摘要:

Indoor radon concentrations in northern Virginia and central Maryland show a strong dependence on weather. Winter tends to be associated with higher than average indoor radon, and summer with lower than average. However, compared to the winter of 1986–1987, the winter of 1987–1988 was warmer and drier. Consequently, winter‐to‐winter indoor radon decreased by about 25%. This winter‐to‐winter decrease is unexpectedly large, and simulates winter‐to‐summer variations that have been reported.

ISSN:0098-4108    

DOI:10.1080/15287398909531335

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The aim of this experiment was to test whether a chelating agent, D‐myo‐inositol‐1,2,6‐trisphosphate (PP56), could reverse cadmium‐induced hypertension. Four groups of weanling female Long‐Evans rats received ad libitum a rye‐based, metal‐poor diet and deionized water fortified with essential metals for 15 mo from the time of weaning. A control group received neither cadmium nor chelating agent. A second group had 0.1 ppm cadmium added to their water from weaning through mo 5. A third group had 60 ppm PP56 added to their water for mo 6–10. The fourth group had 0.1 ppm cadmium added to their water from weaning through mo 5 and 60 ppm PP56 from mo 6–10. All groups were followed without either cadmium or PP56 for mo 11–15. At approximately monthly intervals, systolic pressure was measured by the indirect tail cuff method in unanesthetized rats.

ISSN:0098-4108    

DOI:10.1080/15287398909531336

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Dermal absorption of the insecticide lindane (1δ, 2δ, 3β, 4b, 5δ, 6β‐hexachlorocyclo‐hexane) was determined in rats and rhesus monkeys. Lindane is in widespread use as a 1% cream or lotion scabicide formulation and as a 1% miticide shampoo for body lice control in humans. Results obtained following our in vivo dermal absorption procedure demonstrated that 18 ± 4.1%, 34 ± 5.2%, and 54 ± 26.3% of the applied dose was absorbed following topical applications at a rate of 1.5 μg/cm2(6.2 μg/100 μl of acetone) of the14C‐labeled pesticide to 4.2‐cm2regions of the forearm (n= 8), forehead (n= 7), and palm (n= 4) of rhesus monkeys, respectively. Dose sites were washed with soapy water 24 h posttreatment. Comparative studies in rats (n= 5) dosed middorsally demonstrated 31 ± 9.5% absorption. Statistical analysis of the14C excretion kinetics demonstrated slower clearance of lindane from rats than monkey forearm, forehead, or palm. Intramuscular (im) injections of14C‐lindane gave 52 ± 7.1% recovery in monkey (n= 8) and 64 ± 5.9% in rats (n= 5), suggesting body storage of this lipophilic chemical.

ISSN:0098-4108    

DOI:10.1080/15287398909531337

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Baseline conditions for sample handling, processing, chemical extraction, and chemical analysis of chewing tobacco were established. The chemical solubility patterns for cadmium, copper, nickel, selenium, and zinc in several commercial brands of chewing tobacco were determined. Five extractants were used: water with pH value of 3.0, pH value of 5.4, and pH value of 6.5; amylase (0.1%) and methanol (99.9%). The bulk of the total cadmium, copper, nickel, and zinc in the tobacco samples was in a tightly bound form not extracted to any appreciable degree by the solvents used. Selenium was below detectable limits for each of the extractants. It has been reported that copper and zinc may counter the carcinogenic effects of cadmium and nickel. The extractants solubilized a greater amount of copper and zinc than cadmium and nickel from the total metal present in the chewing tobacco.

ISSN:0098-4108    

DOI:10.1080/15287398909531338

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Forty‐one persons with a history of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) exposure and measured adipose tissue TCDD levels were evaluated for potential health effects. No pattern of clinical abnormalities emerged related to TCDD levels.

ISSN:0098-4108    

DOI:10.1080/15287398909531339

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The short‐term inhalation toxicity of a medium‐boiling coal liquefaction product (CLP) was investigated in the rat. Groups of 5 male and 5 female Sprague‐Dawley rats were exposed to CLP aerosols at 25 mg/m3(low dose) or 100 mg/m3(high dose) 6 h/d, 5 d/w, for 4 wk. The control group was exposed to filtered air while the positive control received diesel fuel aerosols at 100 mg/m3. Male rats exposed to high‐dose CLP aerosols exhibited growth depression and increased hepatic aminopyrine de‐methylase activity compared to control animals. High‐dose females had decreased hemoglobin content and hematocrit values. These biochemical and hematological effects were not observed in animals of either sex treated with the diesel fuel. No other biochemical and hematological changes were observed. Mild histological changes occurred in the liver and thyroid of rats treated with CLP and diesel fuel aerosols. Based on the data presented, inhalation of CLP aerosols resulted in toxicological effects that were similar to those caused by dermal exposure.

ISSN:0098-4108    

DOI:10.1080/15287398909531340

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Benzo[a]pyrene (BaP)IDNA adduct formation appears to be involved in carcinogen‐esis, but the relationship between adduct formation and BaP‐induced immunotoxicity is unknown. We compared DNA adduct formation (32P‐postlabeling analysis) to suppression of polyclonal immune responses (3H‐TdR incorporation and IgM secretion) and decreases in cell viability in B6C3F1 female mouse splenic leukocytes (SPL). BaP administration (200 mglkg, ip) resulted in suppression of polyclonal responses and substantial DNA adduct formation in mouse SPL. SPL adduct levels were similar to those in liver, lung, kidney, and stomach. In vitro exposure of SPL to BaP without rat liver activation enzymes (S9) caused decreases in SPL viability and immune responses that were dependent on dose and exposure period. However, DNA adduct formation in SPL was very low between 1 and 200 μM BaP. S9 enhanced the toxicity of BaP for SPL cultures. Adduct formation was rapid and dose related in + S9 incubates. The low level of BaP activation by SPL was confirmed in microsomal incubations in which splenic microsomes exhibited much lower aryl hydrocarbon hydroxylase (AAH) activity and ability to form DNA‐adducting metabolites than did microsomes from liver or lung. Results indicate that immunosuppression produced by BaP in these systems was due to cytotoxic effects. It appears that these effects were caused by two separate mechanisms, one dependent on and one independent of DNA adduct formation. Since SPL had high levels of DNA adducts after ip injection of BaP, reactive metabolites of BaP may be involved in the immunotoxicity seen in vivo.

ISSN:0098-4108    

DOI:10.1080/15287398909531341

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The dimethylamine salt of14C‐ring‐labeled 2,4‐D was administered to Fischer 344 rats orally (1 and 0.4 mg/kg body weight) and dermally (10 mg/kg body weight). Absorption, distribution, and elimination were determined from14C‐labeled 2,4‐D in blood, tissues, and excreta. Quantitatively, most of the orally administered dose (94–96%) became systemically available within 6 h. Following dermal administration 10% of the dose became systemically available over 72 h. However, peak concentrations in blood and kidneys were achieved within 30 min of dosing by either route. By 1.5 h after dosing, 2,4‐D concentrations in blood, muscle, liver, and kidneys had decreased in both the orally dosed and dermally dosed animals. Between 2 and 8 h, the blood, muscle, liver, and kidney concentrations in dermally dosed animals maintained a plateau while urinary excretion increased, presumably due to continued absorption of 2,4‐D from the skin. The concentrations in orally dosed animals continued to decrease. Following 7 h of dermal exposure, skin cleansing removed about 63% of the applied dose; about 17% of the applied dose remained at the site of dermal dosing. At 8 h, 2,4‐D concentrations in blood, muscle, liver, and kidneys of dermally dosed animals began to decrease, most likely a result of the removal of the reservoir on the skin. However, 2,4‐D continued to be absorbed from skin site, resulting in a slower decline of the 2,4‐D concentrations in these tissues over remainder of the 72‐h study period. By comparison, in animals that had been orally dosed, the absorbed dose was almost completely excreted within 24 h.

ISSN:0098-4108    

DOI:10.1080/15287398909531342

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effect of a single oral dose of 2‐butanol (2.2 ml/kg) or 2‐butanone (1.87 ml/kg) on hepatic ultrastructure and drug‐metabolizing enzyme activity was studied in the rat. A 135–197% increase in acetanilide hydroxylase activity was found in rats sacrificed 12–40 h after dosing with 2‐butanol or 2‐butanone. A 40‐h pretreatment with 2‐butanone produced a 155% increase in aminopyrine N‐demethylase activity. NADPH‐cytochrome c reductase activity and the concentrations of cytochromes P‐450 and b5were largely unaltered 2–40 h after dosing with either agent. Electron microscopic examination of hepatocytes from rats sacrificed 76 h after 2‐butanol or 2‐butanone revealed a marginal increase in the prevalence of smooth endoplasmic reticulum. However, by 40 h, there was a marked proliferation of the smooth endoplasmic reticulum and reduction in rough endoplasmic reticulum in response to both agents. The most marked potentiation of CCI4hepatotoxicity occurred when rats were pretreated with 2‐butanol or 2‐butanone 76 h before CCI4administration. The coincidental finding of maximal CCI4‐induced hepatic injury and elevation of microsomal xenobiotic activity within the same time frame following 2‐butanol or 2‐butanone supports the hypothesis that aliphatic alcohols and ketones potentiate CCI4hepatotoxicity by enhancing biotransformation of the halocarbon to cytotoxic metabolites.

ISSN:0098-4108    

DOI:10.1080/15287398909531343

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Repeated oral administration of bis(4‐amino‐3‐methylcyclohexyl)methane to rats induced unusual ultrastructural changes in Clara cells of the bronchiolar epithelium, involving marked accumulation of electron‐dense inclusion bodies with a lamellar structure in the cytoplasm. The appearance of the inclusion bodies was speculated to result from accumulation of complexes formed between the agent and phospholipids within lysosomes, a condition known as drug‐induced lipidosis. This finding appeared noteworthy, since it might reflect high potential for metabolism of xenobiotic compounds in Clara cells.

ISSN:0098-4108    

DOI:10.1080/15287398909531344

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor