Introduction
One of the largest marine oil spills in history occurred on 20 April 2010 in the Gulf of Mexico. The tragedy was caused by an explosion on the Deepwater Horizon offshore oil platform. The process of capping the oil well took 87 days; it is estimated that 4.1 million barrels of oil were spilled into the Gulf of Mexico as a result (Reddy et al., 2012). In an attempt to remove the oil from water, approximately 4 million liters of chemical dispersant were used over the area of 300 square miles of the oiled water surface; another 2.9 million liters were used on the leaking wellhead (Barron, 2011). The usage of dispersant resulted in severe consequences for both the local population and the fauna and flora of the Gulf of Mexico (Goodbody-Gringley et al., 2013); after five years have passed, the aftermath is still present (CBC News, 2015).
Environmental Risks
The Crux of the Problem and Related Risks
The largest oil spill in history caused unseen pollution of the waters, posing significant risks to both marine and land life. The chemical dispersant Corexit 9500 was used in order to hasten the sinking of the oil on the seabed to protect the beaches and wetlands from the spill. Corexit 9500 consists of organic sulfonic acid salt, glycol ether, oxyalkylate polymers, aliphatic hydrocarbons, and substituted fatty ester. Today, the dispersant is considered to be toxic by itself; retrospectively, it is estimated that it is much more toxic than oil on its own (Almeda, Hyatt, & Buskey, 2014). Combining it with oil leads to an even higher level of toxicity, which can cause even more severe consequences for both marine life and terrestrial creatures (Almeda, Bona, Foster, & Buskey, 2014).
The Toxicity of Corexit 9500
The chemical is toxic to many species. In humans and terrestrial mammals, the exposure to Corexit 9500 causes a rise in epithelial monolayer permeability, which suggests severe lung injury (Li et al., 2015). It also induces cell apoptosis in gills of aquatic species such as zebrafish and blue crabs (Li et al., 2015). Moreover, it has severe effects on benthic invertebrates, causing harm to meroplanktonic larvae, nauplii of the barnacle Amphibalanus and tornaria larvae of the enteropneust Schizocardium sp. suffer from decreased growth rate after exposure to Corexit 9500 and dispersed crude oil (Almeda et al., 2014). Goodbody-Gringley et al. (2013) also found that Corexit 9500 reduces the settlement and survival rates of Porites astreoides and Montastraea faveolata larvae, species which are responsible for coral reefs restoration.
Concerns regarding exposure to humans, other organisms, and the environment
The humans exposed to the concentrations of Corexit 9500 currently present in the contaminated waters suffer from various disorders. Inhaling the spray results in long-lasting respiratory tract damage, possibly harming the respiratory epithelium and causing the obstruction of airways; this also worsens the existing respiratory diseases, e.g., asthma (Li et al., 2015). Exposed human skin develops various diseases (CBC News, 2015). Consuming contaminated fish and other sea species leads to the accumulation of toxins in the organism, which might cause morphological and phenotypical changes (Li et al., 2015). The above mentioned adverse influence on the growth rate of benthic invertebrates may also lead to broken food chains and cause a negative impact on a major part of marine life (Almeda et al., 2014). The decreased survival and settlement rates of coral larvae are likely to lead to coral reefs deterioration, which will prove lethal to numerous species inhabiting them (Goodbody-Gringley et al., 2013).
The risk to humans, other organisms, and the environment
The oil spill caused severe damage to the environment. The use of dispersants leads to faster oil dispersion and its quicker sinking to the water, but an adverse effect of Corexit 9500 use was the deeper penetration of the seabed and the Gulf Coast beaches by oil (Gayle, 2012). The deterioration of coral reefs caused by the decreased numbers of coral larvae poisoned by Corexit 9500 is likely to lead to the degradation of the fishing industry. Besides, the consumption of contaminated species leads to various adverse health conditions in humans, land, and sea animals. The local population, industries, and businesses have already suffered severe outcomes of the tragedy (CBC News, 2015).
Conclusion
As it was possible to see, the use of oil dispersant Corexit 9500 can cause dire consequences to humans, marine and land species, and the environment. Fortunately, the utilization of Corexit 9500 produced a powerful media response; the U.S. Environmental Protection Agency was sued for allowing the use of this chemical to fight the consequences of the Deepwater Horizon oil spill (Matthews, 2012). It had been already forbidden at the time of the spill in a number of countries; the disaster led to mass social campaigns demanding to prohibit its use anywhere. We were not able to find any reports on Corexit 9500 utilization after the BP oil spill. However, there are some initiatives to make it legal; in particular, such initiatives exist in the Canadian government (De Souza, 2015). Hopefully, the severe consequences of the chemical usage discovered by scientists will persuade the governments to use safer substances in case of future disasters.
References
Almeda, R., Bona, S., Foster, C. R., & Buskey, E. J. (2014). Dispersant Corexit 9500A and chemically dispersed crude oil decreases the growth rates of meroplanktonic barnacle nauplii (Amphibalanus improvisus) and tornaria larvae (Schizocardium sp.). Marine Environmental Research, 99, 212-217. Web.
Almeda, R., Hyatt, C., & Buskey, E. J. (2014). Toxicity of dispersant Corexit 9500A and crude oil to marine microzooplankton. Ecotoxicology and Environmental Safety, 106, 76-85. Web.
Barron, M. G. (2011). Ecological impacts of the Deepwater Horizon oil spill: Implications for immunotoxicity. Toxicologic Pathology, 40(2), 315-320. Web.
CBC News. (2015). BP Deepwater Horizon oil spill, 5 years later. Web.
De Souza, M. (2015). Environmentalists urge Canada not to approve oil spill solvent. Web.
Gayle, D. (2012). How attempts to clear up the Deepwater Horizon spill may have made it worse: Dispersant chemicals ‘made oil penetrate Gulf Coast beaches more deeply’. Web.
Goodbody-Gringley, G., Wetzel, D. L., Gillon, D., Pulster, E., Miller, A., & Ritchie, K. B. (2013). Toxicity of Deepwater Horizon source oil and the chemical dispersant, Corexit 9500, to coral larvae.PLOS One, 8(1), 1-10. Web.
Li, F. J., Duggal, R. N., Oliva, O. M., Karki, S., Surolia, R., Wang, Z.,…Antony, V. B. (2015). Heme oxygenase-1 protects Corexit 9500A-induced respiratory epithelial injury across species.PLOS One, 10(4), 1-23. Web.
Matthews, M. (2012). EPA sued over dispersants used in BP oil spill. Web.
Reddy, C., Arey, J., Seewald, J., Sylva, S., Lemkau, K., Nelson, R.,…Camilli, R. (2012). Composition and fate of gas and oil released to the water column during the Deepwater Horizon oil spill. Proceedings of the National Academy of Sciences of the United States of America, 109(50), 20229-20234.