Showing papers in "Environmental Toxicology & Water Quality in 1991"

Tumor promotion and liver injury caused by oral consumption of cyanobacteria

Abstract: Water supply reservoirs in many countries are now affected by intermittent water blooms of cyanobacteria. During 1989 a significant number of domestic supply reservoirs in the United Kingdom developed copious blankets of Microcystis, and pet and sheep deaths were reported due to swimming in or drinking the water. In Australia there are annual blooms of Anabaena and Microcystis in natural lakes and supply reservoirs, many of which are toxic. Studies of epidemics and individual cases of gastroenteritis and hepatitis due to cyanobacterial blooms have been reported from North America, Africa, and Australia. Our studies of the effect of low-concentration oral consumption of Microcystis on mice have shown progressive liver injury with leucocyte invasion and hepatocyte death. Measurements of liver injury in a human population exposed to Microcystis in the domestic water supply indicate similar damage. Recent research has concentrated on the possible tumor-promoting activity of oral consumption of cyanobacterial extracts. A group of mice given dilute Microcystis for one year showed more spontaneous tumors at the highest concentration of cyanobacterial extract. Mice stimulated to grow skin tumors by topical application of dimethylbenzanthracene showed a significantly greater weight of tumors in one group given a Microcystis extract to drink. A comparable group given an Anabaena extract in their drinking water showed no stimulation of tumor growth.

Soil : the environmental source of Escherichia coli and Enterococci in Hawaii's streams

Abstract: The concentrations and sources of Escherichia coli and enterococci in a typical stream (Manoa) in Hawaii were determined. The concentrations of these two sanitary indicator bacteria in Manoa Stream consistently exceeded the new U.S. Environment Protection Agency recreational water standard in freshwater of 126E. coli/100 mL or 33 enterococci/ 100 mL. Escherichia coli but not enterococci was shown to multiply in stream water samples. Soil samples obtained near the stream bank, 10 m from the stream bank as well as from a grassy area on the university campus, were determined to be sources of both E. coli and enterococci. These indicator bacteria were recovered from the surface of the soil as well as from soil samples at depths down to 36 cm. Soil is considered the most likely source for the high concentrations of indicator bacteria naturally present in the freshwater streams of Hawaii.

The relative sensitivity of microtox®, daphnid, rainbow trout, and fathead minnow acute lethality tests

Abstract: Relative sensitivity and correlations between the Microtox® test and three commonly used acute lethality bioassays (i.e., rainbow trout, fathead minnow, Daphnia) are reviewed and discussed. All relevant data available for comparison were separated and evaluated based on chemical groupings. Generally, Microtox was more sensitive than or as sensitive as the acute lethality tests for pure individual organics, but was less sensitive to most inorganics. Microtox was not as sensitive as acute lethality tests to effluents or leachates with a high component of insecticides, herbicides, inorganics, pharmaceuticals or textiles, or highly lipophilic contaminants. As the complexity and toxicity of industrial effluents increased, the correlations and sensitivity of Microtox increased, with a corresponding decrease in data variability. Additionally, limitations of the available data are that (1) comparisons of relative sensitivity varied with the compounds and organisms tested; (2) there was a lack of standardization in approach and a failure to provide adequate details on the origin of the cited toxicity data, which confused and obscured comparisons; and (3) published reviews commonly failed to identify fish species and test details for cited data.

Detection of toxicity of cyanobacteria by Artemia salina bioassay

Abstract: A bioassay for the detection of neuro- and hepatotoxins of cyanobacteria was developed. Larvae of a small shrimp, Artemia salina, were used as the test organism. Two pure toxins, 44 natural bloom samples, and 29 laboratory strains of cyanobacteria were studied. The toxicity of the samples had earlier been tested by mouse bioassay and in most cases by chemical analysis of the toxins. Moderate and high concentrations of toxins in bloom samples can be reliably detected by the Artemia salina method. Out of 29 toxic bloom samples, 4 were found nontoxic to Artemia. According to mouse bioassay, the toxicity of these samples was very low. The pure laboratory-grown strains contained some compounds that were toxic to A. salina but nontoxic to mouse. Because of these compounds, 1 out of 15 nontoxic bloom samples was erroneously analyzed to be toxic. EC50 for hepatotoxin desmethyl 7-microcystin-RR was 5.0 μ/mL. Pure anatoxin-a-hydrochloride was not toxic to larvae, but when added to nontoxic cyanobacterial samples, anatoxin-a was toxic.

Microbiotests in aquatic ecotoxicology: Characteristics, utility, and prospects

Abstract: Small-scale biological tests (microbiotests) have steadily increased in development and application over the last 30 years in the field of aquatic ecotoxicology. Multitrophic level assessment requirements, attractive features of microbiotests, and the constant search for simplicity and cost efficiency of testing are reasons explaining the expanding use of microbiotests. In this article, the major characteristics that advantageously confer popularity on microbiotests are presented and 25 currently applied aquatic toxicity microbiotests are listed. Conducted with bacteria, protozoans, microalgae, small invertebrates, and fish cell lines, these microbiotests represent a realistic cross section of those that are now becoming an essential part of ecotoxicological assessment. Microbiotests can be profitably employed for ranking and screening chemicals, for novel applications enabling rapid detection of ecotoxic effects in complex liquid samples, and for increasing the cost efficiency and diagnostic potential of hazard assessment schemes. Microbiotesting research, development, and applications will continue to surge in the 1990s, driven, among other factors, by the imperative need for cost effectiveness in environmental programs. Research in the fields of ecotoxicology, biotechnology, and immunochemistry should provide interesting breakthroughs to further enhance the specificity and diagnostic value of microbiotests.

Acute toxicity tests using rotifers. III. Effects of temperature, strain, and exposure time on the sensitivity ofBrachionus plicatilis

Abstract: As part of the development of a standardized acute toxicity test, the effect of cyst age, strain, temperature, and exposure time on the toxicity of 21 chemicals to the estuarine rotifer Brachionus plicatilis was investigated. Toxicity was chemical specific, with LC50s ranging from 0.061 mg · L−1 for mecury to 598 mg · L−1 for 2,4-dichlorophenoxyacetic acid. Intralaboratory coefficients of variation averaged 11%, at least three times lower than for other aquatic invertebrate acute tests. The age of rotifer cysts stored up to 27 months had no effect on the sensitivity of test animals, but significant differences in sensitivity were detected among rotifer strains. Test temperatures of 25, 30, and 35°C generally yielded lower LC50s than at 20°C. LC50s decreased by 80–90% for cadmium and pentachlorophenol when toxicant exposure time was increased from 24 to 72 h. Life table analysis of rotifer survival in the controls revealed that 72 h is the longest acute test possible without feeding. A comparison of the sensitivity of the rotifer test to that of sea urchin (Arabacia punctulata) early embryo, sea urchin sperm cell, Microtox®, and Mysidopsis bahia tests revealed comparability for several compounds. However, no species is consistently the most sensitive to all compounds.

Toxicity testing of synthetic and biogenic surfactants on marine microorganisms

Abstract: The toxicity of four synthetic surfactants, two commercial oil dispersants, and six biosurfactants have been examinated. The test systems were (a) bacterial growth inhibition, (b) microalgae growth inhibition, (c) microflagellate growth inhibition, (d) biodegradation, and (e) bioluminescence inhibition (Microtox test). The multiplication of bacteria was stimulated by surfactants, while that of microflagellates and microalgae was inhibited. This may be due to the metabolic usage of surfactants, especially biosurfactants, by bacteria. The bioluminescence was very sensitive to surfactants. No toxicity could be detected with glucose-lipid, produced by the marine bacterium Alcaligenes sp. MM1. Most biosurfactants were degraded faster and possessed higher EC50 values than synthetic dispersants.

Dehydrogenase activity of soil microflora: Significance in ecotoxicological tests

Abstract: Reference CECOTOX-ARTICLE-1991-002View record in Web of Science Record created on 2005-07-15, modified on 2016-08-08

Evaluating three simple methods to assess the microbial quality of drinking water in Indonesia

Abstract: Three simple microbial tests [H2S paper strip, lauryl tryptose broth + 4-methyl-umbelliferyl-β-d-glucoronide (LTB + MUG), Colilert] were used to assess the microbial quality of water in the distribution system of Banjarmasin, the capital city of South Kalimantan Province (Borneo), Indonesia. Martapura River, the source of the drinking water, is contaminated with total coliform, Escherichia coli, and hydrogen sulfide producing bacteria. However, this water is treated and chlorinated to a residual of 1.0 mg/L before it is distributed to the city. No coliform or hydrogen sulfide producing bacteria were detected in the chlorinated water leaving the treatment plant. A total of 46 water samples were obtained from public taps at three subdistricts in the city located 2–8 km from the water treatment plant. Residual chlorine levels ranging from 0.0 to 0.8 mg/L were detected in the 46 drinking water samples. Of these, 47.8% was positive by the H2S test and the Colilert test. The LTB + MUG test was positive in 45.7% of these 46 water samples. Virtually all (96–100%) of the coliform positive samples contained E. coli. The H2S test appears to be a reliable, inexpensive, and especially suitable to assess the microbiological quality of drinking water in Indonesia.

Current and possible alternate indicators of fecal contamination in tropical waters: A short review

Abstract: Bacteria that belong to the total and fecal coliform groups have been used for several decades as indicators of fecal pollution of waters and other systems. The prevailing idea behind this is that these two groups of bacteria cannot replicate outside the gastrointestinal tract of warm-blooded animals. Several studies conducted by this and other laboratories have indicated that these bacteria may be naturally present in certain areas of the world. Naturally occurring fecal coliforms (the genera Escherichia and Klebsiella) have been isolated from pristine sites and from sites where there was no apparent fecal contamination. All these results lead us to the conclusion that these groups of bacteria are not adequate indicators of fecal contamination in tropical areas of the world. Alternate indicators are being tested. This laboratory and others around the world are testing the adequacy of bacteriophages (more specifically, coliphages) for this purpose. In Puerto Rico coliphages have been detected only in areas known to be contaminated with domestic sewage, but not in pristine areas, although high levels of fecal coliforms can be detected at the latter sites. All these results suggest that coliphages may be used as indicators that more realistically demonstrate fecal contamination of waters in tropical areas of the world. In addition, newer techniques, although still in the trial stages, can be used to directly detect pathogens in the environment. Of all the techniques currently available, the polymerase chain reaction is the most promising for the direct detection of pathogens and therefore for the unequivocal evaluation of the biological quality of waters.

Use of bioassays to evaluate river water and sediment quality

Abstract: In trying to establish the extent and degree of impact of point and nonpoint source contaminants on riverine systems, it is important to know the implications of the data obtained from various sampling points in a riverine system. Spatial variability between water and/or sediment samples collected in close approximation at the same sites was assessed by the battery of tests approach. In these samples there appeared to be no consistent relationship between sediment structure, microbial population, and toxicant concentrations. Furthermore the ATP-TOX System and Mutatox tests were the most responsive tests in all types of samples. Since sediments with their bound contaminants may be an important factor in this data interpretation, different methods for releasing and concentrating the sediment bound contaminants were evaluated. The results and implications of these results are described.

Microtesting appraisal of ATP and cell recovery toxicity end points after acute exposure of Selenastrum capricornutum to selected chemicals

Abstract: Employing microtesting procedures, intracellular ATP and cell recovery (96-h cell count determinations) were appraised as toxicity end-point responses after acute (4-h) exposure of the green alga Selenastrum capricornutum to metals (Cu2+, Co2+, Cd2-, Cr3+, Cr6+, Ni2+, Hg2+, Zn2+, B3+), sodium azide, and 4 organic compounds (sodium dodecyl sulphate, 2,4-dichlorophenol, phenol, tebuthiuron). Except for B3-, both end points were able to measure acute metal phytotoxicity effects at concentrations of 5 mg · L−1 or lower. The algal recovery test showed better metal toxicity discrimination than the ATP test on the basis of dose—response slope steepness and elevation differences. Both tests, however, supplied useful complementary information. While the ATP test reacted rapidly to chemical aggression, the recovery test offered pertinent insight into actual long-term consequences of acute exposure. With the nonmetals, both end-point responses were mitigated (sodium azide, sodium dodecyl sulphate, 2,4-dichlorophenol) or insensitive (phenol, tebuthiuron), suggesting low acute exposure risk to algae by these chemicals. Based on 4-h (ATP and cell recovery) EC50 to standard 96-h EC50 ratio values, the algal indicator was shown to have low tolerance to 6 chemicals (Cr3+, Cr6+, Hg2-, Cu2+, sodium dodecyl sulphate, 2,4-dichlorophenol). When compared to acute exposure bacterial assays, the acute exposure ATP and cell recovery microtests competed well in terms of overall sensitivity to a selection of chemicals. In general, this work demonstrates the utility that short-term algal exposure tests can provide for chemical toxicity investigations.

Biodegradation of recalcitrant chlorophenols by cometabolism

Abstract: Under normal conditions in the environment a significant proportion of xenobiotic biodegradation involves cometabolism. Using the cometabolic principle, a procedure was developed to achieve accelerated biodegradation of persistent chemicals. Three stable chlorophenols [3,5-dichlorophenol (DCP), 3,4,5-trichlorophenol (TCP), and 2,3,5,6-tetrachlorophenol (TRCP)], which showed a total resistance to the biodegradation potential of a pentachlorophenol-degrading bacterial culture, were found to be biodegradable using the cometabolic technique. When a low-chlorinated monochlorophenol (3-MCP) was the cometabolite, only the medium-low chlorinated 3,5-DCP was biodegraded, while the medium chlorinated 3,4,5-TCP and the medium-high chlorinated 2,3,5,6,-TRCP were not degraded by the culture. However, all three stable chlorophenols could be rapidly biodegraded when a highly chlorinated pentachlorophenol (PCP) cometabolite was used. If dual cometabolites (3-MCP and PCP) were used, all three stable chlorophenols were biodegraded, but at much slower rate. Maximizing biodegradation by use of the cometabolic technique to achieve accelerated biodegradation of stable chemicals is discussed.

Microbial water quality concerns for water supply use

Abstract: The greatest impact of water pollution on public health comes through drinking water, the source of which may be degraded by point and nonpoint pollution sources including municipal wastewater, storm water runoff, agricultural drainage, and food processing. While water treatment technology can successfully process poor quality source waters containing in excess of 2000 fecal coliforms/100 mL to produce potable water that meets the accepted drinking water standards, there is serious concern that the barriers to microbial breakthrough in the finished water may prove to be dangerously thin. Any momentary break in the treatment train could allow substantial levels of microorganisms to enter the final product—potable water. The burden of water quality enhancement should be a shared responsibility among all discharges and downstream users of these irreplaceable resources. Much can be accomplished through the application of a multiple barrier approach in wastewater treatment, controlled storm water releases, and water supply enhancement. Dischargers must seek to minimize pathogen releases, reduce particulate dispersion, and diminish organics in effluents. These factors impact heavily on the effectiveness of wastewater disinfection. Furthermore, with passage downstream to the water intake, these organic residuals may be the precursors of disinfection by-products created during drinking water treatment. Some water supply operations must revise their treatment practices to provide better protection from the passage of protozoan cysts and enhance the removal of organics before applying disinfection. Disinfection of water supply is critical and will only be consistently effective in a clean processed water.

Estimating the toxicity of chlorinated organic compounds using A multiparameter bacterial bioassay

Abstract: A battery of microbial tests that included contemporary measurement of specific growth rate, intracellular ATP level, and respiration rate proved capable of distinguishing among toxicants that acted primarily as (a) catabolic inhibitors, (b) uncouplers, and (c) inhibitors of biosynthetic processes. The concentration of chlorinated phenols and ethanes that produced a 50% reduction in specific growth rate (ECk50) provided the most useful single-parameter indication of relative chemical toxicity generated within the test battery. Among the chlorinated ethanes tested, toxicity resulted from nonspecific chemical interactions with bacterial membranes, as indicated by correlation between toxicity (ECk50) and measures of lipophilicity. The ECk50 value for 1,2-dichloroethane was 8.5 × 10−3M as compared to 1.7 × 10−4M for the more hydrophobic pentachloroethane. Intermediate ECk50 values were obtained for 1,1,1-trichloroethane and 1,1,2,2-tetrachloroethane. For a comparable degree of lipophilicity, the chlorinated phenols were about an order of magnitude more toxic than chlorinated ethanes. ECk50 values for Spirochaeta aurantia at pH 7 ranged from 1.3 × 10−3M for 2-chlorophenol to 9.4 × 10−6M for penta-chlorophenol. There was indirect evidence that the toxicity of chlorinated phenols arises from both specific and nonspecific chemical interactions with bacterial membranes. The test battery proved capable of distinguishing among the relative toxicities of the chemicals tested at least as well as other bioassay procedures including Microtox and Daphnia-based tests. However, ECk50 was less sensitive than parametric measures of chemical toxicity generated via other procedures.

Testing the influence of chemicals on soil autotrophic ammonium oxidation

Abstract: Nitrification is crucial for the content of inorganic nitrogen in soil and hence of considerable ecological and agricultural importance. The first step in the nitrification process, the oxidation of ammonium to nitrite, is particularly sensitive to chemicals, and the ammonium oxidation activity of soils may thus be used as an indicator of chemical disturbances. A method for the determination of potential nitrification has been tested that measures ammonium oxidation specifically and under optimal conditions, has a good reproducibility, and makes it possible to screen a large number of chemicals during a short period of time. The method has been tested with a number of pesticides. Dithio-carbamate fungicides gave the most pronounced inhibition of ammonium oxidation.

Coliphages as alternate indicators of fecal contamination in tropical waters

Abstract: Strong evidence has recently been found against the use of fecal coliforms as indicator organisms of fecal contamination in tropical waters due to their indigenous nature in pristine waters. There is a great need for the development of more rapid, accurate, and low-cost techniques for determining bacteriological water quality. Coliphages seem to be an excellent alternative. We have developed a method to analyze large volumes of pristine water, which we compared to a commonly used direct method. It involves the filtration of water through positively charged filters and a virus-elution step. The eluent is then mixed with culture medium, a host bacterium, and incubated. We sampled pristine tropical rivers, water collected from bromeliads (epiphytic vegetation), sewage-contaminated waters, and marine waters. Concentrations of indicator bacteria were higher than recommended levels for recreational waters, including bromeliad waters. Indicators levels were higher in bromeliad waters than in sewage-contaminated rivers. Phages were isolated only from waters being used for recreational purposes and from sites known to be contaminated with domestic sewage, but not from pristine or bromeliad waters. These results suggest that there is a correlation between the presence of coliphages and fecal contamination. This further suggests that coliphages may be reliable indicators of fecal contamination in the environment.

Desulfovibrio desulfuricans growth kinetics

Abstract: Growth kinetics of Desulfovibrio desulfuricans, strain NCIMB 9467, was studied in laboratory scale, under well-controlled batch conditions. This research is oriented toward the practical, industrial removal of sulfate and metal ions from mine water. Growth of the microorganism in such waters was verified. From 290 experimental observations ofsulfate and lactate (obtained from 145 culture tubes of 20 mL) the parameters of a Monod model were estimated. Inoculum mass was not measured but it was incorporated as another model parameter. Hydrogen sulfide was removed by addition of ferrous iron, which rapidly formed iron sulfide and precipitated toward the bottom of the culture tube. Parameters were estimated by a nonlinear least squares parameter minimizer. The growth-limiting substrate was the sulfate concentration. Under these conditions the growth of Desulfovibrio desulfuricans was characterized by a maximum growth rate of 25 . h-*, a sulfate affinity constant of 850 mg/L, and a reduced sulfate yield of 6.2 . (biomass per sulfate mass). Inoculum was 1.97 mg of bacteria& and the consumption of lactate was characterized by a yield of 2.5 . lo-' (biomass per lactate mass). Sulfate was reduced at a rate of 400 mg/L/day while lactate was oxidized at a rate of 1100 mglliday. Mine wastewater was used as sulfate source and complemented with lactate as the carbon source. Under these conditions the strain growth was similar to that obtained with the controlled media. It was concluded that no inhibitory effects exist. The reduction velocity obtained, 200 mg/L/day, was lower than before, probably due to inoculum size or strain adaptation. A novel process is proposed to produce solid sulfur from sulfate and sulfur oxides.

Cr and Hg toxicity assessed in situ using the structural and functional characteristics of algal communities

Abstract: The toxicity of mercury and chromium on algal community structure have been assessed using in situ N2ase activity, pigment diversity, autotrophic index, and 14C uptake of algae. The location was in the river Ganga and controlled ecosystem pollution experiment enclosures were used. Maximum inhibition of algal number was observed at 0.8 μg Hg mL−1 followed by 8.0 μg Cr mL−1. Unicellular forms, except for Anorthoneis excentrica, were very sensitive to test metals used. The decline in algal number was concentration dependent and metal specific at generic and species levels. Complete elimination of three and six species was observed respectively at 8.0 μg Cr mL−1 and 0.8 μg Hg mL−1 after 12 days' exposure. Likewise, a concentration-dependent and metal-specific increase in autotrophic index and pigment diversity of phytoplankton was recorded for Hg and Cr. Inhibition of 14C uptake of phytoplankton in Ganga water was almost equal (79%) at 0.8 μg Hg mL−1 and 8.0 μg Cr mL−1 (78%). Although complete inhibition of in situ N2ase was observed at 0.8 μg Hg mL−1, it was only 80% with 8.0 μg Cr mL−1. Our study suggests that heavy metals inhibit both structural and functional variables of phytoplankton in field microcosms. Hence this technique seems to hold potential for the biomonitoring of heavy metal toxicity in the field.

Contamination of domestic water heaters with Legionella pneumophila: Impact of water temperature on growth and dissemination of the bacterium

Abstract: Sediment and tap water from 255 randomly selected domestic water heaters were cultured on buffered charcoal yeast extract agar and two semiselective media to detect the presence of Legionellaceae. Different serogroups of L. pneumophila, the only species of Legionellaceae identified in this study, were found in 84 of the 255 water heaters and this contamination occurred only in electric water heaters (n = 205). Sediment contamination by L. pneumophila was strongly associated with water temperature. The bacterium was detected in 45% (80/176) of the sediments with temperature lower than 40°C and in only 14% (4/29) of the sediments at this or higher temperatures. When the peripheral water temperature was lower than 56°C, 23% (9/39) of the tap water samples were contaminated with Legionella while only one of the 161 samples that were above this temperature contained Legionella. These results do suggest that reducing the water temperature in electric water heaters could play a role in the multiplication of L. pneumophila in the water heaters and in its dissemination in the household.

Regulatory influence of light and temperature on petroleum toxicity to Anabaena doliolum

Abstract: Effects of light and temperature, the most important variables in natural environments, on the toxicity of Assam crude oil extract were examined. Illumination of oil extract increased the degree of inhibition of growth, photosynthesis, and respiration of Anabaena doliolum. Higher light intensities were more effective in inhibiting the test organism. This may result from the formation of highly toxic photooxidation products. The toxicity of oil extract also showed an increase with increase in temperature, even though it might be envisioned that elevated temperature would facilitate the loss of highly toxic volatile fractions. It is possible, therefore, that the toxic effects of petroleum might be more severe in tropical than in temperate climates.

Evidence of genotoxic substances in the Niagara river watershed

Abstract: The SOS chromotest was used to detect genotoxicity of sediment samples from seven locations in the Welland River, Ontario, Canada, in December 1986 and April 1987. DMSO extracts of sediment samples from one location situated directly below the discharge pipe of a polyvinyl chloride plant showed a statistically significant (p < 0.01) genotoxic effect. It was concluded that genotoxic contaminants were associated with vinyl chloride contaminated sediments from this location. At a distance of 5 m downstream of the polyvinyl chloride plant's discharge, the mean SOS induction factor was 2.05, while 100 m further downstream the SOS induction factor had dropped to 1.54. The Ames test was used to detect genotoxicity of samples that gave positive responses in the SOS chromotest. The results of the Ames test were negative. This may suggest that the SOS chromotest is more sensitive than the Ames test for testing genotoxicity in these types of samples.

Uptake and exclusion of plutonium by bacteria isolated from soil near Nagasaki, Japan

Abstract: The ability to bind Pu 4+ during growth in the presence of low concentrations of this ion was compared in 5 strains of bacteria isolated from soil that had been contaminated with Pu by fallout for more than 40 years. Although Pu became associated with all bacterial strains studied, the strength of association varied greatly. These results suggest that different bacteria use different techniques in dealing with Pu 4+ ions. This, in turn, could greatly affect the fate of these ions in natural environments and their subsequent availability for other forms of life

Acute toxicity of Phytolacca dodecandra (Endod‐S) and Niclosamide to snails, Schistosoma mansoni cercaria, Tilapia fish, and soil microorganisms

Abstract: The acute toxicity of two molluscicides, the extract of the plant Phytolacca dodecandra (Endod-S) and Niclosamide, was determined using the following test species: The snails Biomphalaria glabrata (albino) and Biomphalaria pfeifferi, Schistosoma mansoni cercaria, and Tilapia nilotica fish. Endod-S showed a 24-h LC50 of 2.57 and 5.37 mg/L for B. glabrata (albino) and B. pfeifferi respectively. Niclosamide produced a 24-h LC50 of 0.063 mg/L and 0.049 mg/L for B. glabrata (albino) and B. pfeifferi, respectively. The 4-h LC50 for S. mansoni cercaria was 2.92 mg/L for Endod-S and 0.0008 mg/L for Niclosamide. The 24-h LC50 for Tilapia nilotica was 1.82 mg/L for Endod-S and 0.21 mg/L for Niclosamide. The toxicity of Endod-S and Niclosamide to a mixed population of soil microorganisms was measured using oxygen uptake and growth as measured by turbidity. Endod-S was not toxic to the microorganisms. The average Niclosamide toxic end point (IC50) for these bacteria was 450 mg/L.

Coliphages and other microbial indicators in stabilization ponds

Abstract: Coliphages have been reported as promising indicators of viral inactivation in wastewater treatment. Their use in different aquatic environments, however, needs characterization prior to their application. The study of the behavior of coliphages in Chilean stabilization ponds is reported. The experimental system was a discontinuous reactor, subjected to the natural different climate conditions. Chile is a temperate country and this study concentrated on the significantly different behavior of ponds during summer and fall seasons. Coliphages counts using Escherichia coli C (ATCC 13706) as host were compared to most probable number fecal coliforms, Salmonella, and fecal streptococci. The results indicate that coliphages were more resistant to pond treatment than fecal coliforms and Salmonella. Furthermore, coliphages did not reflect climate changes as much as enteric bacteria did, as coliphage die-off rates during warm and cold seasons were 0.5 and 0.3 (Kb, day−1). Summer die-off rates of fecal coliforms (2.0, Kb, day−1) and Salmonella (1.7, Kb, day−1) drastically fell (0.6, Kb, day−1) in the fall. Coliphages and fecal streptococci removal tended to be similar, especially in cold season. It was observed that environmental factors, pH, dissolved oxygen, and algae biomass equally affected removal of all indicators, to different extents. These results suggest that to assess the microbiological efficiency of stabilization ponds, coliphages and fecal coliforms should be considered, as the first represents viral removal while the second represents pathogenic bacterial removal. Both parameters complement each other, particularly when important weather changes are expected.

Microbial enzyme activity and biomass relationships in soil ecotoxicology

Abstract: Multispecies toxicity testing is emerging as a useful tool in ecotoxicological assessments. Understanding the relationship between soil microbial biomass levels and microbial enzyme activities (MEA) is basic to clarifying ecotoxicity effects and bioremediation potential in soil systems. Saturated subsurface soils were exposed to fluctuating concentrations of a mixture of 1-choromethyl-2-methyl naphthalene, phenothiazine and 2,4,2′4′-tetrachlorobiphenyl. An enzyme suite composed of dehydrogenase, amylase, esterase, alkaline phosphatase, and protease was monitored, along with simultaneous biomass estimates using total plate counts for facultative aerobes and anaerobes, acridine orange direct counts (AODC) for total bacteria, and endogenous protein. Results indicate that quantitative biomass levels (AODC) remained relatively constant. Mean log10 values of AODC biomass reached a plateau between 6.45 (±0.15) and 7.06 (±0.10) with coefficients of variation <3.0. AODC adjusted to biovolume carbon estimates indicated that bacterial organic carbon could represent 0.03 and 0.35% of the mean measured levels of total organic carbon depending on the number of cells and the volume of each cell in μm3. Multivariate statistical analyses identified significant correlations among some MEA, biomass measurements, and chemical pollutants. The general implications of these results to ecosystem function and bioremediation potential are discussed.

Ecological effects testing under the Toxic Substances Control Act: Acrylamide

Abstract: Analysis of acrylamide aquatic toxicity data submitted under section 4 of the Toxic Substances Control Act revealed that for acute toxicity studies with bluegill, fathead minnow, and rainbow trout, concentrations of acrylamide necessary to produce 50% mortality decreased by 50-70% as a function of increasing exposure from 1 to 4 days. Analysis of acute toxicity data for Mysidopsis bahia suggested that increases in mortality with increased exposure to acrylamide might also be observed in saltwater organisms. Ratios of acute (4-day) LC50 values to chronic (28-day) maximum acceptable toxic concentrations for this saltwater invertebrate were 26 for parent and offspring survival, 115 for female dry weights, and 975 for male dry weights. These ratios illustrate that long-term acrylamide exposure to sensitive life stages of M. bahia produced adverse effects on reproduction and growth at acrylamide concentrations significantly lower than those suggested by acute LC50 or EC50 values.

Implications of botulism outbreaks in gulls (Larus ridibundus) on the Watershed Management of Lake Kinneret (Israel)

Abstract: Lake Kinneret (Israel), which currently supplies 30% of the national water demands (of which 50% is for domestic purposes), is also utilized for commercial fishery, recreation, and tourism. The measures taken to prevent pollution include, among others, sewage and fish pond waste removal, and burial of industrial and household solid wastes at established garbage dumps. On January 13, 1985, hundreds of dead and moribund gulls (Larus ridibundus) were observed on the shoreline and water surface at the northwest part of the lake, and around the northern garbage dump site. Sick birds exhibited signs that the nervous system was involved, i.e., paralysis of the wings and of the feet, and limberneck. Routine analyses ruled out the possibility that the poisoning was due to pesticides or an infective agent. Botulism intoxication was suspected and type C-botulism toxin was identified in the serum of moribund birds. This is the first record of a botulism outbreak in waterfowl in Israel. The total mortality was approximately 3000–4000 gulls, of which 1200 dead birds were collected and burnt. Investigations revealed that at a garbage dump situated in the vicinity of the lake, waste products of a chicken slaughter house were not buried as required by formal regulations. Examination of lake water, sediments, and vegetations for possible contamination by botulism toxin were negative. The implications of the outbreak on the environment are discussed.

A multiparameter chemical toxicity test using Salmonella typhimurium and Spirochaeta aurantia

Abstract: A battery of measurements, including specific growth rate, intracellular ATP level, and respiration rate, was designed to measure the responses of Salmonella typhimurium and Spirochaeta aurantia to chemical toxicants. The test battery provided both a measure of relative toxicity and an indication of the biochemical mechanism of chemical toxicity. The utility of the battery was investigated using chemicals (cyanide, 2,4-dinitrophenol, chloramphenicol, and dicyclohexylcarbodiimide) for which toxic mechanisms have been clearly established. Test battery results provided a reproducible “signature” for each model compound, which was useful for differentiating among compounds whose primary mechanism of toxicity involves (a) inhibition of catabolic activity leading to oxidative phosphorylation, (b) disruption of membrane integrity, and (c) interference with biosynthetic activity. The responses of the two test organisms to model inhibitors were qualitatively identical and paralleled predictions based on theoretical grounds. In theory, the test battery can measure toxicity among classes of compounds that alternative, single-parameter microbial tests would classify as nontoxic. The microbial test battery described may eventually provide a theoretically superior and economically attractive alternative to established toxicity testing procedures.