Donald J. Lisk

Mammary cancer prevention by regular garlic and Selenium‐enriched garlic

The anticarcinogenic activities of regular (soil-grown) garlic and selenium-enriched garlic (cultivated in the greenhouse) were evaluated using the 7,12-dimethylbenz[a]anthracene-(DMBA) induced mammary tumor model in rats. In Experiment 1, milled regular garlic powder was added to the basal AIN-76A diet at 20 g/kg. The results from different schedules of supplementation suggested that a continuous treatment, which started before DMBA and persisted for the entire duration of the study, was most effective in tumor suppression. In Experiment 2, selected allyl group-containing sulfides that are normal constituents of garlic extract were given by gavage in three single doses immediately before DMBA. Several structurally related compounds were found to be protective during the initiation phase in the mammary cancer model. Although the present study was not designed specifically to elucidate the structure-activity relationship with respect to sulfur chain length or alkyl versus alkenyl substitution, our data showed that diallyl disulfide was more active than diallyl sulfide or allyl methyl sulfide. In Experiment 3, the anticarcinogenic activity of selenium-enriched garlic (containing 150 ppm Se dry weight from growth in a selenium-fertilized medium) was compared with that of regular garlic as well as selenite. Animals given the selenium-enriched garlic (final concentration 3 ppm Se in the diet) developed the fewest mammary tumors. Tissue selenium levels, however, were lower in these animals than in those fed the same amount of selenium from selenite. Our study demonstrated the feasibility of achieving cancer prevention with the use of a selenium-rich food system.(ABSTRACT TRUNCATED AT 250 WORDS)

A review of physical, chemical, and biological properties of fly ash and effects on agricultural ecosystems

Fly ash is the solid material which is carried away from the power plant boiler in the flue gas during coal combustion. The properties of fly ash may vary considerably according to several factors such as the geographical origin of the source coal, conditions during combustion, and sampling position within the power plant. A typical aggregate of fly ash from the combustion of eastern U.S. coals consists of spherical particles embedded in an amorphous matrix. Most fly ash particles are in the silt-sized range of 2-50 microns. The three major mineralogical matrices identified in fly ash are glass, mullite-quartz, and magnetic spinel. The major elemental constituents of fly ash are Si, Al, Fe, Ca, C, Mg, K, Na, S, Ti, P, and Mn. Nearly all naturally occurring elements can be found in fly ash in trace quantities. Certain trace elements, including As, Mo, Se, Cd, and Zn, are primarily associated with particle surfaces. The solubility of fly ash has been extensively investigated. Results of these investigations are largely dependent on factors specific to the extraction procedure. The most abundant species in fly ash extracts are inorganic ions derived from Ca, Na, Mg, K, Fe, S, and C. Boron is much more soluble than other trace elements in fly ash. The forms of some elements in fly ash extracts have been determined, but the species of most trace elements remain unidentified. Long-term leaching studies predict that fly ash will lose substantial amounts of soluble salts over time, but simulation models predict that the loss of trace elements from fly ash deposits through leaching will be very slow. The constituents of coal fly ash include small amounts of radioisotopes which do not appear to be hazardous. A complex mixture of organic compounds is also associated with fly ash particles. The organic compounds identified in fly ash extracts include known mutagens and carcinogens. Better methods for the extraction of organic compounds from fly ash particles must be developed before these compounds can be fully identified and quantified.(ABSTRACT TRUNCATED AT 400 WORDS)

Residues of Total Mercury and Methylmercuric Salts in Lake Trout as a Function of Age

An analysis of the concentrations of total mercury and methylmercuric salts in lake trout of precisely known ages from 1 to 12 years has been carried out. The concentrations of both total mercury and methylmercury increased with the age of the fish. The proportion of methylmercury to total mercury also increased with age.

Trace Metals in Soils, Plants, and Animals

Publisher Summary This chapter discusses the trace metals found in soils, plants, and animals. Metal sources in soils include: (1) metals contained natively in rocks and minerals, from which the soil was formed; (2) metals added as impurities in fertilizers and lime, as constituents of pesticides and manure or as contaminants of sewage sludge; (3) metals in debris from industrial and mining wastes, fossil fuel combustion products, wind-eroded soil particles, atomic testing, pollen, sea spray, and meteoric and volcanic material that settles or rains out; and (4) metals in soil particles displaced through water erosion or metals dissolved or suspended in the water itself. The nature of the plant, including its species, size, growth rate, extent and depth of rooting, transpiration rate, and nutritional requirements, may affect its efficiency for metal absorption from soils. Trees are especially effective, in absorbing many trace metals (including many rare earths), from great depths and translocating them to the leaves as determined by their transpiration rate. The toxicological implications of metals in water are very complex. Metals may exist in water as dissolved ions, in organic complexes, adsorbed on clay particles, as suspended precipitates, contained in decaying organisms and other forms. Heavy metals are absorbed across the entire body surface of fish as well as the gills. They may attach to proteins during this passage and may be tightly protein-bound in the blood. Absorption from the digestive tract also is important since consumed marine plants contain virtually all trace metals in amounts that reflect metal concentrations in the contacting water.

Dietary selenium protection of methylmercury intoxication of Japanese quail

SummarySelenium, as sodium selenite, added at 5 ppm to purified diets of Japanese quail protected against methylmercury intoxication. Selenium fed simultaneously with methylmercury to quail for 9 weeks gave complete protection. However, feeding selenium with methylmercury for 4 weeks, followed by a diet containing only methylmercury, delayed the onset of methylmercury intoxication for 1–2 weeks as compared to quail not pretreated with selenium. On diets which contained 20 ppm of methylmercury but no selenium, over 90% mortality was observed for young quail within 2 weeks, and mature quail within 4 weeks. Methylmercury residues in liver, kidney, and brain are higher in male than female quail. High methylmercury content of these organs, or in produced eggs, does not indicate that birds will show evidence of methylmercury toxicosis.

Determination of Organophosphorus Insecticide Residues Using the Emission Spectrometric Detector.

Emission spectroscopy is an old technique for the analysis of metals and some nonmetallic elements. The sample to be analyzed is excited using a spark, direct current arc, flame, or other means. Photons are emitted when electrons in the excited species of the sample return to a lower energy state. This emitted quantized energy may then be measured photographically, oscilloscopically, or by automatic recording. The frequency of radiation can provide a high degree of specificity for characterizing the species and radiation intensity is used for quantitative analysis.

Environmental implications of incineration of municipal solid waste and ash disposal.

Owing to unsightliness and the threat of groundwater pollution, landfilling of municipal solid waste (MSW) is giving way to incineration in many communities. Environmental contamination from particulate and gaseous emissions containing heavy metals, polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF), polycyclic aromatics (PCA), acids and other compounds from such incinerators, as well as safe ash disposal, are of great concern. Concentration ranges of elements and organic toxicants in incinerator ashes, emissions and cooling waters are given. The literature is reviewed concerning the effects of incinerator operating parameters on emissions. Incinerators equipped with modern pollution control devices (electrostatic precipitators, fabric filters, dry scrubbers, spray towers) and operated at optimum temperature with sufficient oxygen, turbulence (mixing) and residence time for complete combustion appear to minimize ash, elemental, gaseous and organic emissions. Environmental aspects of MSW incineration are considered and reviewed. The presence of metals and organics in incinerator quench water and in leachates from ash disposed in landfills are reviewed, as well as their toxicity to fish. The behavior and effects of atmospheric emissions in soils and plants are discussed. Research on the effect of ash-derived PCDD and PCDF on hepatic microsomal mixed function oxidase activity and the immune system in laboratory animals is cited. The presence of metals, organics and mutagens in the incinerator workplace air and the possible effects of air-borne contaminants on inhabitants nearby is reviewed. Several studies dealing with human risk assessment of MSW incineration are cited.

Selenium content of Brazil nuts from two geographic locations in Brazil

Brazil nuts (Bertholletia excelsa) natively contain very high concentrations of selenium. Since dietary selenium, including Brazil nuts, have been associated with protection against tumor development in laboratory animal studies, it was of interest to determine the selenium content of the nuts from different nut-growing regions of Brazil. In the work reported, 162 nuts from each of two regions (Acre-Rondonia and Manaus-Belem) were individually analyzed for selenium. The average +/- standard deviation and range of selenium concentrations in ppm, fresh weight for nuts from Acre-Rondonia and Manaus-Belem regions were, respectively, 3.06 +/- 4.01 (0.03-31.7) and 36.0 +/- 50.0 (1.25-512.0). The toxicology of Brazil nut consumption is discussed.

Environmental effects of landfills

In the past, landfilling involved burying municipal refuse directly or after on-site burning. Typically, little attention was given to proper siting and engineering to obviate the hazards of the generation of CH4 and toxic leachates as wastes decomposed. Leachates were hopefully attenuated by natural processes (adsorption, precipitation, ion exchange, microbial decomposition or dilution in the unsaturated zone below landfills). Landfills slowly evolved by proper siting, design and management into efficiently operated bioreactors to produce purified CH4 for use as a fuel, and leachates, which were treated biologically and chemically to minimize groundwater pollution. Microbial reactions in landfills are outlined. The amounts and composition of landfill gas and leachate as determined by the interaction of factors such as refuse composition, degree of compaction, temperature, moisture content, refuse age and depth are discussed. Typical inorganic and organic composition of landfill gases and leachates are presented. The potential and real environmental effects on soils, plants, groundwater, aquatic organisms and humans of disposal of municipal refuse by landfilling are reviewed. Finally, the most recent trend in constructing refuse landfills to serve as final storage reservoirs which are deliberately kept dry to minimize gas and leachate production is discussed and illustrated. Present activities in waste recycling to conserve landfill space are outlined.

National survey of elements and other constituents in municipal sewage sludges

Fifty-nine elements, poly chlorinated biphenyls, volatile N-nitrosamines and gamma emission were determined in 30 sewage sludges from 23 American cities using several analytical methods. Relatively high concentrations of toxic metals were found in sludges from specific municipal plants. The pH and levels of calcium and iron in certain of the sludges appeared to reflect the addition of lime, ferric chloride and/or spent pickle liquor during sewage treatment. Of 15 sludges analyzed, the carcinogen, N-nitrosodimethylamine was detected in 14 and various other N-nitrosamines in 12 of them. Based on present federal guidelines, only 7 of the 30 municipal sludges analyzed would be considered suitable for land application owing to their elevated content of one or more heavy metals.