Presence of natural and anthropogenic organic contaminants and potential fish health impacts along two river gradients in Alberta, Canada

In the current study, 28 organic contaminants were measured, many with estrogen‐like activity, in water collected from 16 sites on two rivers in the South Saskatchewan River Basin, Alberta, Canada. The compounds detected included synthetic estrogens (birth control pill compounds and hormone therapy drugs) downstream of municipal wastewater effluents and natural hormones downstream of municipal wastewater effluents and in agricultural areas. Greater concentrations of cholesterol and derivatives, phytosterols, and fecal sterols were measured at the most downstream sites, which indicates cumulative inputs of such compounds in these rivers. A native minnow (longnose dace, Rhinichthys cataractae ) was sampled to assess pathophysiological responses to exposure to compounds with estrogen‐like activity. Hepatic vitellogenin protein was detected in at least one adult male longnose dace from 14 of 15 sites sampled for fish. Vitellogenin was negatively correlated with hepatosomatic ( r  = −0.47, p  < 0.001) and gonadosomatic ( r  = −0.44, p  < 0.003) indices, which suggests potential health impacts in male longnose dace in the South Saskatchewan River Basin. The current study demonstrates that organic contaminants, many with estrogen‐like activity, are distributed over hundreds of kilometers throughout the South Saskatchewan River Basin and not just downstream of major point‐sources. Therefore, many activities within these basins impact water quality in the South Saskatchewan River Basin and affect endemic longnose dace populations. Environ. Toxicol. Chem. 2010;29:2379–2387. © 2010 SETAC