DNA damage caused by organic extracts of contaminated sediment, crude, and weathered oil and their fractions recovered up to 5 years after the 2007 Hebei Spirit oil spill off Korea

Genotoxic Effects of Exposure to Water-Soluble Fraction of Diesel Fuel in Sand Dollar Scaphechinus mirabilis Gametes

Pollution of marine areas with oil and oil products is steadily growing. As part of this connection, the study of the impact of petroleum hydrocarbons on marine hydrobionts is an urgent issue of modern ecotoxicology. In our study, the genotoxic effect of the water-soluble fraction of diesel fuel at different concentrations on the gametes of the sand dollar Scaphechinus mirabilis was evaluated. It was shown that during the incubation of sperm and eggs of a sand dollar in WAF with an oil hydrocarbon content of 1.32; 2.64; 5.37; 7.92 mg/L caused the destruction of the DNA molecule to varying degrees in both types of gametes. In addition, it has been shown that with an increase in the concentration of petroleum hydrocarbons in WAF, a large number of cells with a high level of DNA damage appear. The success of fertilization after exposure of gametes to a water-soluble extract of petroleum hydrocarbons was also evaluated. The relationship between an increase in the concentration of hydrocarbons in the tested solutions and a decrease in the level of fertilization is shown.

Activation of the nucleotide excision repair pathway by crude oil exposure: A translational study from model organisms to the Hebei Spirit Oil Spill Cohort

In order to gain insight into the human health implications of the Hebei Spirit Oil Spill (HSOS), the mechanism of toxicity of the Iranian heavy crude (IHC), the main oil component in the HSOS was investigated in Caenorhabditis elegans and zebrafish. The identified mechanism was translated to humans using blood samples from Taean residents, who experienced HSOS with different levels of exposure to the spill. C. elegans TF RNAi screening with IHC oil revealed the nucleotide excision repair (NER) pathway as being significantly involved by oil exposure. To identify the main toxicity contributors within the chemical mixture of the crude oil, further studies were conducted on C. elegans by exposure to C3-naphthalene, an alkylated polycyclic aromatic hydrocarbon (PAH), which constitutes one of the major components of IHC oil. Increased expression of NER pathway genes was observed following exposure to the IHC oil, C3-naphthalene enriched fraction and C3-naphthalene. As the NER pathway is conserved in fish and humans, the same experiment was conducted in zebrafish, and the data were similar to what was seen in C. elegans. Increased expression of NER pathway genes was observed in human samples from the high exposure group, which suggests the involvement of the NER pathway in IHC oil exposure. Overall, the study suggests that IHC oil may cause bulk damage to DNA and activation of the NER system and Alkylated PAHs are the major contributor to DNA damage. Our study provides an innovative approach for studying translational toxicity testing from model organisms to human health.

eDNA-based bioassessment of coastal sediments impacted by an oil spill

Oil spills offshore can cause long-term ecological effects on coastal marine ecosystems. Despite their important ecological roles in the cycling of energy and nutrients in food webs, effects on bacteria, protists or arthropods are often neglected. Environmental DNA (eDNA) metabarcoding was applied to characterize changes in the structure of micro- and macro-biota communities of surface sediments over a 7-year period since the occurrence of Hebei Spirit oil spill on December 7, 2007. Alterations in diversities and structures of micro- and macro-biota were observed in the contaminated area where concentrations of polycyclic aromatic hydrocarbons were greater. Successions of bacterial, protists and metazoan communities revealed long-term ecological effects of residual oil. Residual oil dominated the largest cluster of the community-environment association network. Presence of bacterial families (Aerococcaceae and Carnobacteriaceae) and the protozoan family (Platyophryidae) might have conferred sensitivity of communities to oil pollution. Hydrocarbon-degrading bacterial families (Anaerolinaceae, Desulfobacteraceae, Helicobacteraceae and Piscirickettsiaceae) and algal family (Araphid pennate) were resistant to adverse effects of spilt oil. The protistan family (Subulatomonas) and arthropod families (Folsomia, Sarcophagidae Opomyzoidea, and Anomura) appeared to be positively associated with residual oil pollution. eDNA metabarcoding can provide a powerful tool for assessing effects of anthropogenic pollution, such as oil spills on sediment communities and its long-term trends in coastal marine environments.

Characterization of endocrine disruption potentials of coastal sediments of Taean, Korea employing H295R and MVLN assays-Reconnaissance at 5years after Hebei Spirit oil spill

Endocrine disrupting potentials were assessed for sediment samples collected near Hebei Spirit oil spill (HSOS) site, between December 2007 and January 2012. For comparison, major crude oil (CO) of HSOS, or its weathered form were assessed. Both raw extracts (REs) and their fractionated samples were tested using H295R and MVLNluc bioassays. In H295R cells, REs of crude and weathered oil (WO), and nine of 14 sediments significantly increased E2 levels, which were correlated with the concentrations of PAHs. Steroidogenic disruption potentials of the sediments generally decreased over time. Among silica fractions of all REs, aromatic hydrocarbons (F2) and polar compounds (F3) caused greater E2 levels. While, in MVLN cell bioassay, only three of 14 sediment REs showed estrogen receptor binding potencies, and no temporal trend was observed. In conclusion, oil spill can cause endocrine disruption in the affected ecosystem through steroidogenic alteration for years, and such potencies attenuate over time.

Ras oncogene and Hypoxia-inducible factor-1 alpha (hif-1α) expression in the Amazon fish Colossoma macropomum (Cuvier, 1818) exposed to benzo[a]pyrene

Benzo[a]pyrene (B[a]P) is a petroleum derivative capable of inducing cancer in human and animals. In this work, under laboratory conditions, we analyzed the responses of Colossoma macropomum to B[a]P acute exposure through intraperitoneal injection of four different B[a]P concentrations (4, 8, 16 and 32 μmol/kg) or corn oil (control group). We analyzed expression of the ras oncogene and the Hypoxia-inducible factor-1 alpha (hif-1α) gene using quantitative real-time PCR. Additionally, liver histopathological changes and genotoxic effects were evaluated through the comet assay. Ras oncogene was overexpressed in fish exposed to 4, 8 of 16 μmol/kg B[a]P, showing 4.96, 7.10 and 6.78-fold increases, respectively. Overexpression also occurred in hif-1α in fish injected with 4 and 8 μmol/kg B[a]P, showing 8.82 and 4.64-fold increases, respectively. Histopathological damage in fish liver was classified as irreparable in fish exposed to 8, 16 and 32 μmol/kg μM B[a]P. The genotoxic damage increased in fish injected with 8 and 16 μmol/kg in comparison with the control group. Acute exposure of B[a]P was capable to interrupt the expression of ras oncogene and hif-1α, and increase DNA breaks due to tissue damage.

Human health and ecological assessment programs for Hebei Spirit oil spill accident of 2007: Status, lessons, and future challenges

Hebei Spirit oil spill (HSOS) of December 2007 is one of the worst oil spill accidents that occurred in Yellow Sea. The affected coastline along the west coast of Korean Peninsula hosts one of the largest tidal flats worldwide, and is home to tens of thousands of human residents. Based on nation-wide concerns on ecosystem damages and adverse human health effects, two separate surveillance programs on ecosystem and human health were initiated: a 10-year follow-up program by Ministry of Oceans and Fisheries to assess ecological impacts of the oil spill, and an exposure and health effect assessment program by Ministry of Environment for the residents of Taean and its vicinity. For the past eight years, extensive monitoring and surveillance data on ecosystem and humans have been accumulated through these programs. But these studies have been conducted mostly independently, and collaborations were seldom made between two programs. The lack of communication resulted in gaps and overlaps between the programs which led to loss of critical information and efficiency. As oil spill can affect both humans and ecosystem through various pathways, collaboration and communication between human and ecosystem health surveillance programs are necessary, and will synergize the success of both programs. Such concerted efforts will provide better platform for understanding the status of impact, and for developing approaches to address human and ecosystem health challenges that may be faced following environmental disasters like HSOS.

Searching for novel modes of toxic actions of oil spill using E. coli live cell array reporter system - A Hebei Spirit oil spill study

Oil is a complex mixture of numerous compounds. Therefore, oil spills near shore can cause various adverse effects on coastal ecosystems. However, most toxicological assessments conducted on oil spill sites have focused on limited modes of toxic actions. In the present study, we utilized the Escherichia coli (E. coli) live cell array system (LCA) to identify novel modes of toxicities of the oil spill-affected sediments. For this purpose, sediment samples were collected from an area heavily polluted by Hebei Spirit oil spill (HSOS) incident of 2007. A total of 93 E. coli reporter genes were used to study responses to the chemicals in the mixture. E. coli K12 strains were exposed to extracts of oil or the sediment, and changes in gene expression were measured. Exposure to extracts of crude and weathered oil resulted in decreased expression in ∼30% of tested genes. However, changes in expression observed after exposure to sediment extracts varied. Sediment extracts containing large concentrations of polycyclic aromatic hydrocarbons (PAH) caused down-regulation of >70% of the genes, while extracts containing lesser total concentrations of PAHs exhibited different trends: genes involved in drug resistance were generally up-regulated, while genes responsive to DNA damage were up-regulated in only two extracts. Results suggest that oil pollution can modulate several toxic response pathways related to DNA repair and antibiotic responses. Results from LCA obtained from the sediment and oil samples were different from those observed in the H4IIE-luc assay. Toxicological implications of such observations deserve further examination. Overall, LCA is a promising tool for screening samples and identifying potential modes of toxicities of environmental samples associated with oil spills.

Identification of genotoxic compounds in crude oil using fractionation according to distillation, polarity and Kow

We examined the degree of DNA damage caused by fractions of crude oil in accordance with the boiling points, polarity and log K_ow. Relatively high DNA damage was observed in the aromatic fraction (290-330°C) and resin and polar fraction (350-400°C). The resin and polar fraction showed relatively high genotoxicity compared with the aliphatic and aromatic fraction at the 1-4 log K_ow range. At the 6-7 log K_ow range, the aromatic fraction showed relatively high DNA damage compared with the aliphatic and resin and polar fraction. In particular, every detailed fraction in accordance with the log K_ow values (aliphatic and aromatic (310-320°C) and resins and polar fractions (370-380°C)) showed one or less than one DNA damage. However, the fractions before separation in accordance with log K_ow values (aliphatic and aromatic (310-320°C) and resin and polar (370-380°C) fractions) showed high DNA damage. Thus, we confirm the synergistic action between the detailed compounds.