Environ. Sci. Technol. 2009, 43, 8066–8071
Effect-Directed Identification of Naphthenic Acids As Important in Vitro Xeno-Estrogens and Anti-Androgens in North Sea Offshore Produced Water Discharges K . V . T H O M A S , * ,† K . L A N G F O R D , † K. PETERSEN,† A. J. SMITH,‡ AND K. E. TOLLEFSEN† Norwegian Institute for Water Research (NIVA), Gaustadalle´en 21, N-0349 Oslo, Norway, and Cefas, Pakefield Road, Lowestoft, NR33 0HT, United Kingdom
Received May 26, 2008. Revised manuscript received August 12, 2009. Accepted September 1, 2009.
Produced water from offshore oil production platforms represents the largest direct discharge of effluent into the offshore environment. Produced water effluents contain a complex mixture of substances which are known to bind to the estrogen receptor (ER) and antagonize the androgen receptor (AR). Short-chain petrogenic alkylphenols have been identified as responsible for around 35% of the ER agonist activity measured in vitro while the compounds responsible for antagonizing the androgen receptor are unknown. For the first time we report that petrogenic naphthenic acids are weak ER agonists that account for much of the 65% of the “unknown” ER agonist potency in North Sea produced waters while also disrupting the binding of AR agonists to the AR ligand receptor. We also report other known petrogenic components such as polycyclic aromatichydrocarbons(PAHs)andalkylphenolsasenvironmental AR antagonists. Our investigation shows that these petrogenic components are responsible for the majority of the ER and AR receptor mediated activity in produced waters. This hypothesis is supported by data from an effects-directed analysis of produced water using normal-phase high-performance liquid chromatography (HPLC) fractionation in combination with the yeast estrogen and androgen assays as well as androgen receptor binding assays of commercially available mixtures of naphthenic acids.
Introduction Produced water from offshore oil production platforms represents the largest direct discharge of effluent into the offshore environment. Produced water is a complex mixture of heavy metals, hydrocarbons, phenols, organic acids, and oil production chemicals (1). Some produced water components are known to be in vitro estrogen receptor (ER) and aryl hydrocarbon receptor (AhR) agonists and androgen receptor (AR) antagonists (2-6). We have previously esti* Corresponding author e-mail:
[email protected]; telephone: +47-2218-51-00; fax: +47-22-18-52-00. † Norwegian Institute for Water Research (NIVA). ‡ Cefas. 8066
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mated that the input of in vitro ER agonists into the North Sea from offshore platforms is the equivalent of up to 11 kg of 17β-estradiol equivalents yr-1 (2). At the same time the total estimated input of in vitro androgen receptor antagonists to the North Sea is the equivalent of 560 t of flutamide equivalents yr-1 (6). Mixtures of petrogenic alkylphenols (C1-C5) present at high concentrations have been identified as produced water ER agonists and are now routinely monitored in both the United Kingdom and Norwegian sectors of the North Sea. An assessment of the levels of petrogenic alkylphenols (C3-C6) discharged into the North Sea has shown that little risk is posed to offshore fish communities (7); however alkylphenols are responsible for as little as 35% of the in vitro ER activity measured in produced waters (8). Even less is known about the risks posed by the occurrence of AR antagonists in produced water. The AR antagonist activity of produced waters, expressed as flutamide (a synthetic oral-anti-androgen) equivalent concentrations range from
