Toxicological and environmental implications on the use of nitrilotriacetic acid as a detergent builder—1

Abstract

Phosphates are unique as causal nutrients in the induction of cultural eutrophication; they are not only critical and growth limiting, but also controllable. Detergents currently constitute 50–70% of phosphates in municipal sewage. Partial substitution of polyphosphate detergent builders by nitrilotriacetic acid NTA has been proposed in an attempt to reduce or reverse eutrophication. Biodegradation of NTA is variable and can be markedly retarded under a wide range of operating field conditions. In model studies, NTA is a strong chelating agent; biodegradation of some heavy metal chelates may be delayed in both model and field studies. There are no available data on the intermediary pathways of biodegradation of NTA; hypothetical pathways based on sequential degradation via secondary amines, primary amines, ammonia, and nitrite and nitrate are proposed. Estimates are made on NTA and nitrate levels to be expected in water under a wide range of conditions; the possibility of human toxic effects due to nitrate increments resulting from NTA degradation, and of the involvement of NTA in nitrosamine synthesis is discussed.