The Toxicity of Acetylenic Alcohols to the Fathead Minnow, Pimephales Promelas: Narcosis and Proelectrophile Activation

Abstract

1. The 96-h LC₅₀ values for 16 acetylenic alcohols in the fathead minnow (Pimephales promelas) were determined using continuous-flow diluters. The measured LC₅₀ values for seven tertiary propargylic alcohols agreed closely with the QSAR predictions based upon data for other organic non-electrolytes acting by a narcosis mechanism.

2. Four primary and four secondary propargylic alcohols were 7 to 4600 times more toxic than the respective narcotic toxicity estimated by QSAR. Metabolic activation to electrophilic α,β-unsaturated propargylic aldehydes or ketones is proposed to account for the increased toxicity.

3. 3-Butyn-1-o1 and 4-pentyn-2-ol, primary and secondary homopropargylic alcohols, were 320 and 160, respectively, times more toxic than predicted. In this case an activation step involving biotransformation to an allenic electrophile intermediate was proposed.