摘要:

Aqueous extracts of four brands (eight types) of rubber nursing nipples purchased in the open market were analyzed for volatileN‐nitrosamines, diphenylamine, and mutagenic activity. N‐Nitrosodimethylamine, N‐nitrosodiethylamine, orN‐nitro‐sopiperidine were found in the aqueous extracts of the nipples and in the nipples themselves. All nipples analyzed contained one or more of the three volatileN‐nitrosamines. Diphenylamine was found to be continously released into aqueous extracts from most brands. Certain nipples produced a positive mutagenic response when incubated withSalmonella typhimurium(TA 100) in a modified liquid suspension test.

ISSN:0098-4108    

DOI:10.1080/15287398309530332

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The toxicity of long‐term exposure to Mount St. Helens volcanic ash was studied in female B6D2F1mice. The mice, fed diets containing 10% ash, were observed for 43 wk. Exposure had no effect on hematology, plasma amino acid levels, food and water consumption, and urinary and fecal output. Mice fed the ash diet grew at a faster rate than mice maintained on the control diet. This increase was reflected in an increase in carcass and gastrointestinal tract weight. Lactic dehydrogenase was elevated throughout the observation period, but other clinical chemistries were normal. Mice suffered no apparent respiratory problems during the 43‐wk observation period. The ash had mixed effects on survival of B16 melanoma‐bearing mice. Sudden exposure and long‐term exposure (30 and 44 wk) in mice injected with a rapidly growing tumor did not affect survival. In contrast, mice implanted with a slow‐growing tumor at 7 and 15 wk of exposure exhibited decreased survival relative to control mice.

ISSN:0098-4108    

DOI:10.1080/15287398309530333

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Diesel‐exhaust‐particle extracts at nontoxic doses were evaluated in BALB/c mouse embryo 3T3 cells and Chinese hamster V‐79 lung cells for their ability to mimic the actions of the known tumor promoter tetradecanoyl phorbol acetate (TPA). The extracts were tested in a two‐stage model of carcinogenesis in 3T3 cells and found to marginally promote the occurrence of transformed foci over a concentration range of 2–10 μg/ml. The particle extracts also caused a loss of cell‐surface fibronectin and produced an increased saturation density of 3T3 cells. Using V‐79 cells, the extracts were found to inhibit metabolic cooperation between cells. Based on these results, it was concluded that diesel‐exhaust particles contain compounds that act as weak tumor promoters.

ISSN:0098-4108    

DOI:10.1080/15287398309530334

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Data for peripheral blood‐lead (PbB) levels for workers of four primary lead smelters in the United States were analyzed to characterize the patterns of PbB elimination. These workers had been removed from their job under the Medical Removal Protection (MRP) provision of the lead standard promulgated in 1978 by the Occupational Safety and Health Administration (OSHA). For each individual removed under the first or second year of the MRP provision, data for blood‐lead levels in relation to length of time removed were applied to four separate mathematical models, namely, linear regression, power curve fit, exponential curve fit, and logarithmic curve fit. The best model was determined by comparing overall correlation coefficients squared (r2) values derived from each model. Separate analyses were also made to test the relationship of PbB elimination rates to PbB levels at the time of the removal, length of occupational lead exposure, and job category. In addition, the duration of the medical removal time under the third‐year MRP provision for the primary lead smelter workers was estimated on the basis of the mathematical model that best fit the data. Based on analysis of data derived from MRP: (1) The exponential model (first‐order kinetics) most consistently and with the highest degree of correlation described PbB elimination patterns while workers were on MRP. (2) No significant relationship was observed between the rate of PbB decrease and (a) the length of employment prior to removal, (b) the preremoval PbB level, or (c) the job categories (skilled versus less skilled employees). (3) The necessary time period for medical removal under a 60/40 trigger would range from 2 to 4 mo for 50% of those removed and from 3 to 6 mo for 80% of those removed. These estimates are in general agreement with OSHA's 1978 estimate and with recent estimates by others.

ISSN:0098-4108    

DOI:10.1080/15287398309530335

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Rat pups taken from dams exposed to lead (Pb) at concentrations of 0, 5, 30, and 200 mg/l of drinking water from 14 d prior to breeding to 21 d postpartum display evidence of delayed maturation of the cerebral cortex. Delayed maturation was observed as an alteration in the ontogeny of metabolic responses of isolated cerebral tissues taken from rat pups of Pb‐treated dams to elevated K+concentrations. These responses were found to undergo substantial developmental changes between 6 and 50 d of postnatal age. The delay in development was most marked with respect to the development of the late reduction of NAD(P)1, which occurs in response to an increase of media K+concentration from 3 to 30 mM. Delays in the development of this response were observed as late as 50 d of age, but assumed the adult pattern by 90 d of age.

ISSN:0098-4108    

DOI:10.1080/15287398309530336

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Potassium dichromate [Cr(VI), hexavalent chromium] and chromic chloride [Cr(III), trivalent chromium] were added to tissue cultures of Chinese hamster ovary (CHO) cells. Cr(III) at 10 μM did not significantly affect cell proliferation. On the other hand, 10 and 1 μM Cr(VI) inhibited cell proliferation, while 0.1 μM did not. Addition of ascorbic acid (50 μg/ml), for periods up to 6 h after Cr(VI), effectively reversed the antiproliferative effects of Cr(VI). Several sulfhydryl‐containing agents, under similar conditions, were ineffective. Cr(III) at 10 μM did not induce sister chromatid exchanges (SCEs) in cultured CHO cells. On the other hand, Cr(VI) did; there was a dose‐response in the SCE induction by Cr(VI) between 0.01 and 1 μM Cr(VI). Addition of ascorbic acid, for periods up to 4 h after Cr(VI), reversed Cr(VI)‐induced SCEs. We suggest that the genotoxic effects of Cr(VI) (i.e., SCE induction) may be causally related to the antiproliferative effects that we observed.

ISSN:0098-4108    

DOI:10.1080/15287398309530337

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Nine phenolic chelating agents were examined as antidotes for acute uranyl acetate intoxication. The ability of these compounds to promote survival was determined and the ability of two of them to remove uranium from the liver and kidney was compared with that of Na3CaDTPA. The most effective compounds of this type in promoting survival were found to be Tiron and p‐aminosalicylic acid, but Tiron was much more effective in decreasing the uranium burden of the liver and kidneys. These compounds exhibit an antidotal action at higher uranium levels than the compounds reported in earlier studies. The compounds all seem to possess a very modest toxicity when administered ip.

ISSN:0098-4108    

DOI:10.1080/15287398309530338

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Seventy‐six fathead minnows were exposed to 12 ppm cadmium for 96‐ h and examined histologically at 1‐wk intervals for 30 d. Thirteen fish (17.1%) died during the exposure period. Lesions associated with acute cadmium toxicity were epithelial necrosis of the skin, oral cavity, gills, olfactory organs, kidney, urinary bladder, ureters, gastrointestinal tract, and hemopoietic organ. The lesions were most severe in fish which died. Survivors had similar but less severe and less extensive lesions. Residual minimal to mild multifocal necrosis was observed In gastrointestinal, branchial epithelium and and hemopoietic tissue up to 29 d postexposure. Radiotracer studies in 50 fish using115Cd demonstrated a rapid uptake and two phase elimination of cadmium by the fish. Rapid elimination of cadmium occurred within 7 wk and was correlated with lesions in the urinary epithelium. Slow phase elimination occurred for at least 3 wk and was correlated with persistant minimal necrosis in several tissues.

ISSN:0098-4108    

DOI:10.1080/15287398309530339

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Following a 10‐min near‐field exposure to sham radiation of 2.45 GHz microwave (MW) radiation at a power density of 10 mW/cm2, male Swiss‐Cox mice were injected with sodium phenobarbital (PB) (150 mg/kg, iv) and the onset and duration of PB‐induced sleep were recorded. MW‐pretreated mice exhibited a decreased PB sleep onset relative to sham when PB was administered 1 to 45 min following irradiation; however, no effect was seen by 24 h. The duration of PB‐induced sleep was increased; however MW pretreatment did not affect the duration of hexobarbital‐ or pento‐barbital‐induced sleep. At the time of onset of PB‐induced sleep, PB concentrations in brain of MW‐irradiated and control groups were the same despite a twofold difference in the time to sleep onset between these groups. But, when measured 5 min following PB injection, the PB concentrations in brain were higher in MW‐pretreated mice, suggesting that a dispositional mechanism accounted for the observed MW effects on PB‐induced sleep. Mice heated for 10 min by an incandescent light bulb served as thermal controls, and under certain conditions exhibited an increase in duration of PB sleep and enhanced brain disposition of PB. The effect of MW exposure on PB sleep onset was also influenced by ambient temperature. The data suggest that MW exposure affects PB‐induced sleep by enhancing the disposition of PB to the brain and that these effects result in part from thermal effects.

ISSN:0098-4108    

DOI:10.1080/15287398309530340

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

To gain experience in thein vitroassay of environmental teratogens, 32 pesticides and TCDD have been tested for their ability to Inhibit tumor cells attachment to polyethylene disks coated with concanavalin A. Of 25 pesticides that inhibited attachment, 23 (92%) have been reported to be teratogenic in mammals or avians. From a qualitative viewpoint, agents that inhibit attachmentin vitroare very likely to be teratogenicin vivo.There was a quantitative correlation between the inhibitory activity and the lowest reported teratogenic dose in chick embryo for nine pesticides. However, no similar correlation between inhibitory concentration, in vitro,and mammalian teratogenicity was found. Presumably maternal effects of absorption, metabolism, and distribution distort the relationship between the dose administered to the mother and the concentration of teratogenic agent at target embryonic tissues. Lack of inhibitionin vitrodid not indicate lack of teratogenicity, as five of eight noninhibitory agents have been reported to be teratogenicin vivo.Such false negatives of the attachment assay may be detectable in complementaryin vitrotests.

ISSN:0098-4108    

DOI:10.1080/15287398309530341

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor