MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(EIC-1117-049760) Solvent Toxicity to Topsmelt Eggs.

Serben, K¹, Eickhoff, C¹, Pinturier, L², ¹ Vizon SciTec Inc., Vancouver, British Columbia, Canada² Total E&P Norge AS, Stavanger, Norway

ABSTRACT- When conducting toxicity tests with poorly water soluble chemicals, it is often necessary to use organic solvents to prepare concentrated stock solutions. The available guidance limits the final concentration of co-solvents in the test solutions to 0.01% or 0.1 mL/L. However, there is no background information or rationale for this value. In some cases, it may be conservative, in others, toxic. Recent toxicity tests conducted at Vizon used dimethyl formamide (DMF) as a solvent in early life stage tests with topsmelt, Atherinops affinis. Significant toxicity (hatching success) was observed in the solvent control, even at lower solvent concentrations (0.005%). An experiment was designed to assess the toxicity of different solvents to topsmelt embryos of varying ages. Tests were conducted with embryos of <2 days old, <4 days old, <6 days old, and <8 days old at test initiation. Four different solvents were tested at 0.005% in seawater: DMF, diethyl ether (Ether), acetone, and dimethyl sulfoxide (DMSO). The test solutions were renewed every second day, and the tests completed when all of the control embryos were hatched. Mean percent viability (embryos that are hatched and normal at test completion) was assessed as the toxicity endpoint. The results indicated that DMF caused significant mortality in young embryos compared to the other solvents tested, and that the sensitivity of the embryos decreased with age at test initiation.

Key words: topsmelt, co-solvent toxicity, early-life stage tests, dimethyl formamide