Plasma vitellogenin in male teleost fish from 43 rivers worldwide is correlated with upstream human population size Jean-Pierre W. Desforges a , Brendan D.L. Peachey a , Pauline M. Sanderson a , Paul A. White b , Jules M. Blais a, * a Department of Biology, University of Ottawa, 30 Marie Curie Street, K1N 6N5, Ottawa, Ontario, Canada b Environmental Health Sciences and Research Bureau, Health Canada, Ottawa, Ontario, Canada Concentrations of vitellogenin in riverine teleost fish were related to population size. article info Article history: Received 1 March 2010 Received in revised form 9 July 2010 Accepted 16 July 2010 Keywords: Vitellogenin Wastewater treatment plant Fish species EDCs Endocrine disrupting chemicals Fish abstract It has been previously demonstrated that vitellogenin (VTG) e a precursor egg yolk protein e is produced in male fish exposed to estrogenic compounds in wastewater treatment plant (WWTP) effluent. However, little attention has been given to examine whether any patterns of male VTG production exists across fish species on a global scale. We hypothesized that a composite measure of human population size over river discharge would best explain variations of protein levels in male fish. We compiled VTG data in 13 fish species from 43 rivers receiving municipal WWTP effluent on 3 continents. We found that human population size explained 28% of the variation in male VTG concen- trations, whereas population/flow rate failed to significantly correlate with VTG. We suggest this result may be explained by the low solubility of estrogenic compounds, resulting in localized contamination near WWTP outfalls, rather than dilution by river water. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Hormone-mimicking xenobiotic chemicals released into natural ecosystems are a potential risk for human and ecosystem health, and have sparked global scientific interest for several decades (Folmar et al., 1996). These chemicals come in a wide variety of forms, and have the capacity to interact with hormone receptors within cells at environmentally relevant concentrations (Hayes et al., 2003). Several researchers have discovered measurable concentrations of numerous EDCs in surface waters, sediments, groundwater, and drinking water around the world (Campbell et al., 2006). Estrogenic EDCs represent a sub-class of compounds that can be divided into two groups: natural hormonal estrogens, and synthetic chemicals that have the ability to mimic or induce estrogen-like responses in exposed organisms (Campbell et al., 2006). The predominant origin of these compounds in aquatic environments has been identified as Wastewater Treatment Plant (WWTP) effluent; however, agricultural run-off and industrial wastewater contribute significantly as well (Atkinson, 2008). Natural steroidal estrogens of significance in WWTP effluents include Estrone (E1), 17b-Estradiol (E2), and Estriol (E3). Synthetic estrogens, or xen- oestrogens, derive from agriculture, industrial plastics, and phar- maceuticals. Notable chemicals in this category include: ethynylestradiol (EE2), a synthetic steroidal estrogen found in oral contraceptive metabolites, alkylphenolic compounds, which origi- nate through the degradation of non-ionic detergents, bisphenol A (BPA), a monomer used primarily in the manufacturing of plastics and resins, in addition to a variety of pesticides (Atkinson, 2008; Folmar et al., 2001). All of these compounds have varying degrees of estrogenic potency, depending on their affinities for estrogen receptors (de Voogt and van Hattum, 2003). Estrogen Equivalent Factors (EEF) are used to express the estrogenicity of compounds in wastewater effluent relative to natural estradiol. E1, E2, and EE2 have been identified as the principal sources of estrogenicity in wastewater effluent, with EEF values of 0.5, 1, and >1.5 respectively (Campbell et al., 2006; Desbrow et al., 1998). Several biomarkers can be used to assess estrogen exposure and estrogenic effects in fish; one of these is male production of vitel- logenin (VTG), an egg yolk precursor protein, which is naturally synthesized in the liver of oviparous vertebrates. In normally functioning female fish, endogenous estrogens, such as E2, regulate the expression of genes that control protein synthesis. Thus, E2 is * Corresponding author. E-mail address: jules.blais@uottawa.ca (J.M. Blais). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2010.07.017 Environmental Pollution 158 (2010) 3279e3284