Environmental Health - Toxic Substances
Investigations - Emerging Contaminants
Treated wastewater effluent has been identified as a source of endocrine disrupting chemicals (EDCs) to the aquatic environment. In collaboration with St. Cloud State University (St. Cloud, Minnesota), two in-situ fish exposure experiments were conducted during 2002 (August and October) at a major metropolitan wastewater treatment plant (WWTP) on the Upper Mississippi River in Minnesota to determine if the effluent causes endocrine disruption in male fathead minnows (Pimephales promelas). The fathead minnows were exposed in parallel experiments to WWTP effluent and WWTP effluent treated with XAD8 macroreticular resin to remove the potential EDCs.
Exposure to WWTP effluent resulted in vitellogenin (a female egg-yoke protein) induction in the minnows, with greater response in October than in August. Concentrations of ammonia, alkylphenolethoxylates (a group of surfactant compounds and their degradation products), 17Β-estradiol (a biogenic female sex hormone), and other EDCs also were greater in October than in August.
Beneficial effects also were observed in the fish exposed to WWTP effluent. In contrast to expectations, the gonadosomatic index (GSI, the ratio between gonad weight and body weight) and other anatomical measures increased in males exposed to WWTP effluent compared to groundwater controls. In addition to the presence of endocrine disrupting compounds in WWTP effluent there are other compounds, such as nutrients and trace metals, that can influence the metabolism, sexual function, and growth of fish. These results show the multifaceted nature of the potential effects in fish exposed to the complex mixture of chemicals and nutrients in WWTP effluent.
Related Science Feature Articles
Barber, L.B., Lee, K.E., Swackhamer, D.L., Schoenfuss, H.L., 2007, Reproductive responses of male fathead minnows exposed to wastewater treatment plant effluent, effluent treated with XAD8 resin, and an environmentally relevant mixture of alkylphenol compounds: Aquatic Toxicology, v. 82, no. 1, p. 36-46, doi: doi:10.1016/j.aquatox.2007.01.003.