• Animal Bioscience
• /
• v.34 no.12
• /
• pp.2012-2022
• /
• 2021

Objective: In most retail centers, primal pork cuts for sale are usually prepared into retail-ready slices and overwrapped with air-permeable plastic film. Also, meat of Korean native black pig (KNP) is reputed for its superior quality, however, its shelf life during retail display has not been studied. Thus, the objective of this study was to evaluate shelf life of prepackaged retail-ready KNP belly and shoulder butt slices during refrigerated display. Methods: Bellies and shoulder butt obtained at 24 h post-mortem from finishing KNP were used. Each belly or shoulder butt was manually cut into 1.5 cm-thick slices. The slices in each cut type were randomly taken and placed on white foam tray (2 slices/tray) overwrapped with polyvinyl chloride film. The retail-ready packages were then placed in a retail display cabinet at 4℃. Shelf life and sensory quality of the samples were evaluated on day 1, 3, 6, 9, 12, and 15 of display. Results: The shoulder butt reached the upper limit (20 mg/100 g) of volatile basic nitrogen for fresh meat after 9 days while, the belly remained within this limit throughout the display time (15 days). Both the cuts reached a thiobarbituric acid reactive substances level of above 0.5 mg malondialdehyde/kg after 9 days. The a^* (redness) values remained unchanged during first 9 days in both cuts (p>0.05). After 9 days, off-flavor was not found in either cut, but higher off-flavor intensity was found in shoulder butt after 12 days. The shoulder butt was unacceptable for overall eating quality after 12 days while, belly still was acceptable after 12 days. Conclusion: The belly showed a longer shelf life compared to the shoulder butt, and a shelf life of 9 and 12 days is recommended for the prepackaged retail-ready KNP shoulder butt and belly slices, respectively.

• Journal of Environmental Health Sciences
• /
• v.47 no.1
• /
• pp.1-19
• /
• 2021

Objectives: Phthalates, which are widely used as plasticizers, have been recognized as endocrine disruptors. In the present study, we provided information on the regulation of these chemicals and summarized the information available on their detection and toxicity in children's products and those of their alternatives. Methods: The regulatory frameworks related to phthalates in children's products in Korea, the United States (US), and the European Union (EU) were compared. Data on the detection concentration of 16 phthalates and seven phthalate alternatives that could be used in polyvinyl chloride (PVC) plastic products for children as well as on their toxicity classification and endocrine disruption toxicity were collected from the literature. Results: Korea adopted US and EU chemical standards for six phthalates (DEHP, BBP, DBP, DINP, DIDP, and DNOP), but not others (e.g., DIBP, DPP, DHP, and DCHP). Among the ten phthalates and seven substitutes for which regulatory standards were not determined, DIBP, DHP, DEHA, DIBA, DINA, and DEHT were detected in children's products made from PVC plastic. DIBP and DHP, which have a reproductive toxicity classification of 1B, were frequently detected in PVC toys. The reproductive toxicity, estrogenicity, and anti-androgenic activity of the unregulated phthalates and their alternatives have been reported in diverse in vitro and in vivo assays. Conclusion: The use of unregulated phthalates and their substitutes in children's products is increasing. Further monitoring and toxicological information on phthalate alternatives is required to develop proper management plans.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.149-149
• /
• 2023

미세플라스틱은 입자크기가 5 mm 이하인 플라스틱으로 정의되며, 수계로 유입된 미세플라스틱은 내분비계 교란물질로 작용하여 생태계에 환경독성을 유발하고 오염물질을 흡착·운반할 수 있는 독성 물질의 매개체로서 미세플라스틱의 위해성에 대한 우려가 증가하고 있다. 본 연구는 수용액에서 다양한 미세플라스틱의 납(Pb) 흡착특성을 평가하고 미세플라스틱의 비표면적에 따른 흡착 효과를 비교하고자 하였다. 플라스틱 종류 중 HDPE (High-density Polyethylene)와 PVC (Polyvinyl Chloride)를 각각 세 가지 크기(Group 1: 2.5 mm - 1.0 mm, Group 2: 1.0 mm - 0.3 mm, Group 3: < 0.3 mm)로 제조하여 분류하였으며, 미세플라스틱 입자크기의 비표면적은 BET(Brunauer, Emmett, Teller)분석을 통하여 측정하였다. 담수환경 조성을 위해 pH 7로 조절한 Pb 용액의 농도(0, 0.5, 1, 5, 10, 30 mg/L)별 흡착실험을 수행하였으며 실험결과를 3가지 흡착등온식(Langmuir, Freundlich, Sips 모델)을 사용하여 미세플라스틱에서 Pb 흡착 거동을 나타내었다. BET 분석 측정결과, PVC의 경우 Group 3 > Group 2 > Group 1 순으로 PVC의 입자크기가 작을수록 비표면적이 크게 나타났으며, HDPE 비표면적 또한 비슷한 경향을 보였다. HDPE와 PVC에서 Pb의 흡착은 Langmuir 모델(R² > 0.97)과 Freundlich 모델(R² > 0.82)보다 Sips 모델(R² > 0.98)이 흡착 거동을 설명하기에 가장 적합하였다. 최대흡착능(Q_m) 상수는 입자크기가 작아질수록 흡착능이 높아지는 추세를 보였으며, 흡착세기(K_F)와 흡착강도(n^-1)는 각 플라스틱의 Group 3(HDPE K_F = 0.028, PVC K_F = 0.032; HDPE n^-1 = 0.225, PVC n^-1 = 0.547)에서 가장 높게 나타났다. 본 연구를 통해 HDPE와 PVC에서 Pb의 흡착특성은 Sips모델로 설명이 가능했으며, 이에 따라 Pb 흡착과정에 복수의 흡착메커니즘이 작용하고 있음을 유추해볼 수 있었다. 미세플라스틱의 입자크기와 비표면적이 Pb 흡착량에 영향을 미치는 것을 알 수 있었으며, 미세플라스틱이 중금속을 흡착하여 생물체 내로 전이시킬 수 있는 매개체 역할의 가능성을 확인하였다.

• Korean Journal of Environmental Biology
• /
• v.40 no.4
• /
• pp.398-404
• /
• 2022

Bis(2-ethylhexyl) phthalate (DEHP) is one of the plasticizers used in the polyvinyl chloride(PVC) industry. It is known to be easily released into the environment. In this study, we investigated effects of DEHP on growth, metabolic pathway, and virulence gene expression in soil-borne bacterial plant pathogen, Pectobacterium carotovorum SCC1 using in vitro assays. As a result, DEHP at 20 ㎍ mL^-1 did not affect the growth, cell membrane permeability, or ATPase activity of P. carotovorum SCC1. However, it decreased succinyl-CoA synthase (SCS) activity in the tricarboxylic acid (TCA) cycle. Relative expression levels of virulence genes encoding pectate lyase and pectin were differentially influenced by DEHP treatment. These results suggest that biological characteristics of P. carotovorum might be influenced by DEHP in soil.

• Safety and Health at Work
• /
• v.14 no.2
• /
• pp.215-221
• /
• 2023

Background: There is little information about the airborne hazardous agents released during the heat treatment when manufacturing a welding material. This study aimed to evaluate the airborne hazardous agents generated at welding material manufacturing sites through area sampling. Methods: concentration of airborne particles was measured using a scanning mobility particle sizer and optical particle sizer. Total suspended particles (TSP) and respirable dust samples were collected on polyvinyl chloride filters and weighed to measure the mass concentrations. Volatile organic compounds and heavy metals were analyzed using a gas chromatography mass spectrometer and inductively coupled plasma mass spectrometer, respectively. Results: The average mass concentration of TSP was 683.1±677.4 ㎍/m³, with respirable dust accounting for 38.6% of the TSP. The average concentration of the airborne particles less than 10 ㎛ in diameter was 11.2-22.8×10⁴ particles/cm³, and the average number of the particles with a diameter of 10-100 nm was approximately 78-86% of the total measured particles (<10 ㎛). In the case of volatile organic compounds, the heat treatment process concentration was significantly higher (p < 0.05) during combustion than during cooling. The airborne heavy metal concentrations differed depending on the materials used for heat treatment. The content of heavy metals in the airborne particles was approximately 32.6%. Conclusions: Nanoparticle exposure increased as the number of particles in the air around the heat treatment process increases, and the ratio of heavy metals in dust generated after the heat treatment process is high, which may adversely affect workers' health.

• Journal of Veterinary Science
• /
• v.24 no.4
• /
• pp.46.1-46.12
• /
• 2023

Background: Heartworm infection in dogs is caused by Dirofilaria immitis and common in shelter animals and outdoors dogs. Caval syndrome can develop with severe infection and physical heartworm removal is essential with heartworm burdens. In this study, we used an improved transvenous heartworm extraction brush, which was expected to cause less cardiovascular damage and allow easier manipulation. Objectives: This study aims to evaluate efficacy of this improved transvenous heartworm extraction brush. Methods: The brush was designed to improve upon the limitations of the previous brush-type devices. The brush was made of a polyvinyl chloride tube and threads of polyamides or polyglyconates. Metal material was inserted at the front tip for easy visualization under fluoroscopy. The eight dogs diagnosed with caval syndrome with large numbers of heartworms and pulmonary hypertension were used in this study. The removal procedure began with the dissection of the subcutaneous tissue around the right jugular vein. The device was inserted through the jugular vein. After insertion, the tube was rotated to catch the heartworms and extracted with the heartworms hanging on the threads. The procedure was repeated several times. Lastly, jugular vein and skin sutures were made. Adulticidal therapy was administered after heartworm removal. Results: The mean number of removed heartworms was 10.5 ± 4.24 and mean number of remaining heartworms was 0.63 ± 1.06. Total procedure time was 72.63 ± 51.36. Except for three cases, heartworms were not detected on ultrasonography after the procedure. No procedure-related side effects were observed within the 1- to 2-mon. Conclusions: An improved transvenous heartworm extraction brush is efficient for heartworm removal in dogs with caval syndrome.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.66 no.1
• /
• pp.39-48
• /
• 2024

Plastic greenhouses are simple structures consisting of lightweight materials such as steel pipes and polyvinyl chloride. However, serious damage occurs due to heavy winds and typhoon every year. To prevent a collapse of structural members, the Ministry of Agriculture and Rural Development has distributed plans and specifications for disaster-resistant standards. Despite these efforts, more than 50% of greenhouses still do not satisfy the disaster-resistant standards. Among the greenhouses that do not meet these standards, 85% are single-span greenhouses proposed 20 years ago. Consequently, there is a need to evaluate the safety of wind loads for the single-span greenhouse. Unfortunately, there are no design specifications for the greenhouses under wind loads. Therefore, a Korean design standard (KDS) has been utilized. KDS is defined with reference to wind speeds occurring once every 500 years, raising concerns about potential overdesign when considering the durability of plastic greenhouses. To address this, the modified wind load, considering the durability of the plastic greenhouse, was calculated, and a safety evaluation was conducted for sigle G-type plastic greenhouse. It was observed that the moment acting on the windward surface was substantial, and there was a risk of the foundation being pulled out if the basic wind speed exceeded 32 m/s. In terms of the combination strength ratio, it was less than 1.0 only on the leeward side when the basic wind speed was 24 m/s and 26 m/s. However, in all other cases, it exceeded 1.0, indicating an unsafe condition and highlighting the necessity for reinforcement.

• Journal of Environmental Health Sciences
• /
• v.50 no.3
• /
• pp.212-220
• /
• 2024

Background: 2-Ethylhexyl diphenyl phosphate (EHDPP) is widely used as a flame-retardant plasticizer in the production of polyvinyl chloride, adhesives, and food packaging. This chemical has been frequently detected in water, sediment, and indoor environments, and its lipophilicity raises concerns about bioaccumulation. Objectives: In this study, the effects of EHDPP on the development, behavioral changes, and growth hormone (GH) endocrine system of zebrafish larvae were investigated. Methods: Fertilized embryos were exposed to various concentrations (control, solvent control, 0.07, 0.7, 7, 70, and 700 ㎍/L) of EHDPP for 96 h. Developmental toxicity endpoints were observed daily. Behavioral changes under light-dark-light conditions and changes in hormones and genes related to GH/insulin-like growth factors (IGFs) axis were determined. Results: Significant decreases in survival, body length and moving distance were observed in zebrafish larvae exposed to 70 and 700 ㎍/L EHDPP. The concentrations of GH and IGF-1 were significantly decreased in zebrafish larvae exposed to 70 and 700 ㎍/L EHDPP. This change was well supported by changes in the transcription of genes involved in GH, IGF, IGF receptors, and IGF binding proteins. Conclusions: Our observations showed that exposure to 70 and 700 ㎍/L EHDPP could disrupt the feedback circuits of the GH/IGFs axis, ultimately leading to developmental toxicity, hypoactivity, and mortality.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.4
• /
• pp.256-262
• /
• 2009

The use of hydrodynamic separator is becoming increasingly popular for suspended solids reduction in urban storm runoff. This study is a laboratory investigation of the use of Vortex Screen to reduce the solids concentration of synthesized storm runoff. The synthesized storm runoff was made with water and addition of particles; manhole sediment, road sediment, fly ash, and ployvinyl chloride powder. Vortex Screen was made of acryl resin with 250 mm of diameter and height of 700 mm. To determine the removal efficiency for various influent concentrations of suspended solids (SS) and chemical oxygen demand (COD), tests were performed with different operational conditions. The samples were taken simultaneously at the influent storage tank and effluent tank, and measured SS and COD concentrations. The ranges of surface loading rate were 110 to 1,550 $m^3/m^2$/day, and influent SS concentrations were varied from 141 to 1,986 mg/L. This paper was intended to evaluate the effect of inlet baffle and the ratio of underflow to overflow ($Q_U/Q_O$) on particle separation efficiency for various particle size using Vortex Screen. It was found that when increase of $Q_U/Q_O$ from 10% to 20%, SS removal efficiency was increased about 6%. The range of SS and COD removal efficiencies of road sediment particle size 125<$d_p$<300 ${\mu}m$ were 68.0~81.0%, 53.1~71.9%, respectively. Results showed that SS removal efficiency with inlet baffle improved by about 10~20% compared without inlet baffle.

• Journal of dental hygiene science
• /
• v.14 no.2
• /
• pp.191-197
• /
• 2014

The purpose of this study was to evaluate the tooth whitening efficacy of 2.9% hydrogen peroxide strip with primer gel of alkaline condition and containing metallic salts as catalyst in-vitro. Hydroxyapatite (HAP) disk was made by compressing and sintering 0.3 g of mixture of HAP powder and polyvinyl alcohol. This HAP disk was stained using modified Stookey's methods. Main bleaching materials were 2.9% hydrogen peroxide strips and the primer gel containing metallic salts as catalyst and pH controller. Stained HAP disks were allocated to each control or experimental groups by color grade. Stained HAP disks were treated for 30 minutes in $37^{\circ}C/80%$ incubator for wetting, then each primer gel according to control or each test group was spread and strips were attached. After 30 minutes for each group strips were detached and HAP disks were washed, dried then color was measured by colorimeter. Efficacy was evaluated by comparing ${\Delta}L$ values of HAP disks at baseline and after treated. Among some kinds of metallic salts for as catalyst, ferric chloride showed best improvement of efficacy and it was statistically significant (p<0.05) compared to control group. Evaluating whitening efficacy according to various pH of primer, efficacy using primer of alkaline condition was increased significantly (p<0.05) compared to control and primers of acidic or neutral conditions. Evaluating whitening efficacy for time course, efficacy of test group for 30 minutes was similar to that of control for 120 minutes. It can be concluded that 2.9% hydrogen peroxide strips using with primer of alkaline condition and containing ferric chloride showed significantly increased whitening efficacy compared to the case of strips only.