There can be many reasons to estimate the properties
of a substance rather than initiate testing.
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To fill data gaps. |
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To provide a working data set quickly. |
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Substances may be difficult to test - valid estimation may be the best option. |
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To provide indicative results to aid interpretation, when test results are unreliable. |
Under REACH the use of non-experimental methods to fill data gaps is accepted where scientifically justified. In PFA's wider experience, the use of category approaches can provide great support to such an approach.
Various methods exist, most of which use the principles of Quantitative Structure-Activity Relationships (QSARs).
Some methods relate one chemical property to another, e.g. prediction of vapour pressure based on the value of boiling point. Some of the most reliable methods use a fragment contribution approach - the structure of the molecule is broken down into key structural components and features, the predicted value is calculated from the contributions of each component.
