Bioaccumulation of pharmaceuticals and stimulants in macrobenthic food web in the European Arctic as determined using stable isotope approach.

Although pharmaceuticals are increasingly detected in abiotic matrices in the Arctic, the accumulation of drugs in the resident biota and trophic transfer have not been yet examined. This study investigated the behaviour of several pharmaceuticals in the rocky-bottom, macrobenthic food web in the coastal zone of Isfjorden (western Spitsbergen) using stable isotope analyses (SIA) coupled with liquid chromatography-mass spectrometry (LC-MS/MS). Across 16 macroalgal and invertebrate species the highest average concentration was measured for ciprofloxacin (CIP) (on average 60.3 ng g-1 dw) followed by paracetamol (PCT) (51.3 ng g-1 dw) and nicotine (NIC) (37.8 ng g-1 dw). The biomagnification potential was assessed for six target compounds of 13 analytes detected that were quantified with a frequency > 50 % in biological samples. The trophic magnification factor (TMF) ranged between 0.3 and 2.8, and was significant for NIC and CIP. TMF < 1.0 for NIC (0.3; confidence interval, CI 0.1-0.5) indicated that the compound does not accumulate with trophic position. The dilution of pharmaceutical residues in the food web may result from limited intake with dietary route, poor assimilation efficiency and high biotransformation rates in benthic invertebrates. TMF for CIP (2.8, CI 1.2-6.4) suggests trophic magnification, a phenomenon observed previously for several antibiotics in freshwater food webs. Trophic transfer therefore plays a role in controlling concentration of CIP in the Arctic benthic communities and should be considered in environmental risk assessment. Biomagnification potential of diclofenac (DIC; 0.9, CI 0.5-1.7), carbamazepine (CBZ; 0.4, CI 0.1-2.1), caffeine (CAF; 0.9, CI 0.5-1.9) and PCT (1.3, CI 0.7-2.7) was not evident due to large 95 % confidence of their TMFs. This study provides the first evidence of drug bioaccumulation in the Arctic food web and indicates that behaviour of pharmaceuticals varies among target compounds.