Toxicity assessment, ecological

Hanson ML, Solomon KR. 2002. New technique for estimating thresholds of toxicity in ecological risk assessment. Environ Sci Technol 36 3257-3264. 

In this chapter, we outline the issues and principles that are relevant to toxicity assessments of combined exposures. The scope of this overview is limited to combinations of chemicals, but excludes the topic of nonchemical stressors acting in concert with chemicals. Because the issues are of a generic nature, we draw on examples from human, environmental, and ecological toxicology. Section 3.2 briefly outlines approaches to mixture effects assessment (Chapter 4 elaborates these approaches in more detail), Section 3.3 discusses mixture effects in relation to modes and mechanisms of action, and Section 3.4 addresses the problems and possibilities of predicting mixture effects. In Sections 3.5 and 3.6, emphasis is on the predictability of synergism and on effects at low concentration or dose levels of chemicals in mixtures. Section 3.7 provides an overview of scarcely available data on mixture effects in real-world exposure scenarios. This chapter ends with an outlook to the future. 

See also Benchmark Dose Exposure Assessment Exposure Criteria Hazard Identification Hormesis, LD50/ LC50 (Lethai Dosage 50/Lethai Concentration 50) Levels of Effect in Toxicoiogicai Assessment Maximum Allowable Concentration (MAC) Maximum Tolerated Dose (MTD) Pharmacokinetics/Toxicokinetics Reference Concentration (RfC) Reference Dose (RfD) Risk Assessment, Ecological Risk Assessment, Human Health Risk Characterization Toxicity, Acute. 

See also Clean Air Act (CAA), (US) Clean Water Act (CWA) (US) Environmental Protection Agency (US) Food and Drug Administration (US) Genetically Engineered Foods Lead Mercury Occupational Safety and Health Act, US Organisation for Economic Cooperation and Development Polychlorinated Biphenyls (PCBs) Risk Assessment, Ecological Risk Assessment, Human Health Toxic Substances Control Act. 

Ranking based on regional and global exposure estimations and qualitative human health and ecological toxicity assessment - European Union Risk Ranking Method. 

See also American Conference of Governmental Industrial Hygienists Biomarkers, Human Health Biotransformation Dose-Response Relationship Exposure Hazard Identification Medical Surveillance Occupational Safety and Health Administration Psychological Indices of Toxicity Risk Assessment, Ecological Risk Assessment, Human Health. 

Smolders, R., Bervoets, L., Wepener, V. and Blust, R. (2003a) A conceptual framework for using mussels as biomonitors in whole effluent toxicity. Human Ecological Risk Assessment, 9, 741-760. 

In addition to soil contamination with explosives and MC-related compounds, DND sites often have elevated concentrations of metals [53,54], Consequently, risk assessment at such sites should consider not only the presence of MC but also the potential effects of their interactions with metal co-contaminants on the toxicity to ecological receptors [61], Robidoux et al. [53,54] reported that ecotoxicological effects (such as the effects on earthworm reproduction) in soil with contaminant mixtures could not be attributed entirely to the toxicity of MC when in the presence of elevated concentrations of metals. In contrast, reproduction toxicity in earthworms correlated with TNT concentrations in TNT-contaminated soils having low metal concentrations [62], Findings in these and other reports show that mixtures... 

Additional investigations will be required to resolve the effects of multiple contaminant interactions on the toxicity to ecologically relevant receptors. Risk assessment of contaminant mixtures can be advanced further by developing toxicity benchmark data that consider physical and chemical properties of the soil in order to more accurately determine chemical bioavailability and toxicity at contaminated sites. 

Direct toxicity assessment (DTA) can also be used to account for the combined effects of contaminants. Measurements taken from biological and ecotoxicological tests are more directly related to ecological risk, because they measure the biological effects from a mixture of contaminants and, in doing so, provide an implicit indication of the bioavailability of the contaminants. Some tests can be simple and cost-effective in comparison to screening for multiple chemical... 

Ma, L., Li, J. Lu, Z. 2013. Pollution characteristics and potential ecological toxicity assessment of heavy metals in surface sediments of Xinglin Bay, Xiamen. Ecological Science 32(2) 212-217. 

There are two components to the analysis phase characterization of exposure and characterization of effects. Overall, this phase is similar to the exposure and toxicity assessment components of a human health risk assessment. The primary differences relate to the variety of ways in which exposure and toxicity can be measured in an ecological risk assessment. 

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