摘要:

A number of studies carried out in other countries have shown the existence of negative correlations between coronary mortality and the hardness of water supplies. Data on water hardness throughout Taiwan have been collected from Taiwan Water Supply Corporation (TWSC) to examine the ecological correlation between deaths from coronary disease (1981–1990) and total hardness in drinking water. Analysis demonstrates a significant negative association between drinking water hardness and coronary mortality. After adjustment for the urbanization index, coronary mortality in municipalities with soft water was estimated to be 9.6% higher than that in municipalities with hard water. The weighted multivariate-adjusted regression coefficient indicated a decrease of 0.053 in standardized mortality ratios (SMRs) for every 100 mg/L increase in total hardness in drinking water after allowing for the urbanization condition.

ISSN:0098-4108    

DOI:10.1080/00984108.1996.10662166

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Lung exposures to complexes of coordinated iron can be associated with a neutrophilic alveolitis. We tested the hypothesis that lung inflammation after intratracheal instillation of mineral oxides in rats increases with surface-complexed [Fe3+]. The 10 mineral oxides employed had measurable [Fe3+] complexed to the dust surface. The metal was incompletely coordinated, as demonstrated by the ability of the particles to catalyze electron transfer and generate thiobarbituric acid (TBA) reactive products of deoxyribose. After exclusion of those silicates containing structural iron within the crystal lattice, there was a significant correlation between the concentration of chelatable metal and TBA-reactive products (r= 0.82;p=.04). Four days after intratracheal instillation of the 10 mineral oxide particles into rats, lavage neutrophils and protein were significantly increased for all dusts compared to injected saline. Among those dusts with no structural iron, the correlation between chelatable iron concentrations and percentage neutrophils did not reach significance (r= 0.73;p= .10), but that between metal and lavage protein did (r= 0.80;p= .05). We conclude that (1) mineral oxides complex iron cations at the surface, (2) in vitro measures of oxidant generation increase with the concentration of surface iron among those dusts with no structural iron, and (3) acute inflammation following introduction of these particles into the lower respiratory tract also increases with surface iron concentrations among those mineral oxides with no structural iron.

ISSN:0098-4108    

DOI:10.1080/00984108.1996.10662167

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Two inhalation studies were performed with a vaporized sample of commercial-grade diisopropyl ether (DIPEJ. In the subchronic study, Sprague-Dawley rats (14/sex) were exposed to 0 (both untreated and sham-exposed controls), 480, 3300, or 7100 ppm DIPE for 6 h/d, 5 d/wk, for ~90 d. DIPE itself accounted for 91–95% of the vapors, with the remainder being a mixture of 27–29 compounds. Exposure to DIPE did not adversely affect clinical signs, body weight, serum chemistry, hematology, or the number of sperm or spermatids. Exposure of males to 7100 ppm resulted in hypertrophy of liver cells associated with increased liver weight and in increased kidney weight with an increased incidence of hyaline droplets in proximal tubules of the kidney. Females had increased weight of both liver and kidney, although kidney increased only in relation to sham-exposed controls and no morphological changes were observed in either organ. At 3300 ppm, weights of liver and kidney were again increased in males; the liver weights were increased in females only compared to sham-exposed controls and not untreated controls. No abnormalities were observed morphologically. No changes were observed with 480 ppm. In the developmental toxicity study, pregnant Sprague-Dawley rats (22/group) were exposed to 0 (both untreated and sham-exposed controls), 430, 3095, or 6745 ppm for 6 h/d on gestation d 6–15. Animals were sacrificed on gestation d 20. With 6745 ppm, dams had a slight reduction in body weight gain and a significant decrease in food consumption. A concentration-related increase in the incidence of rudimentary 14th ribs was observed, but its significance was uncertain. There was no apparent toxicity, either maternal or fetal, at the lowest exposure concentration. Both studies indicated a low order of toxicity for DIPE.

ISSN:0098-4108    

DOI:10.1080/00984108.1996.10662168

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Clarified slurry oil (CSO), syntower bottoms (STB), and distillate aromatic extract (DAE) are refinery streams produced by processing crude oil. Each of these refinery streams is rich in both hydrocarbons having carbon numbers of C20 or greater and polycyclic aromatic compounds. Available data indicate that some refinery streams are developmentally toxic (manifested primarily as increased embryolethality and growth retardation) by the dermal route of exposure. However, there is no conclusive evidence for their being teratogenic. The present studies were designed to further explore the suspected teratogenic potency of refinery streams while at the same time limiting embryolethality. To profile teratogenic effects as a function of gestation day, pregnant rats received a single oral dose (2000 mg/kg) of CSO, STB, or DAE on one of gestation days (GD) 11–14; DAE and STB were also administered on GD 15. To profile effects as a dose response function, rats received a single oral dose of CSO, DAE, or STB on GD 12 at 125, 500, and 2000 mg/kg. Control animals were similarly treated but were administered tap water. On GD 20, dams were necropsied and the fetuses evaluated for normal development. In general, evidence of maternal toxicity (i.e., decreased body weight gain, decreased thymus weight) was observed at doses greater than or equal to 500 mg/kg. For each refinery stream tested, the incidence of resorption was greatest on GD 11. A common pattern of fetal malformations was observed for all of the refinery streams tested and included cleft palate, diaphragmatic hernia, and paw and tail defects. The incidence and type of malformation observed were influenced by the gestation day of exposure. The incidences of external and skeletal malformations were greatest on GD 11 and 12 for fetuses exposed to CSO; on GD 13 and 14, the incidence of malformation was comparable for CSO- and STB-exposed fetuses. The incidence of visceral anomalies was greatest on GD 11–13 for fetuses exposed to CSO and STB; on Gestation D 14, the incidence was comparable for each of the refinery streams tested. In general, the ability to produce adverse effects on development was greatest for CSO and least for DAE. Effects produced by STB were comparable to or less severe than those observed for CSO.

ISSN:0098-4108    

DOI:10.1080/00984108.1996.10662169

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Polycarboxylates enhance detergent soil removal properties and prevent encrustation of calcium salts on fabrics during washing. Laundry wastewater typically reaches wastewater treatment plants, which then discharge into aquatic environments. The yearly average concentration of a 4500 molecular weight (MW) sodium acrylate homopolymer reaching U.S. wastewater treatment plants will be approximately 0.7 mg/L Publications showing the low to moderate acute aquatic toxicity of polycarboxylates are readily available. However, there are no published evaluations that estimate wastewater removal and characterize the probability of exceedance of acceptable chronic aquatic exposure. WW-TREAT can be used to estimate removal during wastewater treatment and PC-CRIDS can be applied to characterize risk for exceedance in wastewater treatment plant outfalls. After adjustments for the MW distribution of the homopolymer, WW-TREAT predicted that 6.5% will be removed in primary treatment plants and 60% will be removed in combined primary and activated sludge treatment plants. These estimates are consistent with wastewater fate tests, but underestimate homopolymer removal when homopolymer precipitation is included. Acceptable levels of chronic outfall (receiving water) exposure were based on aquatic toxicity testing in algae, fish, and Daphnia magna. PC-GRIDS predicted that no unreasonable risk for exceedance of acceptable chronic exposure will occur in the outfalls of U.S. wastewater plants. Future development of wastewater treatment models should consider polymer MW distribution and precipitation as factors that may alter removal of materials from wastewater.

ISSN:0098-4108    

DOI:10.1080/00984108.1996.10662170

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A bioassay protocol was optimized for measuring the potency of effluents or waterborne chemicals for inducing mixed-function oxygenase (MFO) activity of rainbow trout (Oncor-hynchus mykiss). Measurements of ethoxyresorufin O-deethylase (EROD) can be made with an established endpoint assay using large volumes of reagents and tissue. However, a new kinetic microplate assay offers significant savings in time, reagents, and sample volumes. Data are distributed lognormally and must be log transformed before statistical analyses. EROD activity increases with exposure time to pulp mill effluent, and a 4-d exposure provides a near-maximal response. Optimum fish size conforms to standard practices in fish toxicology; loading rates should not exceed 1 g of fish per liter of test solution per day. Feed should be withheld from test fish 48 h before testing to reduce the variance of measured activity, and anaesthetizing fish with MS-222 does not affect their response to MFO inducers. Pulp mill effluents do not lose their potency during 2–3 wk of exposure at temperatures ranging from −20 to 13°C, whether stored in plastic or glass. Steel containers were associated with slight losses in potency. Bioassays of MFO induction in fish exposed to liquid effluents are practical and conform to standard practice for testing the lethality of waterborne chemicals. The results are sufficiently precise that differences among means based on five fish per treatment can be discriminated statistically when activity changes by threefold or more.

ISSN:0098-4108    

DOI:10.1080/00984108.1996.10662171

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0098-4108    

DOI:10.1080/713851065

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

ISSN:0098-4108    

DOI:10.1080/00984108.1996.10662165

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor