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CADDIS Volume 2: Sources, Stressors & Responses

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Reproductive effects of WWTP effluents

Municipal effluents often contain endocrine disrupting chemicals (EDCs), which can mimic or interfere with normal hormone signaling in aquatic animals and result in adverse reproductive effects (Jobling & Tyler 2003). Standard wastewater treatment practices typically are not effective at removing these chemicals.

Examples of known or suspected EDCs found in WWTP effluents include:

Natural hormones (e.g., 17β-estradiol)

Synthetic hormones and other pharmaceuticals (e.g., 17α-ethynlestradiol)

Pesticides (e.g., diazinon, lindane, atrazine)


Toxic metals (e.g., copper, mercury, cadmium)


Bisphenol A

Courtesy of NY DEC

Vajda et al. (2008) examined the estrogenic effects of WWTP effluent on white suckers in Boulder Creek, CO. They found that intersex fish—fish that containing both ovarian and testicular tissue—comprised 18-22% of the population downstream of the WWTP outfall, but were not found upstream. Fish downstream of the outfall also had altered sex ratios, reduced sperm production, increased vitellogenin levels (a protein associated with egg development in females), and reduced gonad size (Fig 15).

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Figure 15. Evidence of reproductive impairment in white suckers collected from sites upstream (upstream) and downstream (effluent) of the Boulder WWTP on Boulder Creek, in terms of (A) % males, (B) sperm abundance in males, (C) plasma vitellogenin concentrations in males, and (D) gonadosomatic index in females.
From Vajda DW et al. 2008. Reproductive disruption in fish downstream from an estrogenic wastewater effluent. Environmental Science & Technology 42:3407-3414. © 2008 American Chemical Society. Reprinted with permission.

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