摘要:

Bioconcentration factors (BCF) or bioaccumulation factors (BAF) reported for 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD or dioxin) in aquatic environments encompass a wide range of values, from less than 1000 to 189,000 I/kg. These values are based on concentrations of TCDD in various environmental media including water, sediment, or food. Under the Federal Water Pollution Control Act and its enabling regulations (40 CFR 700–740, 400–470), point source discharge limits are established so that the nominal receiving water concentration will not exceed the water quality criterion. To be consistent with this regulatory process, the water quality criterion should also be calculated using an accumulation factor that is based on a nominal water concentration. The regulatory process for developing a water quality criterion for TCDD requires the selection of a BAF that describes the relationship between the source to be regulated and the fish tissue concentration.

ISSN:0098-4108    

DOI:10.1080/15287399209531666

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A mouse preimplantation embryo culture system was utilized to characterize the in vitro embryotoxicity of petroleum creosote (PC), a complex mixture of aliphatic and polycyclic aromatic hydrocarbons. ICR mouse embryos, collected on d 3.5 of gestation (blastocyst stage), were exposed for 7 h to varying concentrations of petroleum creosote in serum‐supplemented culture medium. Parallel embryo cultures were exposed to PC in medium supplemented with rodent hepatic S9 micro‐somal fractions to monitor the role of bioactivation in PC‐induced embryotoxicity. Embryos were subsequently cultured in control medium for 72 h and observed for viability as well as specific, time‐dependent developmental end points—hatching and attachment to the culture dish at 48 h, and trophoblastic outgrowth with a distinct inner cell mass at 72 h. Embryonic viability varied in inverse proportion to PC concentration. Petroleum creosote caused embryolethal effects at concentrations of 33 μg/ml of culture medium and 54 μg/ml. Embryotoxicity was not observed at 22 μg/ml. Culture supplementation with rodent hepatic S9 fractions did not modify, either qualitatively or quantitatively, the embryotoxicity of PC in vitro. These findings implicate PC as a prenatal toxicant and support environmental and human health concerns regarding PC exposure from PC‐containing chemical waste sites.

ISSN:0098-4108    

DOI:10.1080/15287399209531667

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A recirculating multispecies test system was developed in conjunction with a study of the fate and persistence of a model microbial pest control agent on non‐target marine and freshwater organisms. The basic unit of the system was a 113‐/ glass aquarium with vertical biological filters in the center of the aquarium, such that two compartments were formed. This allowed the sequestration of predator and prey species within the same system. Organisms from six phyletic groups were subjected to a genetically altered strain of Pseudomonas putida for 15–29 d in either artificial seawater or fresh water. The system was able to maintain the animals for these periods with a minimum of maintenance. Additionally, the system design lent itself to disinfection, dismantling, and rebuilding between experiments with a minimum of labor, and has potential for longer‐term studies.

ISSN:0098-4108    

DOI:10.1080/15287399209531668

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An automated system was developed for evaluating changes in respiratory symptoms in guinea pigs over a long period with a personal computer. The data on breathing curves obtained with a body plethysmograph were analyzed to determine respiratory rate, expiration/inspiration ratio, ventilation ratio, and other parameters. With this system, respiratory changes in guinea pigs, such as increase or decrease of respiratory rate, expiration/inspiration ratio, and ventilation ratio, and death of animals could be easily observed.

ISSN:0098-4108    

DOI:10.1080/15287399209531669

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Residues of toxic chemicals in human tissues and fluids can be important indicators of exposure. Urine collected from a subsample of the second National Health and Nutrition Examination Survey was analyzed for organochlorine, organophos‐phorus, and chlorophenoxy pesticides or their metabolites. Urine concentration was also measured. The most frequently occurring residue in urine was penta‐chlorophenol (PCP), found in quantifiable concentrations in 71.6% of the general population with an estimated geometric mean level of 6.3 ng/ml. Percent quantifiable levels of PCP were found to be highest among males. Quantifiable concentrations of 3,5,6‐trichloro‐2‐pyridinol (5.8%), 2,4,5‐trichlorophenol (3.4%), para‐nitrophenol (2.4%), dicamba (1.4%), malathion dicarboxylic acid (0.5%), malathion alpha‐monocarboxylic acid (1.1%), and 2,4‐D (0.3%) were found, but at much lower frequencies. No quantifiable levels of 2,4,5‐T or silvex were found. Preliminary analyses showed an apparent relationship between residue concentration and two measures of urine concentration (osmolality and creatinine). A large segment of the general population of the United States experienced exposure to certain pesticides, including some considered biodegradable, during the years 1976–1980.

ISSN:0098-4108    

DOI:10.1080/15287399209531670

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Fischer 344 rats were exposed to three concentrations of exhaust generated by an M85 methanol‐fueled engine (methanol with 15% gasoline) without catalyst for 8 h/d, 7 d/wk for 7, 14, 21, or 28 d. Concentration‐ and time‐dependent yellowing of the fur was prominent in all treated groups. Concentration‐dependent increases in the erythrocyte count, hematocrit, hemoglobin concentration, formaldehyde in plasma, and carboxyhemoglobin in the erythrocytes, and decrease in serum alkaline phosphatase activity were seen after all exposure periods. Histopathologically, lesions were found in the nasal cavity and lungs after 7 d of exposure. Squamous metaplasia of the respiratory epithelium of level 1 (level of the posterior edge of the upper incisor teeth) lining of the nasoturbinate andlor maxilloturbinate and infiltration of neutrophils into the submucosa, and decreases of Clara cells in the terminal bronchiolus and of cilia in the bronchiolar epithelium, were observed in the high‐concentration group (carbon monoxide, 94 ppm; formaldehyde, 6.9 ppm; methanol, 17.9 ppm; nitrogen oxides, 52.7 ppm; nitrogen dioxide, 10.6 ppm). The histopathological extents of several lesions increased slightly with the exposure time. Slight squamous metaplasia and hyperplasia of the respiratory epithelium at level 1 were also observed in the medium‐concentration group (one in three of the high‐concentration group). No histopathological changes were found in the olfactory epithelium of the nasal cavity. In the low‐concentration group (one in nine of the high‐concentration group), no marked histopathological changes in these organs were observed. These results may suggest that the lesions observed in the nasal cavity of rats exposed to methanol‐fueled engine exhaust were mainly caused by formaldehyde, although other components in the exhaust also may have affected nasal cavity andlor lungs to less extent.

ISSN:0098-4108    

DOI:10.1080/15287399209531671

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Picric acid (2,4,6‐trinitrophenol) is widely used in industry, by the military, and as a research/clinical chemistry reagent. Characterization of the toxicity of this chemical has been limited. Thus the acute toxicity, distribution, and metabolism of picric acid were investigated using Fischer 344 rats. The LD50 for picric acid following oral dosing of male and female rats was established as 290 and 200 mg/kg, respectively. Blood gas analysis indicated severe acidosis during acute intoxication. Metabolism of picric acid was limited to reduction of nitro groups to amines. Metabolites isolated from urine included N‐acetylisopicramic acid (14.8%), picramic acid (18.5%), N‐acetylpicramic acid (4.7%), and unidentified components (2.4%). Approximately 60% of the parent picric acid was excreted unchanged. The plasma half‐life for picric acid was 13.4 h with a gut absorption coefficient (ka) of 0.069 h−1. Twenty‐four hours following oral administration of [14C]picric acid (100 mg/kg), the primary depots of radioactivity (per gram tissue basis) were blood, spleen, kidney, liver, lung, and testes. Respective tissue/blood ratios were 0.37, 0.31, 0.28, 0.26, and 0.22. All other tissue assayed had partition ratios < 0.20, with brain and adipose tissue having the least amount of radioactivity. Tissue/blood ratios wereessentially maintained over a 48‐h postadministration period. Binding (in vitro) of [14C]picric acid to plasma proteins (whole blood preparations) demonstrated both high‐ and low‐affinity binding sites, with dissociation constants of 3.18 × 10−6and 2.85 × 10−4M, respectively. The findings of this investigation provide information on the acute toxicity, metabolism, and distribution of picric acid, which can be used in risk assessment analyses and in the design of subchronic and chronic toxicity tests.

ISSN:0098-4108    

DOI:10.1080/15287399209531672

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A series of experiments was conducted to determine the feasibility of using mice to screen for possible dietary mycotoxin interactions before testing them with swine. Selected mycotoxins, deoxynivalenol (DON) and T‐2 toxin, were fed to young mice, alone and in combination. The severity of effects on body weights caused by DON (0–20 mg OONIkg diet) was more pronounced in a doss‐related manner when the animals were exposed to contaminated diets starting at 21 d of age than at 28 d (Experiment 1) as reflected in the analysis of variance. The relative variance among diets after 7 d was twice as great for the younger than for the older mice. In both age groups, the weight gain response was linear, similar to that seen in growing swine. In Experiment 2, a significant (p < .05) diet type × DON interaction for food consumption evident after 7 d, indicated that the effect of DON depended on the type of diet (freeze‐dried vs. regular mash). There was no difference in food efficiency between diet type, but a strong dose‐dependent effect due to DON was observed. When DON and T‐2 toxin were fed together to young mice, a significant (p < .001) linear decrease in weight gain and food consumption was observed after 7 d on the contaminated diet as the toxin concentration increased.

ISSN:0098-4108    

DOI:10.1080/15287399209531673

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Metabolites of ethoxyquin (EQ, 1,2‐dihydro‐6‐ethoxy‐2,2,4‐trimethylquinoline) in the urine of sheep and rats were separated and identified by gas chromatography‐mass spectrometry (GC‐MS). Sheep were given diets containing EQ or EQ · HCI (0.5% of total diet) and urine samples were collected for the first 24 h and for another 24‐h period after 12 d of feeding. Rats were given EQIcorn oil (0.08 g EQ/d/ rat) orally for 7 d and urine samples were collected at ambient temperature for a 24‐h period following 6 d of dosing. The urine samples were extracted with ethyl acetate at pH 5, and the concentrated extracts were analyzed by GC‐MS. Ethoxyquin was identified in all sheep urine samples collected during the first 24 h of feeding, and EQ and hydroxylated EQ were identified in all urine samples collected after 12 d of feeding. In contrast, EQ, hydroxylated EQ, and dihydroxylated EQ were identified in urine collected from rats fed EQ for 7 d.

ISSN:0098-4108    

DOI:10.1080/15287399209531674

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0098-4108    

DOI:10.1080/15287399209531665

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor