title: Synergistic effect of piperonyl butoxide on acute toxicity of pyrethrins to Hyalella azteca.
abstract: A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the synergistic effect of piperonyl butoxide (PBO) on pyrethrin toxicity. Concentrations of PBO <4 µg/L caused no toxicity enhancement, whereas toxicity increased with PBO concentrations between 4 µg/L and 15 µg/L. Additive toxicity calculations showed that true synergism accounted for an increase in pyrethrin toxicity (decrease in median lethal concentration) of 1.4-fold to 1.6-fold and varied only slightly between 4 µg/L and 15 µg/L PBO, whereas direct toxicity of PBO accounted for an additional increase in mixture toxicity (up to 3.2-fold) that was proportional to PBO concentration. The results can be used to assess the risk of measured or predicted co-occurring concentrations of PBO and pyrethrins in surface waters. Environ Toxicol Chem 2016;35:2111-2116. © 2016 SETAC.
authors.affiliation: Compliance Services International, Lakewood, Washington, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Giddings
authors.affiliation: Compliance Services International, Lakewood, Washington, USA.
authors.forename: James
authors.initials: J
authors.lastname: Gagne
authors.affiliation: MGK, Minneapolis, Minnesota, USA.
authors.forename: Janice
authors.initials: J
authors.lastname: Sharp
mesh_terms: D033304:Amphipoda / Q000187:drug effects*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D007306:Insecticides / Q000737:chemistry / Q000633:toxicity*; D007928:Lethal Dose 50; D015394:Molecular Structure; D010882:Piperonyl Butoxide / Q000737:chemistry / Q000633:toxicity*; D011722:Pyrethrins / Q000737:chemistry / Q000633:toxicity*; D023382:Toxicity Tests, Acute; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D014874:Water Pollutants, Chemical; D010882:Piperonyl Butoxide
keywords: Hyalella azteca; Piperonyl butoxide (PBO); Pyrethrins; Pyrethroid; Synergism