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Produced water (PW) is a significant byproduct of offshore oil and gas production, constituting a major waste stream in the North Sea. Existing regulations address only the dispersed aliphatic hydrocarbon content in PW, and limited attention is given to other potentially hazardous compounds, including benzene, toluene, ethyl benzene and xylene (BTEX), polycyclic aromatic hydrocarbons (PAHs), phenols, water-soluble petroleum constituents as well as production-related chemicals. In this study, Danish oil production PW samples were subjected to purge and trap extraction on granular activated carbon for volatile compounds identification and quantification by GC-MS analysis. The obtained analytical data correlate with toxicity assessments conducted on three trophic levels, bacteria (Aliivibrio fischeri), algae (Skeletonema costatum) and copepods (Acartia tonsa) on the whole effluent as well as on treated samples. The removal of the PW volatile fraction by purging experiments resulted in a decrease in toxicity response from 37% ± 23-65% ± 16 across the tested species. The chemicals identified in this study and their toxicity response enhance the comprehension of the PW effluent composition and inform the development of strategies for offshore reservoir wastewater., Competing Interests: Declaration of competing interest This research was funded by the Danish Offshore Technology Centre and the Danish Underground Consortium (Total Energies, Blue Nord, and Nordsøfonden) under the Produced Water Management program. These entities provided the samples and data materials used in this study. The private entities had no role in the study design, data collection, analysis, or decision to publish the results. Due to a confidential disclosure agreement with the funding entities, we cannot disclose detailed information about the provenance of the produced water (PW) samples, except for the general area of origin. We are also restricted from sharing confidential raw data on the mass spectroscopy composition of produced water. Despite these restrictions, the funding entities did not interfere with or influence the content or conclusions of this manuscript. The authors do not hold any patents or copyrights relevant to the work presented in this manuscript. There are no other activities or affiliations that the authors believe may merit disclosure in relation to this manuscript., (Copyright © 2024. Published by Elsevier Ltd.)