Toxicity of short‐chain alcohols to the nematode Caenorhabditis elegans: A comparison of endpoints

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Abstract
The toxicities of 4 short‐chain alcohols—namely methanol, ethanol, iso‐propanol and iso‐butanol—were compared in the nematode Caenorhabditis elegans using several different ecotoxicological endpoints. Range‐finding tests were conducted using transgenic PC161 worms carrying a double reporter construct (GFP plus lacZ) linked to the stress‐inducible hsp16‐1 promoter. These tests showed little response from the GFP reporter, but gave good dose–response curves for the lacZ reporter—showing clear induction at 0.5% v/v ethanol in an overnight assay, but only at 4% in a shorter 6‐h assay. Comparison of the short‐term dose–response curves shows a confusing pattern of differences between the four alcohols tested, although dose‐dependence is evident across at least part of the concentration range. Feeding inhibition assays are somewhat inconclusive with regard to alcohol type, although iso‐butanol and iso‐propanol appear more toxic than ethanol, while methanol is least toxic. To resolve some of the remaining ambiguities, we also used a fecundity assay to show that iso‐propanol is more toxic than ethanol, and a lethality assay to show that iso‐butanol is more toxic than iso‐propanol. Most of the endpoints studied are consistent with the following order of toxicity: iso‐butanol > iso‐propanol > ethanol ≥ methanol. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:87–95, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com). DOI 10.1002/jbt.20060