title: Effects of deionized water on sensitivity of zebra mussels (Dreissena polymorpha) to toxic chemicals.
abstract: Previous studies showed that zebra mussels begin to die within a few days of immersion in deionized water and that potassium was about 10 times more toxic to zebra mussels when applied in deionized than in normal aquarium water. This study investigated whether deionized water enhanced the sensitivity of zebra mussels to other toxic substances, by comparing viability of mussels after 24 hr exposure to various substances applied in aquarium water and deionized water. Toxicity of sodium hypochlorite was enhanced approximately two orders of magnitude in deionized water: in aquarium water, 10 mg/l < LD50 < 100 mg/l; in deionized water, 0.1 mg/l < LD50 < 1 mg/l. A shift of two orders of magnitude in toxicity was also observed for ouabain: in aquarium water, 10(-4) M < LD50 < 10(-3) M; in deionized water, 10(-6) M < LD50 < 10(-5) M. The toxicity of ouabain was unchanged by the addition of 37 mg KCl/l aquarium water. Virtually no shift in toxicity due to deionized water was observed for niclosamide and for Endod. For niclosamide, LD50 in deionized water was slightly less than 10(-5) mg/l and in aquarium water slightly above 10(-5) mg/l. For Endod, the LD50 was between 5 and 10 mg/l in both media. The largest shift in toxicity in deionized water occurred for Noxfish (rotenone), for which LD50 shifted from approximately 1 mg/l in aquarium water to less than 10(-4) mg/l in deionized water. Enhancement of toxicity due to deionized water is thus not an additive effect, but varies with the toxic substance, probably according to the mechanism of toxicity.
authors.affiliation: Department of Physiology, Wayne State University, Detroit, MI 48201.
authors.forename: J U
authors.initials: JU
authors.lastname: Walker
authors.forename: J L
authors.initials: JL
authors.lastname: Ram
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000187:drug effects*; D004347:Drug Interactions; D007477:Ions; D007928:Lethal Dose 50; D009534:Niclosamide / Q000633:toxicity; D010042:Ouabain / Q000633:toxicity; D011189:Potassium Chloride / Q000633:toxicity; D012402:Rotenone / Q000633:toxicity; D012973:Sodium Hypochlorite / Q000633:toxicity; D014867:Water; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D007477:Ions; D014874:Water Pollutants, Chemical; D012402:Rotenone; D014867:Water; D010042:Ouabain; D011189:Potassium Chloride; D009534:Niclosamide; D012973:Sodium Hypochlorite