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Weltje L.,BASF | Rufli H.,Ecotoxsolutions | Heimbach F.,Bayer CropScience | Wheeler J.,Hill International | And 2 more authors.
Integrated Environmental Assessment and Management | Year: 2010

This paper describes the basis for a water-only acute chironomid toxicity test guideline using first-instar larvae. The method is based on the OECD test guidelines for the acute Daphnia sp. immobilization test and the long-term tests with Chironomus sp., reflecting the common test procedures currently used by the European agrochemical industry. Development of this guideline proposal is important under the European Plant Protection Products Directive (91/414/EEC), under which an insect species may be required to be tested, particularly for certain insecticides, for which Daphnia sp. may not be representative of the sensitivity of nontarget aquatic invertebrates. Chironomus sp. is a freshwater insect currently used in different international test guidelines. Because their ready availability as a test organism, with culturing conditions and certain test methods already established, Chironomus sp. is regarded as a suitable additional freshwater invertebrate species for regulatory testing. Integr Environ Assess Manag 2010;6:301-307. © 2009 SETAC. Source

Rufli H.,Ecotoxsolutions
Environmental Toxicology and Chemistry | Year: 2012

It has become common practice in many laboratories in Europe to introduce the criterion "moribund" to reduce the suffering in fish acute lethality tests. Fish with severe sublethal symptoms might be declared moribund and are removed from the test as soon as this occurs (premature discontinuation of experiment). Moribund fish affect main study outcomes as the median lethal concentration (LC50) derived on fish declared as moribund may be lower than the conventional LC50. This was evaluated by a retrospective analysis of 328 fish acute toxicity tests of an industry laboratory based on five different definitions of moribund, and of 111 tests from 10 other laboratories from Europe and the United States. Using the criterion of moribund 10 to 23% of the fish were being declared as moribund in 49 to 79% of the studies. In 36 to 52% of the studies, the LC50 moribund was lower than the conventional LC50 depending on the definitions of moribund. An inclusion of the moribund criterion in an updated Organisation for Economic Cooperation and Development guideline for the acute fish toxicity test would reduce the period of suffering by up to 92h, lowering the value of the main toxicity endpoint by a factor of approximately 2, and maximal by a factor of approximately 16. © 2012 SETAC. Source

Rufli H.,Ecotoxsolutions | Springer T.A.,Wildlife Conservation Society
Environmental Toxicology and Chemistry | Year: 2011

OECD (Organisation for Economic Co-operation and Development) Guideline 203, Fish Acute Toxicity Test, states that the test should be performed using at least five concentrations in a geometric series with a separation factor not exceeding 2.2, with at least seven fish per concentration. However, the efficiency of this design can be questioned, because it often results in only one concentration that causes partial mortality (mortality >0% and <100%). We performed Monte Carlo computer simulations to assess whether more efficient designs could allow reductions in fish use. Simulations indicated that testing with six fish per concentration could yield 50% lethal concentration (LC50) estimates of quality similar to those obtained using seven fish. Experts attending a workshop organized to consider this finding and to identify the best methods for reducing fish use concluded that significant reductions could best be achieved by modifying the test paradigm. They suggested initiating testing using a 96-h fish embryo test instead of juvenile fish to cover the range from the upper threshold concentration (the lowest 50% effective concentration [EC50] in existing algae and daphnia studies) to the highest concentration with no mortality. This would be followed by a confirmatory limit test with juvenile fish at the highest concentration with no mortality or by a full test with juvenile fish, if a point estimate of the LC50 is required. © 2010 SETAC © 2011 SETAC. Source

Knacker T.,ECT Oekotoxikologie GmbH | Boettcher M.,University of Heidelberg | Frische T.,German Federal Environment Agency | Rufli H.,Ecotoxsolutions | And 5 more authors.
Integrated Environmental Assessment and Management | Year: 2010

Current standard testing and assessment tools are not designed to identify specific and biologically highly sensitive modes of action of chemicals, such as endocrine disruption. This information, however, can be important to define the relevant endpoints for an assessment and to characterize thresholds of their sublethal, population-relevant effects. Starting a decade ago, compound-specific risk assessment procedures were amended by specifically addressing endocrine-disrupting properties of substances. In 2002, the Conceptual Framework, agreed upon by OECD's Task Force on Endocrine Disrupters Testing and Assessment, did not propose specific testing strategies, and appropriate testing methods had not yet been developed and approved. In the meantime, the OECD Test Guidelines Programme has undertaken important steps to revise established and to develop new test methods, which can be used to identify and quantify effects of endocrine-disrupting chemicals on mammals, birds, amphibians, fish, and invertebrates. For fish testing of endocrine-disrupting chemicals, the first Test Guidelines have recently been adopted by the OECD and validation of further test systems is under progress. Based on these test systems and the experience gained during their validation procedures, we propose a 3-step fish testing strategy: 1) Weight-of-evidence approach for identifying potential sexual endocrine-disrupting chemicals; even after advanced specification of systematic criteria, this step of establishing initial suspicion will still require expert judgment; 2) in vivo evaluation of sexual endocrinedisrupting activity in fish by applying in vivo fish screening assays; sufficient data are available to diagnose the aromataseinhibition and estrogen-receptor agonist mechanisms of action by indicative endpoints (biomarkers), whereas the ability of the respective biomarkers in the screening assay to identify the estrogen-receptor antagonists and androgen-receptor agonists and antagonists requires further validation; 3) characterization of sexual endocrine-mediated adverse effects including threshold concentrations; in cases when the most sensitive population-relevant endpoints and the most sensitive time window for exposure are known for the mechanisms of action, the fish full life-cycle or 2-generation test, which are the normal definitive tests, might be abbreviated to, e.g., the fish sexual development test. In the European Union, the measurement of indicative endpoints in the definitive test might be crucial for the authorization procedure under REACH and plant-protection products. The results of the definitive tests can be used in existing schemes of compound-specific environmental risk assessments. ©2010 SETAC. Source

Weyman G.S.,Makhteshim Agan UK Ltd. | Rufli H.,Ecotoxsolutions | Weltje L.,BASF | Salinas E.R.,BASF
Environmental Toxicology and Chemistry | Year: 2012

Aquatic toxicity tests with substances that are poorly soluble in water have been conducted using different methods, and estimates of toxicity have varied accordingly. The present study illustrates differences in toxicity values resulting from variation in test designs and solution preparation methods, and offers guidance on the best way to conduct these tests. Consequences for environmental risk assessment and classification are also discussed. The present study mainly considers active ingredients of plant protection products, but is also considered relevant to other chemicals. It is recommended that toxicity tests be conducted only up to the saturation limit, dispersants avoided, and solvents used only if necessary to support handling and speed of dissolution. Analytical measurements of exposure concentrations should reflect what organisms are exposed to. If acute toxicity testing at the saturation limit yields no adverse effects, further testing should not normally be required; the toxicity value of the endpoints should be considered as the saturation limit and adverse classification should not be required. Chronic testing, if required, should then be conducted at the practical saturation limit as this is the most realistic worst-case exposure scenario. If no adverse effects occur, the risk should be acceptable because higher aqueous exposure cannot occur. This could be substantiated by testing additional species. Assessment factors on no observed effect concentration (NOEC) values at the saturation limit require careful consideration in the risk assessment to avoid unnecessarily low regulatory acceptable concentrations. © 2012 SETAC. Source

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