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 15,125 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This paper focuses on the incremental impacts of coal ash and flue gas desulfurization (FGD) wastes associated with increased coal usage by utilities and industry under the National Energy Plan (NEP). In the paper, 1985 and 2000 are the assessment points using the baseline data taken from the Annual Environmental Analysis Report (AEAR, September 1977). In each EPA region, the potential mix of disposal options has been broadly estimated and impacts assessed therefrom. In addition, future use of advanced combustion techniques has been taken into account. The quantities of coal ash and FGD wastes depend on ash and sulfur content of the coal, emission regulations, the types of ash collection and FGD systems, and operating conditions of the systems and boiler. The disposal of these wastes is (or will be) subject to Federal and State regulations. The one key legal framework concerning environmental impact on land is the Resource Conservation and Recovery Act (RCRA). RCRA and related Federal and State laws provide a sufficient statutory basis for preventing significant adverse health and environmental impacts from coal ash and FGD waste disposal. However, much of the development and implementation of specific regulations lie ahead. FGD wastes and coal ash and FGD wastes are currently disposed of exclusively on land. The most common land disposal methods are inpoundments (ponds) and landfills, although some mine disposal is also practiced. The potential environmental impacts of this disposal are dependent on the characteristics of the disposal site, characteristics of the coal ash and FGD wastes, control method and the degree of control employed. In general, the major potential impacts are ground and surface water contamination and the "degradation" of large quantities of land. However, assuming land is available for disposal of these wastes, control technology exists for environmentally sound disposal. Because of existing increases in coal use, the possibility of significant environmental impacts, both regionally and nationally, exists regardless of whether the NEP scenario develops or not. Existing baseline data indicate that with sound control technology and successful development and implementation of existing regulatory framework, regional scale impacts are likely to be small; however, site-specific impacts could be significant and need to be evaluated on a case-by-case basis. Both Federal and privately-funded programs are developing additional data and information on disposal of FGD sludges and coal ash. Continuation of these programs will provide additional vital information in the future. However, further information in several areas if desirable: further data on levels of radionuclides and trace metals in these wastes: studies on biological impacts of trace metals; and completion of current and planned studies on disposal problems associated with advanced combustion techniques like fluid bed combustion.
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PMID:Health and environmental impacts of increased generation of coal ash and FGD sludges. Report to the Committee on Health and Ecological Effects of Increased Coal Utilization. 54 Jun 14

Environmental standards for 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin, TCDD) are currently being considered by regulatory agencies worldwide. Among these are limits for tap water, soil at industrial sites, residential soil, fish, ambient air, and fly ash. Thus far, in the United States, no standards have been promulgated but a few have been suggested. This paper critically evaluates several aspects of previously proposed approaches to setting limits for TCDD in residential soil and soil within industrial sites. Factors and assumptions which significantly affect the predicted degree of hazard associated with exposure to soil contaminated with low levels of dioxin are discussed. This paper shows how different, more justifiable assumptions than those used by the Centers for Disease Control (CDC) regarding the quantities of soil typically consumed by children, TCDD's nongenotoxicity, dermal exposure to soil, the concentration of airborne soil particles, dioxin's bioavailability in soil, and extrapolation of the dose response curve can profoundly affect the results of the risk assessment and, subsequently, the magnitude of the recommended limits. Two case studies which quantitatively illustrate the effect of these assumptions on the risk estimates are presented. Non-U.S. regulatory agencies have considered TCDD's nongenotoxicity in estimating that the virtually safe dose (VSD) or acceptable daily dose for dioxin is approximately 10 pg/kg/day (10,000 fg/kg/day). These approaches are compared and contrasted with the method used by the United States EPA whose risk estimates are higher and whose VSD is approximately 1,000-fold lower. Alternative approaches to interpreting the cancer data indicate that a VSD of 130 pg/kg/day is more scientifically justified than risks estimated using standard approaches. This assessment indicates that a soil concentration of TCDD considerably in excess of 1 ppb should be acceptable for residential and nonresidential areas.
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PMID:A critical examination of assumptions used in risk assessments of dioxin contaminated soil. 377 86

Selenium can have severe ecological impacts on aquatic ecosystems even when waterborne concentrations are in the low microgram per liter (ppb) range. Episodes of environmental contamination have occurred that clearly illustrate the potential toxicity of this trace element to aquatic organisms. Wastes and effluents produced by the power industry are highly concentrated sources of selenium and constitute hazardous wastes when introduced into aquatic ecosystems. The continued use of a wet-basin system of coal-ash disposal at power plants is only feasible if several environmental variables are considered along with models of trace element cycling and accumulation, and pretreatment of effluents. Other power industry operations, such as coal gasification and liquifaction, must include provisions for treating effluents as an integral part of construction design. The ecological data base indicates that new, rigorous water quality criteria for selenium are needed; criteria presently proposed by EPA and others would not protect freshwater life if adopted as standards by regulatory agencies. This data base has been utilized by the State of North Carolina to develop sound, defensible environmental standards for selenium in surface waters. Ecological information can be used nationwide to establish reasonable and prudent regulations governing selenium-laden effluents from the power industry.
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PMID:Ecological basis for regulating aquatic emissions from the power industry: the case with selenium. 409 87

Prostaglandins (PGs) are known to have various effects on bone metabolism. The supplementation of essential fatty acids (EFAs), the precursors of PGs, leads to increased intestinal calcium absorption and calcium balance. It is, however, not known whether increased calcium absorption and calcium balance will enhance the calcium content in bone. Male Sprague-Dawley rats (n = 40) aged 5-12 weeks were supplemented with EFAs. The main dietary EFAs, linoleic acid (LA) and alpha-linolenic acid (ALA) were administered in a ratio of 3:1 as a control group. The conversion of LA to ALA to the PG precursors is slow, with the first step, delta-6-desaturation being rate limiting. Fatty acids beyond this rate-limiting step, gamma-linolenic acid (GLA, n-6) and eicoapentaenioc acid (EPA, n-3), were administered to different groups in the ratios 3:1, 1:1 and 1:3 to explore the impact of different ratios of n-6 and n-3 EFAs. Intestinal calcium absorption (mg/24 h) increased by 41.5% in the 3:1 supplemented group, compared with the control group. The decrease in urinary calcium (mg/24 h) correlated with the increase in n-3 level. The calcium balance (mg/24 h) and bone calcium (mg/g bone ash) increased significantly in the 3:1 (41.5% and 24.7%) group, compared with the control. The increase in bone calcium might be attributed to an EFA-induced increase in circulating PGs. An increased synthesis of PGs acting on target bone cells, as well as changes in membrane fluidity, may underlie these observations.
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PMID:The effect of different n-6/n-3 essential fatty acid ratios on calcium balance and bone in rats. 767 19

At the same time that carcinogenicity of very thin glass fibers after intrapleural and intraperitoneal (ip) administration was demonstrated (1,2) researchers found that gypsum fibers and HCI-leached chrysotile fibers were easily soluble in the peritoneal cavity. This led to the conclusion that the chemical composition of fibers was not responsible for the carcinogenesis but that the degree of carcinogenic potency of a fiber depended on the extent to which it retained its fibrous structure. A thin glass fiber with a low biodurability did not induce tumors after ip injection of a high dose, although the ip test had been criticized for being "overly sensitive." The ip model has been the most successful for determining carcinogenicity of inorganic fibers and establishing dose-response relationships; but to determine the possibilities and limitations of this test model, very high doses of nonfibrous silicon carbide and of a slightly durable glass fiber type were injected ip in Wistar rats. No obviously acute or chronic toxic effect was observed in 90 weeks, but there was a 40% incidence of serosal tumors in the group treated with glass fibers. A pilot study on the persistence of slag fibers in the omentum of rats after ip injection showed a half-time of about 1 year. It was calculated that an ip injection of 10(9) fibers would lead to a concentration of fiber numbers in the ash of the omentum in the same range as the concentration in the lung after 2 years of inhalation exposure. The long-term inhalation study with fibers in rats has been called the "gold standard" for risk characterization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Significance of durability of mineral fibers for their toxicity and carcinogenic potency in the abdominal cavity of rats in comparison with the low sensitivity of inhalation studies. 788 19

The Columbus Municipal Waste-to-Energy (Columbus WTE) facility in Columbus, Ohio, began operation in June, 1983 and ceased operation in December, 1994. During its operation, it was estimated to have released nearly 1,000 grams of dioxin Toxic Equivalents (TEQs) per year. This compares to a 1994 estimate of 9,300 g TEQ/yr from all sources emitting dioxins into the air in the United States (EPA, 1994), and to total releases of dioxins near or below 1,000 grams TEQ/Yr for England (Eduljee and Keyke, 1996), Belgium (Wevers and De Fre, 1995), and West Germany (Fiedler and Hutzinger, 1992). Because of the magnitude of emissions from this single source, studies were undertaken to evaluate the impacts to air and soil near the incinerator. This paper presents analyses evaluating dioxin concentrations and profiles in four media: stack gas, ambient air within 3 km of the incinerator, soil samples up to 8 km from the incinerator, and incinerator ash. Principal findings include: 1) an "incinerator signature" profile, as defined by stack gas emissions, was found in the ash and in subsets of the air and soil matrices, 2) soil concentrations declined from directly outside the incinerator property to the city at large, 3) an urban background soil concentration of dioxin Toxic Equivalents (TEQs) was estimated at 4 pg/g, while concentrations generally within 2 km of the incinerator ranged from 4-60 pg TEQ/g, 4) an urban background air concentration was estimated at 0.05 pg TEQ/m3, while air concentrations at a specific location about 2 km in the downwind direction of the incinerator had concentrations of 0.17 and 0.35 pg TEQ/m3 during two sampling dates, 5) analysis of the soil monitoring data in combination with the stack test data suggests that less than 2% of emitted dioxins can be found in the soil near the incinerator, and 6) principal component analysis suggests that the fraction of total concentration of OCDD is the single feature explaining most of the variation of all concentration profiles. This paper discusses these and other findings, and their implications.
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PMID:Relationships between dioxins in soil, air, ash, and emissions from a municipal solid waste incinerator emitting large amounts of dioxins. 982 36

/ The purification of incinerator gases produces large quantities of fly ash and used lime [a combination referred to as air pollution control residues (APCR)], both of which contain elevated levels of metals. This paper describes biological solubilization assays utilizing Thiobacillus ferrooxidans to leach metals from APCR to render them nonhazardous. The multistage solubilization process involves an alkaline aqueous phase that removes some Pb. In the second phase, the APCR are acidified to pH 4 with H(2)SO(4), then inoculated with a bacterial culture that has been acclimated in the presence of 2% Fe (FeCl(3)). Several rinses and decantings achieve removal of the leachable metals. The final step involves the addition of Ca(H(2)PO(4))(2) and an increase in the treatment pH prior to the final filtration. Viability of thiobacilli in APCR was poor. Despite this problem, the removal of Pb was 35.9%, 46.0%, and 68.7% (for APCR containing 1594, 3026, and 5038 mg Pb/kg, respectively), which demonstrates greater metal removal with increased APCR contamination. Zn removal varied from 68.2% (8273 mg Zn/kg APCR) to 79.5% (16,873 mg Zn/kg APCR), which was positively correlated to the level of residue contamination, whereas Cu was removed in the proportions of 26.9% (495 mg Cu/kg APCR) to 68.2% (465 mg Cu/kg APCR). Cadmium removal appeared to be independent of the level of Cd in the APCR; Cd was removed to the greatest degree, with a variation of 92.0% (129 mg Cd/kg APCR) to 94.7% (267 mg Cd/kg APCR). The treated APCR were tested using four different leachate tests. The APCR released 43 mg Pb/liter during contact with water, and 7.40 mg Cd/liter during TCLP [the toxicity characterization leaching procedure of the United States Environmental Protection Agency (US EPA)]. After biological treatment, the leachate from TCLP was within the acceptance criteria of the US EPA, if the pH of the APCR was increased to pH 5 after the biological treatment. In the case of the Transport Canada leaching test, a betterment of the process is required in order to satisfy the stringent regulatory level of 0.5 mg Cd/liter (0.68 and 0.57 mg/liter).KEY WORDS: Thiobacilli; Metals removal; Fly ash; Incinerator; Hazardous waste.http://link.springer-ny.com/link/service/journals/00267/bibs/24n4p517.html</HEA
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PMID:Decontamination of Fly Ash and Used Lime from Municipal Waste Incinerator Using Thiobacillus ferrooxidans. 1050 64

Speciation of Cr(VI) in solid environmental samples is challenging because of the transformations between Cr(VI) and Cr(III). EPA method 3060A completely extracts Cr(VI) in a hot alkaline solution and preserves the solublized Cr(VI). This procedure, however, can oxidize Cr(III) in some chemical forms. On the other hand, the reverse transformation may occur during neutralization and acidification following the extraction step. We developed a method that is capable of monitoring and correcting for such bidirectional species transformations to determine Cr(VI) in solid samples. In this method, we spike a sample with a 53Cr(VI) spike (enriched in 53Cr) and a isoCr(III) spike (enriched in 50Cr). The large quantity of isoCr(III) in an easily oxidizable form competes with sample Cr(III) in the oxidization, reducing the method-induced oxidation of sample Cr(III). This method also corrects for the reduction of Cr(VI). The theory is presented and is evaluated experimentally. The analysis of chromite ore processing residue, fly ash, and standard reference material SRM 1645 showed that the oxidation of sample Cr(III) could cause positive biases as high as 163% if no correction is performed.
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PMID:Correction of species transformations in the analysis of Cr(VI) in solid environmental samples using speciated isotope dilution mass spectrometry 1105 27

An extraction process with saponins was evaluated for removing heavy metals from MSW (municipal solid waste) incinerator fly ashes. Two different fly ashes, A and B, were treated on a laboratory scale with three triterpene-glycoside type of saponins, M, Q, and T, in the pH range 4-9. The results were compared with those of the HCI and EDTA treatment. The treatment with saponins extracted 20-45% of Cr from the fly ashes. Saponins were also effective in extracting Cu from fly ash A attaining 50-60% extraction. Saponin T extracted 100% of Pb from fly ash A at pH around 4. The extraction of Zn with the saponin treatment was similar to that of the HCl treatment. Further, Cr, Cu, Pb, and Zn were fractionated by sequential extraction to investigate the effect of saponins on each fraction. Extraction behavior of other elements during the saponin treatment was also studied. The leaching test on the residues received after the saponin treatment showed that the fly ashes were successfully detoxified to meet the landfilling guideline.
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PMID:Extraction of heavy metals from MSW incinerator fly ash using saponins. 1105 96

Pulmonary tissue injury and repair processes involve complex and coordinated cellular events such as necrosis, inflammation, cell growth/differentiation, apoptosis, and remodeling of extracellular matrix. These processes are regulated by expression of multiple mediator genes. Commercially available microarray blots and slides allow screening of hundreds to thousands of genes in a given tissue or cell preparation. However, often these blots do not contain cDNAs of one's interest and are difficult to interpret. In order to analyze the tissue expression profile of a large number of genes involved in pulmonary injury and pathology, we developed a rat gene array filter using array technology. This array consisted of 27 genes representing inflammatory and anti-inflammatory cytokines, growth factors, adhesion molecules, stress proteins, transcription factors and antioxidant enzymes; 3 negative controls, and 2 blank spots. Using rat gene-specific polymerase chain reaction (PCR) primer pairs, cDNAs for these genes were amplified and cloned into a TA vector. Plasmids with recombinant cDNA inserts were purified and blotted onto a nylon membrane. Lung total RNA was isolated at 3 or 24 h following intratracheal (IT) exposure of male Sprague Dawley rats to either saline (control), residual oil fly ash (ROFA; 3.3 mg/kg) or metals found in one instillate of ROFA: nickel (NiSO(4); 1. 3 micromol/kg) or vanadium (VSO(4); 2.2 micromol/kg). (32)P-Labeled cDNA was generated from RNA samples in a reverse transcriptase reaction and subsequently hybridized to array blots. Densitometric scans of array blots revealed a twofold induction of interleukin (IL)-6 and TIMP-1 at 24 h post ROFA or Ni exposure. The pulmonary expressions of cellular fibronectin (cFn-EIIIA), ICAM-1, IL-1beta, and iNOS genes were also increased 24 h post ROFA-, V-, or Ni-exposure. Consistent hybridization of beta-actin in all array blots and absence of hybridization signals in negative controls indicated gene specific hybridization. ROFA or metal-induced increase in the expression of IL-6 observed in array blot was validated by Northern blot hybridization. Developing a pulmonary rat gene array may provide a tool for screening the expression profile of tissue specific markers following exposure to toxic air contaminants.
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PMID:A pulmonary rat gene array for screening altered expression profiles in air pollutant-induced lung injury. 1111 90


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