title: Fathead minnow response to broad-range exposure of β-sitosterol concentrations during life-cycle testing.
abstract: The β-sitosterol concentration in pulp and paper mill effluents is typically greater than that of other phytosterols and has been shown to cause a variety of effects in fish. The authors exposed fathead minnow (Pimephales promelas) to low (22 ± 0.93 µg/L), medium-low (70 ± 2.1 µg/L), medium-high (237 ± 5.5 µg/L), and high (745 ± 16.2 µg/L) concentrations of β-sitosterol as well as negative (water), positive (ethynyl estradiol, 16 ± 0.58 ng/L), and carrier (0.6 mL/L acetone) controls. Fish were monitored over a full life cycle for population-level endpoints including growth and survival, reproductive endpoints (e.g. fecundity, sex steroids and vitellogenin, gonado-/hepatosomatic indices, and gonad histology). No significant differences were seen in fish growth, mortality, or reproduction with β-sitosterol exposure, although a trend for lower egg production in β-sitosterol exposures relative to the water control may be related to the acetone carrier. All ethynyl estradiol-exposed fish were smaller, showed female characteristics, and did not spawn. Sex steroid and vitellogenin were highly variable with no detectable treatment-related differences. Gonadal tissue showed no β-sitosterol-related differences in reproductive development and spawning capability, although most ethynyl estradiol-exposed males had ovarian tissue and were not spawning-capable. The results indicate that β-sitosterol exposure had little apparent impact on fathead minnow survival, growth, and reproduction even at concentrations >10 times that of typical effluents, although small sample size and variability precluded fully evaluating treatment responses on sex steroids and vitellogenin.
authors.affiliation: National Council for Air and Stream Improvement, Anacortes, Washington, USA.
authors.forename: Camille A
authors.initials: CA
authors.lastname: Flinders
authors.forename: William R
authors.initials: WR
authors.lastname: Streblow
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Philbeck
authors.forename: Diana L
authors.initials: DL
authors.lastname: Cook
authors.forename: David E
authors.initials: DE
authors.lastname: Campbell
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Brown-Peterson
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Gross
mesh_terms: D000818:Animals; D003530:Cyprinidae / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000187:drug effects; D006066:Gonads / Q000033:anatomy & histology / Q000187:drug effects; D008018:Life Cycle Stages; D008297:Male; D012098:Reproduction / Q000187:drug effects; D012855:Sitosterols / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D012855:Sitosterols; D014874:Water Pollutants, Chemical; C025473:gamma-sitosterol
keywords: Ethynyl estradiol; Fathead minnow; Life-cycle assessment; β-Sitosterol