Ecotoxicity studies

A case can often be made to omit studies as scientifically unnecessary, because it is possible to conduct an adequate risk assessment without them. This is most often the case if the substance decomposes to degradants of known hazardous properties. For example the substance may hydrolyse rapidly to non-toxic products, so the key issue is to establish that this happens rapidly in the stomach before the parent substance can be absorbed. There may then be a case for omitting the expensive long-term animal studies, providing it is also established that there is no dermal or inhalation absorption from these exposure routes. In a similar way, it may be justified to omit ecotoxicity studies on a substance which hydrolyses or otherwise decomposes in the aquatic environment to stable products that have already been tested. 

The shape of the ecotoxicity/time curve from the ecotoxicity studies. 

Dutka, B.J. Mclnnis, R. Jurkovic, A. Liu, D. Castillo, G. Water and sediment ecotoxicity studies in Temulko and Rapel river basin, Chile. Environ. Toxic. Water Quahty 1996, 11, 237-247. 

Once the basic concept had been agreed to then most of the expansion could be accomplished by changing some definitions. For example, a "laboratory" has become a "test facility" and a "test facility" can be defined as the place where a test is conducted. This immediately moves us out of the traditional laboratory and encompasses field studies, ecotox studies, genetic tox studies, reentry studies, etc. 

The next change in definition has to do with the term that we we have been using. Please note that I have mentioned field studies, ecotox studies, genetic tox studies. What is a "study" The current GLP regulations define a study" as shown below ... 

The information contained in the results of an ecotoxicity study has a special significance with respect to chemical analysis. Integrating chemical and ecotoxicological studies offer the same advantages as environment quality estimation and enables... 

The information required for a notification is the chemical identity, amount manufactured or imported, use, physico-chemical properties, ecotoxicity studies, available mutagenicity studies and animal toxicity, indir t long-term effects on humans and recommendations for disposal and labelling. The data requirements for the notification of new substances are based on the OECD MPD and arc very similar to those in the EC. The minimum information required is listed in Table 34.1. There are no official reduced data requirements for notification of substances to be supplied only in low amounts, although FOEFL will negotiate on a case-by-case basis for certain of the standard tests to be omitted, especially if the substance is to be used in special applications or has special disposal methods which minimise environmental contamination. Studies are to be conducted in compliance with GLP to OECD guidelines or their equivalent. 

Ecotoxicity studies on transformation products have generally looked at acute endpoints and much less data is available on chronic and sublethal responses. It would be beneficial to generate data so that we can explore relationships between parent chronic toxicity and the chronic toxicity of the associated transformation products. 

Only biodegradation tests, preferably normative, can conclude that a given material is biodegradable, but they carmot conclude, in any case, its eco-compatibility. In an attempt to approach this, other tests must complement those that determine the biodegradability of materials, such as chemical analyses and ecotoxicity studies. This is the focus of other norms based on those devoted to studying biodegradability and are supplemented by new tests. Thus, we answer the question posed in the article title in fact, biodegradabihty tests are ultimately only part of certification standards, whether this may be NF EN 13432, or NF U 52001 or all other equivalent norms. 

The PNEC value is obtained by dividing the acute toxicity value for the most sensitive species (i.e. the lowest of IC50 for algae, EC50 for Daphnia and LC50 for fish) identified in ecotoxicity studies by a large assessment factor. If data from chronic studies with fish or Daphnia are available, the assessment factor is reduced. 

From the ecotoxicity studies conducted for freshwater, marine and sediment organisms, the Predicted No Effect Concentration (PNEC) for each compartment can be derived. 

The inventory results should be presented in clear form, how much and what substances from the environment enter the system and how much get out. These results serve for subsequent life cycle impact assessment [48], The aim of the life cycle impact assessment is to measurably compare the environmental impacts of product systems and to compare their severity with new quantifiable variables identified as impact category. The impact categories are areas of specific environmental problems such as global warming, climate changes, acidification, eutrophication, ecotoxicity and others. Already in the phase of definition of the LCA study scope, it is necessary to describe what impact category will be applied and which of their environmental mechanisms will serve as a basis for impact assessment [46],... 

The data situation for additives in LCIA seems to be somewhat better than for the LCI [4]. Characterization factors exist for a number of additives and for a number of impact categories. Nevertheless, the fist is nowhere near complete. Especially for the impact categories of human toxicity and ecotoxicity, impact factors are missing. Approaches exist to calculate such factors based on substance characteristics. In this volume, LCIA factors are derived for a large number of additives based on such approaches [5]. The lack of such factors, therefore, seems to be less of a problem for including additives in LCA case studies than the lack of LCI data. 

In a study by Andersson et al. [30], the possibilities to use quantitative structure-activity relationship (QSAR) models to predict physical chemical and ecotoxico-logical properties of approximately 200 different plastic additives have been assessed. Physical chemical properties were predicted with the U.S. Environmental Protection Agency Estimation Program Interface (EPI) Suite, Version 3.20. Aquatic ecotoxicity data were calculated by QSAR models in the Toxicity Estimation Software Tool (T.E.S.T.), version 3.3, from U.S. Environmental Protection Agency, as described by Rahmberg et al. [31]. To evaluate the applicability of the QSAR-based characterization factors, they were compared to experiment-based characterization factors for the same substances taken from the USEtox organics database [32], This was done for 39 plastic additives for which experiment-based characterization factors were already available. 

A few decades ago the range of chemical descriptors used was very limited. Let us take the example of Corwin Hansch s studies, in which he described the relationship between ecotoxicity and a series of parameters, including log P... 

Reference toxicological values for HRA for the selected pollutants were obtained from ISS/ISPESL [21] and IRIS [22] databases or derived from animal in vivo studies (rat or mouse) and using appropriate safety factors while PNEC concentrations were obtained from previously selected peer-reviewed freely available databases [23] such as ECOTOX [24], ChemIDPlus advanced [25] and specific reviews. 

In response to the concern expressed by the shellfish farmers operating in the Ebro River delta about the potential positive role of pesticides on the oyster and mussel mortalities observed in the area, our group, commissioned by and with the collaboration of the Catalan Water Agency (ACA), carried out a comprehensive study in which chemical and toxicity data were combined to assess potential toxic presures present in the delta. To this end, a combined approach scheme integrating the measurement of various general physicochemical parameters in water, quantitative chemical analysis of pesticides in water and biota, and ecotoxicity assays in water was applied to a series of samples collected at springtime (between mid-April and mid-June 2008) from six selected sites of the delta the two (northern and southern)... 

In this case, the mineralogical studies on the mechanism of sulfide alteration and on the genesis and evolution of secondary oxidation products are of paramount environmental relevance because they allow a better understanding of the source and the mechanisms of release of the ecotoxic elements and the effective... 

Potentially it may be useful to have an expert report to collect, summarise and evaluate all the available literature data and in-house studies to get an overall view of the toxicity, environmental fate or ecotoxicity of a substance. A simple expert report would be on a single hazardous property, such as toxicokinetics or long-term general toxicity, and in effect would be a review article. 

N. Mathur, P. Bhatnagar, P. Nagar and M.K. Bijamia, Mutagenecity assessment of effluents-fromtextile/dye industries of Sanganer, Jaipur (India) a case study. Ecotox. Environ. Saf., 61 (2005) 105-113. 

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