There are relatively few data available for NPEs, but, based on their structure, the BCF is expected to decrease with increasing chain length, and NPECs are not expected to bioaccumulate. The major route for the release of NP and NPEs to the Canadian environment is through discharge of effluents. The composition of the mixture can differ considerably among the various effluents, depending on the source and the degree and type of treatment. Textile mill effluents represent a major source of NPEs to the environment. There appears to be a recent decrease in discharge of NPEs from pulp and paper mills, but there are very few data available to validate this conclusion.
Municipal effluents are a significant source of NPEs and are widespread across Canada.
Untreated effluents can have high levels of NP, NP1EO and NP2EO, which may exceed thresholds for chronic effects in the aquatic environment. Treated effluents have relatively low levels of NPEs with longer EO chain lengths. NP1EO and NP2EO can remain at levels that may result in potential chronic toxicity in final effluents. There is potential for chronic toxicity to occur in aquatic biota due to exposure to NPEs and their metabolites in a variety of effluents. This can be associated with different metabolites of NPEs, depending on the source and degree and type of treatment.