Lung epithelial cell death induced by oil-dispersant mixtures

Investigation into the oil removal from sand using a surface washing agent under different environmental conditions

Spilled oil frequently reaches the shorelines and affects coastal biota and communities. The application of surface washing agents is an important shoreline cleanup technique that can help remove stranded oil from substrate surfaces with the advantages of high removal efficiency, low toxicity, and strong economic viability. In this study, the investigation into the oil removal from contaminated sand using a surface washing agent under variable environmental conditions was conducted. A preliminary test was conducted to obtain the optimal combination of operating factors of surface washing agent-to-oil ratio (SOR) 2:1, mixing speed 150 rpm, and mixing time 30 min. The results of single-factor experiments showed that high temperature and humic acid concentration of flush water contributed to the performance of a surface washing agent, while salinity and kaolinite concentration could inhibit its performance. The factorial analysis revealed the main effects of temperature and salinity, and the interactive effects of temperature and salinity as well as salinity and humic acid concentration that were significant to the washing efficiency of the surface washing agent. In addition, the comprehensive assessment of a surface washing agent from the aspects of toxicity, detergency, dispersion properties, and field trials was conducted. The results have significant implications for future application of surface washing agents in the shoreline cleanup.

Chemically dispersed oil is cytotoxic and genotoxic to sperm whale skin cells

Two major oil crises in United States history, the 1989 Exxon-Valdez oil spill in Alaska and the 2010 Deepwater Horizon Oil Rig explosion in the Gulf of Mexico, drew attention to the need for toxicological experiments on oil and chemically dispersed oil. We are still learning the effects these spills had on wildlife. However, little data is known about the toxicity of these substances in marine mammals. The objective of this study is to determine the toxicity of Alaskan oil, as well as chemically dispersed oil. Oil experiments were performed using the water accommodated fraction of Alaskan oil (WAF) and the chemically enhanced water accommodated fraction of Alaskan oil (CEWAF). The Alaskan WAF is not cytotoxic to sperm whale skin cells though it did induce chromosome damage; S9-mediated metabolism did not affect the cytotoxicity of WAF but did increase the levels of chromosome damage. Alaskan CEWAF is more cytotoxic and genotoxic than the WAF; S9 mediated metabolism increased both cytotoxicity and genotoxicity of CEWAF. Analysis of the PAH content of Alaskan WAF and CEWAF revealed a forty-fold increase in the total levels of PAHs in CEWAF compared to WAF. These findings show that chemically dispersed oil leads to higher levels of PAH exposure which are more toxic and likely to lead to longer and more persistent health effects.

The deepwater horizon oil spill coast guard cohort study: A cross-sectional study of acute respiratory health symptoms

INTRODUCTION

Over 8500 United States Coast Guard (USCG) personnel were deployed in response to the Deepwater Horizon (DWH) oil spill; however, human respiratory effects as a result of spill-related exposures are relatively unknown.

METHODS

USCG personnel who responded to the DWH oil spill were queried via survey on exposures to crude oil and oil dispersant, and acute respiratory symptoms experienced during deployment. Adjusted log binomial regressions were used to calculate prevalence ratios (PRs) and 95% confidence intervals (CI), investigating the associations between oil spill exposures and respiratory symptoms.

RESULTS

4855 USCG personnel completed the survey. More than half (54.6%) and almost one-fourth (22.0%) of responders were exposed to crude oil and oil dispersants, respectively. Coughing was the most prevalent symptom (19.4%), followed by shortness of breath (5.5%), and wheezing (3.6%). Adjusted analyses showed an exposure-response relationship between increasing deployment duration and likelihood of coughing, shortness of breath, and wheezing in the pre-capping period. A similar pattern was observed in the post-capping period for coughing and wheezing. Adjusted analyses revealed increased PRs for coughing (PR=1.92), shortness of breath (PR=2.60), and wheezing (PR=2.68) for any oil exposure. Increasing frequency of inhalation of oil was associated with increased likelihood of all three respiratory symptoms. A similar pattern was observed for contact with oil dispersants for coughing and shortness of breath. The combination of both oil and oil dispersants presented associations that were much greater in magnitude than oil alone for coughing (PR=2.72), shortness of breath (PR=4.65), and wheezing (PR=5.06).

CONCLUSIONS

Results from the present study suggested strong relationships between oil and oil dispersant exposures and acute respiratory symptoms among disaster responders. Future prospective studies will be needed to confirm these findings.

Ophthalmic effects of petroleum dispersant exposure on common murres (Uria aalge): An experimental study

The safety of chemical dispersants used during oil spill responses is largely unknown in birds. We captured common murres in Monterey Bay, CA and exposed them to Corexit EC9500a, crude oil, or a combination in artificial seawater. We performed ophthalmic examinations and measured intraocular pressures and tear production before and after exposure. Loglinear analysis found that exposure to oil or dispersant was related to the development of conjunctivitis and corneal ulcers. Odds ratios for birds exposed to oil or dispersant were positive and significant for the development of conjunctivitis, while odds ratios for the development of corneal ulcers were positive and significant only for birds exposed to a high concentration of oil. Ocular exposure to dispersants and petroleum in seabirds may cause conjunctivitis and may play a role in the development of corneal ulcers. These results have implications for policymakers who develop protocols for the use of dispersants during marine oil spills.

Corexit-EC9527A Disrupts Retinol Signaling and Neuronal Differentiation in P19 Embryonal Pluripotent Cells

Corexit-EC9500A and Corexit-EC9527A are two chemical dispersants that have been used to remediate the impact of the 2010 Deepwater Horizon oil spill. Both dispersants are composed primarily of organic solvents and surfactants and act by emulsifying the crude oil to facilitate biodegradation. The potential adverse effect of the Corexit chemicals on mammalian embryonic development remains largely unknown. Retinol (vitamin A) signaling, mediated by all-trans retinoic acid (RA), is essential for neural tube formation and the development of many organs in the embryo. The physiological levels of RA in cells and tissues are maintained by the retinol signaling pathway (RSP), which controls the biosynthesis of RA from dietary retinol and the catabolism of RA to polar metabolites for removal. RA is a potent activating ligand for the RAR/RXR nuclear receptors. Through RA and the receptors, the RSP modulates the expression of many developmental genes; interference with the RSP is potentially teratogenic. In this study the mouse P19 embryonal pluripotent cell, which contains a functional RSP, was used to evaluate the effects of the Corexit dispersants on retinol signaling and associated neuronal differentiation. The results showed that Corexit-EC9500A was more cytotoxic than Corexit-EC9527A to P19 cells. At non-cytotoxic doses, Corexit-EC9527A inhibited retinol-induced expression of the Hoxa1 gene, which encodes a transcription factor for the regulation of body patterning in the embryo. Such inhibition was seen in the retinol- and retinal- induced, but not RA-induced, Hoxa1 up-regulation, indicating that the Corexit chemicals primarily inhibit RA biosynthesis from retinal. In addition, Corexit-EC9527A suppressed retinol-induced P19 cell differentiation into neuronal cells, indicating potential neurotoxic effect of the chemicals under the tested conditions. The surfactant ingredient, dioctyl sodium sulfosuccinate (DOSS), may be a major contributor to the observed effect of Corexit-EC9527A in the cell.

Effects of corexit oil dispersants and the WAF of dispersed oil on DNA damage and repair in cultured human bronchial airway cells, BEAS-2B

Large quantities of dispersants were used as a method to disperse the roughly 210 million gallons of spilled crude oil that consumed the Gulf of Mexico. Little is known if the oil-dispersant and oil-dispersant mixtures on human airway BEAS-2B epithelial cells. Here we present the cytotoxic and genotoxic in vitro effects on the human lung cells BEAS-2B following exposure to and oil-dispersant mixtures on human airway BEAS-2B epithelial cells. Here we present the cytotoxic and genotoxic in vitro effects on the human lung cells BEAS-2B following exposure to Corexit dispersants EC9500 and EC9527, Water Accommodated Fraction (WAF) -crude, WAF-9500 + Oil, and WAF-9527 + Oil. Cellular cytotoxicity to WAF-dispersed oil samples was observed at concentrations greater than 1000 ppm with over 70% of observed cellular death. At low concentration exposures (100 and 300 ppm) DNA damage was evidenced by the detection of single strand breaks (SSBs) and double strand breaks (DSBs) as measured by alkaline and neutral comet assay analyses. Immunoblot analyses of the phosphorylated histone H2A.X (ɣ-H2A.X) and tumor suppressor p53 protein confirmed activation of the DNA damage response due to the exposure-induced DNA breaks. Although, many xenobiotics interfere with DNA repair pathways, in vitro evaluation of the nucleotide excision repair (NER) and DSB repair pathways appear to be unaffected by the oil-dispersant mixtures tested. Overall, this study supports that oil-dispersant mixtures induce genotoxic effects in culture.

Evaluation of Pulmonary and Systemic Toxicity of Oil Dispersant (COREXIT EC9500A(®)) Following Acute Repeated Inhalation Exposure

INTRODUCTION

Oil spill cleanup workers come into contact with numerous potentially hazardous chemicals derived from the oil spills, as well as chemicals applied for mitigation of the spill, including oil dispersants. In response to the Deepwater Horizon Macondo well oil spill in the Gulf of Mexico in 2010, a record volume of the oil dispersant, COREXIT EC9500A, was delivered via aerial applications, raising concern regarding potential health effects that may result from pulmonary exposure to the dispersant.

METHODS

The current study examined the effects on pulmonary functions, cardiovascular functions, and systemic immune responses in rats to acute repeated inhalation exposure of COREXIT EC9500A at 25 mg/m(3), five hours per day, over nine work days, or filtered air (control). At one and seven days following the last exposure, a battery of parameters was measured to evaluate lung function, injury, and inflammation; cardiovascular function; peripheral vascular responses; and systemic immune responses.

RESULTS

No significant alterations in airway reactivity were observed at one or seven days after exposure either in baseline values or following methacholine (MCh) inhalation challenge. Although there was a trend for an increase in lung neutrophils and phagocyte oxidant production at one-day post exposure, there were no significant differences in parameters of lung inflammation. In addition, increased blood monocytes and neutrophils, and decreased lymphocyte numbers at one-day post exposure also did not differ significantly from air controls, and no alterations in splenocyte populations, or serum or spleen immunoglobulin M (IgM) to antigen were observed. There were no significant differences in peripheral vascular responsiveness to vasoconstrictor and vasodilator agonists or in blood pressure (BP) responses to these agents; however, the baseline heart rate (HR) and HR responses to isoproterenol (ISO) were significantly elevated at one-day post exposure, with resolution by day 7.

CONCLUSIONS

In summary, acute repeated exposure to COREXIT EC9500A did not alter pulmonary function, lung injury/inflammation, systemic immune responses, or vascular tone, but did cause transient chronotropic effects on cardiac function.

Effects of COREXIT dispersants on cytotoxicity parameters in a cultured human bronchial airway cells, BEAS-2B

The objective of this study was to assess the cytotoxicity of COREXIT dispersants EC9500A, EC9527A, and EC9580A on human airway BEAS-2B epithelial cells. Cells were exposed to dispersants for 2 or 24 h at concentrations ranging from 0 to 300 ppm. COREXIT EC9527 at 100 ppm produced 50% viability loss as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) at 24 h. COREXIT 9527 at 200 ppm produced 50% cell death at 2 h and 100% at 24 h. At 300 ppm COREXIT 9527 induced 100% cell death at 2 or 24 h. In the case of COREXIT 9500A 50% cell viability was noted with 200 ppm at 2 or 24 h, with a significant decrease in cell survival to 2% at 300 ppm. In contrast, no marked change in cell viability was observed in cells treated at any COREXIT 9580A concentration examined. Western blot analysis showed an increase in expression of LC3B, a marker of autophagy, in cells treated for 2 h with 300 ppm COREXIT EC9527A as well as 100 or 300 ppm Corexit EC9500A. No marked effect on LC3B expression was observed for any COREXIT 9580A concentration. Apoptosis markers as measured by cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP) were detectable only in cells incubated with 300 ppm COREXIT EC9527A. Although all three dispersants induced enhanced generation of reactive oxygen species (ROS) after 2-h treatment at 300 ppm, Western blot analysis revealed that 2-h incubation was not sufficient to induce a significant change in the protein expression of superoxide dismutases SOD1, SOD2, and SOD3. Data thus indicate exposure to certain dispersants may be harmful to human airway epithelial cells in a concentration-dependent manner.