Microtox Acute Test

As many areas additionally suffer from lack of electricity and acute shralages of normal infra-stnictural facilities, coupled with the fact that there is no idea of the magnitude of the contamination in tmns of either concentration or area, the Microtox Acute Test is an ideal tool for initial surveys to enhance the outline hazard assessment and provide useful information for a meaningful risk assessment. 

A novel extension of the Microtox Acute Test has resulted in the development of a new test system which uses a dark strain of luminescent bacteria to measure genotoxicity of chemicals or environmental samples. 

Table 14.3 summarizes comparative data showing the increased sensitivity of the Microtox Chronic Test when compared with the standard Microtox Acute Test The chronic test shows an average 50 times greater sensitivity over the acute test for the compounds tested. Table 14.4 compares this new chronic test method with die Ceriodaphnia dubia chronic test procedure developed by the US EPA. These comparative data show similar sensitivities for these 2 chronic test methods. Additional comparative studies using these 2 test methods are underway using complex environmental samples. These results will be published in the near future and should reermfirm the utility of diis relatively simple, rapid, and cost-effective alternative chronic test procedure. 

Hauser, B., Schrader, G. and Bahadir, M. (1997) Comparison of acute toxicity and genotoxic concentrations of single compounds and waste elutriates using the Microtox/Mutatox test system, Ecotoxicology and Environmental Safety 38 (3), 227-231. 

Freshwater sediments Heavy metals Hg, Pb, Cu, Ni, Zn, Mn, Fe, Cd TOC Humus compound content Sulfur and nitrogen content PAH TOC V. fischeri Microtox Basic Solid-phase Test, Microtox Acute Toxicity Basic Test) V. fischeri Daphnia magna... 

The Microtox acute toxicity test is based upon measuring metabolic inhibition using a standard suspension of luminescent bacteria. Since bioluminescence is a direct measure of metabolic activity in these wganisms, measuring the rate of light output is a simple way to measure metabolic inhibition (toxicity). The test system has been in use for over 10 years and is the subject of many reports, reviews and application studies as well as being... 

Research and development efforts over the last 2 years have provided new and useful infraination about the genetics and physiology of the light producing mechanism in the luminescent bacterium Vibrio fischeri. These research and development efforts, along with years of experience gained from the development and application of the Microtox Acute Toxicity Test, has resulted in the development of a new Microtox Chronic Toxicity Test System using luminescent bacteria [57]. 

Table 143 ECj, (mg r ) values for the Microtox chronic and acute test methods...

Toxicity in estuarine sediments—use of Mutatox and Microtox to evalu- 173 ate the acute toxicity and genotoxicity of organic sediments Toxicity tests for the analysis of pore water sediment a comparison of 4 174... 

Jung, K. and Bitton, G. (1997) Use of Ceriofast for monitoring the toxicity of industrial effluents comparison with the 48-h acute Ceriodaphnia toxicity test and Microtox , Environmental Toxicology and Chemistry 16 (11), 2264-2267. 

Pardos, M., Benninghoff, C., Gueguen, C., Thomas, R., Dobrowolski, J. and Dominik, J. (1999a) Acute toxicity assessment of Polish (waste)water with a microplate-based Hydra attenuata assay a comparison with the Microtox test, The Science of The Total Environment 243-244, 141-148. 

Vibrio fischeri, Microtox light inhibition test Pseudokirchneriella subcapitata, micro-algal growth inhibition assay Daphnia magna, acute immobilization test Ceriodaphnia dubia, chronic reproduction and survival test Thamnocephalus platyurus, Thamnotoxkit lethality assay. 

Microtox test) Vibrio fisheri ISO 11348-3 (1999) Inhibition of bioluminescence Acute... 

Due to the different fate of lubricants during their use, e.g. contamination by fuel and combustion products of engine oils, the toxicity of used lubricants may be significantly different than that of fresh oils. Fluids which are considered environmentally friendly must not only be biodegradable, but also relatively nontoxic, in both their initial form and degradation products. Their effects on flora and fauna must be minimal. There are two common tests to evaluate toxicity the Microtox and the Rainbow Trout bioassay. Considerable environmental toxicity testing has been carried out on esters fluids. Esters cause minimal acute toxicity by ingestion and skin absorption. 

While it alone cannot substitute for acute or sublethal hazard assessment which covers all species, Microtox can be useful in a battery of screening tests or to supplement data obtained in other toxicity bioassays. 

The OECD Daphnia spp acute immobilisation and reproduction tests. A mainstay in aquatic toxicity testing, Daphnia tests have been used also to evaluate the toxicity of contaminated groundwaters and leachates (Kross and Cherryholmes, 1992). As with any of the aquatic tests, the principal problem with the Daphnia test is the need to extract a suitable aqueous sample. This problem is illustrated by Kross and Cherryholmes (1992), who compared D. magna and Microtox assay results in leachates but found a poor correlation between the two methods. 

We developed the first expert system that incorporates a working set of rules for a type of QSAR referred to as a linear solvation energy relationship or LSER (13-17) to predict LSER variable values from SMILES string formalism. The program also uses these LSER results and information about toxicity to predict acute toxicity to four representative organisms the fathead minnow (Pimephales promelas), the crustaceans Daphnia magna and Daphnia pulex. and Photobacterium phosphoreum. the luminescent agent in the Microtox test. 

Bioassav Data Sets and Multiple Linear Regression Equations The expert system predicts the acute toxicity of a chemical to four representative aquatic organisms and reports toxicity as either EC50--is the effective concentration at which either 50% of the animals (Daphnia pul ex or D. magna) were immobilized or 50% of the luminescence (the Microtox test) was diminished--or LC50, the lethal concentration for 50% of the fish (fathead minnows) in the study. 

Table III. Predicted (P) vs Experimental (E) LSER Parameter Values and Acute Toxicities for the Microtox Test (MT), Daphnia pulex (DP), Daphnia magna (DM), and the Fathead Minnow (FM)...

A battery of tests developed by Dutka et al. 1986 to test the sediments of near-shore sites of Lake Ontario (Canadian part) is used to exemplify the definitions and some results of HDT. In Lake Ontario 55 sediment samples were tested, thus, the set E contains 55 objects. Dutka et al. classified their results and used discrete scores instead of the measured (raw) data. For our analysis we have adopted their classification. Thus, s, denotes the score of the i-th test of the battery. Five specific tests form the actual battery (1) Fecal Coliforms FC , as an indicator designed to control the health state of the sediments, (2) Coprostanol CP and (3) Cholesterol CH both being indicators of loadings by fecals, (4) Microtox tests MT and (5) Genotoxicity tests GT disclosing some kind of acute toxicity and the potential for carcinogenicity, respectively (see Table 3). 

Microtox Solid-phase test SDI Vibrio fischeri is added to a suspension of the test sample. Subsequently, the mixture is filtered using the device supplied with the kit, and the light emission of the supernatant is determined. The method is a further development of the acute luminescent bacteria test for aqueous samples. Contact test with Bacillus cereus DSM No. 351 Effects on the dehydrogenase activity of the test bacterium after an exposure time of 2 hours are investigated using resazurine reduction (Ronnpagel etal. 1995). 

Embryo hatching success and posthatch larval survival of the marine fish Sciaenops ocellatus were not affected by RDX at the highest concentration achieved without the use of a solvent carrier (299 pmoles L 1) [15] (Table 4.6). At its solubility limit, this chemical was also neither acutely toxic to marine crustaceans and polychaetes, nor exhibited sublethal effects in tests with echinoids [15], whereas adverse effects were observed with the macroalga U.fasciata zoospore germination, the polychaete D. gyrociliatus reproduction, and the 30-min Microtox bioluminescence endpoints [15,30] (Table 4.6). 

Munkittrick K. R., Power, E. A., Sergy, G. A. 1991. The relative sensitivity of Microtox , Daphnia, rainbow trout, fathead minnow acute lethality tests. Environmental Toxicology and Water Qualtity 6 35-62. 

The plastic sample also must pass several marine toxicity tests, including P0I540X (microbial oxygen absorption), Microtox (microbial bioluminescence) test, fish Acute Toxicity (static conditions) OPPTS 850.1075, Daphnia Acute Toxicity (static conditions) OPPTS 850.1010, or Static Algal Toxicity Test OPPTS 850.5400. The plastic samples must also have less than 25% of maximum allowable concentrations of regulated heavy metals. 

---