Whole Effluent Toxicity Data and Discharge Volumes to Assess the Likelihood that Environmental Risks of Offshore Produced Water Discharges Are Adequately Controlled.

In 2012, the Oslo-Paris (OSPAR) Commission adopted Recommendation 2012/5 for a risk-based approach (RBA) to the management of produced water discharges from offshore installations. As part of this recommendation, OSPAR requires that the environmental risk of the discharge of produced water is characterized based on whole effluent toxicity (WET) studies and/or on a substance-based assessment. In this paper we describe an assessment of the likelihood that the environmental risk of produced water discharges is adequately controlled based on WET data for 19 oil- and gas-producing platforms and their discharge volumes. Our analysis shows that, with the selected risk criterion of predicted exposure concentration (PEC)/predicted no-effect concentration (PNEC) should not exceed 1 at 500 m, there is a mean likelihood of 99.5% (or more) that the environmental risk from the produced water discharges is adequately controlled for installations that discharge 30 × 103 m3 /y (or less). The method presented in this paper can be used for screening purposes to ensure that efforts are directed toward installations with a high likelihood that risk is not adequately controlled. Integr Environ Assess Manag 2019;15:584-595.