Biological effects-based assessment

Biological effects-based assessment of in situ risks (in situ BEB A) at sites where sediment quality and potentially sediment management is to be considered. 

Biological effects-based assessment of the ex situ quality of dredged sediments (ex situ BEBA) in order to select sediment management options (e.g. free or confined disposal or treatment options). 

Den Besten, P.J., De Deckere, E., Babut, M.P., Power, B., DelValls, T.A., Zago, C. Oen, A.M.P. and Heise, S. (2003) Biological effects-based sediment quality in ecological risk assessment for European waters, Journal of Soils and Sediments 3, 144-162. 

A final means of assessing combined exposure is through the direct application of biological testing for effects-based assessment of complexly polluted media (e.g., effluents, soils, sediments). For the use of bioassays for direct assessment of complex mixtures, the reader is referred to Chapter 4. 

Pohl, E. and J. Pohl-Ruling, Dose Distribution in the Human Organism Due to Incorporation of Radon and Decay Products as a Base for Epidemiological Studies, in Proceedings of the International Radon Specialist Meeting on the Assessment of Radon and Daughters Exposures and Related Biological Effects, Rome, (RD Press)pp. 

The Sediment Quality Triad (SQT) is an effects-based conceptual approach that can be used to assess and determine the status of contaminated sediments based on biology (laboratory and/or in situ toxicity tests), chemistry (chemical identification and quantification), and ecology (community structure and/or function). It provides a means for comparing three different lines of evidence (LOE) and arriving at a weight of evidence (WOE) determination regarding the risk posed by contaminated sediments. Effectively, each LOE comprises an independent assessment of hazard combined and integrated, they provide an assessment of risk. 

Effects-based approach for assessing the status of contaminated sediments based on chemistry, biology and ecotoxicology. Volume 2(10). 

Alternative methods include (1) computer-based methods (mathematical models and expert systems) (2) physicochemical methods, in which physical or chemical effects are assessed in systems lacking cells and, most typically, (3) in vitro methods, in which biological effects are observed in cell cultures, tissues, or organs. 

If the toxic effect of a chemical combination is tested and compared with the effect of the individual chemicals, it may happen that the effect of the tested mixture deviates from the effect predicted by CA or IA. This mixture can be considered as 1 combination of the endless number of other possible combinations in which these chemicals can be mixed. If more combinations of this specific set of chemicals are tested, it can happen that effects of a number of different combinations at low concentrations differ from CA or IA, but that the effects of high-concentration combinations are well predicted. Such a systematic deviation pattern may be relevant for risk assessment, or may provide insight into the modes of action. Three types of systematic deviations from CA or IA can be defined as biologically relevant, based on studies published in the literature ... 

When risks are very low, the subtracted term is so small that its impact on Rm is negligible (e.g., for r, = 0.01 and r2= 0.02, Rm = 0.01 + 0.02 - 0.0002 = 0.0298, or -0.03) thus, low risks such as those typically found in environmental risk assessments can be approximated by simple summation. Effects addition, a concept rarely applied, is a special case of RA where the biological measurements are summed across the mixture components and then a judgment is made regarding potential adverse effects based on the total measurement. Finally, when a mixture contains components with more than 1 MOA that cause the same health outcome, CA and RA methods can be integrated to assess risk (USEPA 2003b). See also Chapter 4. 

Sources of data that might be used in the construction of stressor-response functions include the results of toxicity tests (lethal, chronic) performed under controlled laboratory conditions, direct measures of exposure and response in controlled field experiments, and the application of statistical relationships that estimate the biological effects of chemicals based on physical or chemical properties of specific toxicants. The order of preference among these sources of data lists field observations as the most valuable, followed by laboratory toxicity tests, and finally by the use of empirical relationships. In the absence of directly relevant data, the development of stressor-response functions may require the use of extrapolations among similar stressors or ecological effects for which data are available. For example, effects might have to be extrapolated from the available test species to an untested species of concern in an ERA. Similarly, toxicity data might be available only for a chemical similar to the specific chemical stressor of concern in an ERA, and thereby require an extrapolation from one chemical to another to perform the assessment. 

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