The Health Impact Assessment (HIA) under REACH includes a comprehensive narrative description of all the expected changes or impacts:
1) The human health endpoints affected both qualitatively and quantitatively;
2)The possible values used associated with human health end-points and the estimates of monetised impacts;
3) The significance of the impacts;
4) The certainty and confidence in the description of the impacts;
5) All relevant assumptions/decisions and estimated uncertainties relating to what has been included, measurements or data sources.
Link to guidance.