Development and application of methods for quantifying pharmaceuticals in Eurasian otters (Lutra lutra)

Kumar, Emmelianna (2022) Development and application of methods for quantifying pharmaceuticals in Eurasian otters (Lutra lutra). Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

The work presented in this thesis assessed the risks that pharmaceuticals and other chemicals of emerging concern pose to Eurasian otters (Lutra lutra). A method using accelerated solvent extraction (ASE) was developed to quantify lipid content in otters, improving our ability to accurately monitor and model concentrations of pollutants in individual biological tissues. A conventional gravimetric extraction method was used as a reference method for comparison, and demonstrated that the ASE method was more accurate (-22% error compared with -48% error) and more precise (7%CV compared with 27%CV) when applied to the lipid-rich samples investigated in this study. Rapid, targeted screening methods were developed to determine concentrations of a suite of pharmaceuticals, to investigate the risk that pharmaceutical residues pose to otters. These methods were validated in canine blood and bile before being applied to wild otters. The results showed that the target analytes were not present above the lower limit of detection (LLOD) in any of the blood or bile samples tested. As the LLODs were well below the corresponding predicted critical effect concentrations, these results suggest that the target analytes are unlikely to pose an immediate risk to otters in Sweden. A rapid, nontargeted screening method was used to search for other potential organic pollutants in the blood of these otters, to estimate the otter exposome. The results tentatively identified 153 xenobiotic compounds, from ten chemical classes, including pesticides, pharmaceuticals, perfluoroalkyl substances and industrial chemicals. Some of these chemicals are highly toxic, carcinogenic, genotoxic, neurotoxic and reprotoxic, and are reported in this species for the first time in this thesis. The detection of compounds that have potential to cause endocrine disruption is particularly concerning as an increase in reproductive abnormalities has been reported in male otters in Sweden. Further biomonitoring of Eurasian otters, using a combination of targeted and non-targeted approaches, is recommended to obtain information about the concentrations, and ultimately the potential effects of, chemicals of emerging concern in this species. Inclusion of a larger number of otter samples in future research would be advantageous to test for differences among demographic groups.