Ecological Modeling in Risk Assessment - Chapter 12

-Ngoại suy mô hình độc tính hoặc ước tính độc tính của một hóa chất cho một loài trên cơ sở độc tính của nó, các loài khác thường taxonomically liên quan, hoặc ước tính một thiết bị đầu cuối từ các thiết bị đầu cuối kiểm tra khác. Phép ngoại suy mô hình nói chung là phương pháp tiếp cận nonmechanistic sử dụng dữ liệu thực nghiệm để cố gắng để có được một kết quả chính xác cho câu hỏi cụ thể quan tâm. Mô hình ngoại suy khác nhau đại diện cho một trong hai loài nhạy. | CHAPTER 12 Toxicity-Extrapolation Models Jenée A. Colton Toxicity-extrapolation models either estimate the toxicity of a chemical to one species on the basis of its toxicity to other typically taxonomically related species or estimate one endpoint from other test endpoints. Extrapolation models are generally nonmechanistic approaches that use empirical data to attempt to obtain a precise result for the specific question of interest. Various extrapolation models representing either species-sensitivity distributions or interspecies interendpoint extrapolation methods are reviewed below. Species-sensitivity distribution models estimate toxicity thresholds for biological communities from laboratory toxicity data. The basis for a species-sensitivity distribution is essentially a frequency distribution of toxicity thresholds . the median lethal concentrations LC50s or NOEC for individual test species Figure . These models have been the basis for the development of environmental quality criteria . Stephan et al. 1985 OECD 1992 Premises for Risk Management 1987 as cited in van Leeuwen 1990 . Essentially a level of protection for the community is selected that corresponds to a percentile of the species-sensitivity distribution. For example the EPA ambient water quality criteria are assumed to protect 95 of the aquatic community because EPA selected the 5th percentile of the species-sensitivity distribution for a given chemical as the value of the criterion Stephan et al. 1985 . Species interactions are not taken into account in these models. The accuracy of the extrapolation models is inherently limited because of their use of data from laboratory tests on a limited number of species that are easily maintained in the laboratory. The underlying assumption for all extrapolation models is that the tolerance of laboratory species tested under laboratory conditions is similar to that of all other related species. Also laboratory exposure to chemicals and the .