Short-term Chronic Tests Research Articles

Evaluation of toxicity of waters from the surface sources of water supply and drinking water of Zhytomyr city by the method of short-term chronic biotesting

The goal of the researches is to increase the informativeness of testing water from the surface sources of water supply and drinking water at the expense of the use of african clawed frog. Method of the researches is biotesting with determination of test sign of immobilization the marsh frog (Rana ridibunda Pallas, 1771) and african clawed frog (Xenopus laevis Daudin, 1802) at term 8-day exposition of individuals. During a biotesting for lack of immobilization R. ridibunda it is not discovered toxicity of water, but on the basis of immobilization X. laevis the low level of toxicity of them in within 25–50% is defined. Assessment of chronic toxicity of waters from the surface sources of water supply and drinking water is expedient to conduct, using the biotesting with X. laevis. It is shown the high sensibility of these test-organisms in comparison with R. ridibunda (in average to 28.2% in acute lethal tests with exposition time 4 day and to 41.3% in short-term chronic tests with exposition time 8 day).

Development of a short-term chronic toxicity test with a tropical mysid

There is an increasing need to develop reliable methodologies for chronic toxicity testing using tropical species. The present work aimed at developing a suitable short-term chronic toxicity test with Mysidopsis juniae using zinc (Zn) and nickel (Ni) as model chemicals and growth (length and dry weight), survival, and egg production (number of females with eggs) as endpoints after seven days of exposure. Survival and growth of newborn M. juniae were affected by chronic exposure to zinc, while nickel affected only survival. For zinc, dry weight was the most sensitive endpoint with significant effects even at the lowest tested concentration (75μgZn·L−1), whereas for nickel, survival was the most sensitive parameter (LC20 of 26μgNi·L−1). Egg production was not affected. M. juniae short-term chronic testing is a sensitive approach to evaluating metal toxicity; further studies are necessary to assess chronic toxicity for others contaminants in the proposed assay.

Multigeneration Method to Evaluate Effects of Pollutants on the Reproduction of Freshwater Snails

Ecotoxicity tests have been useful to guide regulatory decisions for pollution control to prevent adverse effects on aquatic ecosystems. Routine assays are based on acute or sub-chronic exposures and may be inadequate for detecting a reproductive impairment after long-term exposure to low concentrations of pollutants. To help adress this gap was proposed a mutigeneration method to evaluate the effects of chemicals on the reproduction of Biomphalaria tenagophila snail. Chemicals tested include two environmental pollutants, the pesticide endosulfan and the industrial chemical nonylphenol ethoxylate. Adult snails (10 per concentration) were individually exposed to non acutely lethal concentrations for two generations. Endpoints evaluated include: survival, fecundity and embrionic development. Results showed that some adverse effects on reproduction were observed only after continuous exposure lasting longer than one generation. A comparative analysis with results of classic short-term chronic tests show that the multigeneration study designed seems to be a sensitive approach to evaluate chronic effects of environmental pollutants.

Biological assays for aquatic toxicity testing

A number of aquatic toxicity tests have been established for South African use, which include fish and Daphnia lethality tests, microbiotests, and short-term chronic tests. Studies on effluents and surface waters showed that all the tests have a viable role to play in water quality management. The most advantageous use of the tests is in battery form, so that tests can complement each other. The fish and Daphnia lethality tests, and algal growth inhibition test are recommended for regulatory and management purposes of effluents. If receiving water is used for drinking water purposes, the Ames Salmonella mutagenicity and toad embryo teratogenicity tests should be included in the battery of tests. Some of the rapid microbiotests, e.g. the protozoan oxygen uptake test, bacterial growth test and enzyme tests, could be valuable screening tools to identify and categorize toxic effluents.

Biological assays for aquatic toxicity testing

A number of aquatic toxicity tests have been established for South African use, which include fish and Daphnia lethality tests, microbiotests, and short-term chronic tests. Studies on effluents and surface waters showed that all the tests have a viable role to play in water quality management. The most advantageous use of the tests is in battery form, so that tests can complement each other. The fish and Daphnia lethality tests, and algal growth inhibition test are recommended for regulatory and management purposes of effluents. If receiving water is used for drinking water purposes, the Ames Salmonella mutagenicity and toad embryo teratogenicity tests should be included in the battery of tests. Some of the rapid microbiotests, e.g. the protozoan oxygen uptake test, bacterial growth test and enzyme tests, could be valuable screening tools to identify and categorize toxic effluents.

Evidence that variability in ambient fathead minnow short-term chronic tests is due to pathogenic infection

An examination of results from ambient fathead minnow subchronic toxicity tests identified a common characteristic of the tests, which manifests itself as a large among-replicate and between-test variance in survival. The unusual replicate-specific mortality in tests with ambient water appears to be due to pathogenic bacteria or fungi. This finding is based on the following facts: a comparison of survival among replicates in effluents and ambient waters showed that when mean survival was low (40- 70%), among-replicate variation for ambient tests was greater than it was for the effluent tests; in 63 tests conducted at three locations over nearly 3 years, treating the water with ultraviolet (UV) light improved survival; a seasonal pattern to survival was present at ambient sites; survival was higher when minnows were separated by using 1 minnow/beaker rather than the standard system of 10 minnows/beaker; and survival tended to be higher in ambient sites contaminated with low levels of chlorine. The existence of the pathogen(s) does not mean that the test cannot be used effectively to assess toxicity of ambient waters; instead, it indicates that factors other than toxicity may need to be taken into consideration when interpreting the results. Keywords—Ambient toxicity testing Pathogen Fathead minnow

Application of the short-term chronic test with Ceriodaphnia dubia in identifying sources of toxicity in industrial wastewaters.

Application of the short-term chronic test with Ceriodaphnia dubia in identifying sources of toxicity in industrial wastewaters.

Use of the mayflyStenonema Modestum(Heptageniidae) in subacute toxicity assessments

This study presents the results of subacute toxicity testing with the mayfly (Ephemeroptera), species Stenonema modestum (Heptageniidae). This species is ubiquitous to many streams in the eastern United States and Canada and is associated with unpolluted sediments and water. The results show that counts of molts or exuviae over a 7–14-d exposure period can be a sensitive indicator of chronic growth effects. Molt production was a more sensitive indicator of pollutant effects than length of organism or width of head capsule measurements. Tests using coal mine effluents indicated that the 7-d molt production end point was often more sensitive than the 14-d molt or survival end point. This was due to either a short-term stimulatory effect on molting or effluent variability over time. Molt stimulation was not observed in tests using NaCl or silver nitrate. Tests with these compounds and coal mine effluents demonstrated that the methods and end points provide repeatable and relatively sensitive data. Test precision was comparable to U.S. Environmental Protection Agency 7-d short-term chronic tests. Molt production of Stenonema modestum in laboratory tests proved to be a reliable predictor of instream effects due to a metal-finishing effluent. Furthermore, simultaneous tests of sediment elutriates and ambient samples from the stream pinpointed probable mechanisms behind the observed instream impact on Stenonema modestum. This method should be amenable to other mayfly species, making it a potentially useful tool in site-specific water quality and sediment quality studies.

An evaluation of a short-term chronic effluent toxicity test using sheepshead minnow ( Cyprinodon variegatus) larvae

In response to recent changes in National Pollutant Discharge Elimination System (NPDES) permit regulations, rapid (7-day) static renewal toxicity tests have been developed to detect chronic (sublethal and lethal) effect concentrations of municipal and industrial effluents on freshwater and marine/estuarine organisms. This paper evaluates results from short-term (7-day) chronic effluent tests measuring effects on the growth and survival of the larvae of estuarine sheepshead minnow ( Cyprinodon variegatus). Growth was the more sensitive endpoint in 52% of the effluent tests; survival was most sensitive in 7% of the tests. Growth and survival were equally sensitive endpoints in 26% of the tests, while there was no effect on either endpoint at the highest test concentration in 15% of the tests. Four short-term chronic tests were conducted concurrently with early life stage (ELS) tests using a common effluent. Effect concentrations were generally (two of three) within one dilution (a factor of three). Comparison of short-term chronic and ELS tests were also conducted with reference single chemicals and the results were slightly better than the effluent comparisons. A series of ten intralaboratory tests and seven interlaboratory tests were conducted to assess the variability among tests results. Toxicity in these tests varied by no more than one test concentration interval. We concluded that this sheepshead minnow test is suitable to estimate chronic values for complex effluents discharged to marine/estuarine environments within the NPDES permit regulations.