Article original / Original article Intérêt du dosage de quatre éléments minéraux dans les eaux usées pour le suivi des activités médicales Four mineral elements as biomarkers of medical activities in wastewaters

Objective: Environmental pollution by various substances such as pharmaceuticals or metals is a topic of major interest. We measured metals as biomarkers of medical activities in different wastewaters. Method: Wastewater was collected from Rouen University hospital and at three stages of the Rouen treatment plant process (inlet, middle and outlet). Silver (Ag), iodine (I), platinum (Pt) and gadolinium (Gd), four metals that are used in various medical activities, were quantified by inductively coupled plasma-mass detector (ICP-MS) each day, for 29 days. Results: The limits of quantification for these elements were: 107 Ag = 0.58 µg/ L- 127 I = 0.2 µg/ L- 157 Gd = 0.004 µg/ L- 195 Pt = 0.01 µg/L. On working days, median hospital wastewater metal concentrations for these elements were, respectively, 3, 13, 13 and 27 times higher than the urban ones. For these elements, median hospital wastewater concentrations were significantly higher on working days compared with non-working days (weekend and holidays) (1.0 × 10 −5 < p < 2.0 × 10 −4 ). Conclusion: Silver, iodine, gadolinium and platinum are excellent indicators of medical activities. Silver for silver