLI cases in Korea.

Changes in air pollution levels after COVID-19 outbreak in Korea.

In order to control the spread of COVID-19, social distancing measures were implemented in many countries. This study investigated changes in air pollution during the social distancing after the COVID-19 outbreak in Korea. Ambient PM2.5, PM10, NO2, and CO that are particularly related to industrial activities and traffic were reduced during the social distancing in response to the COVID-19 outbreak. In March 2020, immediately after social distancing, mean levels of PM2.5, PM10, NO2, and CO decreased nationwide from last year's mean levels by 16.98 µg/m3, 21.61 µg/m3, 4.16 ppb, and 0.09 ppm, respectively (p-value for the year-to-year difference <0.001, =0.001, =0.008, <0.001), a decrease by 45.45%, 35.56%, 20.41%, and 17.33%, respectively. Changes in ambient O3 or SO2 were not observed to be attributable to social distancing. Our findings, that such effort for a short period of time resulted in a significant reduction in air pollution, may point toward reducing air pollution as a public health problem in a more sustainable post-COVID-19 world.