Assessment of radiation exposure from cesium-137 contaminated roads for epidemiological studies in Seoul, Korea.

OBJECTIVES: We aimed to assess the radiation exposure for epidemiologic investigation in residents exposed to radiation from roads that were accidentally found to be contaminated with radioactive cesium-137 ((137)Cs) in Seoul. METHODS: Using information regarding the frequency and duration of passing via the (137)Cs contaminated roads or residing/working near the roads from the questionnaires that were obtained from 8875 residents and the measured radiation doses reported by the Nuclear Safety and Security Commission, we calculated the total cumulative dose of radiation exposure for each person. RESULTS: Sixty-three percent of the residents who responded to the questionnaire were considered as ever-exposed and 1% of them had a total cumulative dose of more than 10 mSv. The mean (minimum, maximum) duration of radiation exposure was 4.75 years (0.08, 11.98) and the geometric mean (minimum, maximum) of the total cumulative dose was 0.049 mSv (<0.001, 35.35) in the exposed. CONCLUSIONS: An individual exposure assessment was performed for an epidemiological study to estimate the health risk among residents living in the vicinity of (137)Cs contaminated roads. The average exposure dose in the exposed people was less than 5% of the current guideline.

Metabolic syndrome in carbon disulfide-poisoned subjects in Korea: does chemical poisoning induce metabolic syndrome?

OBJECTIVE: Mass carbon disulfide (CS(2)) poisoning was reported at a viscose rayon factory in Korea. We evaluated the association between CS(2) poisoning and the prevalence of metabolic syndrome. METHODS: The cases (n = 170) involved CS(2)-poisoned subjects, who participated in a health examination conducted at a hospital in Korea in 2005. The controls (n = 170) were selected randomly from the participants in the third Korean National Health and Nutrition Examination Survey. Metabolic syndrome was defined as having at least three of following metabolic abnormalities: abdominal obesity, elevated triglyceride, reduced high-density lipoprotein cholesterol, elevated blood pressure, and elevated fasting glucose levels. RESULTS: After adjusting for covariates (age, gender, education, marital status, alcohol consumption, and smoking), CS(2)-poisoned subjects had an increased risk of metabolic syndrome (prevalence ratio 1.57, 95% CI 1.25-1.98). CONCLUSIONS: The findings suggest that CS(2) poisoning may increase the risk of metabolic syndrome.

Assessment of vibration produced by the grinders used in the shipbuilding industry of Korea.

The objective of this study is to estimate the prevalence of finger blanching among the workers in a shipyard of Korea using the dose-response relationship suggested by ISO 5349. The characteristics of vibration exposure produced by six types of grinders were investigated. Vibration measurement was made under the real work conditions. Exposure time was estimated by questionnaire and direct observation. In addition, cold provocation tests were performed, and the results from the tests were compared with the estimated prevalence. As a result, 4 hour-energy-equivalent frequency-weighted accelerations of the finishing grinding (FG) and the prepainting grinding (PG) jobs were 6.23 m/s(2) and 13.39 m/s(2), respectively. The mean exposure time for holding the grinders was 4.64 h per day. Using the ISO 5349 method, it was predicted that after exposure to vibration for 10.79 yr, about a half of the FG workers could develop finger blanching. For the PG workers, the corresponding predicted latency was 5.02 yr. A discrepancy was found between the results from the ISO relationship and those from the cold provocation tests. A linear regression model was suggested employing vibration acceleration and vibration exposure time as explanatory variables for vascular dysfunction.

Effect of metalworking fluid mist exposure on cross-shift decrement in peak expiratory flow.

Exposure to metalworking fluids (MWF) mist and cross-shift decrements in peak expiratory flow (PEF) were evaluated and their relationship was analyzed using several statistical methods. The objective of this study was to assess workers, exposure to MWF mineral mist and to find the MWF mist level for predicting cross-shift decrements in PEF. A total of 158 workers handling water-soluble MWF had MWF mist exposures with an arithmetic mean (AM) of 0.4 mg/m(3) (range: LOD-13.5 mg/m(3)), and 9.2% of workers (219) showed a cross-shift decline greater than 10% in PEF. MWF mist exposure and cross-shift decrements in PEF that were matched (n=113) were linearly significantly associated (R(2)=0.036, p=0.045) although the correlation was quite weak (r=0.189). We found a slight increase in cross-shift decrements in PEF with increased exposure to MWF aerosol mass concentration. The MWF mist exposure level was categorized into two or three groups by the cutoffs of either the National Institute for Occupational Safety and Health's Recommended Exposure Level (NIOSH REL: 0.5 mg/m(3)) or the American Conference of Governmental Industrial Hygienists Notice of Intended Change (ACGIH NIC: 0.2 mg/m(3)). The cross-shift decrement in PEF observed from workers exposed to > or =0.2 mg/m(3) was slightly higher than that of the exposure level of < or =0.2 mg/m(3) at p=0.207 while significant differences among categorized exposure groups (2 categories, <0.5 and > or =0.5 mg/m(3), or 3 categories, <0.2, 0.2-0.5 and > or =0.5 mg/m(3)) were not detected. In order to find out whether there is a specific level that allows us to predict cross-shift decrements in PEF, several statistical models were constructed. Logistic regression showed that the MWF concentration, whether treated as a continuous variable or a categorical variable, was not significantly associated with cross-shift decrements dichotomized by a cutoff of either 10% or 15% in PEF. We couldn't find evidence of a significant PEF decrement increase with increasing exposure category. Thus, we concluded that PEF decrements measured in workers exposed to MWF mist concentrations greater than either 0.2 mg/m(3) or 0.5 mg/m(3) was not significantly different from those found in workers exposed to lower MWF mist concentrations. Further study is needed to establish the level of MWF mineral mist predicting non-malignant respiratory health effects.

Heart-rate variability of carbon disulfide-poisoned subjects in Korea.

OBJECTIVES: Mass poisoning by carbon disulfide (CS(2)) occurred in a viscose-rayon factory in Korea. Including 38 who had died, 830 employees were diagnosed as CS(2) poisoned. We evaluated the heart-rate variability (HRV) among CS(2)-poisoned subjects, to discover whether CS(2) may affect HRV and whether its toxic effect persists after exposure has ceased. METHODS: The case group comprised 71 retired male workers with CS(2) poisoning. The control group comprised 127 public officials of the same age-range who had no history of organic-solvent exposure and cardiovascular diseases. Information on individual age, height, weight, cigarette smoking, alcohol drinking, regular exercise, medical and occupational history, and ECG recordings of the two groups were collected through medical examination and self-administered questionnaire. Time (maximum, average, minimum RR interval) and frequency domain measures [low (LF), high (HF), and total power spectrum (TPS)] of the two groups were analyzed. RESULTS: In univariate analysis, time domain measures of the two groups did not differ significantly, while frequency domain measures in the case group was significantly lower than in the control group except for HF power. In multivariate analysis, previous history of CS(2) poisoning was inversely related to all frequency domain measures and significantly affected LF power. CONCLUSIONS: This study suggests that CS(2) may cause heart-rate impairment and its toxic effect persists after exposure has ceased. Based on this study, HRV measurement can be considered as a useful tool to assess toxic effects of CS(2) both in current and retired workers.