This review paper reports the consensus of a technical workshop hosted by the European network, NanoImpactNet (NIN). The workshop aimed to review the collective experience of working at the bench with manufactured nanomaterials (MNMs), and to recommend modifications to existing experimental methods and OECD protocols. Current procedures for cleaning glassware are appropriate for most MNMs, although interference with electrodes may occur. Maintaining exposure is more difficult with MNMs compared to conventional chemicals. A metal salt control is recommended for experiments with metallic MNMs that may release free metal ions. Dispersing agents should be avoided, but if they must be used, then natural or synthetic dispersing agents are possible, and dispersion controls essential. Time constraints and technology gaps indicate that full characterisation of test media during ecotoxicity tests is currently not practical. Details of electron microscopy, dark-field microscopy, a range of spectroscopic methods (EDX, XRD, XANES, EXAFS), light scattering techniques (DLS, SLS) and chromatography are discussed. The development of user-friendly software to predict particle behaviour in test media according to DLVO theory is in progress, and simple optical methods are available to estimate the settling behaviour of suspensions during experiments. However, for soil matrices such simple approaches may not be applicable. Alternatively, a Critical Body Residue approach may be taken in which body concentrations in organisms are related to effects, and toxicity thresholds derived. For microbial assays, the cell wall is a formidable barrier to MNMs and end points that rely on the test substance penetrating the cell may be insensitive. Instead assays based on the cell envelope should be developed for MNMs. In algal growth tests, the abiotic factors that promote particle aggregation in the media (e.g. ionic strength) are also important in providing nutrients, and manipulation of the media to control the dispersion may also inhibit growth. Controls to quantify shading effects, and precise details of lighting regimes, shaking or mixing should be reported in algal tests. Photosynthesis may be more sensitive than traditional growth end points for algae and plants. Tests with invertebrates should consider non-chemical toxicity from particle adherence to the organisms. The use of semi-static exposure methods with fish can reduce the logistical issues of waste water disposal and facilitate aspects of animal husbandry relevant to MMNs. There are concerns that the existing bioaccumulation tests are conceptually flawed for MNMs and that new test(s) are required. In vitro testing strategies, as exemplified by genotoxicity assays, can be modified for MNMs, but the risk of false negatives in some assays is highlighted. In conclusion, most protocols will require some modifications and recommendations are made to aid the researcher at the bench.

The scientific community has invested effort into standardising methodologies for the regulatory ecotoxicity testing of engineered nanomaterials (ENMs), but the practical requirements for bioaccumulation testing of ENMs have been given less attention.

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The Organisation for Economic Co-operation and Development (OECD) Test Guidelines Programme is involved in the international harmonization and validation of test methods to evaluate effects of chemicals, including potential endocrine active substances. To meet their existing and foreseen regulatory needs in this area, OECD member countries have encouraged the development of test methods and their emergence at the OECD level. Validation activities are underway in countries and industry to ascertain the relevance and reliability of these tests to enable future regulatory acceptance. This includes work on development and (sexual) reproduction of aquatic invertebrates. What is the importance of mechanistic information in regulating chemicals, and how to address the issue of possible endocrine disruption in invertebrates while integrating these tests in a regulatory scheme are the current questions faced by the OECD countries.

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The effects of heavy metal deposition from four different metalworks on soil respiration, ATP content, and toxicity to Photobacterium phosphoreum were examined. Soil samples were collected along a transect through the pollution gradients. Vegetation and soil types were homogeneous throughout the transects. Soil respiration was measured as CO2 production in closed bottles using an IR‐gas analyzer. The ATP content was measured with a bioluminometric assay after trichloracetic acid extraction of soil. The toxicities of distilled water extracts of soil samples were evaluated by the standard P. phosphoreum toxicity test and the metal content of these water extracts was measured as the bioavailable fraction of the heavy metal pollution in the soil. Soil respiration and ATP content were strongly affected by the heavy metal content in the soil. The correlation between the methods was high. The P. phosphoreum procedure can be used to estimate the toxicity of soils heavily polluted by metals. However, soil respiration and ATP content appear to be more sensitive indicators of soil pollution. © 1994 by John Wiley & Sons, Inc..