Barbara S. Shane

Adsorption of heavy metals by green algae and ground rice hulls

Abstract This research demonstrates the applicability of low cost, readily available alternate adsorbents to remove and recover toxic heavy metals from water. Heavy metal ion adsorption has been investigated using two different adsorbing biomasses, algae and rice hulls. Algal biomass adsorption studies were conducted with: As, Cd, Co, Cr, Pb, Ni and Zn, and rice hull biomass adsorption studies were conducted with: As, Cd, Cr, Pb and Sr. Both biomasses were dried and pulverized to maximize surface area. The green alga, Chlorella minutissima, adsorbed greater than 90% of the initial Pb, and greater than 98% of the initial Co concentrations. Rice hulls (Mars and Rico Varieties) exhibited similar adsorption percentages: 94% for Sr, and greater than 99% for Pb. The rate of adsorption was fast; the solution metal concentration reached equilibrium within minutes. The cell wall metal complex was found to be stable; the bound metal did not desorb over time under static conditions. Most cationic metal ions could be...

Mutant frequencies and mutation spectra of dimethylnitrosamine (DMN) at the lacI and cII loci in the livers of Big Blue transgenic mice.

The lacI gene in Big Blue transgenic rodents has traditionally been used as a surrogate gene for in vivo mutations. Recently, a more efficient and less expensive assay involving direct selection in the smaller lambda cII gene has been developed. Little is known, however, about the comparative sensitivity of the two loci or their influence on the recovered mutation spectrum following mutagen treatment. We have compared the mutation frequency (MF) and mutational spectrum (MS) of lacI and cII from the same DNA samples isolated from the liver of control and dimethylnitrosamine (DMN)-treated mice. A three-fold (p<0.01) increase in the MF was observed at both loci in the DMN-treated group compared to the corresponding control groups. While the DMN-induced mutation spectrum at lacI was significantly different from its corresponding spontaneous mutation spectrum (p<0.001), the mutation spectrum at cII (p>0.28) was not. The mutation spectra at the two loci from the DMN-treated mice resembled each other but the 4, 2.5 and 12-fold increase in the mutation frequency of A:T>T:A transversions, single base deletions and deletions of more than four base pairs, respectively, at lacI, altered the spectra significantly (p<0.007). The number of mutations of these classes at cII was also increased, but the fractions were lower than at lacI. The spontaneous mutation spectra at the cII and lacI loci resembled each other except for the seven-fold increase in G:C<C:G transversions in the cII spectrum resulting in a significant difference (p<0.0001) between the spectra. Our initial data indicates that although cII is as sensitive to mutation induction as lacI, fewer sites are available for certain classes of mutations to be manifest resulting in an apparent lack in change in the mutation spectrum.

Mutant frequency of lacI in transgenic mice following benzo[a]pyrene treatment and partial hepatectomy.

The Big Blue, transgenic mouse provides an in vivo mutation system that permits the study of pharmacodynamic parameters on mutant frequency (MF) following xenobiotic exposure. We have studied the effects of cellular proliferation on the frequency of mutations in the lacl transgene by evaluating the MF in the liver of male C57B1/6 Big Blue mice following treatment with benzo[a]pyrene (B[a]P) and a partial hepatectomy. Mice received either 40 mg/kg of B[a]P in corn oil or corn oil alone by i.p. injection on three consecutive days, followed by a partial hepatectomy on the fourth day. Three days later (i.e., 7 days following the initial B[a]P injection), the animals were sacrificed and the MF in the liver was compared to the MF observed in the liver of the same mouse at the time of hepatectomy. Induction of cytochrome P-450 1A (CYP1A) following B[a]P treatment was evident by Western blot analysis. The MF in untreated control animals was not significantly different at hepatectomy (4.7 +/- 0.8 x 10(-5)) and 3 days later, at sacrifice (3.0 +/- 0.4 x 10(-5)). Neither was the MF observed in the B[a]P-treated mice at the time of sacrifice (12.0 +/- 2.1 x 10(-5)) significantly different from the MF observed at the time of hepatectomy (10.6 +/- 5.3 x 10(-5)). However, B[a]P-treatment resulted in a 4.0-fold increase in MF at sacrifice which was significantly different (p < 0.05), when compared to the untreated controls. The B[a]P-treated mice at hepatectomy showed a modest 2.2-fold increase in MF which was not statistically significantly different from the untreated controls. In addition, both control and B[a]P-treated tissues gave sectored mutant plaques. The sectored plaque frequency (SPF) was significantly elevated (p < 0.05) in the B[a]P-treated mice at hepatectomy (4.2 +/- 1.0 x 10(-5)) and sacrifice (7.3 +/- 2.4 x 10(-5)) as compared to the respective frequency in the control mice at hepatectomy (1.9 +/- 0.7 x 10(-5)) and sacrifice (1.4 +/- 0.2 x 10(-5)). One explanation for this data is the persistence of the B[a]P adducts in the mouse genomic DNA that was packaged into the lambda phage, and ultimately fixed as mutations in Escherichia coli.

Subchronic administration of phenobarbital alters the mutation spectrum of lacI in the livers of Big Blue transgenic mice.

Phenobarbital (PHE) is a liver carcinogen in B6C3F1 mice and a weak mutagen that does not appear to form DNA adducts. To investigate PHE mutagenicity in vivo, B6C3F1 Big Blue(R) male transgenic mice harboring the lambdaLIZ shuttle vector containing the lacI target gene were fed PHE at 2500 ppm for 180 days. A modest increase in the mutant frequency (MF) from 5.02+/-2.4x10(-5) in the control group to 6.88+/-0.754x10(-5) in the PHE-treated group, which was marginally different (p<0.05), was obtained. To better assess the relevance of this increase in MF, a random collection of mutants from each PHE-exposed mouse was sequenced. After correcting for clonal expansion, which is the most conservative approach, the MF in the PHE-treated mice decreased to 6.39+/-1.02x10(-5), an insignificant difference (p=0.10) from that in control group. Despite this modest increase in MF, the mutation spectrum obtained from the PHE-exposed group was significantly different (pA:T transitions remained the same in the two spectra. It is postulated that the increase in transversions at G:C base pairs found in the PHE-derived spectrum is likely due to oxidative damage as a result of induction of CYP2B isozymes by the chronic administration of PHE. Results from this study demonstrate that PHE alters the spectrum of mutations, rather than inducing a significant global increase in the MF. The PHE-derived spectrum of lacI mutants from the liver of Big Blue(R) B6C3F1 male mice was remarkably similar (p=0.8) to that generated by oxazepam (OX), a compound which also induces CYP2B isozymes following chronic administration of the drug.

Organic toxicants and mutagens in ashes from eighteen municipal refuse incinerators

Ashes, obtained from about one-fourth of the operating municipal refuse incinerators in the United States, were analyzed for a range of organic toxicants and mutagens. Thirty percent of the ash samples, which consisted of bottom ash or bottom ash-fly ash mixtures, contained 20–74% organic matter. Thirty percent of the ashes contained direct-acting and/or promutagens which revertedSalmonella typhimurium TA98 or TA100. Sixty percent of the ashes contained more than 5 ng/g of polychlorinated biphenyls. The concentration of tetra- and pentachlorinated biphenyls were higher than the mono-, di-, hepta- and octachlorinated biphenyls. A similar distribution of congeners was seen in polychlorinated dibenzodioxins found in the ashes. The major volatileN-nitroso compounds found in the ashes wereN-nitrosodimethylamine andN-nitrosomorpholine. Other classes of compounds which were found in the ashes included chlorinated benzenes, phthalates, and substituted benzothiophenes.

Arylamine activation following chronic ethanol ingestion by rats : studies on the liver S9, microsomal and cytosolic fractions and comparison with Aroclor 1254 pretreatment

That enzyme fractions derived from animals chronically fed alcohol can alter the metabolism of carcinogenic xenobiotic compounds has been documented. To further understand this relationship the mutagenicity of 3 aromatic amines was determined in the Ames test, employing activation systems derived from rats maintained on an alcohol-containing liquid diet, an isocaloric control liquid diet or Aroclor 1254-pretreated animals fed standard laboratory chow. Depending upon protein and substrate concentrations, S9 from ethanol-fed rats was 30-50% less efficient than S9 from pair-fed rats in activating arylamines (2-aminofluorene, 2-aminoanthracene and 2-acetylaminofluorene) to mutagens in Salmonella typhimurium TA98 and TA100. Cytosolic fractions from ethanol-fed animals always resulted in greater arylamine activation than that of controls whereas the opposite was true of the microsomal compartment in which the ethanol-treated group was consistently less active than the controls. The cytosolic N-acetyltransferase activities with respect to 2 different substrates, isoniazid and 2-aminofluorene, were unaffected by ethanol consumption, indicating that this activity probably does not account for the different activation profiles exhibited by the ethanol and pair-fed cytosolic systems. Both the cytosolic and microsomal compartments are required for maximal expression of the mutagenicity of each arylamine however, each compartment can activate arylamines independently of the other. Reconstituting cytosol with microsomes from ethanol- and pair-fed rats, but not Aroclor-pretreated rats, resulted in a synergistic activation of the aromatic amines and displayed an effect similar to that of S9. Compared to Aroclor pretreatment and pair-fed controls, microsomes from ethanol-fed rats displayed the least capacity for activating any of the arylamines to mutagens. Microsomes from Aroclor-pretreated rats accounted for at least 80% of the S9-mediated activation of each of the arylamines to mutagenic metabolites which was in marked contrast to the contribution of the microsomal fractions to the S9 activity in the ethanol- (5-20% of S9 activity) and pair-fed systems (22-30% of S9 activity). The data indicate that 2 opposing reactions occur in S9, a cytosolic activity that augments and a microsomal activity that attenuates the mutagenicity of arylamines. Both activities are modified by ethanol consumption and Aroclor pretreatment.

Mutagenicity of urine from greenhouse workers.

The mutagenicity of urine from spray applicators in 12 greenhouses in 1986 has been evaluated. The workers served as their own controls. Urine samples reflecting pesticide exposure were collected at the end of the day of application and a corresponding control sample was collected 3 d later. Using Salmonella typhimurium bacterial tester strains TA98 and TA100 with and without S9 activation, seven workers showed no significant differences (p less than 0.05) in the mutagenicity of their exposed and control urine. Of the five remaining workers, three, who wore no respirators, showed significantly higher (p less than 0.05) concentrations of mutagens in their exposed urine sample as compared to their respective controls. The mutagenicity of certain of the compounds applied by these latter workers is discussed.

Hepatic monooxygenase induction and promutagen activation in channel catfish from a contaminated river basin

To better understand the etiology of cancer in fish from polluted waters, the impact of environmental contaminants on xenobiotic metabolism of channel catfish (Ictalurus punctatus) from a highly polluted water body, Devils Swamp in southeastern Louisiana, has been investigated. Fish from Devils Swamp bioaccumulated polynuclear aromatic hydrocarbons (PAH), chlorinated hydrocarbon insecticides (CHI), and polychlorinated biphenyls (PCB) in fat tissue, the latter exceeding 7000 ppb. Reference catfish from the University farm, Ben Hur, were virtually devoid of PAH, CHI, and PCB. Liver microsomal enzymes (MFO) from Devils Swamp fish were markedly induced. The specific content of cytochromes P450 and b5 and the specific activities of NAD(P)H-cytochrome c reductase were two to three times higher than those of Ben Hur fish. Consistent with this induction, a 9000g supernatant from Devils Swamp but not Ben Hur fish activated 2-aminofluorene and benzo[a]pyrene (BP) to mutagens in the Ames test. BP metabolism by Devils Swamp fish liver microsomes was inhibited to a greater extent by alpha-naphthoflavone than was BP metabolism by Ben Hur fish microsomes. This finding indicates that the induced activity in the Devils Swamp fish liver was the result of P450 isozymes characteristic of PAH/PCB induction. Thus, exposure of fish to environmental pollutants can alter MFO leading to enhanced metabolic activation of promutagens to mutagens.

Mutagens, toxicants, and other constituents in small city sludges in New York State

An analytical survey was conducted of sewage sludges from 15 small cities in New York State for mutagens, forty-four elements, polychlorinated biphenyls (PCBs) and radioactivity. Low levels of mutagenicity were detected in several of the samples. PCBs were very high in only one sample. A number of toxic elements were found at elevated concentrations in specific sludges but it is not possible to relate these to specific industrial sources with certainty. The concentrations of specific toxicants in five city sludges were above presently suggested federal guidelines for their suitability for land application. Gamma emission was comparatively low in all samples. The problems of analytical sampling and possible sources of specific constituents in sludge are discussed.

Variability over time in the mutagenicity of ashes from municipal solid-waste incinerators

Incineration of municipal solid waste as an alternative to its disposal in landfills has advantages such as volume reduction and generation of energy. However, both air emissions and the residual ash may pose environmental and human health hazards. The Ames mutagenicity assay was used to determine the mutagenicity of fly and bottom ash from two incinerators over time. This assay is an alternative to costly and time-consuming chemical analyses and is more realistic for the assessment of the best disposition of the ash i.e. whether it could pose a risk to handlers of the ash, whether it can be used in cement or as a fertilizer or whether it should be relegated to a landfill. The mutagenic potency of fly and bottom ash on a per g weight basis of material is similar. Furthermore, the variability over time in mutagenicity indicates that constant monitoring of incineration products and byproducts is essential.