Effects of boric acid on various microbes,plants, and soil invertebrates

Purpose  

Terrestrial ecotoxicology includes the investigation of the impact of chemicals on soils and soil-inhabiting organisms, whereby ecotoxicological effects are mainly assessed using single-species laboratory tests. As part of laboratory testing, reference substances, with known toxicity, are regularly used to confirm the sensitivity of the cultivated test organisms over time. Furthermore, reference substances are also applied in ring test evaluations for the validation of new test methods. The present work evaluates boric acid for its suitability as a potential reference substance for tests with higher plants and soil organisms (e.g., invertebrates and microbial communities).     

Strategies for risk assessment of existing chemicals in soil

In the risk assessment of industrial chemicals, an assessment of the risk to soil should be performed whenever relevant inputs occur via the following pathways: application of sewage sludge, wet or dry deposition, application as a pesticide constituent (e.g. solvent or metabolite), irrigation. An evaluation of the results for 34 chemicals from the first EU priority list showed that only 35% of the risk assessments for the terrestrial compartment were performed on the basis of at least 2 valid tests with soil organisms. In the vast majority of cases, the equilibrium partitioning method was used to extrapolate from aquatic to soil toxicity. However, no indications exist for a correlation between aquatic and terrestrial toxicity. Moreover, the exposure routes for soil organisms (uptake via pore water, air included in soil pores, ingestion of soil particles) are much more complex than those for aquatic organisms. As a new approach, it is therefore suggested that, in cases of relevant exposure (e.g. estimated or measured concentrations of >10 μg/kg), an assessment should generally be performed on the basis of valid terrestrial tests rather than on an extrapolation from the aquatic toxicity. It is recommended that prolonged exposure tests should be used already for an initial assessment of substances that have a strong tendency to adsorb on soil particles and thus a long residence time in soil. A decision scheme for the risk assessment of industrial chemicals in soil is presented, trigger values, testing strategies as well as assessment factors for derivation of a Predicted No Effect Concentration (PNEC_soil) are discussed. An example of a terrestrial risk assessment for substances from the first EU priority list is given in order to illustrate current practice.     

Comparisons of terrestrial and aquatic bioassays for oil-contaminated soil toxicity

Background  Petroleum products are widely used in various sections of industry and they are one of the most abundant sources of environmental contamination. These products are classified by their physico-chemical properties such as boiling point, density and viscosity. Oil contamination in the environment is primarily evaluated by measuring the chemical concentrations of petroleum products in the solid or water phase. The results of chemical analyses do not correspond directly with the harmful environmental effects of petroleum products on the soil flora and fauna, because the interactions between oil compounds and the production of their methabolites in soil are not measured in chemical assessments. These kinds of effects of complex chemical mixtures in soil can be estimated by bioassays. Therefore, ecotoxicological tests are important for estimating soil quality in the risk assessment of oil-contaminated soil sites. Objectives  The objective of this study was to examine the oil-contaminated soil site of a closed petrol station with both chemical and ecotoxicological methods. The goals of this study were to compare the sensitivity of the terrestrial and aquatic bioassays and to compare the toxicity responses of aquatic bioassays determined from three different extraction procedures. In addition, our aim was to characterise a cost-effective battery of bioassays that could be applied to a comparison of oil-contaminated soils. It was in our interest to investigate oil-contaminated soil with oil concentrations of 2500–12000 mg/kg and to find out the possible differences between terrestrial and aquatic toxicity tests. Methods  Six soil samples from a closed petrol station were examined for toxicity with terrestrial and aquatic tests. Terrestrial tests includedEnchytraeus albidus survival and reproduction assays and seed germination assays using wheat, cress, lettuce, and red clover seeds and growth inhibition assays of onions. The toxicities of the water-extractable fractions of the soil samples obtained from three different extractions were tested with aquatic bioassays based on plants (onion and duckweed growth inhibition tests), microbes (luminescent bacteria test), and enzyme inhibition (reverse electron transport test, RET). Chemical analyses of the solid samples were carried out simultaneously. Results. Oil concentrations ranged from 2500 to 12000 mg/kg, BTEX varied from 300 to 2800 mg/kg, and fuel additives: MTBE and TAME from 0.0 1 to 260 mg/kg. Only the sample contain-ing 12000 mg/kg oil had a significant toxic impact on all test organisms. Soil samples with oil concentrations 2500–6200 mg/ kg had no or only slight adverse effects on the test organisms with one exception, theE. albidus reproduction test. TheE. albidus survival and reproduction tests were the most sensitive bioassays of the terrestrial tests, and the luminescent bacteria test of the aquatic tests.     

The use of Folsomia candida (Collembola,Isotomidae) in bioassays of waste

There is a high probability that urban compost, sewage sludge and ash will come in contact with natural terrestrial ecosystems. The present paper investigates the extent to which the Folsomia candida population development test (now a standardised ecotoxicological test, ISO 11267, for testing the impact of pure chemicals on soil fauna) can be applied to the detection of the toxicity of these wastes, the goal being to evaluate ecotoxicity of wastes before they are spread on land. We show that some potentially useful information on waste toxicity can be obtained with this test, but the results must be interpreting with caution, indeed, problems can arise from differences in pH, humidity and organic matter content of the waste relative to the characteristics of the dilution soil. On the basis of the results of these assays, we propose a classification of the toxicity of seven wastes.     

An emerging energetic soil contaminant,CL-20, can affect the soil invertebrate community in a sandy loam soil

We investigated the effects of nitramine explosive CL-20 (China Lake compound 20) on the indigenous soil invertebrate community in Sassafras sandy loam (SSL) soil using a 12-week soil microcosm assay. Freshly collected SSL soil was amended with CL-20 to prepare multiple treatment concentrations ranging from 0 (acetone control) to 10,300 mg kg⁻¹. The selected concentration range of CL-20 adequately assessed the concentration–response relationships for total microarthropods, and for individual microarthropod groups. The overall composition of microarthropod community in SSL soil was not affected by exposure to CL-20, based on the number of taxonomic groups present in the individual treatments after 12 weeks. However, community structure analysis revealed greater sensitivity to CL-20 by predatory mesostigmatid mites. Microarthropod and nematode communities showed contrasting sensitivities to CL-20 in SSL soil. Total numbers of nematodes were either unaffected or significantly (p < 0.05) increased in CL-20 treatments compared with control. Only predator group among nematodes was consistently adversely affected by exposure to CL-20. The abundance of predatory nematodes decreased in a concentration-dependent manner throughout the 12-week exposure. Microcosm assay with corresponding community structure analysis can provide the means for validating the ecotoxicity data from standardized laboratory tests, both complimenting and expanding upon the ecotoxicological significance of data from standardized single-species toxicity tests.     

The use of bioassays for evaluating the toxicity of sewage sludge and sewage sludge-amended soil

Background and Aims  

In soils, the most commonly mentioned hazardous substances are metals. One of the sources of its accumulation is the application of sewage sludge. However, little information is available regarding the estimation of the toxicity of sewage sludge or soil treated with sewage sludge, even by means of a battery of bioassays. In this study an evaluation of a battery of bioassays was carried out for toxicity assessment of sewage sludge and sewage sludge-treated soil. The objectives of this study were a) to compare the sensitivity of the different bioassays for the toxicity determination of sewage sludge contaminated with metals and soil treated with this sewage sludge, b) to elaborate a procedure for the attribution of sewage sludge samples to hazard classes based on the ecotoxicological data, and c) to evaluate the suitability of elutriate bioassays and microbial toxicity tests for the assessment of sewage sludge-treated soil.     

Soil pollution by nonylphenol and nonylphenol ethoxylates and their effects to plants and invertebrates

Background, aim, and scope  

Nonylphenol polyethoxylates (NPEOs) are a widely used class of nonionic surfactants known to be toxic and endocrine-disrupting contaminants. Their use and production have been banned in the European Union and substituted by other surfactants considered as environmentally safer. However, their use continues in many countries without any legal control. Discharges of effluents from wastewater treatment plants and the application of sewage sludge application, landfilling, and accidental spillage to soils are the major sources of NPEOs in the environment. The biodegradation of these surfactants is relatively easy, leading to the accumulation of the simplest chemical forms of nonylphenol ethoxylates (NP, NP1EO, and NP2EO) and nonylphenol carboxy acids (NP2EC or NP1EC). However, these are also the most toxic end-products and have a higher environmental persistence. Compared to aquatic ecosystems, not much is known about the effects of NPEOs in terrestrial organisms, with few studies mainly centered on the effects on plants and soil microorganisms. The main aim of this study is to provide the range of concentrations of NPEOs with ecotoxicological effects on different plants and soil invertebrate species. In addition, we aim to identify the main soil properties influencing their toxicity.     

Proposal of a testing strategy and assessment criteria for the ecotoxicological assessment of soil or soil materials

Background and Scope  Information on a potential contamination of soils or soil materials are derived by chemical analysis which takes place specifically for a given substance. For a comprehensive assessment, information on the bioavailable and mobile contaminant fraction, including all metabolites, is desirable. During the last years several research projects were initiated in Germany, to supplement the chemical analyses and to elaborate a suitable testing strategy. The main goal of this contribution is to elucidate the results of these research projects and to summarize the test strategy, which is recommended based on these results. Results and Conclusion  Ecotoxicological tests, which are standardized for the assessment of chemicals, were regarded as a suitable starting basis for a cost effective, pragmatic approach. Aquatic tests (testing of aqueous soil extracts) focus on the retention function of soils and terrestrial tests (testing of soil) on the habitat function. Suitable reference systems for the terrestrial tests and assessment criteria for both test types (terrestrial and aquatic) were elaborated. On the basis of a round robin test and a laboratory comparison test, a minimal test battery was established. This minimal test battery can be supplemented by further tests if more or specific information is required. Outlook  The recommendations should encourage the discussion regarding the application of biological methods for the assessment of soil quality. Such an assessment is or at least can be required by soil protection laws which have been adopted in some European countries within the last years.     

Cu and Ni Mobility and Bioavailability in Sequentially Conditioned Soils

The potential ecological hazard of metals in soils may be measured directly using a combination of chemical and biological techniques or estimated using appropriate ecological models. Terrestrial ecotoxicity testing has gained scientific credibility and growing regulatory interest; however, toxicity of metals has often been tested in freshly amended soils. Such an approach may lead to derivation of erroneous toxicity values (EC₅₀) and thresholds. In this study, the impact of metal amendments on soil ecotoxicity testing within a context of ion competition was investigated. Four coarse-textured soils were amended with copper (Cu) and nickel (Ni), incubated for 16 weeks and conditioned by a series of total pore water replacements. Rhizon^TM extracted pore water Cu, Ni, pH and dissolved organic carbon (DOC) concentrations were measured after each replacement. Changes in ecotoxicity of soil solutions were also monitored using a lux-based biosensor (Escherichia coli HB101 pUCD607) and linked to variations in soil solution metal and DOC concentrations, pH and selected characteristics of the experimental soils (exchangeable calcium (Ca) and magnesium (Mg)). Prior to conditioning of soils, strong proton competition produced relatively high EC₅₀ values (low toxicity) for both, Cu and Ni. The successive replacement of pore waters lead to a decline of labile pools of metals, DOC and alleviated the ecotoxicological protective effect of amendment impacted soil solution chemistry. Consequently, derived ecotoxicity values and toxicity thresholds were more reflective of genuine environmental conditions and the relationships observed more consistent with trends reported in historically contaminated soils.     

Toxicity of chemical warfare agent HD (mustard) to the soil microinvertebrate community in natural soils with contrasting properties

A microcosm technique was used to determine the ecotoxicity of the chemical warfare agent HD (mustard) to the indigenous soil microinvertebrate communities. HD was thoroughly incorporated into Sassafras sandy loam (SSL) soil (4.9% OM) and an oak-beech forest silt loam soil (FS, 16% OM) at nominal HD concentrations ranging from 6 to 1076 mg kg⁻¹. After a 7-day incubation period, microarthropods were extracted from soils using a high-gradient extractor and sorted to Acari suborders Prostigmata, Mesostigmata, and Oribatida, and the insect order Collembola. Nematodes were extracted using Baermann funnels and were sorted into bacterivore, herbivore, fungivore and omnivore/predator trophic groups. Microarthropods were more sensitive to HD in both soil types compared with nematodes. The EC₅₀ values for total numbers of microarthropods in SSL and FS were similar (65 and 71 mg kg⁻¹, respectively). The EC₅₀ values for total numbers of nematodes were 130 and 235 mg kg⁻¹, respectively. Toxicity of HD to nematodes was significantly greater in SSL soil compared to FS, based on 95% confidence intervals. Results show that community-level assessment of chemical toxicity in soil using a microcosm assay is sufficiently robust and can provide the means for validating the ecotoxicity data from standardized laboratory single-species toxicity tests.     

Toxicity of chemical-warfare agent HD to Folsomia candida in different soil types

We investigated the ecotoxicity of the chemical-warfare agent (CWA) HD (Mustard) using Collembola reproduction test with numbers of adults and juveniles as measurement endpoints. Toxicity tests were conducted using soils with contrasting parameters to investigate the effects of soil properties on chemical toxicity. These included standard artificial soil (SAS; 10% OM; 6 pH), O’Neill-Hall sandy loam (OHSL; natural soil with 4.3% OM; 5.1 pH), and Sassafras sandy loam (SSL; natural soil with 2% OM; 4.9 pH). Soils were individually spiked with HD concentrations ranging from 1 to 125 mg kg^–1. Lowest observed effect concentrations (LOECs) for adult mortality were 25, 50, and 6.97 mg kg^–1 for SAS, OHSL, and SSL, respectively. The LOECs for reproduction were 6.97, 6.25, and 1.9 mg kg^–1 for SAS, OHSL, and SSL, respectively. HD toxicity to both adults and juveniles was greater in SSL. These results show that soil toxicity testing should not rely solely on the adult acute endpoints using artificial soils, but should include assays with reproductive endpoints using natural soils with varying physical and chemical parameters to adequately assess toxicity to test species.     

Influence of Soil Organic Carbon on Acute and Chronic Toxicity of Plant Protection Products to Poecilus cupreus (Coleoptera, Carabidae) Larvae (4 pp)

Background, Aims and Scope   Variability of results from terrestrial ecotoxicological tests with arthropods demonstrate the importance of understanding the impact of soil composition has on the bioavailability of pollutants. Beside other soil parameters, the organic C content is known to be relevant to bioavailability. The aim of the present paper was to detect lethal and sublethal effects of plant protection products on soil-dwelling larvae of the carabid beetle Poecilus cupreus under different concentrations of soil organic C. The study was based on a familiar laboratory test method. Methods   Larvae of the laboratory-reared carabid beetle P. cupreus were exposed to dimethoate in a standardised soil (Lufa 2.1), modified to four different concentrations of organic C between 0.5 to 2.8% by admixing peat. Dimethoate was applied to the soil surface at rates ranging between 40 and 250 g a.i./ha. Some larvae were exposed to an application of water to act as a control. One larva was released per test tube, with at least 20 larvae per treatment group. Effects on mortality and developmental time of the larvae and on the hatching weight of adult beetles were recorded. Dimethoate was selected as the test item because some dose-response data for different soils were already available and because the reproducibility of test results with dimethoate had already been shown in a previous ring test. Results and Discussion   With increasing concentration of organic C in the soil substrate, mortality decreased at all tested rates of dimethoate. Consequently, LC50 values increased from 39 to 107 g a.i./ha with increasing organic C content from 0.5 to 2.8%. The results suggest higher bioavailability of dimethoate with decreasing content of organic C. The replication and magnitude of sublethal effects (hatching weight and developmental time) was insufficient to detect a clear interaction between dimethoate and organic C. Conclusion   The results of the experiment reveal that the concentration of organic C in the soil substrate is influential on the effects and, by association, the toxicity of dimethoate to larvae of P. cupreus. For the interpretation of terrestrial ectotoxicological tests with arthropods, the composition of the substrate has to be taken into account. Recommendations and Outlook   For reliable and reproducible test results, a well-defined and thoroughly controlled composition of the test soil is highly recommended. Test results should be used for risk assessments only after having taken the soil composition, especially the organic C content, into account.     

Tackling the heterogeneity of soils in ecotoxicological testing an euro-soil based approach

Goal, Scope and Background  In terrestrial ecotoxicology, standardised test methods using plants, earthworms and insects are available for the evaluation of effects induced by heavy metals, organic chemicals and, in particular, pesticides. Currently, these tests are performed either by using so-called Artificial Soils or (more or less) arbitrarily selected natural soils. Consequently, the test results depend not only on the intrinsic physico-chemical properties of the test chemical, but are also significantly influenced by the variable properties of the chosen soil In order to standardise the. test conditions and, at the same time, to relate the test results to representative soil types within the EU, it is proposed to modify the EURO-Soil concept for testing purposes. Main Features  The EURO-Soil concept, i.e. the selection of a limited number of soils that are representative for Europe, was originally developed for the performance of standardised environmental fate tests. Despite many problems in detail, soils from six sites all over Europe were identified that cover a wide range of soil properties (e.g. texture, pH, organic matter content) and, therefore, very different conditions concerning the bioavailability and, in turn, the effects of chemicals. Obviously, the routine use of EURO-Soils as a control or test substrate would require large amounts of soil. Therefore, it is proposed to modify this concept in such a way that all soils similar to one of the six EUROSoils can be used for ecotoxicological tests. Results and Discussion  It is assumed that the six EURO-Soils are representative for wide areas of the European Union, but at the same time it is neglected that some soils typical for, e.g. Northern Scandinavia, have to be identified in the future. All soils having similar properties (i.e. texture, pH, C/N ratio, and organic matter content) as one of the original EURO-Soils are called SIM-Soils. In this contribution, ‘ranges’ are proposed for four main properties and the six EUROSoils, thus allowing the identification of the SIM-Soils. However, since these properties cover a continuum, soils cannot be classified easily into a small number of classes; expert knowledge is required in order to decide whether a natural soil belongs to a certain SIM-Soil class or not. In the long run, this classification must take biological parameters like their suitability for standard test organisms into account as well. Recommendation and Outlook  The soils selected so far (at least one for each EURO-Soil) are actually tested using different biological test methods. Further tests are necessary in order to decide which tests can be done in which soil and whether new test systems, e.g. covering acid soils, have to be developed. However, it is already clear that the standard test species differ distinctly regarding their sensitivity towards soil properties. It is recommended to use the SIMSoils in order to provide the authorities with more field-relevant, data when assessing chemicals in the terrestrial environment.     

Acute and chronic isopod testing using tropical Porcellionides pruinosus and three model pesticides

An approach for testing acute and chronic ecotoxicological effects of pesticides on isopods in the laboratory is presented. Laboratory cultures of tropical Porcellionides pruinosus were used. The pesticides Benomyl, Carbendazim and lambda-Cyhalothrin served as model chemicals. The toxicity tests were done with five to six concentrations and one untreated control in four replicates containing 10 individuals per vessel. The test was performed at 28 °C, in permanent darkness and it lasted 14 days. Each chemical was mixed in 250 g DW per vessel of OECD artificial, LUFA 2.2 standard, tropical artificial or tropical natural soil in acute tests. Chronic tests were performed using 150 g DW OECD artificial or LUFA 2.2 standard soil. Both adult mortality and number of juveniles showed a high sensitivity of P. pruinosus towards lambda-Cyhalothrin while Carbendazim and Benomyl had a very low and no toxicity, respectively. Further research and optimization of the chronic test design are required.     

Effects of azoxystrobin,chlorothalonil, and ethoprophos on the reproduction of three terrestrial invertebrates using a natural Mediterranean soil

The potential terrestrial toxicity of three pesticides, azoxystrobin, chlorothalonil, and ethoprophos was evaluated using reproduction ecotoxicological tests with different non-target species: the collembolan Folsomia candida, the earthworm Eisenia andrei, and the enchytraeid Enchytraeus crypticus. All reproduction tests were performed with natural soil from a Mediterranean agricultural area (with no pesticide residues) in order to improve the relevance of laboratory data to field conditions. Controls were performed with natural and standard artificial soil (OECD 10% OM). The fungicide azoxystrobin showed the highest toxicity to earthworms (EC₅₀ = 42.0 mg a.i. kg⁻¹ dw soil). Collembolans were the most sensitive taxa in terms of sublethal effects of chlorothalonil with an EC₅₀ of 31.1 mg a.i. kg⁻¹ dw soil followed by the earthworms with an EC₅₀ of 40.9 mg a.i. kg⁻¹ dw soil. The insecticide ethoprophos was the most toxic to collembolans affecting their reproduction with an EC₅₀ of 0.027 mg a.i. kg⁻¹ dw soil. Enchytraeids were generally the least sensitive of the three species tested for long-term effects. Earthworms were not always the most sensitive species, emphasizing the need to increase the number of mandatory assays with key non-target organisms in the environmental risk assessment of pesticides.     

Phytotoxicity of some chloroanilines and chlorophenols, in relation to bioavailability in soil

Soil adsorption and the effect of four chlorophenols and three chloroanilines on the growth of lettuce (Lactuca sativa) were determined in two soil types differing in organic matter content and pH. Adsorption increased with increasing organic matter content of the soils. Phytotoxicity, based on dosed amounts, was significantly higher in the soil with the low level of organic matter. This difference could be reduced by recalculating the EC₅₀ values for the effect of the test substances on plant growth in mg kg-1 dry soil towards concentrations in mg L-1 pore water using data from soil adsorption experiments. For pentachlorophenol only this recalculation increased rather than decreased the difference between the two soils, however, when the EC50 values for pentachlorophenol were corrected for the difference in soil pH, almost the same values resulted for both soils. Calculated EC₅₀ values on the basis of pore water concentrations appeared to be in good agreement with values determined in nutrient solution tests. These results indicate that, for plants, the toxicity and therefore the bioavailability of organic chemicals in soil mainly depend on the concentration in the soil solution, and can be predicted on the basis of sorption data. Attempts to develop QSARs relating log EC₅₀ values in μmol L^?1 pore water with lipophilicity (expressed as the octanol/water partition coefficient: log K_ow,) of the test substances resulted in a statistically significant relationship. This relationship was further improved by correcting the chlorophenol data for dissociation effects.     

Duration of the standard earthworm avoidance test: Are 48 h necessary?

Ecotoxicological tests are often recommended for the environmental risk assessment (ERA) of contaminated soils. In comparison to chemical residue analysis that focuses on individual contaminants, ecotoxicological tests are able to integrate the effects of the overall contamination, including interactions between individual contaminants, as well as between the contaminants and the various soil properties. However, their use is limited by the fact that the most sensitive tests are chronic tests such as the earthworm reproduction test which lasts 56 days. In order to promote the use of ecotoxicological tests for the routine assessment of contaminated test soils, the usage of short-term earthworm avoidance tests were investigated in the German project ERNTE. According to the International Organization for Standardization (ISO) guideline no. 17512-1, such a test has a duration of just 48 h which, although less than chronic tests, is still quite long in comparison to modern methods of chemical analysis whereby results are often available within 24 h (“on-site analysis”). Therefore, we assessed the effects of shortening the duration of the earthworm avoidance test from 48 to 24 h on the resulting ecotoxicological data. Eight uncontaminated natural soils and 22 contaminated natural soils containing a wide range of chemicals were tested concurrently for 24 and 48 h. Additionally, seven of the uncontaminated natural soils (one was excluded due to its low pH) plus Organization for Economic Co-operation and Development (OECD) artificial soil or LUFA (Landwirtschaftliche Untersuchungs- und Forschungsanstalt, Speyer, Germany) St. 2.2 soil were spiked with two model chemicals (zinc nitrate-tetrahydrate and tributyltin-oxide (TBT-O)) and tested accordingly. It was also investigated whether the results would differ when using either standard LUFA St. 2.2 or OECD artificial soil as a control when contaminated natural soils were tested. Statistical analysis of the data indicates that a decrease in test duration in general did not result in a different assessment of the test soils. In view of the fact that an ERA of contaminated soils is increasingly starting with an on-site analysis (i.e. data are available within 24 h) it is recommended to change the existing ISO guideline, i.e. to decrease the test duration from 48 to 24 h. In doing so, the use of a multi-concentration design increases the robustness of the test results. Both OECD and LUFA St. 2.2 soils are equally suitable as controls.     

Validation of Microplate Bioassays for the Assessment of Contaminated and Remediated Sites

Background, Goal and Scope  Bioassays are frequently used to investigate the water extractable ecotoxicological and genotoxicological potential of contaminated soil samples. A laboratory intercomparison study was performed for validation of miniaturised biological test systems for the assessment of contaminated and remediated sites. The successful performance of this study resulted in an optimisation of microplate assays with respect to the testing of chemicals and environmental samples. Methods  For this purpose, miniaturised bioassays were chosen, which, because of their stage of development, are suitable for routine application in the characterisation of the water extractable ecotoxicological and genotoxicological potential of soils. These ecotoxicological and genotoxicological assays were performed with contaminated soil samples by three institutions at the same time. Results and Discussion  The toxicological assessment of the contaminated and remediated soil samples using LID-values, as a rule, was highly uniform. Some minor deviations could, for the most part, be explained by the heterogeneity of the soil samples and, to a lesser extent, by methodical aspects. The difference in sensitivity towards contaminants of the two bacteria Vibrio fischeri and Pseudomonas putida was pointed out. In the algae test with Desmodesmus subspicatus, the influence of the highest sample concentrations on the growth controls became obvious. It was recommended to modify the experimental setup of the microtitration plate, i.e. to place growth controls located next to both the lowest and the highest dilution steps of the sample. The Ames-test did in some cases provide new information on the genotoxicity of the samples, but is not considered useful in a test battery for the evaluation of the genotoxic potential because of its great expense in time and work. Conclusions  The investigations in this laboratory-intercomparison study for the assessment of the water extractable toxic potential of soil samples show that different bioassays are needed, which, in contrast to chemical-analytical methods, can detect the complete effects of all present pollutants in contaminated and remediated soils and solid substrates path-specifically. Recommendations and Outlook  If the recommended modifications for the performance of the bacterial and algae growth inhibition assays on microplates are taken into consideration, these tests can substitute the tests performed on a macro scale. The usefulness of the umu-test and the NM2009-test for the investigation of the genotoxic potential has been proven. Although the tests performed on microplates require much lower sample amounts, it is recommended that sample amounts be eluted in accordance with current guidelines to ensure representativity of the sample. Further work should focus on toxicity identification studies in the future by combining chemical and toxicological analyses.     

Bioaccumulation studies with <Emphasis Type="Italic">Eisenia fetida</Emphasis> using an established degradation test system

Background  

Earthworms are considered as an appropriate test system to assess the bioaccumulation potential of substances in the terrestrial environment. For regulatory purposes test methods were developed and incorporated in the validation process. A test design that is particularly suited for testing ¹⁴C-labelled substances will be described here. This design was adapted from an established degradation test system for bioaccumulation tests with earthworms in soil. The antibiotic sulfadiazine was used as test substance in this study. Due to the biological activity and the widespread entering into soil by manure application, veterinary medicines have become the target of ecotoxicological risk assessment. A German research group provided the soil samples mixed with liquid pig manure, which contained the ¹⁴C-labelled test substance after having passed through the gut of animals. This exposure pathway reflects the real environmental conditions. Therefore, sulfadiazine was tested even though a significant bioaccumulation potential was not expected to be detected owing to its chemical properties.     

Sensitivity of <Emphasis Type="Italic">Eisenia fetida</Emphasis> in comparison to <Emphasis Type="Italic">Aporrectodea caliginosa</Emphasis> and <Emphasis Type="Italic">Lumbricus terrestris</Emphasis> after imidacloprid exposure. Body mass change and histopathology

Purpose  

The use of only one or a few species—representing an entire taxon—in ecotoxicological standard tests poses risk of underestimating the impact of toxicants on the environment. In earthworm ecotoxicity tests, the species Eisenia fetida or Eisenia andrei are commonly used, and there is evidence that these species respond relatively insensitive towards environmental pollution. With the present study, we wanted to evaluate the risk of underestimating effects of the insecticide imidacloprid in soil organisms by comparing E. fetida with two other earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) regarding their sensitivities towards soil contaminated with this widely used insecticide.