Assessing the potential hazard of chemical substances for the terrestrial environment. Development of hazard classification criteria and quantitative environmental indicators

Fast evaluation of the safety of chemical reactions using cytotoxicity potentials and bio-Strips

We introduce new quantitative environmental metrics - "cytotoxicity potentials" - which can be used for the preliminary evaluation of the safety of chemical reactions from the viewpoint of the cytotoxicity of their components. We also elaborate the concept of bio-Profiles to be employed for fast estimation of the potential environmental dangers of chemical processes by (1) including the common cytotoxicity scale for all routes of synthesis of a particular product and (2) proposing a novel, more compact representation of the bio-Profiles themselves in the form of bio-Strips. These improvements allow direct comparisons of various synthetic routes for a particular target product, thus providing faster assessment of the reactions in question from the viewpoint of their "overall cytotoxicity". The advantages of these developments are illustrated by 36 routes of synthesizing 1,1'-biphenyl and 72 routes of synthesizing 4-methoxy-1,1'-biphenyl. The effect of incomplete conversion on bio-Strips and their metrics is also discussed. In addition, we address the impact of the selection of a particular cell line on the evaluation of the reaction safety by comparing the results obtained in three cell lines of various origins.

Analysis of the ecotoxicity data submitted within the framework of the REACH Regulation: part 4. Experimental terrestrial toxicity assays

This paper summarises the terrestrial ecotoxicity data submitted in the REACH registration dossiers and disseminated by ECHA. The analysis describes both the guidelines and the test species mostly used by registrants. REACH information requirements in relation to the effects on terrestrial organisms encompass three trophic levels; invertebrates, plants and micro-organisms, and the study of both long and short-term exposure. The results observed for soil invertebrates showed that on one hand there was a clear prevalence for testing on the species recommended by the standard test guidelines. On the other, the reporting included a large variety of species from very different families, demonstrating the feasibility for conducting toxicity tests on a number of relevant groups e.g. for species sensitivity distribution approaches. Standard toxicity testing with terrestrial plants under REACH follows a different approach and requires simultaneous testing on several species, using the same test conditions, adapted to each species, if needed. The test methods used to conduct the studies were only reported for 30% of cases. The most extensively reported test guidelines for terrestrial plants were OECD 208, ISO 11269-1 and ISO 11269-1. Information requirements for soil micro-organisms under REACH are related to the analysis of functional endpoints instead of on species or taxa. As recommended in REACH, OECD 216 and OECD 217 were the most often used test methods for soil micro-organisms. But overall, the test method was reported for only about 40% of the experimental studies. Moreover, it is noted that information on potential effects on soil micro-organisms is available for a limited number of REACH registered substances. The assessment suggests that providing waiving justifications and collecting available information, which in many cases might be well used for covering standard REACH data requirements, have been the main approaches used by registrants for the first REACH registration deadline.

Literature review of baseline study for risk analysis - the landfill leachate case

There is growing awareness and public concern about environmental impacts of waste management and disposal. Environmental policy instruments have been strengthened and associated governmental programmes have increased in recent years, resulting in high level strategies for waste management. Risk assessment is now an essential tool in the prioritisation of environmental and human health protection. However, regulators need to compare the full range of risks on a sound and consistent basis. Comparing risks from such diverse sources poses a significant challenge, and traditional hazard and risk assessments are no longer sufficient. Consideration now needs to be given to a much wider range of factors if risk assessment is to be used as an aid to more integrated decision-making process. For this purpose, baseline study - the foundation of risk assessment - can play a crucial role. To date limited research has been conducted on the need, parameters, requirements, and constituents of baseline study particularly in the context of how, why, and what information is to be collated in order to render risk assessments more appropriately integrated and complete. To establish the 'state-of-the-art' of baseline study, this paper comprehensively reviews the literature regarding environmental risk assessment in general terms, and then proceeds to review work that is specifically related to landfills and landfill leachate, thereby identifying knowledge gaps and shortfall areas. This review concludes that a holistic baseline study procedure for waste disposal sites, which risk assessors could use for carrying out risk analyses specifically for landfill leachate, does not as yet exist.

Comparing the sensitivity of soil invertebrates to pesticides with that of Eisenia fetida

The sole routine testing of the standard earthworm Eisenia fetida for the terrestrial risk assessment of pesticides has been under much debate since other soil invertebrates may be more sensitive than this standard test species. However, the very low availability of laboratory toxicity data for taxa other than E. fetida has greatly hampered sensitivity comparisons. In the present study, the relative tolerance (T(rel)) approach was used to enable comparing toxicity thresholds obtained from the US-EPA ECOTOX database, for main terrestrial taxonomic groups and pesticidal types of action (insecticides, fungicides, herbicides, and other) separately. Analyses confirmed previously reported lower and higher sensitivity of collembolans to fungicides and insecticides, respectively. However, various other discrepancies in susceptibility relative to E. fetida were encountered as indicated by species sensitivity distributions and/or calculated 95% confidence intervals of T(rel) values. Arachnids and isopods were found to be more sensitive to insecticides, and nematodes to fungicides, as compared to E. fetida. Implications of study findings for the terrestrial risk assessment of pesticides are discussed.

QSPR modeling of soil sorption coefficients (K(OC)) of pesticides using SPA-ANN and SPA-MLR

A quantitative structure-property relationship (QSPR) study was conducted to predict the adsorption coefficients of some pesticides. The successive projection algorithm feature selection (SPA) strategy was used as descriptor selection and model development method. Modeling of the relationship between selected molecular descriptors and adsorption coefficient data was achieved by linear (multiple linear regression; MLR) and nonlinear (artificial neural network; ANN) methods. The QSPR models were validated by cross-validation as well as application of the models to predict the K(OC) of external set compounds, which did not contribute to model development steps. Both linear and nonlinear methods provided accurate predictions, although more accurate results were obtained by the ANN model. The root-mean-square errors of test set obtained by MLR and ANN models were 0.3705 and 0.2888, respectively.

Evaluation of approaches for terrestrial hazard classification

Hazard assessment is an essential element in the evaluation of the potential effects of chemical substances on the environment. To date, most work has focused on hazard assessment schemes for the aquatic environment, but in recent years, a number of proposals have been developed for other environmental compartments. Due to limited datasets, the suitability of the toxicity cut-off values in these schemes has not been fully determined and the practicalities associated with using these approaches have not been fully established. This study, which focused on the soil compartment, was performed to examine cut-off values proposed by two terrestrial hazard assessment schemes and establish the availability of data. Data on earthworms indicated that current proposals for toxicity cut-off values are appropriate. However, analysis of IUCLID (International Uniform ChemicaL Information Database) indicates that even for commonly used high production volume chemicals, insufficient data are available to enable classification. Whilst the necessary data may already be available for selected groups of substances (e.g. pesticides and veterinary medicines), a significant experimental testing programme would therefore be required before a terrestrial classification system could be applied widely. Such data may become available in the future as a result of initiatives such as REACH.

Screening the leaching tendency of pesticides applied in the Amu Darya Basin (Uzbekistan)

The Amu Darya River, one of the most important water resources for Uzbekistan and Turkmenistan, was declared a World Disaster Zone in 1991. The great increase in irrigation and the use of pesticides has led to both a lack of water and drinking water contamination. The aim of the present study, part of an EU project on water management guidelines, was to evaluate the leachability of 71 organic pesticides commonly employed in the area, and to assess compounds that could potentially contaminate the river and impair drinking water quality. A multivariate approach is proposed for the pesticide screening, condensing information from different environmental partition indexes (GUS, "modified LEACH", LIN) into a single ranking, the Global Leachability Index (GLI). For a selected data set in water medium this super-index identifies three classes with a risk potential for pesticide leachability, and allows the selection of a small number of chemicals for an analytical survey.

Hazard and risk assessment of chemicals for terrestrial ecosystems

Risk assessment for terrestrial ecosystems represents a great challenge due to their complexity. Pragmatic approaches, such as independent assessments for soil and 'above soil' organisms, are unrealistic. This communication presents a workable alternative, extending the role of the hazard identification. For each chemical, a set of selected ecological receptors and exposure routes is considered. Terrestrial vertebrates, soil-ground-foliar dwelling invertebrates, plants, and soil micro-organisms, are potential receptors subjected to direct and indirect exposures. Direct exposures cover those related to the emissions during the Life Cycle of the chemical. Indirect exposures focus on those occurring after the emission, related to the fate and behaviour of the molecule in the environment. Direct exposures are regulated by the production-use-disposal patterns. Indirect exposures are regulated by intrinsic (physicochemical, biological) properties. Hazard identification considers the toxicological profile and the exposure potential for each receptor, and selects the key receptors for the assessment. Risk analysis includes, for each receptor, all potential exposure routes and the corresponding timings. Food chain biomagnification is quantified on the basis of toxicokinetic data and a three vertebrate species model, suitable for top-predators and humans. A higher tier approach, considering the lack of homogeneity of the exposure and probabilistic assumptions, can also be conducted.

Screening of pesticides for environmental partitioning tendency

The partitioning tendency of chemicals, in this study pesticides in particular, into different environmental compartments depends mainly on the concurrent relevance of the physico-chemical properties of the chemical itself. To rank the pesticides according to their distribution tendencies in the different environmental compartments we propose a multivariate approach: the combination, by principal component analysis, of those physico-chemical properties like organic carbon partition coefficient (Koc), n-octanol/water partition coefficient (Kow), water solubility (Sw), vapour pressure and Henry's law constant (H) that are more relevant to the determination of environmental partitioning. The resultant macrovariables, the PC1 and PC2 scores here named leaching index (LIN) and volatality index (VIN), are proposed as preliminary environmental partitioning indexes in different media. These two indexes are modeled by theoretical molecular descriptors with satisfactory predictive power. Such an approach allows a rapid pre-determination and screening of the environmental distribution of pesticides starting only from the molecular structure of the pesticide, without any a priori knowledge of the physico-chemical properties.