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Worker exposure to N,N-dimethylacetamide (DMAC) in an acrylic fiber manufacturing facility was measured, over a 1-year study period, by full-shift (12 hours) personal air monitoring for DMAC and by biological monitoring for levels of DMAC, N-methylacetamide (MMAC), and acetamide in spot urine samples. Ninety-three of 127 male workers in seven job classifications in the solution preparation and spinning departments of the plant were monitored on the second consecutive workday after at least 3 days off for the first 10 months of the study and on both the first and second days during the study's final 2 months. Postshift urinary MMAC levels were significantly correlated (P < .0001, r2 = .54) with DMAC in air levels. An air level of 6.7 ppm 12-hour time-weighted average (TWA) corresponded to a urine MMAC level of 62 mg/g creatinine in a postshift spot urine sample obtained after the second consecutive workday. To minimize exposure misclassification due to variability in the regression relationship, a level of 35 mg MMAC/g creatinine in a postshift spot urine sample was recommended as a biomonitoring index. Postshift urine MMAC levels did not appear to plateau at higher air levels, nor did it appear that the DMAC demethylation metabolic mechanisms became saturated at threshold limit value (TLV)-level air-exposure levels. Urine MMAC levels in postshift samples obtained the second workday appeared to be greater than levels in postshift first-day samples, but the number of days until this postshift level would plateau could not be determined from this study.(ABSTRACT TRUNCATED AT 250 WORDS)

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Worker exposure to N,N-dimethylacetamide (DMAC) in an acrylic fiber manufacturing facility was measured, over a 1-year study period, by full-shift (12 hours) personal air monitoring for DMAC and biological monitoring for levels of DMAC, N-methylacetamide (MMAC) and acetamide in post-shift spot urine samples. Evidence of liver toxicity was assessed by serum clinical chemistry tests (serum levels of total bilirubin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and gamma-glutamyl transpeptase) at least once during the study period for all 127 male workers in the two study departments and for 217 male in-plant controls with no previous or current exposure to DMAC. If a worker's biomonitoring results exceeded one of two "trigger" values established for the study (60 mg MMAC/g creatinine or 136 mg DMAC equivalent/g creatinine), additional serum clinical chemistry tests were conducted at weekly intervals for 3 weeks. DMAC-exposed workers were classified as either high exposure, if one or more biomonitoring result exceeded one of the trigger values, or unspecified exposure if none of them did. Control-group employees were classified as no-exposure. Mean DMAC in air levels for the high- and unspecified-exposure groups appeared to differ (geometric mean DMAC in air levels of 1.9 and 1.3 ppm 12-hour time-weighted average, respectively). No significant DMAC exposure-related trends in hepatic serum clinical chemistry results were detected. Neither transient increases in serum analyte levels after a "high" biomonitoring result (one that exceeded a trigger value) nor an elevated mean level over the study period when compared with in-plant controls were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

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The composition of animal communities developing from planktonic larvae in aquariums. A marked increase in the abundance of the annelid Polydora ligni in aquariums containing sand and flowing estuarine water was altered in the presence of the carbamate insecticide Sevin (carbaryl). Treatments were control and concentrations of Sevin that averaged 1.1, 11.1, and 103 micrograms/l; each treatment was replicated 8 times. Animals that colonized aquarium sand were collected in a 1-mm mesh sieve after 10 wk of exposure. Mollusks' arthropods, annelids, and nemerteans were the numerically dominant phyla. The average number of species per aquarium was significantly less (alpha = 0.05) in aquariums containing 11.1 or 103 micrograms/l than in those containing 1.1 micrograms/l or in control aquariums. The abundant clam Ensis minor grew significantly less in length at the higher concentrations of Sevin. The amphipod Corophium acherusicum was particularly affected; significantly fewer were found at all concentrations than in the control aquariums containing 103 micrograms/l corresponded to a marked decrease in the number of other annelids and to a significant absence of nemerteans.

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