Evaluation of probabilistic ecological risk assessment methodology using aquatic microcosms and azinphos-methyl

dc.contributor.advisorSolomon, K.R.
dc.contributor.authorTakacs, Peter
dc.date.accessioned2021-04-26T19:47:25Z
dc.date.available2021-04-26T19:47:25Z
dc.date.copyright1999
dc.degree.departmentDepartment of Environmental Biologyen_US
dc.degree.grantorUniversity of Guelphen_US
dc.degree.nameMaster of Scienceen_US
dc.description.abstractThe general trend toward probabilistic risk assessment in aquatic toxicology relies on some key assumptions, several of which are questionable. At present, only a few studies have been carried out to evaluate the probabilistic approach. To this end, a multi-species outdoor microcosm study was conducted using the organophosphorus insecticide azinphos-methyl, the freshwater fish ' Pimephales promelas' and 'Lepomis gibbosus', as well as zooplankton. A regression design was used with 5 treatment levels (0.1-100 [mu]g/L) and a control. Comparison of the 96 hr LC50s for fish (31.7 and 3.2 [mu]g/L, respectively) with the 10th percentile of the acute sensitivity distribution (0.9 [mu]g/L) indicates that this extrapolated value would not correspond to acute toxicity in these species. Based on literature data, the multi-species no observable effect concentration (NOEC) for ' Daphnia' sp. (0.1 [mu]g/L) coincides with the chronic and acute 10 th centiles (0.092 and 0.15 [mu]g/L) of the single species invertebrate sensitivity distributions. For fish, the multi-species NOEC for survival (0. 17 [mu]g/L is below the acute 10th centile of 0.9 [mu]g/L, which is not protective. Probabilistic risk assessment of azinphos-methyl in Southern Ontario surface waters indicates that up to 30% of fish and 50-70% of invertebrate species may be acutely impacted. The applicability of probabilistic extrapolation to ecosystem level effects is highly uncertain and thus difficult to reconcile.en_US
dc.identifier.urihttps://hdl.handle.net/10214/25395
dc.language.isoen
dc.publisherUniversity of Guelphen_US
dc.rights.licenseAll items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectprobabilistic risk assessmenten_US
dc.subjectaquatic toxicologyen_US
dc.subjectmulti-species outdoor microcosm studyen_US
dc.subjectorganophosphorusen_US
dc.subjectinsecticideen_US
dc.subjectazinphos-methylen_US
dc.subjectfreshwater fishen_US
dc.subjectPimephales promelasen_US
dc.subjectLepomis gibbosusen_US
dc.subjectzooplanktonen_US
dc.titleEvaluation of probabilistic ecological risk assessment methodology using aquatic microcosms and azinphos-methylen_US
dc.typeThesisen_US

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