Surrogate data

It is advisable, then, in a tiered approach to concentrate first on crops and activities (scenarios) that are considered to be relevant with respect to the expected level of exposure and to exclude those not relevant. Second, whether or not the toxicological properties of the product may lead to general restrictions on re-entry should be investigated. If both the likelihood of reentry and the hazard due to the toxicity of the compound cannot generally be neglected, a risk assessment over several steps should be carried out. The assessment may be based on surrogate data and "worst-case" assumptions at first and then refined, if necessary. One possible approach to a tiered evaluation procedure is presented in Figure 1. 

Surrogate Data Calculation, Read-Across and SAR/QSAR... 

Registration dossiers for substances at below 100 tonnes per annum will not be evaluated, so it is up to the registrant to make the case for using non-standard data and surrogate data. If and when the substance is evaluated, however, it may turn out that some new... 

Data uncertainties depend on the type of data being used in the model, such as surrogate data, expert judgement, default data, modelled (extrapolated) data, etc. ... 

Sufficiently similar mixtures. Another approach is to use surrogate data on one whole mixture to conduct the risk assessment of another. This applies the concept of sufficient similarity, defined as 2 mixtures close in chemical composition where there are small differences in their components and in the proportions of their components. Key issues for similar mixtures include assessing the similarity of analytical chemistry and toxicological data for mixtures. In this case, an RfD, RfC, or slope factor could be calculated for the mixture of concern using data on a sufficiently similar mixture. This concept is also used in specific applications to groups of similar mixtures that are produced by similar processes, for example, the comparative potency method as applied to diesel exhaust emissions (Lewtas 1985,1988 Nesnow 1990). 

Surrogate data Substitute data or measurements on one substance (or population) used to estimate analogous or corresponding values for another substance (or population) (PMRA, 2003). 

Integration of Surrogate Data and Estimations with Physiological Simulation... 

A9.5.2.3.3 Experimentally derived BCF values of high quality are ultimately preferred for classification purposes as such data override surrogate data, e.g. Kow. 

Tetko IV, Abagyan R, Oprea TI. Surrogate data—A secure way to share corporate data. J Comput Aided Mol Des 2005 19 749-64. 

Studies for notification of new chemical substances are to be conducted to OECD guidelines or their equivalent. They must be conducted by a laboratory whose practices are consistent with the principles of OECD GLP, and Canadian GLP is to be developed. Pre-notification consultations with Environment Canada may be useful, to establish whether specific existing non-standard or non-GLP studies are acceptable, if surrogate data (/e, SAR, QSAR or other calculation methods) would be adequate instead of actual tests, or if requests for waivers for specific data requirements will be likely to be accepted. 

Ihe policy for use of surrogate studies has been published in the Federal Register (June 25, 1980), cind the philosophy and mechanics of the use of surrogate data have been discussed in various public fora (1,2). 

In conclusion, the use cf surrogate data for exposure assessments will most certainly continue. The resources required to carry out field studies for every crop/application method/ pesticide ccmbination would be overwhelming. BAB s goal is to derive reliable and useful correlations which will obviate the need for requiring such extensive studies. 

The bootstrap evaluates the error rate on a number of surrogate data sets constructed by sampling the original data set. Suppose that the original... 

Data uncertainty. The simulation of the climatic forcing starts with the joint distribution functions of the random variables involved in the process which are themselves based on the surrogated data. To this respect, the validity of the model results depends on the length and quality of the climatic database. 

Methodology performance assessment Using above empirical data on soil Pb Estimates using surrogate data Modeled estimate compared to surrogate data, other point source sites... 

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