Bioconcentration of polycyclic musks in fathead minnows caged in a wastewater effluent plume

The synthetic polycyclic musks HHCB (Galaxolide^®) and AHTN (Tonalide^®) were monitored in fathead minnows (FHMs) caged for a month at various locations in the North Saskatchewan River (NSR), upstream and downstream of the Gold Bar wastewater treatment plant that serves the city of Edmonton, AB, Canada. In addition, the distribution of these musk compounds in the river was predicted using the fugacity-based Quantitative Water Air Sediment Interface (QWASI) model. In FHMs caged 0.15 km downstream of the wastewater outfall, mean concentrations of HHCB and AHTN were 7.4 and 0.4 μg g⁻¹ wet weight, respectively. These are among the highest reported concentrations of these musk compounds in fish exposed to treated wastewater. The musk concentrations in FHMs were significantly lower further downstream of the outfall. High bioconcentration factors (BCFs) in FHMs that exceeded 10⁴ higher than estimated concentrations in water indicated that there were low rates of biotransformation of the musks in the fish. In the FHMs caged at the site closest to the wastewater outfall, HHCB concentrations in FHMs were comparable to the body burdens that have been reported to moderate expression of vitellogenin in female rainbow trout, indicating that fish in the NSR downstream of the wastewater outfall may be at risk of anti-estrogenic effects. The QWASI model applied to six individual river sections of the NSR predicted that the largest fluxes of HHCB and AHTN would be for downstream transport in water, which explains why FHMs accumulated elevated concentrations of the musks at the furthest downstream site, 9.9 km from the wastewater discharge. - Highlights: • Caged fish near an urban wastewater outfall had very high concentrations of musks. • High bioconcentration of musks in fish indicated low biotransformation rates. • A model showed the largest flux of musks in the river was for downstream transport.