• Environmental Analysis Health and Toxicology
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• v.14 no.1_2
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• pp.35-43
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• 1999

A number of disinfection by-products (DBPs) are formed as a result of the addition of chlorine into the public water supply and some of them have been suggested to cause adverse health effects on humans. However, the estimation of human ingestion exposure to each DBP has been performed simply by multiplying the concentration of a chemical in the cold tap water by the volume of water consumed during a given period of time. However, a questionnaire concerning water consumptions administered to sixty people residing in Chunchon showed that the volume of tap water consumed accounted for approximately 70% of the total volume of water consumed and that of heated water represented approximately 94% of tap water ingested. Heating durations for water-containing foods (e. g., soups and pot stews) and heated beverages (e. g., barley tea) were grouped into 10, 20, 30, and 35 minutes. Based on these time frames, an aluminum pot containing one liter of tap water was heated for the above respective time periods using a gas range to determine the variations of the concentrations of individual DBPs by heating. The pH and total residual chlorine were measured before and after heating. Collected water samples were carried to the laboratory and analyzed for eight DBPs and total organic carbon. Chloroform, bromodichloromethane, chloral hydrate, 1, 2-dichloro-2-propanone, 1, 1, 1-trichloropropanone, and dichloroacetonitrile were not detected following heating for 10 minutes and longer. The concentration of dichloroacetic acid (DCAA) was elevated with heating duration, resulting in the averages of 2.0, 3.1, 4.7, and 12 times the initial concentration, respectively, for 10, 20, 30, and 35 minute heating periods. On the other hand, the concentration of trichloroacetic acid (TCAA) decreased with heating duration, with 0.65, 0.40, 0.34, and 0.19 times lower than the initial concentration. Therefore, it is suggested that ingestion exposure to DCAA increases with heating duration but that ingestion exposure to TCAA decreases. In addition, while the amount of DCAA was elevated at the initial time periods (10 or 20 minutes) and then slowly decreased, that of TCAA was rapidly decreased. In conclusion, water-heating processes during cooking influence the concentrations of individual DBPs in the tap water, with lower levels for volatile DBPs and TCAA, and higher levels for DCAA. Therefore, concentration change needs to be taken into consideration in the estimation of human ingestion exposure to DBPs.

• Journal of Life Science
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• v.26 no.2
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• pp.181-189
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• 2016

The aim of this study was to identify the effects of dithiopyr (DTP), a herbicide, on behavior in zebrafish. The toxicity of DTP has rarely been investigated in fish. In the present study, zebrafish were exposed to different concentrations of DTP in the range of 10-20 μM for 48 h in a test container, in order to measure the value of median lethal concentrations (LC₅₀). Behavioral experiments were performed, including the novel tank test (NTT) and the open field test (OFT), to assess stress responses or locomotion. After exposure to the DTP solution at a sublethal concentration of 2.5–10 μM for 6 min, the behavior of the zebrafish was observed for 6 min. In the acute toxicity test, the LC₅₀ value of DTP showed as 14.49 μM in the zebrafish. The NTT showed that the duration of immobility and the velocity were significantly increased by exposure at a concentration of 5 μM of DTP, compared with a control group (p<0.05). However, compared with the control group, DTP significantly decreased the distance moved and the frequency at the top of the tank, and significantly increased the turn angle and duration at the bottom, in a concentration-dependent manner (p<0.05). In addition, in the OFT, exposure to DTP significantly decreased the distance moved and velocity compared with the control group (p<0.05). Exposure to DTP also significantly increased the duration of immobility, the turn angle, and the meandering movement, in a concentration-dependent manner (p<0.05). Further, exposure to DTP at a low concentration elevated whole-body cortisol levels in the zebrafish. The results of this study thus suggest that DTP induces a toxic response and negative effects on behavior and the endocrine system in zebrafish.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6559-6564
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• 2014

Objective: To evaluate the efficacy and safety of bevacizumab in the treatment of patients with metastatic colorectal cancer (mCRC). Methods: In a single-center, observational study of 91 Chinese patients with mCRC who received bevacizumab in combination with chemotherapy was conducted. Objective response rates (ORRs), progression-free survival (PFS), overall survival (OS) and adverse events were recorded, and the relationships between various clinical factors and PFS or OS were evaluated by Cox proportional hazards models. Results: Treatment with bevacizumab and chemotherapy was effective and tolerable. Univariate analysis showed that PFS and OS were significantly associated with the Eastern Cooperative Oncology Group performance status (ECOG-PS) score, duration of bevacizumab exposure, and whether chemotherapy was continued after discontinuation of bevacizumab treatment. A multivariate analysis showed that the duration of bevacizumab exposure and whether chemotherapy was continued after discontinuation of bevacizumab were independent prognostic factors for PFS and OS. Conclusion: In Chinese mCRC population, the shorter the duration of exposure to bevacizumab and chemotherapy, the worse the prognosis is.

• Journal of the Optical Society of Korea
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• v.20 no.2
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• pp.269-275
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• 2016

This study has investigated the feasibility of 980-nm low-energy pulsed near-infrared laser stimulation to evoke auditory responses, as well as the effects of radiant exposure and pulse duration on auditory responses. In the experiments, a hole was drilled in the basal turn of the cochlea in guinea pigs. An optical fiber with a 980-nm pulsed infrared laser was inserted into the hole, orientating the spiral ganglion cells in the cochlea. To model deafness, the tympanic membrane was mechanically damaged. Acoustically evoked compound action potentials (ACAPs) were recorded before and after deafness, and optically evoked compound action potentials (OCAPs) were recorded after deafness. Similar spatial selectivity between optical and acoustical stimulation was found. In addition, OCAP amplitudes increased with radiant exposure, indicating a photothermal mechanism induced by optical stimulation. Furthermore, at a fixed radiant exposure, OCAP amplitudes decreased as pulse duration increased, suggesting that optical stimulation might be governed by the time duration over which the energy is delivered. Thus, the current experiments have demonstrated that a 980-nm pulsed near-infrared laser with low energy can evoke auditory neural responses similar to those evoked by acoustical stimulation. This approach could be used to develop optical cochlear implants.

• The Korean Journal of Pain
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• v.25 no.2
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• pp.81-88
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• 2012

Background: In discography performed during percutaneous endoscopic lumbar discectomy (PELD) via the posterolateral approach, it is difficult to create a fluoroscopic tunnel view because a long needle is required for discography and the guide-wire used for consecutive PELD interrupts rotation of fluoroscope. A stereotactic system was designed to facilitate the determination of the needle entry point, and the feasibility of this system was evaluated during interventional spine procedures. Methods: A newly designed stereotactic guidance system underwent a field test application for PELD. Sixty patients who underwent single-level PELD at L4-L5 were randomly divided into conventional or stereotactic groups. PELD was performed via the posterolateral approach using the entry point on the skin determined by premeasured distance from the midline and angles according to preoperative magnetic resonance imaging (MRI) findings. Needle entry accuracy provided by the two groups was determined by comparing the distance and angle measured by postoperative computed tomography with those measured by preoperative MRI. The duration and radiation exposure for determining the entry point were measured in the groups. Results: The new stereotactic guidance system and the conventional method provided similarly accurate entry points for discography and consecutive PELD. However, the new stereotactic guidance system lowered the duration and radiation exposure for determining the entry point. Conclusions: The new stereotactic guidance system under fluoroscopy provided a reliable needle entry point for discography and consecutive PELD. Furthermore, it reduced the duration and radiation exposure associated with determining needle entry.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.102-108
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• 2008

Many alternative biocidal additives were applied to antifouling paint to replace TBT, and Sea-Nine 211 is one of alternating organic booster compounds used in antifouling paint. In this study, extent of Sea-Nine 211 toxicity on marine benthic bivalve is evaluated. Sea-Nine 211 was injected to surf clam, Pseudocardium sachalinensis, that inhabitate northern part of Gangwon Province, Korea. Survival rate of the clam and xenobiotics metabolizing enzyme activities in digestive gland were measured during 4 day-exposure period. The results were compared with those of TBT exposed clam. There were no mortality of clam in the solvent (DMSO) control group and the three Sea-Nine 211 exposure groups (5, 25, 50 mg kg$^{-1}$ body weight), while the clam exposed to 1, 2 and 5 mg kg$^{-1}$ TBT chloride (TBTC) demonstrated 70, 30 and 0% survival rate, respectively. The Sea-Nine 211 exposure group showed a tendency of cytochrome P450 (CYP) induction according to the exposure duration, on the other hand, CYP content was decreased in the TBT exposure group. NADPH cytochrome P450 reductase activity slightly increase according to the exposure duration in the Sea-Nine 211 exposure group, while TBTC inhibit its activity as CYP content. Moreover, there was no significant change of NADH cytochrome b5 reductate activity in the clam epxosed to Sea-Nine 211. In the TBTC exposure group, its activity increased in early exposure period and then significantly decreased the rest of exposure period. All the results indicate that Sea-Nine 211 demonstrated a tendency to induce CYP level, while TBTC inhibits the CYP level, NADPH cytochrome P450 reductase and NADH cytochrome b5 reductase activities.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.5 s.110
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• pp.503-513
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• 2006

The duration time of aircraft noise event is also an important factor for the evaluation of civil aircraft noise, which is considered as a notable characteristic of military aircraft noise. SEL is proved as a suitable noise metric for the measuring military aircraft noise of various flight pattern considering the duration time of noise event. This study reviews whether SEL is a suitable for measuring civil aircraft noise and study shows SEL is fairly compensating the duration time of civil aircraft noise event for the evaluation of aircraft noise. Noise metric for the evaluation aircraft noise based on SEL is more appropriate than based on $L_{MAX}$ for compensating duration time of noise event either military aircraft or civil aircraft. In this reason, current formula of WECPNL based on energy average of measured $L_{MAX}$ for the evaluation of aircraft noise impact in 'Test Method of Noise and Vibration of Korea' is recommended to be amended to formula of WECPNL based on energy average of measured SEL considering compensation of noise event duration time, if WECPNL is not based on measured EPNL, a metric compensating duration time.

• Safety and Health at Work
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• v.11 no.3
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• pp.249-261
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• 2020

Background: Hearing loss is one of the most prevalent worker health conditions worldwide. Although the effect of noise exposure on hearing is well researched, other workplace exposures may account for significant hearing loss. The aim of this review was to determine whether occupational hand-arm vibration exposure through use of power or pneumatic tools, independent of noise exposure, is associated with permanent hearing loss. Do workers suffer from hand-arm vibratione-induced hearing loss? Methods: Peer-reviewed articles published in English between 1981 and 2020 were identified through five online databases with five search keywords. Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, including online database search methodology, study selection, article exclusion, and assessment of potential study design confounders and biases, were followed. Results: Database searches retrieved 697 articles. Fifteen articles that reported 17 studies met the criteria for review. All but two studies revealed statistically significant associations between occupational exposure to hand-arm vibration and hearing loss. The majority of the study results revealed associations between hand-arm vibration and hearing loss, independent of potential age and noise confounders. Conclusion: Few studies have examined the association between occupational exposure to hand-arm vibration and hearing loss. Dose response data were limited as only one study measured vibration intensity and duration. Although the majority of studies identified statistically significant associations, causal relationships could not be determined. Further research using standardized and uniform measurement protocols is needed to confirm whether the association between occupational exposure to hand-arm vibration and permanent hearing loss is causal and the mechanism(s).

• Fire Science and Engineering
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• v.10 no.2
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• pp.20-27
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• 1996

This paper discussed the limit of existing safety controls where the use of land around hazardous industry. There is a gap between engineering evaluation of acceptable criteria for loss reduction and risk exposure to the areas of high risk outside plants from the aspects of risk perception. The paper performed how land use safety could be designed between the density of uses with the duration of risk exposure by type of land use. It concluded the needs of multi-dimensional presentation for an appropriate risk controls on existing and future land use safety.

• Toxicological Research
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• v.33 no.1
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• pp.7-14
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• 2017

Didecyldimethylammonium chloride (DDAC) is used in many types of biocidal products including tableware, carpets, humidifiers, and swimming pools, etc. In spite of increased chances of DDAC exposure through inhalation, studies on the inhalation toxicity of DDAC are not common even though the toxicity of DDAC might be significantly higher if it were to be administered through routes other than the respiratory system. DDAC aerosols were exposed to Sprague-Dawley rats in whole body exposure chambers for a duration of 13 weeks. The Mass Median Aerodynamic Diameters of the DDAC aerosol were $0.63{\mu}m$, $0.81{\mu}m$, and $1.65{\mu}m$, and the geometric standard deviations were 1.62, 1.65, and 1.65 in the low ($0.11{\pm}0.06mg/m^3$), the middle ($0.36{\pm}0.20mg/m^3$) and the high ($1.41{\pm}0.71mg/m^3$) exposure groups, respectively. Body weight was confirmed to be clearly influenced by exposure to DDAC and mean body weight was approximately 35% lower in the high ($1.41{\pm}0.71mg/m^3$) male group and 15% lower in the high ($1.41{\pm}0.71mg/m^3$) female group compared to that of the control group. In the bronchoalveolar lavage fluid assay, the levels of albumin and lactate dehydrogenase had no effect on DDAC exposure. The lung weight increased for the middle ($0.36{\pm}0.20mg/m^3$) and the high ($1.41{\pm}0.71mg/m^3$) concentrations of the DDAC exposure group, and inflammatory cell infiltration and interstitial pneumonia were partially observed in the lungs of the middle ($0.36{\pm}0.20mg/m^3$) and the high ($1.41{\pm}0.71mg/m^3$) exposure groups. However, severe histopathological symptoms, including proteinosis and/or fibrosis, were not found. Based on the results of the changes in the body weight and lung weight, it is considered that the NOAEL (no-observed adverse effect) level for the 13-week exposure duration is $0.11mg/m^3$.