• Korean Chemical Engineering Research
• /
• v.43 no.2
• /
• pp.259-265
• /
• 2005

Binary isothermal vapor-liquid equilibrium(VLE) data were measured for water+n-methylformamide(NMF), benzene+NMF and toluene+NMF systems by using headspace gas chromatography(HSGC) at 353.15K. Additionally, the ternary liquid-liquid Equilibrium(LLE) data were determined by measuring of tie-line for the systems of NMF+benzene+n-heptane and NMF+toluene+n-heptane at 298.15 K. The measured isothermal binary VLE data have no azeotropes and were correlated well with $g^E$ model equations of Margules, van Laar, Wilson, NRTL and UNIQUAC. The experimental ternary tie line data were also correlated well with NRTL and UNIQUAC models. Besides their accuracy was analyzed by Hirata-Fujita and Maior-Swenson equations.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.24 no.3
• /
• pp.345-352
• /
• 2014

Objectives: This study is aimed to describe the current situation about urinary biomarker N-methylformamide(NMF) for workers exposed to N,N-dimethylformamide(DMF) according to industrial classification. Materials: Special health examination records of the workers who had undergone urinary biological monitoring in 2013 were collected. The numbers and percentage of workers, whose urinary NMF values were above the limit of detection(LOD) and above the biological exposure index(BEI) were calculated. Health relatedness with DMF as judged by their doctors was also described. All description was classified according to the $9^{th}$ Korean Standard Industrial Classification(KSIC). Results: It appeared that most workers exposed to DMF belong to manufacturing section(80.7%). The geometric mean(GM) values of urinary NMF were 6.25 mg/L, 3.54, and 3.86 for the manufacturing section, professional, scientific and technical activities section, and for the construction section respectively. In detail, it seemed that division of textiles(except apparel) (GM 7.51 mg/L), division of leather, luggage and footwear(11.59 mg/L), and division of rubber and plastic products(6.89 mg/L) were highly exposed to DMF with a high percentage of workers with urinary NMF values above BEI. This was probably due to the effect of skin absorption that the division of leather, luggage and footwear showed the highest urine NMF GM. Conclusions: It seemed that workers in manufacture industries such as textile, leather, luggage, footwear, rubber and plastic products were highly exposed to DMF. So, efforts should be focused on those industries in order to effectively diminish worker's exposure. Further studies to compare DMF air-monitoring with bio-monitoring according to industrial classification should be considered.

• Journal of Preventive Medicine and Public Health
• /
• v.39 no.2
• /
• pp.171-176
• /
• 2006

Objectives : The objective of this study is to assess the factors influencing biological monitoring of textile coating factory workers exposed to N,N-dimethylformamide(DMF). Methods : We studied 35 workers who were occupationally exposed to DMF from 9 textile coating factories. The study was carried out in two phases; summer and winter. While air concentration of DMF, temperature and humidity were assessed in order to monitor the atmospheric conditions, biological monitoring was done to determine the internal dose by analyzing the N-methylformamide(NMF) collected from urine at the beginning and end of the shift. Questionnaires and medical surveillance were also obtained during the two phases. Results : Median air concentrations of DMF in winter and summer were 1.85 ppm and 2.78 ppm respectively. Also the difference between the urinary NMF concentration at the beginning and end of the shift $({\Delta}NMF)$ was always significant in each season (P < 0.001). The correlations between log DMF in air, log end-of-shift urinary NMF (r=0.555, P < 0.001) and log ${\Delta}NMF$ (r = 0.444, P < 0.001) was statistically significant in summer. The temperature, humidity, a shift system and different styles of clothing worn were significantly different during the two phases. In a multivariate analysis, temperature and the concentration of DMF in the air were the main factors influencing biological monitoring of textile coating factory workers. Conclusions : Concerning more comprehensive prevention measures to reduce exposure for those workers occupationally exposed to DMF, dermal exposure conditions such as temperature and humidity together with the air concentration of DMF should be assessed and biological monitoring is necessary to reduce adverse health effects, especially during the summer.

• Analytical Science and Technology
• /
• v.26 no.5
• /
• pp.315-325
• /
• 2013

The possibility of acute hepatotoxicity caused by dimethylformamide (DMF) requires regular monitoring of the workers who are using DMF to prevent the occupational disease. The authors performed ambient and biological monitoring of workers involved in synthetic leather manufacturing processes using DMF to assess the correlation between the markers of ambient and biological monitoring of DMF. The authors monitored 142 workers occupationally exposed to DMF from 19 workshops in the synthetic leather and ink manufacturing industries located in northern region of Gyeonggi-do. The subjects answered questionnaire on work procedure and use of personal protective equipment to be classified by exposure type. DMF in air samples collected using personal air samplers, diffusive and active sampler, was analysed using gas chromatograph-flame ionization detector (GC-FID) with DB-FFAP column (length 30 m, i.d. 0.25 mm, film thickness 0.25 ${\mu}m$). Urinary N-methylformamide (NMF) was analysed using gas chromatograph-mass selective detector (GC-MSD) at selected ion monitoring (SIM) mode with DB-624 column (length 60 m, i.d. 0.25 mm, film thickness 1.40 ${\mu}m$). Geometric mean (GM) and geometric standard deviation (GSD) of the ambient DMF was $6.85{\pm}3.43$ ppm, and GM and GSD of urinary NMF was $42.3{\pm}2.7$ mg/L. The ratio of subjects with DMF level over 10 ppm was 44%, and those with urinary NMF over 15 mg/L was 87%. NMF in urine adjusted by DMF in air was $4.61{\pm}2.57$ mg/L/ppm and $9.50{\pm}2.41$ mg/L/ppm, respectively, with or without respirator. There was seasonal differences of NMF in urine adjusted by DMF in air, $7.63{\pm}2.74$ mg/L/ppm in summer and $4.53{\pm}2.29$ mg/L/ppm in winter. The urinary NMF concentration which corresponds to 10 ppm of ambient DMF was 52.7 mg/L (r=0.650, n=128). Considering the difference of the route of exposure which resulted from the compliance of wearing personal protective equipment, the estimated contribution of respiratory and dermal exposure route for DMF was 48.5% vs. 51.5%.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.20 no.4
• /
• pp.225-235
• /
• 2010

This study was aimed to assess the status of working environment, health care management status and cause of exposure in manufactories using dimethylformamide (DMF). For the purpose, airborne concentration of DMF in the workplaces and N-methylformamide (NMF) in worker's urine were measured with job type and process. In addition, management of local exhaust ventilation system (LEV) and personal protective equipment (PPE) was evaluated at 35 work places (107 workers) located in Busan and Gimhae area. Mean DMF concentrations in work places by job type and process were of high level measured in printing and record media reproduction (5.23 ppm) and flaking process (2.48 ppm). Workers in adhesive job were measured a large amount of urine NMF (21.59 mg/${\ell}$). 98.1% of DMF handling workers were provided respirators, but 67.3% of those workers used them. The main reasons for not using respirators were inconvenience and difficulty of breathing. Airborne concentrations of DMF were higher in the workplaces in which LEVs were working abnormally, but there was not statistically significant. In addition, the urine NMF levels were correlated with management of LEV within the workers who did not use the respirators (p<0.048). These results implied that LEV should be installed and maintained properly to protect the workers from the exposure to DMF. Management of PPE should be also necessary to protect the workers from chemical hazards.

• Safety and Health at Work
• /
• v.2 no.3
• /
• pp.229-235
• /
• 2011

Objectives: In this study, we summarized the External Quality Assessment Scheme (EQAS) for the biological monitoring of occupational exposure to toxic chemicals which started in 1995 and continued until a $31^{st}$ round robin in the spring of 2010. The program was performed twice per year until 2009, and this was changed to once a year since 2010. The objective of the program is to ensure the reliability of the data related to biological monitoring from analytical laboratories. Methods: One hundred and eighteen laboratories participated in the $31^{st}$ round robin. The program offers 5 items for inorganic analysis: lead in blood, cadmium in blood, manganese in blood, cadmium in urine, and mercury in urine. It also offers 10 items for organic analysis, including hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid, N-methylformamide, N-methylacetamide, trichloroacetic acid, total trichloro-compounds, trans,trans-muconic acid, and 2,5-hexanedione in urine. Target values were determined by statistical analysis using consensus values. All the data, such as chromatograms and calibration curves, were reviewed by the committee. Results: The proficiency rate was below 70% prior to the first round robin and improved to over 90% for common items, such as PbB and HA, while those for other items still remained in the range of 60-90% and need to be improved up to 90%. Conclusion: The EQAS has taken a primary role in improving the reliability of analytical data. A total quality assurance scheme is suggested, including the validation of technical documentation for the whole analytical procedure.

• Toxicological Research
• /
• v.29 no.3
• /
• pp.187-193
• /
• 2013

The effects of toluene in dimethylformamide (DMF)-induced hepatotoxicity were investigated with respect to the induction of cytochrome P-450 (CYP) and the activities of related enzymes. The rats were treated intraperitoneally with the organic solvents in olive oil (Single treatment groups: 450 [D1], 900 [D2], 1,800 [D3] mg DMF, and 346 mg toluene [T] per kg of body weight; Combined treatment groups: D1+T, D2+T, and D3+T) once a day for three days, while the control group received just the olive oil. Each group consisted of 4 rats. The activities of the xenobiotic metabolic enzymes and the hepatic morphology were assessed. The immunoblots indicated that the expression of CYP2E1 was considerably enhanced depending on the dosage of DMF and the CYP2E1 blot densities were significantly increased after treatment with both DMF and toluene, compared to treatment with DMF alone. The activities of glutathione-S-transferase and glutathione peroxidase were either decreased or remained unaltered after treatment with DMF and toluene, whereas the lipid peroxide levels were increased with increasing dosage of DMF and toluene. The liver tissue in the D3 group (1,800 mg/kg of DMF) showed signs of microvacuolation in the central vein region and a large necrotic zone around the central vein, in rats treated with both DMF (1,800 mg/kg) and toluene (D3T). These results suggest that the expression of CYP2E1 is induced by DMF and enhanced by toluene. These changes may have facilitated the accelerated formation of N-methylformamide (NMF) from toluene, and the generated NMF may directly induce liver damage.

• Analytical Science and Technology
• /
• v.13 no.2
• /
• pp.258-267
• /
• 2000

The result of five year's experience on Inter-laboratory Comparison for Analyses of Heavy Metals and Organic Solvent Metabolites in Biological Samples was described. Since 1995, around a hundred laboratories in the Occupational Health have participated this program twice per year by the Industrial Safety and Health Law. Four metals in blood and five organic solvent metabolites in urine were examined. Reference samples were made by spiking standard materials to human blood or urine pools treated previously to give homogeneity and stability for a specific time periods. Some reference samples for organic solvent metabolites were made from workers' urine who were exposed to the organic solvents. Some items such as Lead in blood and Hippuric acid in urine showed good accordance between participants while the other items such as Mercury and N-methylformamide in urine showed poor proficient rate. The results were published in the internet or newspaper to help the consumer of the laboratory's service to get the information on them and to make competition between them. The inter-laboratory's comparison program have done greate role to improve the ability of analysis and reliability of analytical data produced from each laboratory.