Aquatic ecotoxicity tests

Vibrio fischeri (trade name Microtox ). The V.fischeri used in the Microtox tests during this study were supplied as freeze-dried batches of reagent by Azur Environmental (SDI), Hook, Hampshire, UK. These were stored at 4°C prior 

The 5 and 15 min EC50 values (those concentrations causing a 50% reduction in light output after 5 and 15 min of exposure, respectively) were calculated using the Microbics (SDI) version 6 software supplied with the instrument. 

After 24 and 48 hours the numbers of immobilised (i.e. not observed to swim during a 15 second observation period following gentle agitation of the test solution) D. magna were recorded. 

The reconstituted freshwater used during the D. magna culture and tests was prepared following a recipe recommended as being suitable for producing a hard water by the US Environmental Protection Agency (USEPA, 1975). The tests were carried out in a temperature-controlled room set at a nominal 20 2°C with artificial illumination of the test vessels on a 16 h light/8 h dark automatic cycle. 

The 24 h and 48 h EC50 values (those concentrations causing 50% immobilisation of the Daphnia after 24 h and 48 h of exposure, respectively) were calculated with their 95% confidence limits by either Probit analysis (Finney, 1971) or moving average angle analysis (USEPA, 1985). 

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For the preparation of aqueous elutriates from solid samples the standard methods DIN 38414-4 [30] or EN 12457 [31] can be used. Ten parts of water are added to one part of sample dry matter and the mixture is continuously shaken for 24 h. A clear solution is obtained by centrifugation or filtration and can be used for aquatic ecotoxicity tests. If necessary, a smaller amount of water can be used (e.g., a dilution of 1 5). 

Aquatic ecotoxicology evaluates the probability of an adverse impact of a substance on the aquatic environment at the present as well as in the future, considering the total flow into the system (Klein, 1999). It encompasses laboratory ecotoxicity tests on appropriate test organisms to explore relationships between exposure and effect under controlled conditions as well as studies of the effects of substances or effluents under a variety of ecological conditions in complex field ecosystems (Chapman, 1995). 

Standardized ecotoxicity tests (bioassays) have been developed and optimized over the last few years and encompass the effects on bacteria, daphnia and fish (DIN 38 412, parts 30, 31 and 34). These tests are designed to assess the toxicity on aquatic organisms. They are quick to perform, easy to handle and comparatively inexpensive, with the goal of allowing the toxicity of a complex water matrix to be estimated. However, they use pre-concentration steps so that it is possible that not all byproducts are recovered (which itself is hard to prove). 

Tier 2 PRA process involved developing environmental exposure data and chronic toxicity data distributions for individual POPs. The mean concentrations of POPs in local marine water measured at various locations were used as exposure data in the construction of the exposure distribution. The chronic toxicity data distribution was established based on published international acute toxicity data (LC50, EC50) on a variety of aquatic organisms tested in many jurisdictions, drawn primarily from the USEPA ECOTOX database (2002) (available at http //www.epa.gov/ ecotox). If the upper 5th centile of the measured chemical exposure data distribution did not exceed the lower 5th centile of its estimated chronic toxicity distribution, the potential ecological risk posed by the chemical was judged to be tolerable (Hall and Giddings, 2000). 

Babich, H. and Borenfieund, E. (1987) Cultured fish cells for the ecotoxicity testing of aquatic pollutants,... 

Zeeman M (1995) Ecotoxicity testing and estimation methods developed under Sect. 5 of the Toxic Substances Control Act (TSCA). Chap. 23, In Rand G (ed) Pimdamentals of Aquatic Toxicology Effects, Environmental Fate, and Risk Assessment, 2nd edn. Taylor Francis, Washington, D.C., pp 703 - 715... 

Aquatic organisms used for ecotoxicity tests are bacteria, algae, Crustacea and fish. 

Fourteen formulations of chemical alternatives were submitted to EPA under confidentiality and they were assessed based on numerous human health and ecotoxicity endpoints in addition to bioaccumulation potential and environmental persistence. They were also screened for potential exposure to workers, users and the aquatic environment. Where data gaps existed, EPA experts used models and chemical analogs to estimate the hazard for a particular endpoint. The literature and test data reviews were published in the final report, Environmentally Preferable Options for Furniture Fire Safety Low Density Furniture Foam . In addition, each hazard endpoint was ranked with a concern level (High, Moderate or Low) based on the criteria used by the EPA s New Chemicals Program to rate the concern level of new chemicals submitted under the Toxic Substance Control Act (TSCA). As seen in Figure 8.2, where the hazard endpoint rankings are bold, the value is based on experimental data. Where the hazard endpoints are presented in italic font, the value is estimated based on models or chemical analogs. In this way, detailed hazard information was summarized and presented in a clear and concise format. 

A case can often be made to omit studies as scientifically unnecessary, because it is possible to conduct an adequate risk assessment without them. This is most often the case if the substance decomposes to degradants of known hazardous properties. For example the substance may hydrolyse rapidly to non-toxic products, so the key issue is to establish that this happens rapidly in the stomach before the parent substance can be absorbed. There may then be a case for omitting the expensive long-term animal studies, providing it is also established that there is no dermal or inhalation absorption from these exposure routes. In a similar way, it may be justified to omit ecotoxicity studies on a substance which hydrolyses or otherwise decomposes in the aquatic environment to stable products that have already been tested. 

Kovacs, T.G. Gibbons, J.S. Trembaly, L.A. O Connor, B.I. Martel, P.H. Vos, R.H. The effects of a secondary treated bleached Kraft mill effluent on aquatic organisms as assessed by short term and long term laboratory tests. Ecotox. Environ. Safe. 1995, 31, 7-22. 

In brief, the PEEP index is a useful HAS to apply in comparative studies of wastewater effluents to assess their ecotoxicity and toxic loading. Some of its advantages include the fact that it considers results from different toxicity tests and endpoints, while integrating all possible antagonistic, additive or synergistic interactions that can occur between toxicants in a complex liquid sample. Furthermore, the use of a single PEEP value becomes very useful for decisionmakers who are then able to take science-based decisions to prioritize corrective actions on industries whose effluents are the most toxic for the aquatic environment. It is also noteworthy to point out that the PEEP index can be applied anywhere with any number or type of tests and endpoints to suit the needs and expertise of laboratories internationally. 

Cripe, C.R., Walker, W.W., Pritchard, P.H., Bourquin, A.W. (1987) A shake-flask test for estimation of biodegradability of toxic organic substances in the aquatic environment. Ecotox. Environ. Saf. 14, 239-251. 

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