Pharmaceutical Residues in Fishes and Macro Invertebrates around the Wastewater Treatment Plant Site at the University Teaching Hospital of Yaoundé, Cameroon

Introduction: Hospital effluents are one of the main sources of dissemination of pharmaceutical residues in hydro system. Worldwide, analyses of these effluents have revealed the presence of various pharmaceuticals. Very few studies assessing the contamination of solid matrices by pharmaceutical residues have been carried out in Africa, specifically in Cameroon.

Objectives: The study aimed to detect pharmaceutical residues in solid environmental matrices at sites around the discharge of the effluent from the Yaoundé University Teaching Hospital.

Methods: Four hundred and fifty-nine (459) macro invertebrates and twenty (20) Nile tilapia were collected in three sampling sites before and beyond the wastewater treatment plant of the Yaoundé University Teaching Hospital. The specimens were conserved in a cooler prior to freeze drying and grinding. The powders were sent for analysis at the Sefako Makgatho Health Sciences University in South Africa. The analysis was carried out using an ultra-high-performance liquid chromatography coupled with a triple quadrupole tandem mass spectrometer.

Results: A total of ninety-nine pharmaceutical residues related to seventeen pharmacological classes were detected in all samples of macro invertebrates (72) and Nile tilapia (55 for fish viscera and 58 for fish flesh) collected. Antibiotics were the most represented (23.2 %), followed by anti-inflammatory (18.2 %), and anti-parasitics (9.1 %). More than half (53.6 %) of the drug residues detected in the fish samples were of the anti-inflammatory (21,71 %), antihypertensive (17,67 %) and antibiotic (13,13 %) classes. The number of drug residues detected in the macroinvertebrates before the treatment plant (41) was smaller than those detected after the treatment plant (67).

Conclusion: Five therapeutic classes (antibiotics, anti-inflammatories, antihypertensive, antiparasitics and hormones) were mostly represented.These results are in line with the importance of considering diet of fishes and/or humans as an exposure pathway based on the great similarity in pharmaceutical composition between macroinvertebrates and Nile tilapia.