Temporal extrapolation

Spatial variability, temporal variability, biological variability, the presence of gradients, and multiple stressors. Spatial and temporal extrapolations are at the highest tier of extrapolation and build upon the other methods of extrapolation. 

Extrapolation used to infer toxicity from one type of exposure regimen to another is often termed temporal extrapolation. The most common of these extrapolations is that from acute to chronic exposures, but the issue of pulsed versus continuous exposure is also important in assessing possible effects in real-world environmental settings. These extrapolations may involve the use of modified tests with standard species or whole-model ecosystems to simulate realistic exposures such as those of variable duration or those of pulsed exposure for compounds that rapidly dissipate in the environment. In many cases, these involve alterations in exposure route and intensity, both of which can have significant impacts on the toxic responses. Extrapolation from acute responses to NOECs or chronic responses is particularly important as chronic tests are more costly and time-consuming than acute tests. Methods for accurate and precise acute-to-chronic extrapolations have been developed and are available as computer programs such as ACE (Mayer et al. 1999, 2001 De Zwart 2002 Ellersieck et al. 2003) and are discussed in Chapter 6. 

Temporal Extrapolation in Ecological Effect Assessment of Chemicals... 

Landscape ecotoxicology This section describes current developments and extrapolation tools used in landscape ecotoxicology. Because ecological effect assessment of chemicals at the landscape level requires the integration of both spatial and temporal aspects, this section in particular builds further on the data presented in Chapter 6 on temporal extrapolation in ecological effect assessment of chemicals. 

Temporal extrapolation is important in terms of the duration of the exposure, the number of exposures, and the nature of the response to these in the organism. Chapter 6 reviews relationships between temporal exposure in relation to acute-to-chronic extrapolation, reversibility, and latency in terms of the interaction between substances and individual organisms. Other temporal extrapolation approaches are needed when considering temporal processes in organisms themselves. These relate to seasonal variability in sensitivity, recovery at the population level, and adaptation to stressors. 

Derivation of AEGL-1 (key study, critical effect, dose-exposure concentration, uncertainty factor application and justification, temporal extrapolation, assumptions, confidence, consistency with human data if... 

J. C. Hebden, M. Tziraki, D. T. Delpy. Evaluation of the temporally extrapolated absorbance method for dual-wavelength imaging through tissuehke scattering media. Appl Optics 36 ... 

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