The team’s next step is to determine the extent to which pharmaceutical waste is present in plants, crustaceans, bivalve molluscs and fish, along with assessing the potential for it to accumulate in the food chain, the researchers were quoted as saying in the statement.

Substances found in the river include residues from antibiotics, anti-hypertensives and anti-inflammatories. These were found in over 90% of water samples collected in the Tagus estuary, according to the statement.

Anti-depressants, lipid regulators and anti-epileptics were also identified.

Thirty-two researchers are involved in the study, whose conclusions are to be published in the print edition of the 'Marine Pollution Bulletin' in October.