[The analysis of urinary N-methylacetamide by GC-NPD with a direct injection].

OBJECTIVE: To establish a method to detect N-methylacetamide (NMAC) concentration in urine of workers occupationally exposed to NMAC with directly injecting the sample into capillary gas chromatography. METHODS: After frozen urine samples were isolated from precipitation by centrifugation, the aliquot of supernatant was pretreated by protein precipitation with dilution of methanol. The methanol supernatant was separated by Polyethylene Glycol (PEG) capillary columns and detected by nitrogen phosphorous detector (NPD). RESULTS: Good linearity was obtained in the concentration range of 1.0 ∼ 250 mg/L. The correlation coefficient was 1.0000. The minimum detection limit of NMAC in urine was 0.2 mg/L. The method recovery rates were 96.0% ∼ 99.4% at three different concentrations. The mean recovery rate was 97.8%. The relative standard deviations (RSD) of intra- and inter-day were between 1.5% ∼ 3.4%. CONCLUSION: The method was simple, rapid, selective and sensitive and was applicable to detect the urinary NMAC concentration for monitoring occupational exposure levels.

[The interventions effect-assessment of the workers exposed to N, N-dimethylformamide by percutaneous in a synthetic leather factory].

OBJECTIVE: To assess the effects of interventions on synthetic leather workers exposed to N, N-dimethylformamide (DMF) by skin. METHODS: Twenty-six workers exposed to DMF were recruited. The level of DMF in ambient or handwash solution and N-methylformamide (NMF) in end-shift urine samples were detected before interventions and after interventions for six months. RESULTS: After interventions the levels of DMF in ambient reduced 52.7% from (63.27 +/- 52.67) mg/m3 to (29.95 +/- 23.79) mg/m3. The levels of NMF in urine samples reduced 17.9% from (2.07 +/- 0.32) mg/g Cr to (1.70 +/- 0.29) mg/g Cr (P < 0.01). The mean level of DMF in handwash solution reduced 53.4% from 0.88 +/- 0.40 mg to 0.41 +/- 0.81 mg. CONCLUSION: This study showed that the multi-intervention measures (engineering control, personal protection and health promotion) should be used for the synthetic leather workers occupationally exposed to DMF.

[Determination of trimethyltin chloride in urine by headspace-gas chromatography].

OBJECTIVE: To establish a detection method for trimethyltin chloride in urine by the Head space-GC. METHOD: After derivatizing trimethyltin chloride, the urines was separated by the head space-gc, and then the trimethyltin chloride detected qualitatively and quantificationally. RESULTS: In the concentration range of 0.02 ∼ 0.40 mg/L urinary trimethyltin chloride, showed a quadratic, r = 0.9992, detection limit was 0.005 mg/L, the relative standard deviation was 1.9% ∼ 2.5%, recovery was 92.0% to 100%, the urine samples can be saved at least 90 days in -18°C refrigerator. CONCLUSION: The instrument, reagents involved in the detection require low, the operations to processing samples are simple, high sensitivity, less interference, good reproducibility, and suitable for quantitative and qualitative analysis, convenient to promotion.

[The impact of N, N-dimethylacetamide on the health of workers].

OBJECTIVE: To explore the hepatic toxicity and the exposure biomarkers of N, N-Dimethylacetamide. METHODS: One hundred forty five objects were chosen by stratified random sampling method. The investigation was performed using questionnaire and physical examination. The air concentrations of DMAC in the workshops were monitored. The urine samples were collected and analyzed after work everyday or at the weekend. The correlation between the air concentrations of DMAC in the workshops and the concentrations of urinary NMAC wee analyzed by regression. RESULTS: The air concentration of DMAC in the spinning workshop was higher than others. The morbidity of abnormal hepatic function was 12.4%, 61.1% of workers with abnormal hepatic function appeared in one year after exposure to DMAC in the workshops ( r=0.44, P<0.01). CONCLUSION: The abnormal heptic function was found in workers exposed to DMAC for short period. The concentration of urinary NMAC can serve as the exposure biomarker of DMAC.

[The protein expression profiles induced by trimethyltin chloride in Vero cells].

OBJECTIVE: To explore the biomarkers and mechanism of kidney toxicity induced by trimethyltin chloride (TMT-Cl) through analyzing the differences of protein expression profiles between vero cells and vero cells exposed to TMT-Cl. METHODS: The differences of protein expression levels of three paired samples of vero cells and vero cells exposed to TMT-Cl were compared by two-dimensional gel electrophoresis (2-DE) and liquid chromatography-electrospray ionization-linear trap quadrupole (LC-ESI-LTQ). The differences of expression levels of Annexin A1 and α-Tubulin proteins were validated with western blot assay, and the differences of mRNA expression levels of Annexin A1 and α-Tubulin genes were detected with quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). RESULTS: Fifteen spots of differential expression in protein profiles between vero cells and vero cells exposed to TMT-Cl were found, and 9 of these spots were identified by LC-ESI-LTQ. The expression levels of 3 proteins (Annexin A1,similar to RAN protein and a hypothetical protein) increased and the expression levels of 6 proteins(growth factor receptor-bound protein 10, tubulin alpha 6, heterogeneous nuclear ribonucleoprotein, similar to elongation factor SIII p15 subunit, S-adenosylhomocysteine hydrolase and a hypothetical protein) reduced. The expression levels of α-Tubulin protein and mRNA significantly decreased in vero cells exposed to TMT-Cl, as compared with vero cells (P < 0.01). The expression of Annexin A1 protein in all exposure groups was significantly up-regulated, the expression of Annexin A1 mRNA in the groups exposed to 25 and 50 µmol/L TMT-Cl was significantly down-regulated, and The expression of Annexin A1 mRNA in the group exposed to 100 µmol/L TMT-Cl was significantly up-regulated (P < 0.01). CONCLUSIONS: The results of present study suggest that 9 proteins with differential expression detected by LC-ESI-LTQ may be related to the kidney toxicity induced by TMT-Cl, which can serve as the biomarkers of early diagnosis and therapeutic effect for the kidney toxicity induced by TMT-Cl.

[Investigation on dermal contamination among workers occupationally exposed to dimethylformamide].

OBJECTIVE: To establish a method for the determination of dimethylformamide (DMF) and investigate dermal contamination and absorption among workers occupationally exposed to DMF. METHOD: 37 workers exposed to DMF were divided randomly into two groups. DMF was washed down by isopropyl alcohol in A group (16 workers) and water in B group(21 workers).Gas chromatography was used for the quantification of dermal contamination and N-methylformamide(NMF) in urine, correlative study was done between them. RESULTS: DMF could be detected in all samples in A group, but could not be detected in B group. The miscellaneous peaks could be completely separated from the DMF peak in the sample spectrum, without manual inference. The highest degree of total dermal contamination was observed in wet spinning workshop [(2.84 +/- 1.31) mg], postprocessing workshop [(2.50 +/- 0.95) mg] and dry spinning workshop [(1.95 +/- 0.61) mg] were lower. The respiratory cumulative exposure dosages were 351.3, 201.3 and 135.2 mg respectively. The average DMP concentration in air of the third printing processing workshop, the dry spinning workshop and the wet spinning workshop was 60.2, 89.6, 156.4 mg/m3 respectively, and the respiratory tract contamination in the workers of the three workshops were 135.2, 201.3 and 351.3 mg respectively. There was statistical independence between the quantification of total dermal contamination and NMF in urine (r = 0.176, P > 0.05). CONCLUSION: Isopropyl alcohol is the effective washing solvent.When the concentration of DMF in workplace air is above the occupational exposure limit, respiratory tract absorption is the principal pathway of DMF absorption,but dermal contamination of DMF should not be ignored.

[Abnormal liver function associated with polymorphism of GSTT1, GSTM1 and CYP2E1 in workers exposed to N, N-dimethylformamide].

OBJECTIVE: To investigate abnormal liver function associated with polymorphism of GSTT1, GSTM1 and CYP2E1 in workers exposed to N, N-dimethylformamide. METHODS: Sixty-nine workers with abnormal liver function in a synthetic leather factory were recruited as case. One hundred and twenty five control subjects with similar work tasks were selected from the same factory. Genotypes for GSTT1 and GSTM1 were determined by multiplex PCR, and for CYP2E1 PstI by PCR-RFLP assay. RESULTS: The frequency of positive GSTM1 was 59.42% in cases and 38.40% in control, with an odds ratio (OR) of 2.34,95% CI: 1.29-4.29 (P=0.005). For GSTT1 and CYP2E1 PstI, the frequencies of genotypes showed no significant difference between case and control. CONCLUSION: GSTM1 positive genotype may be genetic risk factors for development of abnormal liver function in workers exposed to N, N-dimethylformamide.

[Biological monitoring of workers exposed to trimethyltin chloride].

OBJECTIVE: To investigate suitable biomarkers for workers exposure to trimethyltin chloride (TMT-cl). METHODS: Urinary samples of 44 male workers from five TMT-cl occupational poisoning incidents were collected. Methyltin mercaptide stabilizers and waste plastics used in the incidents were also collected. The levels of TMT-cl in all the samples were determined by gas chromatography. The concentration of blood potassium for each poisonings was determined compared to control group (50 male workers of a food company), and the correlation between blood potassium and urinary TMT-cl were also determined. RESULTS: TMT-cl was detected in urine of all the poisonings. The results were (0.869 +/- 0.392) microg/L (severe poisoning), (0.963 +/- 0.482) microg/L (moderate poisoning), (0.716 +/- 0.384) microg/L (mild poisoning) respectively and the difference was statistically significant (P < 0.01). But the severity of the clinical status did not seem to be closely correlated to the level of urinary TMT-cl (F = 1.88, P > 0.05). In the severe poisonings, there were no differences in urinary TMT-cl on day 4 after poisoning from day 1 (P > 0.05). In contrast, urinary TMT-cl was decreased significantly on day 4 than on day 1 in mild and moderate poisonings (P < 0.01). On day 21, levels of urinary TMT-cl of all the poisonings were higher than those of the workers exposed to TMT-cl who had no clinical status (P < 0.01). Blood potassium levels of exposed group was 77.3% which was significantly lower than normal value (P < 0.01). The concentration of blood potassium was lower than normal value (3.5 mmol/L) and was correlated with the severity of the clinical status (F = 4.45, P < 0.05). Level of urinary TMT-cl of exposed group was negatively correlated with blood potassium (r = -0.4456, P < 0.01). CONCLUSION: Level of urinary TMT-cl can be used as exposure biomarker of TMT-cl poisoning. Blood potassium is an early biomarker of effect for TMT-cl poisoning so as to find poisoning population early.

[Abnormal liver function associated with occupational exposure to N, N-dimethylformamide in synthetic leathers works].

OBJECTIVE: To investigate the hepatotoxic effects of N, N-dimethylformamide (DMF) in the workers of a synthetic leathers factory, and the effects on liver function of covariates such as alcohol consumption and other factors. METHODS: The workers were classified into three groups (low, high and the control) by the concentration of DMF in workplace which was determined in the past two years. A questionnaire was drawn up for relevant demographic characteristics and other factors influencing liver function. The bloods were collected for laboratory test which included parameters especially relevant to the liver (ALT AST and gamma GT). RESULTS: Low and high-exposure groups were significantly associated with elevated ALT and gamma GT, and high-exposure group was significantly associated with elevated Liver index. Modeling by stepwise regression analysis demonstrated that high concentration of DMF and BMI were associated with and elevated ALT, gamma GT and Liver index, besides DMF and BMI, the elevation of ALT was also associated with high TRIG. AST was only associated with alcohol consumption. The AST/ALT ration < 1 was present in 86.7% of the exposure workers of liver function abnormal. CONCLUSION: DMF can cause liver function alternations even if air concentration of DMF was below PC-TWA. Besides the levels of DMF exposure, obesity (BMI) and alcohol consumption are covariates alternating liver function. Liver index can be a parameter for assessment liver function, and the AST/ALT ration < 1 may serve as markers of risk in health screening programs.