[Biological limit value for occupational exposure to N, N-dimethylacetamide].

OBJECTIVE: To establish Biological Limit Value (BLV) for N, N-dimethylacetamide (DMAC). METHOD: 201 workers in 3 spandex factories exposed to DMAC were recruited. Air samples were collected using personal air samplers, and urine samples from each works were collected at the end of shift at end of workweek. The urinary metabolite NMAC and air samples of DMAC were determined by gas chromatography (GC). Percentile and relative internal exposure (RIE) were analyzed and proposed a BLV for DMAC. RESULTS: The number of workers who exposure to DMAC below OELs were 133 (66.2%) among 201 workers monitored. Geometric mean (range) concentration of DMAC in air was 19.4 (0.40 ∼ 300.12) mg/m(3), and that of NMAC in urine was 23.7 (1.30 ∼ 189.42) mg/g Cr. A linear correlation was found between the personal air DMAC and creatinine-adjusted NMAC levels in urine collected at the end of shift at end of workweek (F = 188.872, R(2) = 0.487,P < 0.001). The relationship can be described by the equation Log (NMAC mg/g Cr) = 0.685 + 0.455 log (DMAC mg/m(3)). According to the equation the current China OELs value of 20 mg/m(3) would lead to a mean NMAC concentration of 18.92 mg/g Cr. The 90th percentile biomonitoring result below 20 mg/m(3) 8-hour TWA is 23.9 mg MMAC mg/g Cr, and that of NMAC in urine calculated by relative internal exposure (RIE) was 19.0 mg/g Cr. CONCLUSION: A BLV of 20 mg/g Cr NMAC in urine at the end of shift at end of workweek for DMAC was recommend by reference to official values from other countries.

[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.

[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.

[PCBs concentrations in human milk collected from a polluted area--exposure risk for feeding infants].

OBJECTIVE: To determine the concentration of PCBs and the distribution of dioxin-like compounds in human milk collected from a polluted area where discarded electronic equipment is dismantled, and to evaluate the risk for feeding infants. METHODS: The authors collected 20 and 12 milk samples from the polluted area and nearby town, respectively. Milk samples were analyzed for total PCBs (t-PCBs) by gas chromatography, and two mixed milk samples from the two areas were detected the distribution of dioxin-like compounds. RESULTS: t-PCBs in human milks of polluted area and control area were 0.39 - 3.92 microg/g fat and 0.46 microg/g (only one sample was detectable), respectively. The TEQ of PCB126 contribute to total TEQ of dioxin-like compounds was similar to other countries and regions. The TEQs of PCBs of the polluted and control area were 59 pg/g fat and 6 pg/g fat, respectively. CONCLUSION: The TEQ of PCBs of polluted area was much higher than other countries and regions, and the dioxin-like compounds intake of infants was much higher than the Tolerable Daily Intake (TDI) for dioxin recommended by WHO.