EFFECT OF HOMOLOG DISTRIBUTION ON THE TOXICITY OF ALCOHOL ETHOXYLATES

Previous work established a high correlation between the potential env ironmental toxicity of oxyethylenated nonionic surfactants and the ave rage degree of ethoxylation. For this reason, it was considered of int erest to determine whether a narrow- or broad-range homolog distributi on of polydisperse commercial alcohol ethoxylates would influence toxi city. Ethoxylated fatty alcohols, both linear and branched, were synth esized with sodium hydroxide or an unconventional calcium-based cataly st. Toxicity tests were run on Daphnia magna and luminescent marine ba cteria. Toxicity of ethoxylated alcohols as a function of type of etho xylate homolog distribution (narrow or broad) and average degree of po lyaddition is analogous for both test species. However, narrow-range e thoxylates show lower toxicity values than conventional ethoxylates. D ifferences in toxicity values between broad- and narrow-range ethoxyla tes depend on the degree of ethoxylation.