as the 9 mole adduct are not estrogenic but during sewage treatment the alkylphenol ethoxylates are biodegraded via shortening of the ethoxylate chain to short chain ethoxylates and carboxylic acid derivatives and finally alkylphenols which are all estrogenic table i indicates that short chain ethoxylates are less estrogenic than the unsubstituted equivalent but substitution of the hydroxyl group with a similar sized propylene oxide derivative results in a much greater reduction in activity biodegradation of the primary branched ethoxylated alkylphenols results in the production of estrogenic metabolites but secondary hydroxyl groups cannot be oxidized to carboxylates by bacteriological activity and therefore the biodegradation of propoxylated alkylphenols is less likely to result in the formation of estrogenic intermediates it has also been shown via degradation studies that upon degradation propoxylated phenols or alkylphenols do not degrade into an estrogenically active material without being bond by any particular theory we believe the branched propylene oxide directly attached to the phenolic ring is very slowly degraded and that the ring itself is preferentially degraded leaving no residual alkylphenol degradation studies have confirmed this pathway 122 5 g of propylene carbonate 1 18m was reacted with 234 5 g of nonylphenol using potassium carbonate.