Correction factors (CFs) (table ) have been previously calculated in a systematic pharmacokinetic review by . To achieve representative results, the number of observations performed in each study was used for weighting calculated CF values. These CFs are utilised to calculate drug intake in a community, PNDI, by using the amount of AA and/or metabolites detected in wastewater and correcting for human excretion percentage. SPY has been included in this study but it is of note that this AA is no longer prescribed for use in humans in the UK. It is however, a major vetrinary pharmaceutical. SPY and aSPY are both major metabolites for SLZ, which is prescribed for humans in the UK as an anti-inflammatory drug.