Risk assessment environmental

Environmental risk assessment is required for substances which are classified as dangerous for the environment , or if there are the following other reasonable grounds for concern  

Environmental risk assessment examines the potential adverse effects to ecosystems from exposure of the aquatic, terrestrial and air components. Initial assessment normally focuses on the aquatic compartment, including effects on microorganisms in waste water treatment plants. This first tier risk assessment can be extended to cover the sediment part of the aquatic compartment and the soil compartment. At higher tonnage levels, effects relevant to the food chain are evaluated, i.e., secondary poisoning. Diderich in Chapter 8 of (73) discusses the principles of EU environmental risk assessment. 

The objective is to predict the concentration of the substance below which adverse effects in a particular environmental compartment are not expected to occur, i.e., the predicted no effect concentration (PNEC). However, in some cases, it may not be possible to establish a PNEC, and a qualitative estimation has to be made instead. An assessment factor is applied to 

Risk assessment for any given environmental compartment is a comparison of the PEC with the PNEC, i.e., the PEC PNEC ratio. If this ratio is below 1, there is no immediate concern. If the ratio is above 1, the assessor decides on the basis of its value and other relevant factors what conclusions apply. If it has not been possible to derive a PEC/PNEC ratio, the risk assessment is a qualitative evaluation of the likelihood that an adverse effect will occur. 

The process that evaluates the likelihood that adverse ecological effects may occur or are 

A Textbook of Modern Toxicology, Third Edition, edited by Ernest Hodgson ISBN 0-471-26508-X Copyright 2004 John Wiley Sons, Inc. 

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Ferrari B, Mons R, Vollat B, Fraysse B, Paxeus N, Lo Giudice R, Pollio A, Garric J (2004) Environmental risk assessment of six human pharmaceuticals are the current enviommental risk assessment procedures sufficient for the protection of the aquatic environment Environ Toxicol Chem 23 1344-1354... 

A biomarker is here defined as a biological response to an environmental chemical at the individual level or below, which demonstrates a departure from normality. Responses at higher levels of biological organization are not, according to this definition, termed biomarkers. Where such biological responses can be readily measnred, they may provide the basis for biomarker assays, which can be nsed to stndy the effects of chemicals in the laboratory or, most importantly, in the field. There is also interest in their employment as tools for the environmental risk assessment of chemicals. 

In environmental risk assessment, the objective is to establish the likelihood of a chemical (or chemicals) expressing toxicity in the natural environment. Assessment is based on a comparison of ecotoxicity data from laboratory tests with estimated or measured exposure in the field. The question of effects at the level of population that may be the consequence of such toxicity is not addressed. This issue will now be discussed. 

The development of models incorporating biomarker assays to predict the effects of chemicals upon parameters related to r has obvious attractions from a scientific point of view and is preferable, in theory, to the crude use of ecotoxicity data currently employed in procedures for environmental risk assessment. However, the development of this approach would involve considerable investment in research, and might prove too complex and costly to be widely employed in environmental risk assessment. 

Another issue is the development and refinement of the testing protocols used in mesocosms. Mesocosms could have a more important role in environmental risk assessment if the data coming from them could be better interpreted. The use of biomarker assays to establish toxic effects and, where necessary, relate them to effects produced by chemicals in the field, might be a way forward. The issues raised in this section will be returned to in Chapter 17, after consideration of the individual examples given in Part 2. 

Thns far, the discussion has dealt primarily with biomarker responses in living organisms. In the next section, consideration will be given to the exploitation of this principle in the development of bioassay systems that can be nsed in environmental monitoring and environmental risk assessment. 

Herbicides constitute a large and diverse class of pesticides that, with a few exceptions, have very low mammalian toxicity and have received relatively little attention as environmental pollutants. Much of the work in the held of ecotoxicology and much environmental risk assessment has focused on animals, especially vertebrate animals. There has perhaps been a tendency to overlook the importance of plants in the natural world. Most plants belong to the lowest trophic levels of ecosystems, and animals in higher trophic levels are absolutely dependent on them for their survival. 

A central theme of this text is the development of biomarker assays to measure the extent of toxic effects caused by chemicals both in the field studies and for the purposes of environmental risk assessment. 

There is a continuing interest in the development of biomarker assays for use in environmental risk assessment. As discussed elsewhere (Section 16.6), there are both scientific and ethical reasons for seeking to introduce in vitro assays into protocols for the regulatory testing of chemicals. Animal welfare organizations would like to see the replacement of toxicity tests by more animal-friendly alternatives for all types of risk assessment—whether for environmental risks or for human health. 

Apart from the use of this approach to study the ecotoxicology of neurotoxic pollutants in the field, it also has potential for use during the course of environmental risk assessment. An understanding of the relationship between biomarker responses to neurotoxic compounds and effects at the population level can be gained from both field studies and the use of mesocosms and other model systems. From these it may be possible to define critical thresholds in biomarker responses of indicator species above which population effects begin to appear. In the longer term, this approach... 

The following sections will attempt to look ahead to likely fntnre problems with organic pollntion, to probable changes in the ways in which it is stndied and monitored, and in the tests and strategies used for environmental risk assessment of organic chemicals. 

At the practical level, an ideal mechanistic biomarker should be simple to use, sensitive, relatively specific, stable, and usable on material that can be obtained by nondestructive sampling (e.g., blood or skin). A tall order, no doubt, and no biomarker yet developed has all of these attributes. However, the judicious use of combinations of biomarkers can overcome the shortcomings of individual assays. The main point to emphasize is that the resources so far invested in the development of biomarker technology for environmental risk assessment has been very small (cf the investment in biomarkers for use in medicine). Knowledge of toxic mechanisms of organic pollutants is already substantial (especially of pesticides), and it grows apace. The scientific basis is already there for technological advance it all comes down to a question of investment. 

Ecotoxicology is primarily concerned with effects of chemicals on populations, communities, and ecosystems, but the trouble is that field studies are expensive and difficult to perform and can only be employed to a limited extent. In the main, environmental risk assessment of pesticides and certain other chemicals has to be... 

Boutonnet JC et al. (1999) Environmental risk assessment of trifinoroacetic acid. Human Ecol Risk Assess 5 59-124. 

ENVIRONMENTAL SAMPLING FOR HAZARDOUS WASTES Table I. The Process of Environmental Risk Assessment... 

Dr Georg Geisler is a product safety expert and modeller working with RCC Ltd, a Contract Research Organisation based in Basel, Switzerland. In this function, he conducts environmental risk assessments of pesticides, biocides and other chemicals, as well as safety assessments for pesticide residues in the food chain. In 2003, Georg Geisler earned his Ph.D. on environmental life-cycle assessment of pesticides at ETH Zurich. In 1999, he had received a Diploma in environmental chemistry at the Friedrich-Schiller University, Jena, Germany. 

Mathematical Modeling Application to Environmental Risk Assessments... 

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