GreenScreen EM is a specially formulated version of GreenScreen GC used for environmental monitoring of genotoxic and cytotoxic contaminants. GreenScreen EM comprises a convenient cuvette based protocol and dedicated portable instrumentation.
Applications:
- Toxicity assessment of contaminated surface and ground waters
- Monitoring of industrial effluent discharges
- Screening of soil samples from contaminated land
- Tracing sources of environmental contamination
- Characterisation and monitoring of effluent treatment processes
- Toxicity profiling of environmentally relevant chemicals
Aquatic Toxicity Testing:
Environmental toxicity assessment conventionally requires the use of aquatic organisms such as algae, Daphnia, marine bacteria or fish, producing a variety of data such as EC50s, LD50s and LOECs using measures such as the number of fatalities, diminished respiration or behavioural endpoints. GreenScreen EM can also be used to determine EC50s and LOECs for test samples by measuring inhibition of cell proliferation during incubation. Field trials have shown that GreenScreen EM has a sensitivity which correlates well with other ecotoxicity tests such as Daphnia and is an effective screening tool for acute toxicity.
With regard to genotoxicity testing there is no standardised approach to assessing surface waters and effluents. There are a number of genotoxicity tests available, many of which are used in the pharmaceutical arena for screening pure compounds. Some of these assays have been used in environmental monitoring and research studies have included the micronucleus test, the Comet assay and various bacterial assays such as Ames and Mutatox. However, all these tests require skilled laboratory workers and are expensive and time consuming to perform. In contrast, GreenScreen EM allows the assessment of genotoxicity using a simple and rapid fluorescence measurement.
Features of GreenScreen EM:
- Rapid (overnight) determination of genotoxicity and acute toxicity
- Simple protocol using portable instrumentation
- Test organisms which can be rapidly cultivated on demand as required
- Use of minimum equipment and laboratory provisions
- Minimum sample preparation and low volumes required (10 ml)
- Can be used as a rapid screening tool to identify pollution problems or relevant samples worthy of more detailed and expensive chemical or toxicological analysis
Why Test for Genotoxicity?
Genotoxins present in the environment can originate from a number of anthropogenic sources, such as chemical manufacturing plants, textile and dye industries, pulp and paper mills, petroleum refineries, landfill and waste disposal sites. The presence of genotoxins is of immediate concern for the welfare of the environment and human health. Links have been made between the presence of tumours in fish and oil spillages, whilst human exposure to industrial wastes have in the past caused a variety of genotoxic effects, including cancer, birth defects, heart disease and reproductive anomalies. Genotoxicity is often however, a more subtle sub-cytotoxic effect.
Current and soon to be implemented legislation in the UK & Europe is resulting in increasingly stringent controls on effluent discharges, highlighting the inclusion of other indicators, such as genotoxicity, in standard monitoring requirements. The new Water Framework Directive (2000/60/EC) came into effect in December of 2003. This represents the most comprehensive piece of legislation to date, and is intended to produce a common approach to protecting and setting environmental objectives for all ground and surface waters within the European Community, taking into account chemical and ecological parameters. The Directive identifies "substances or their breakdown products, which have carcinogenic or mutagenic properties", as one of the main pollutants of concern.
The Integrated Pollution Prevention and Control (IPPC) Directive (96/61/EC) will be encompassed by the Water Framework Directive. The IPPC Directive strongly encourages the use of novel technologies by Industry in order to minimise harm to the environment, and the adoption of BAT (Best Available Techniques) by Industry plays an important part in the issuing of permits to discharge.
Protocol:
The assay can be used in a screening mode testing a single concentration of the sample, and giving semi-quantitative assessment of genotoxicity and cytotoxicity. Alternatively, by testing up to 6 sample dilutions, a quantitative assessment of genotoxicity (LOEC) and cytotoxicity (EC50 and LOEC) and is determined. A standard GreenScreen EM kit contains sufficient materials for 4 batches of 6 tests.
The assay uses a simple cuvette-based protocol. After resuscitating the test and control yeast strains, the yeast reagents are mixed with an equal volume of sample, typically 1 ml, in a cuvette. The cuvette is sealed with a breathable membrane, and left overnight to incubate. Untreated controls and standard toxic compounds are also run for comparison.
Following incubation the yeast is re-suspended and the cuvettes are placed in a dedicated reader, which measures their optical density and fluorescence. Acute toxicity reduces the relative optical density (proportional to cell proliferation) whilst genotoxicity increases cell fluorescence.
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