An ecological risk assessment for the use of the biocide, dibromonitrilopropionamide (DBNPA), in industrial cooling systems

A tiered approach was employed to determine risks posed to aquatic organisms exposed to dibromonitrilopropionamide (DBNPA). Tier one assessments used conservative exposure and toxicity data and indicated that potential toxicity warranted a more rigorous risk assessment. Tier two used discharge and stream dow data to develop a probabilistic model of DBNPA concentrations reaching the stream. Predicted 90th percentile in-stream DBNPA concentrations were compared to all available toxicity data for aquatic organisms at several different trophic levels. The EC10 for one organism was similar to the calculated 90th percentile of DBNPA concentrations in streams. Using the complete EC10 data set and comparing the 10th percentile EC10 with the 90th percentile environmental concentration, DBNPA did not pose a measurable risk to the aquatic ecosystem.