Effects-related parameters

Toxicity is not a specific property of any particular contaminant, but the result of interactions between the substance and the species exposed to it. The toxic potential of chemicals to affect cells, organs and organisms adversely is determined by the affinity for and the effectivity of the interactions between the chemical agent and the biological components (e.g. the receptors) in the organism, as well as the dose or concentration of the contaminant. The potential toxic effects may partly be compensated by the defence mechanisms of the affected biota (repair, regeneration and regulation at different levels of the 

Ecotoxicity is supposed to be concerned with any damaging effects of chemicals on species, populations and their environment, through which the structure, function, stability or repair mechanisms of the ecosystem may be impaired. The actual impact may occur at different trophic levels of ecosystem organization with the targets including  

The task for ecotoxicity assessment is to provide qualitative and quantitative indicators of the potential environmental impacts of chemicals, such as changes in the abundance of individual species or the diversity of the species community, taking into account the concentration and the time of exposure (dose-response relationships). Toxic action at the level of the organism may be classified according to Ariens (1984)  

Reversible (selective) interactions with specific sites of action clear concentration-effect relationships acute and subacute effects additivity of effects 

Irreversible interactions with target molecules occurrence on exposure to reactive toxicants 

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The biosensors together with the effect-related parameters or biochemical responses for environmental monitoring are very complex, but they will give a clear picture of the health status of the investigated system. 

Effects-related parameters toxicity to fish toxicity to Daphnia toxicity to algae toxicity to mammals mutagenicity. 

Validation status of QSAR models for exposure- and effects-related parameters... 

Estimations of effects-related parameters are subject to varying degrees of uncertainty (Table 6.2) that depend on the inhomogeneity of the underlying experimental material. 

Table 6.2 Methods and validation status for estimating effects-related parameters.

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