Ana sayfa/What are read-across and QSAR?
What are read-across and QSAR?
Read-across and QSAR are alternative methods for predicting a substance’s properties from data on similar substances or from computational models. KKDIK (Turkey REACH) and REACH allow their use, with sound scientific justification, to reduce animal testing and close data gaps without new tests — saving cost and time.
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Read-across and QSAR in one sentence
Both approaches let you fill a data gap without running a new test. QSAR predicts an effect from the molecular structure, while read-across transfers data from a similar substance to the target substance. Both are accepted when the reasoning is documented and defensible.
When read-across is accepted
Structural similarity alone is not sufficient. Metabolism and mode of action should also align, and the source data must be reliable and complete. Where the justification is weak, the authority is likely to request the actual study instead.
What the justification file contains
- Identity and purity of the target and source substances
- Structural similarity analysis and an honest account of the differences
- Comparison of metabolism and mode of action
- Reliability assessment of the source data
- Explicit statement of uncertainties and limitations
Cost and time impact
A long-term animal study is expensive and takes months to complete. A well-built read-across file removes much of that burden. However, a rejected file costs more time than the study would have taken, so the decision should follow a proper data quality review.
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Official source: KKDIK Regulation — Turkish Official Gazette.
Endpoint by endpoint
Some physicochemical properties and simpler toxicological endpoints are more readily accepted from prediction. Complex endpoints such as reproductive toxicity demand a far more detailed justification. The strategy is therefore built endpoint by endpoint rather than as a single decision for the whole substance.