Ecotoxicity methods

Most of the standardised ecotoxicity methods recommend the use of synthetic or other well-known and fully defined control matrices. The control is needed to detect the behaviour (growth, survival) of the test organisms in the absence of toxic or harmful agents. These results are the reference values, defined as 0% inhibition or 100% vitality, and are the basis for the calculation of sample inhibition. 

Oxime carbamates are generally applied either directly to the tilled soil or sprayed on crops. One of the advantages of oxime carbamates is their short persistence on plants. They are readily degraded into their metabolites shortly after application. However, some of these metabolites have insecticidal properties even more potent than those of the parent compound. For example, the oxidative product of aldicarb is aldicarb sulfoxide, which is observed to be 10-20 times more active as a cholinesterase inhibitor than aldicarb. Other oxime carbamates (e.g., methomyl) have degradates which show no insecticidal activity, have low to negligible ecotoxicity and mammalian toxicity relative to the parent, and are normally nondetectable in crops. Therefore, the residue definition may include the parent oxime carbamate (e.g., methomyl) or parent and metabolites (e.g., aldicarb and its sulfoxide and sulfone metabolites). The tolerance or maximum residue limit (MRL) of pesticides on any food commodity is based on the highest residue concentration detected on mature crops at harvest or the LOQ of the method submitted for enforcement purposes if no detectable residues are found. For example, the tolerances of methomyl in US food commodities range from 0.1 to 6 mg kg for food items and up to 40 mg kg for feed items. ... 

The protocols of analytical methods and bioassays include the sampling and preparation steps of the test matrix before the test procedures. The sampling should be conducted in accordance with ISO 5667-16. There are already available harmonised protocols according to Hansen et al. [49]. The statistics of the ecotoxicity data should be conducted in accordance with ISO/CD 20281. 

The ISO protocol for the biochemical response EROD (ISO 23893-2/AWI) as a recent example of a bioanalytical (biomarker) [49,50] method standardised under ISO for fish needs harmonisation with the other test systems and between the laboratories (users) before implementation. Use of biomarkers (biochemical responses) in multi-arrays for environmental monitoring according to Hansen et al. [50] is complementary to chemical analysis since they can alert for the presence of ecotoxic compounds. Bringing into the WFD, the effect-related approaches concerning bioassays and biomarkers are only relevant in the context of the QN of environmental relevant substances and the good chemical status. But it is rather difficult to transfer the monitored biochemical responses or biomarkers into an operational effect-related standard. They serve as the basis for environmental protection against hazardous substances. In relation to... 

Freshwater media based on the OECD 203 ecotoxicity testing medium for fish and daphnia have been used in all T/DP testing of metals, metal compounds and alloys in the pH range 6-8.5 to date. However, the composition of a marine medium is also given in the T/DP section of the GHS, and by implication, a method for marine T/D testing is open for development and validation. While not currently required for REACH dossiers, T/D data in marine media and attendant classification proposals may be required in the future for marine shipping. 

EEC Directive 92/69/EEC (1992) Official Journal of the EEC L383 A Methods for the determination of ecotoxicity C.2. Acute toxicity for Daphnia... 

Europe s controversy over soft PVC toys looks set to continue after EU health experts rejected the best available method for assessing the dangers to children. The so-called Dutch migration test was designed to mimic the way phthalate softeners leak out of PVC when it is sucked or chewed. Manufacturers had hoped the EU s Scientific Committee for Toxicity, Ecotoxicity and the Environment would accept the method as a standard test for phthalate migration, allowing it to be used across the EU, but the committee ruled that the Dutch test was unreliable. It also rejected a similar test developed in the UK, and issued a list of changes that would have to be made before either... 

British Health and Safety Commission (BHSC). Testing for acute toxicity to Daphnia. In Methods for the Determination of Ecotoxicity BHSC London, 1982 14-18. 

Interpretation of ecotoxicity is still more of an art than a science. Perhaps the greatest advances in this area will come from increasing nnderstanding of the structure-activity correlations for chemicals. However, at the present time, further effort is necessary to integrate the wide range of different types of assessment currently employed, which range over almost every scientific discipline. In the strictest sense, the laboratory methods described can permit only comparative evalnation of chemicals under the test conditions. Extrapolation from laboratory results to predict what will happen when chemicals enter the natural environment must be improved. 

WASTOXHAS is the acronym for WASte ecoTOXic Hazard Assessment Scheme. This method was developed to ensure that unacceptable adverse effects would not arise from landfilled or re-used waste disposal. It is dedicated to assess the long-term leaching hazardous impact of any solid waste containing potentially hazardous substances (e.g., bulk, stabilized, solidified, or vitrified wastes as well as contaminated soils or sediments intended for soil disposal). 

Table 6. Ecotoxicological limits defined in the French proposal for criterion and evaluation methods of waste ecotoxicity based on an L/S ratio of 10 (FME, 1998).

VII. Screening chemicals for their environmental behavior by comparative evaluation. Ecotox. Environ. Saf. 6, 60-81. Freitag, D., Balhorn, L., Geyer, H., Korte, F. (1985) Environmental hazard profile of organic chemicals. An experimental method for the assessment of the behaviour of chemicals in the ecosphere by simple laboratory tests with C-14 labelled chemicals. 

The USEPA Office of Pollution Prevention and Toxics (OPPT) (Q)SAR Analysis Methods Branch assesses the model domain for ecotoxicity (Q)SAR determined by structural attributes used to predict toxicity. For example, the domain for molecular... 

When the REACH system is introduced, it is possible that additional human health and ecotox-icological information could be required for up to 30,000 existing chemicals, which are currently marketed in volumes greater than 1 t/year (t.p.a.). Therefore, QSAR and other computer-based methods for predicting toxicity are expected to play an increasingly important role, not only for the priority setting of chemicals that need further assessment, but also for hazard assessment purposes. As yet no formal procedures have been put in place for the use of QSAR in the REACH system. 

Okkerman PC, van der Plassche EJ, Emans HJB, Canton JH. 1993. Validation of some extrapolation methods with toxicity data derived from multiple species experiments. Ecotox Environ Saf 25 341-359. 

Usable methods for measuring ecotoxicity are necessary for the development of efficient strategies for bioremediation. The toxicity of soils to animals, however, cannot always be predicted by knowing only the contaminants and their concentrations (Charrois et al., 2001). There is a need for methods that will determine the risk due to contaminants that are actually bioavailable, so that the environment can be protected without unacceptably high clean-up costs. Future regulations should consider not... 

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