Effect-Directed Identification of Naphthenic Acids As Important in Vitro Xeno-Estrogens and Anti-Androgens in North Sea Offshore Produced Water Discharges

Abstract

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 aromatic hydrocarbons (PAHs) and alkylphenols as environmental 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.

Reproductive development of yellow perch (Perca flavescens) exposed to oil sands–affected waters

“…The effect of commercial naphthenic acids and of wastewater extracts from North Sea oil production on the yeast androgen bioassay was recently examined by Thomas et al [28], and the material was found to be antiandrogenic. This finding raises the possibility that oil sands naphthenic acids may be antiandrogenic to fish.…”

“…Male fathead minnows exposed to 5 mg/L of the same extract had lower plasma levels of 11-ketotestosterone, whereas those exposed to 10 mg/L had lower concentrations of both testosterone and 11-ketotestosterone. Thomas et al [28] also raised the possibility that PAHs can bind to androgen receptors. It is known that tailings porewater contained PAHs [2], and they were present in sediment and insects from the Demonstration and Bison Pond [3].…”

Microbial biodegradation of aromatic alkanoic naphthenic acids is affected by the degree of alkyl side chain branching

“…For example, Dawson et al (1996) demonstrated the toxicity of aromatic acids, including benzoic acid and a range of phenylalkanoics, using Xenopus embryos, whereas Zhao et al (1998) reported the toxicity of a range of benzoic acids to Vibrio fischeri, Daphnia magna and carp. More recently, Thomas et al (2009) showed a mixture of 2 0 -, 3 0 -and 4 0 -isobutylphenyl-4-pentanoic acids as environmental androgen receptor antagonists. Despite this, there is insufficient information on the metabolism of aromatic alkanoic acids, and the microorganisms involved in their biodegradation are unknown.…”

Compositional properties characterizing commonly transported oils and controlling their fate in the marine environment

“…Their main characteristic is higher polarity which, as a consequence, affords higher water solubility and bioavailability/toxicity. [62][63][64] Furthermore, this fraction can also contain transformation products generated through weathering, such as oxidated polycyclic compounds which can be present at even higher concentrations than the parent compounds. 65 These have been reported in marine environmental matrices at toxic levels 66,67 and can be persistent.…”