Tag Archives: South Korea

Daily confirmed coronavirus cases in Singapore, Hong Kong, Taiwan, South Korea, Japan Thailand, and USA

jodi-feb-22

click here for the source of the above figure.

 

 

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A Model for Developing Water and Sanitation Capacity

Nitrosamines in Sewage Treatment Plants and Water Environment, Korea

Ji-Hyun Lee, Jeong-Eun Oh. A comprehensive survey on the occurrence and fate of nitrosamines in sewage treatment plants and water environment. Science of the Total Environment 556 (2016) 330–337.

A comprehensive examination of nitrosamines was conducted in a water system, which included sewage treatment plants (STPs), river water, and seawater to understand their characteristic occurrence and fates in whole real water system. The concentrations of nitrosamines were highest in the STP influent (1440–29,100 ng/L), followed by the river water (26.0–5180 ng/L), the STP effluent (9.58–310 ng/L), and seawater (44.2–155 ng/L). The samples were especially affected by proximity to the industrial zone and the samples collected near industrial complex had much higher levels than others with different distribution patterns. In the STPs, nitrosamines were mostly eliminated during biological treatment processes (86.7–95.0%), while they were formed through chlorination processes (−59.6 to −27.7%), which is consistent with previous surveys. The primary clarifier showed insignificant elimination tendencies (5.6–28.2%). Although removal by ultraviolet light was effective (73.2–94.1%), more surveys may be needed because of conflicting results in other studies. Among water quality parameters, nitrosamines in waste water were linked with organic carbon and nitrogen levels.

Fluoride study in South Korea

This is the typical type of study conducted that is used to support fluoridation of water. Why such studies are still done is a mystery. Take it at face value, but such studies are not useful in my view. Indeed, the title of the paper is misleading as the “systemic effect” was deduced, not measured directly.

Cho HJ, Jin BH, Park DY, Jung SH, Lee HS, Paik DI, Bae KH. Systemic effect of water fluoridation on dental caries prevalence. Community Dent Oral Epidemiol. 2014 Jan 16. doi: 10.1111/cdoe.12091.

OBJECTIVES: The aim of this study was to evaluate the systemic effect of water fluoridation on dental caries prevalence and experience in Cheongju, South Korea, where water fluoridation ceased 7 years previously.

METHODS: A cross-sectional survey was employed at two schools where water fluoridation had ceased (WF-ceased area) and at two schools where the water had never been fluoridated (non-WF area). The schools in the non-WF area were of a similar population size to the schools in the WF-ceased area. Children of three age groups were examined in both areas: aged 6 (n = 505), 8 (n = 513), and 11 years (n = 467). The differences in the mean number of decayed or filled primary teeth (dft) and the mean number of decayed, missing, or filled permanent teeth (DMFT) scores between areas after adjusting for oral health behaviors and socio-demographic factors were analyzed by a Poisson regression model.

RESULTS: The regression model showed that the DMFT ratio for children aged 11 years in the WF-ceased area was 0.581 (95% CI 0.450-0.751). In contrast, the dft ratio for age 6 in the WF-ceased area was 1.158 (95% CI 1.004-1.335). Only the DMFT ratio for age 8 (0.924, 95% CI 0.625-1.368) was not significant.

CONCLUSIONS: While 6-year-old children who had not ingested fluoridated water showed higher dft in the WF-ceased area than in the non-WF area, 11-year-old children in the WF-ceased area who had ingested fluoridated water for approximately 4 years after birth showed significantly lower DMFT than those in the non-WF area. This suggests that the systemic effect of fluoride intake through water fluoridation could be important for the prevention of dental caries.

NDMA exposure from chlorindated water in South Korea….

Hekap Kim and Kichan Han. Ingestion Exposure to Nitrosamines in Chlorinated Drinking Water. Environ Health Toxicol. 2011; 26: e2011003. doi:  10.5620/eht.2011.26.e2011003

Objectives: N-Nitrosodimethylamine (NDMA) is classified as a probable human carcinogen by the United States Environmental Protection Agency (US EPA) and is formed during the chlorination of municipal drinking water. In this study, selected nitrosamines were measured in chlorinated drinking water collected from Chuncheon, Kangwon-do, Republic of Korea, and a risk assessment for NDMA was conducted.

Methods: Twelve water samples were collected from 2 treatment plants and 10 household taps. Samples were analyzed for 6 nitrosamines via solid-phase extraction cleanup followed by conversion to dansyl derivatives and high-performance liquid chromatography-fluorescence detection (HPLC-FLD). Considering the dietary patterns of Korean people and the concentration change of NDMA by boiling, a carcinogenic risk assessment from ingestion exposure was conducted following the US EPA guidelines.

Results: NDMA concentrations ranged between 26.1 and 112.0 ng/L. NDMA in water was found to be thermally stable, and thus its concentration at the end of boiling was greater than before thermal treatment owing to the decrease in water volume. The estimated excess lifetime carcinogenic risk exceeded the regulatory baseline risk of 10-5.

Conclusions: This result suggests that more extensive studies need to be conducted on nitrosamine concentration distributions over the country and the source of relatively high nitrosamine concentrations.

Click here for full paper (Open Source).

Fluoride ingested in infant formula and baby food, South Korea

Noh HJ, Sohn W, Kim BI, Kwon HK, Choi CH, Kim HY. Estimation of Fluoride Intake From Milk-Based Infant Formulas and Baby Foods. Asia Pac J Public Health. 2013 Mar 5.

The aim of this study was to examine the amount of fluoride ingested from infant formula and baby food in infants aged up to 6 months in South Korea. The fluoride content of 20 commercially available formulas and 8 baby food samples from 4 different brands was measured using a modified microdiffusion method and fluoride ion selective electrode. The amount of fluoride (F) ingested by infants was estimated assuming that the samples were reconstituted with water containing 0, 0.5, 0.8, and 1.0 ppm F. When the reconstituted formulas and baby foods contained 0.8 ppm F water, the infants were estimated to ingest fluoride in the range of 0.018 to 0.298 mg/kg/day. The findings of this study suggest that there is a need for clear guidelines for fluoride consumption by infants that should be followed by manufacturers and parents.

Click here for full paper (Open Source).