Chapter 2
Conventional Risk Assessment of Environmental Contaminants
Jean-Claude Amiard, and Claude Amiard-Triquet
Abstract
Conventional risk is assessed by using a four-tier approach including hazard identification, assessment of exposure (predicted environmental concentrations), hazard characterization (predicted no effect concentrations) and risk characterization based upon the risk quotient (predicted environmental concentration/predicted no effect concentration for water, sediment, and biota). This core procedure is used worldwide with some differences in the details and is described here using the European Union recommendations. Ecotoxicity databases have been compiled in many countries. The current procedures suffer many limitations, mainly because of the dominant use of standardized bioassays involving single species and unique substances, generally neglecting the dietary route of exposure and the effects of mixtures. The most important weaknesses include large uncertainties in extrapolating data across doses, species, and life stages, poor assessment of contaminants with nonmonotonic dose–response relationship, the lack of data (e.g., environmental degradation) for emerging contaminants, and the noninclusion of adaptation in polluted environments.
Keywords
Dose–effect relationship; Emission assessment; Environmental fate; Hazard identification; PECs; PNECs; Risk quotient approach; SSDs
Chapter Outline
Introduction
Environmental influences on health, particularly the role of water quality, have been recognized as anciently as in the treatise called “Airs, Waters, Places” by the Greek physician Hippocrates in the second half of the fifth century BC. However, environmental concern has developed more recently, particularly with the use of synthetic organic chemicals after the Second World War. “Silent Spring” by
Rachel Carson (1962) has had a key role for environmental science and the society, documenting the detrimental effects on the environment—particularly on birds—of the unreasonable use of pesticides. The term “ecotoxicology” was coined by René Truhaut in 1969 who defined it as “the branch of toxicology concerned with the study of toxic effects, caused by natural or synthetic pollutants, to the constituents of ecosystems, animal (including human), vegetable and microbial, in an integral context” (published in
Truhaut, 1977). The development of ecotoxicology has allowed the implementation of retrospective risk assessment, considering the effects of the dispersion of chemical compounds into the environment and possibly mitigating them, as also prospective risk assessment that aims at assessing the future risks from releases of new and existing chemicals into the environment.
Environmental risk assessment aims at the protection of ecosystems, considering their structure, functioning, and services. Predictive risk assessment aims at assessing the future risks from releases of chemicals into the environment. In the United States, the federal Toxic Substances Control Act gives the US Environmental Protection Agency (USEPA) the authority to regulate, and even ban, the manufacture, use, and distribution of both new and existing chemicals (
Schierow, 2009). In Europe, a significant improvement occurred recently with a new chemical policy, REACH, for Registration, Evaluation, and Authorization of Chemicals (
CEC, 2003). Procedures needed to reach this aim have been adopted in many countries (
USEPA, 1998;
ANZECC and ARMCANZ, 2000;
CCME, 2007;
NITE, 2010;
Gormley et al., 2011) and supranational organizations such as the Organisation for Economic Co-operation and Development (
OECD, 2012b) and European Environment Agency (
EEA, 1998;
TGD, 2003). These procedures are regularly updated using scientific enhancements. A systematic literature review conducted in the Elsevier database (ScienceDirect) using the terms “environmental risk assessment” AND “aquatic” have shown that about 200 papers were published from 2010 until May 13, 2014, including several reviews regrouped in the third edition of the
Encyclopedia of Toxicology. The Society of Environmental Toxicity and Chemistry is also very active in this field, as shown by the workshop “Closing the gap between academic research and regulatory risk assessment of chemicals” held in 2013 in Glasgow, Scotland (
http://www.setac.org/members/group_content_view.asp?group=90708&id=189652&hhSearchTerms=%22Environmental+and+risk+and+assessment%22, accessed 13.05.14). The European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) is an independent association that cooperates in a scientific context with intergovernmental agencies, governments, health authorities, and other public and professional institutions with interests in ecotoxicological and toxicological issues relating to chemicals. ECETOC’s Targeted Risk Assessment tool calculates the risk of exposure from chemicals to workers, consumers, and the environment (
http://www.ecetoc.org/research?q=Targeted%20Risk%20Assessment%20%28TRA%29%20tool).
Despite different guidelines having been launched in many national and supranational regulatory bodies, the procedures follow the same general scheme.
2.1. Principles for Environmental Risk Assessment
The meaning of the words hazard and risk is not totally clear for everybody, even in dictionaries. For example, one dictionary defines hazard as “a danger or risk,” which helps explain why many people use the terms interchangeably. Among specialists of (eco)toxicology, hazard is defined as any source of potential damage, harm, or adverse health effects on something or someone under certain environmental conditions. However, it is clear that damage can occur only if organisms are exposed to hazard. Risk is the chance or probability that an organism will be harmed or experience an adverse health effect if exposed to a hazard.
The procedures currently in use for conventional risk assessment are depicted in
Figure 2.1. The first step consists in the identification of hazard based on physicochemical properties, ecotoxicity, and intended use (
EEA, 1998). Criteria for the selection of priority substances include their degree of persistency, toxicity, and bioaccumulation (for details, see
http://www.miljostatus.no/en/Topics/Hazardous-chemicals/Hazardous-chemical-lists/List-of-Priority-Substances/Criteria-for-the-selection-of-Priority-Substances/, accessed 13.05.14). In Europe, 45 substances or groups of substances are on the list of priority substances for which environmental quality standards were set in 2008 (amended in 2013), including selected existing chemicals, plant protection products, biocides, metals, and other groups such as polyaromatic hydrocarbons and polybrominated biphenyl ethers (PBDEs). The complete list is available at
http://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:32013L0039 (accessed 4.12.14). Two lists have special significance to water quality regulatory programs in the US Clean Water Act: a list of 65 toxic pollutants and a list of 129 priority pollutants (
http://water.epa.gov/scitech/methods/cwa/pollutants-background.cfm#pp, accessed 13.05.14).
Figure 2.1 Principles for environmental risk assessment.
When a hazard has been identified, there is the need to assess the fate and effects of pollutants. Studying the fate and the biogeochemical cycle of pollutants in ecosystems is crucial in determining the environmental risk assessment because knowledge is needed on the release of pollutants in water, air, and sediment/soil because many exchanges occur between them (
Figure 2.2). It is also important to take into account the trophic transfer of pollutants from sediment (suspended in the water column or deposited) and microorganisms to invertebrates (filter-feeders or deposit feeders) then predatory fish (omnivorous, carnivorous, supercarnivorous). When these data are available, they can be used in models for predicted environmental concentrations (PECs). Modeling is particularly useful for certain emerging contaminants such as nanoparticles that cannot be directly measured in environmental matrices (
Chapter 17).
When a substance has been recognized as hazardous, there is the need to carry out hazard characterization (
Figure 2.1). This step mainly aims at determining the relationship between the concentration of a given pollutant in a medium and the noxious effects that this substance can induce in organisms. The main parameters that may be determined from experimental tests include the no observed adverse...
