Abstract
The research objective was to study the presence of DNA damages in haddock exposed to petrogenic or pyrogenic polyaromatic hydrocarbons (PAHs) from different sources: 1) extracts of oil produced water (PW), dominated by 2-ring PAHs; 2) distillation fractions of crude oil (representing oil-based drilling mud), dominated by 3-ring PAHs; 3) heavy pyrogenic PAHs, mixture of 4/5/6-ring PAHs. The biological effect of the different PAH sources was studied by feeding juvenile haddock with low doses of PAHs (0.3–0.7 mg PAH/kg fish/day) for two months, followed by a two-months recovery. In addition to the oral exposure, a group of fish was exposed to 12 single compounds of PAHs (4/5/6-ring) via intraperitoneal injection. The main endpoint was the analysis of hepatic and intestinal DNA adducts. In addition, PAH burden in liver, bile metabolites, gene and protein expression of CYP1A, GST activity, lipid peroxidation, skeletal deformities and histopathology of livers were evaluated. Juvenile haddock responded quickly to both intraperitoneal injection and oral exposure of 4/5/6-ring PAHs. High levels of DNA adducts were detected in livers three days after the dose of the single compound exposure. Fish had also high levels of DNA adducts in liver after being fed with extracts dominated by 2-ring PAHs (a PW exposure scenario) and 3-ring PAHs (simulating an oil exposure scenario). Elevated levels of DNA adducts were observed in the liver of all exposed groups after the 2 months of recovery. High levels of DNA adduct were found also in the intestines of individuals exposed to oil or heavy PAHs, but not in the PW or control groups. This suggests that the intestinal barrier is very important for detoxification of orally exposures of PAHs.
Highlights
The North Sea is impacted by human activity from many sources, including direct industrial discharges, urban runoff from land, offshore discharges from oil platforms and ship traffic, and atmospheric deposition from long-range transport of pollutants [1]
Our results indicate that juvenile haddock responded quickly to both oral exposure and intraperitoneal injection of polyaromatic hydrocarbons (PAHs)
Evidence of metabolism was seen in Oil and PAH, through increased CYP activity and levels of bile metabolites
Summary
The North Sea is impacted by human activity from many sources, including direct industrial discharges, urban runoff from land, offshore discharges from oil platforms and ship traffic, and atmospheric deposition from long-range transport of pollutants [1]. A major concern for the North Sea environment has been chronic and acute discharges of petroleum compounds, including polyaromatic hydrocarbons (PAHs), from more than 500 oil and gas (O&G) installations. The Tampen region in the Northern part of the North Sea holds some of the main oil fields both in the Norwegian and British sectors, with extensive production for more than 40 years. Oil pollution in the Tampen region has several possible sources, including PW and large deposits of oil-contaminated drill cuttings, i.e. solid material removed from bore drilling [3, 4]. Sediments in the North Sea contain a general background level of mainly pyrogenic PAHs [5]
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