Plagiarised from Wikipedia and not inherently villainous anyway. The Deepwater Horizon oil spill (also referred to as the BP oil spill, the BP oil disaster, the Gulf of Mexico oil spill, and the Macondo blowout) was an oil spill in the Gulf of Mexico on the BP-operated Macondo Prospect, considered the largest accidental marine oil spill in the history of the petroleum industry, estimated to be between 8% and 31% larger in volume than the earlier Ixtoc I oil spill. Following the explosion and sinking of the Deepwater Horizon oil rig, which claimed 11 lives,a sea-floor oil gusher flowed unabated for three months in 2010. The gushing wellhead was not capped until after 87 days, on 15 July 2010. The total discharge is estimated at 4.9 million barrels (210 million US gal; 780,000 m3).
A massive response ensued to protect beaches, wetlands, and estuaries from the spreading oil, using skimmer ships, floating boom, controlled burns, and 1.84 million US gallons (7,000 m3) of Corexit oil dispersant. After several failed efforts to contain the flow, the well was capped and declared sealed on 19 September 2010. However, the months of spill, along with response and cleanup activities, caused extensive damage to marine and wildlife habitats and the Gulf's fishing and tourism industries, as well as human health problems. Environmental and health consequences are continuing, with study and investigation ongoing. Some reports indicate the well site may be continuing to leak.
Numerous investigations have explored the causes of the explosion and spill. Notably, the U.S. government's September 2011 report pointed to defective cement work on the well, finding BP most at fault but also faulting Deepwater Horizon operator Transocean and contractor Halliburton. Earlier in 2011, a White House commission likewise blamed BP and its partners for making a series of cost-cutting decisions and not having a system sufficient to ensure well safety, but also concluded that the spill was not an isolated incident caused by "rogue industry or government officials", but resulted from "systemic" root causes and "absent significant reform in both industry practices and government policies, might well recur".
The disaster spawned over 130 private lawsuits as well as civil and criminal federal prosecutions. In November 2012, BP settled the federal case by pleading guilty to 11 counts of manslaughter related to the explosion and fire, and agreeing to pay a record breaking $4.525 billion in fines and other payments.] BP faces other potential enormous payouts to thousands of fishermen, businesses and others harmed by the spill. In November 2012 the EPA announced that BP will be temporarily banned from seeking new contracts with the US government because of the company's "lack of business integrity" during the disaster.
The Deepwater Horizon was a 9-year-old semi-submersible, mobile, floating, dynamically positioned drilling rig that could operate in waters up to 10,000 feet (3,000 m) deep. Built by South Korean company Hyundai Heavy Industries and owned by Transocean, the rig operated under the Marshallese flag of convenience, and was chartered to BP from March 2008 to September 2013. It was drilling a 35,050 feet (10,680 m) deep exploratory well in approximately 5,100 feet (1,600 m) of water. The well is situated in the Macondo Prospect in Mississippi Canyon Block 252 (MC252) of the Gulf of Mexico, in the United States' exclusive economic zone. The Macondo well is located roughly 41 miles (66 km) off the Louisiana coast. BP was the operator and principal developer of the Macondo Prospect with a 65% share, while 25% was owned by Anadarko Petroleum Corporation, and 10% by MOEX Offshore 2007, a unit of Mitsui.
At approximately 9:45 pm CDT, on 20 April 2010, high-pressure methane gas from the well expanded into the drilling riser and rose into the drilling rig, where it ignited and exploded, engulfing the platform. At the time, 126 crew members were on board: seven BP employees, 79 of Transocean and employees of various other companies. Eleven workers were never found despite a three-day Coast Guard (USCG) search operation and are believed to have died in the explosion. Ninety-four crew were rescued by lifeboat or helicopter, 17 of whom were treated for injuries.
Volume and extent of oil spill
Main article: Volume and extent of the Deepwater Horizon oil spillSee also: Timeline of the Deepwater Horizon oil spillAn oil leak was discovered on the afternoon of 22 April when a large oil slick began to spread at the former rig site. While originally BP authorities gave their best estimate of a flow rate of 1,000 to 5,000 barrels per day (160 to 790 m3/d), according to the Flow Rate Technical Group, (FRTG) 62,000 barrels per day (9,900 m3/d) was a more realistic figure. The total estimated volume of leaked oil approximated 4.9 million barrels (210,000,000 US gal; 780,000 m3) with plus or minus 10% uncertainty. This makes it the largest accidental oil spill in history. BP challenges this figure, saying that the government overestimated the volume; however, emails released in 2013 show that BP's internal estimates matched those of FRTG. BP also argues that government figures do not reflect over 810,000 barrels (34 million US gal; 129,000 m3) of oil that was collected or burned before it could enter the Gulf waters.
According to the satellite images, the spill directly impacted 68,000 square miles (180,000 km2) of ocean which is comparable to the size of Oklahoma. By early June 2010, oil had washed up on 125 miles (201 km) of Louisiana's coast and along Mississippi, Florida, and Alabama barrier island coastlines. Oil sludge appeared in the Intracoastal Waterway and on Pensacola Beach and the Gulf Islands National Seashore. In late June, oil reached Gulf Park Estates, its first appearance in Mississippi. In July, tar balls reached Grand Isle and the shores of Lake Pontchartrain. In September a new wave of oil suddenly coated 16 miles (26 km) of Louisiana coastline and marshes west of the Mississippi River in Plaquemines Parish. In October, weathered oil reached Texas. As of July 2011, about 491 miles (790 km) of coastline in Louisiana, Mississippi, Alabama and Florida were contaminated by oil and a total of 1,074 miles (1,728 km) had been oiled since the spill began. As of December 2012, 339 miles (546 km) of coastline remain subject to evaluation and/or cleanup operations.
Concerns were raised about the appearance of underwater, horizontally-extended plumes of dissolved oil. Researchers concluded that deep plumes of dissolved oil and gas would likely remain confined to the northern Gulf of Mexico and that the peak impact on dissolved oxygen would be delayed and long lasting.
Two weeks after the wellhead was capped on 15 July 2010, the surface oil appeared to have dissipated, while an unknown amount of subsurface oil remained. Estimates of the residual ranged from a 2010 NOAA report that claimed about half of the oil remained below the surface to independent estimates of up to 75%. That means that over 100 million US gallons (2.4 Mbbl) remained in the Gulf. As of January 2011, tar balls, oil sheen trails, fouled wetlands marsh grass and coastal sands were still evident. Subsurface oil remained offshore and in fine silts. In April 2012, oil was still found along as much as 200 miles (320 km) of Louisiana coastline and tar balls continued to wash up on the barrier islands. In 2013, some scientists at the Gulf of Mexico Oil Spill and Ecosystem Science Conference said that as much as one-third of the oil may have mixed with deep ocean sediments, where it risks damage to ecosystems and commercial fisheries.
Efforts to stem the flow of oil
First BP unsuccessfully attempted to close the blowout preventer valves on the wellhead with remotely operated underwater vehicles. Next it placed a 125-tonne (280,000 lb) containment dome over the largest leak and piped the oil to a storage vessel. While this technique had worked in shallower water, it failed here when gas combined with cold water to form methane hydrate crystals that blocked the opening at the top of the dome. Pumping heavy drilling fluids into the blowout preventer to restrict the flow of oil before sealing it permanently with cement ("top kill") also failed.
BP then inserted a riser insertion tube into the pipe and a stopper-like washer around the tube plugged the end of the riser and diverted the flow into the insertion tube. The collected gas was flared and oil stored on the board of drillship Discoverer Enterprise. Before the tube was removed, it collected 924,000 US gallons (22,000 bbl; 3,500 m3) of oil. On 3 June 2010, BP removed the damaged drilling riser from the top of the blowout preventer and covered the pipe by the cap which connected it to another riser. On 16 June a second containment system connected directly to the blowout preventer began carrying oil and gas to service vessels where it was consumed in a clean-burning system. The government's estimates suggested the cap and other equipment were capturing less than half of the leaking oil. On 10 July the containment cap was removed to replace it with a better-fitting cap ("Top Hat Number 10"). Mud and cement were later pumped in through the top of the well to reduce the pressure inside it, completing the temporary measures.
Considerations of using explosives
In mid-May, United States Secretary of Energy Steven Chu assembled a team of nuclear physicists, including hydrogen bomb designer Richard Garwin and Sandia National Laboratories director Tom Hunter. Oil expert Matthew Simmons maintained that a nuclear explosion was the only way BP could permanently seal the well and cited successful Soviet attempts to seal off runaway gas wells with nuclear blasts. A spokesperson for the US Energy Department said that "neither Energy Secretary Steven Chu nor anyone else" ever considered this option. On 24 May BP ruled out conventional explosives, claiming that if blasts failed to clog the well, "we would have denied ourselves all other options."
Transocean's Development Driller III started drilling a first relief well on 2 May. GSF Development Driller II started drilling a second relief on 16 May. On 3 August, first test oil and then drilling mud was pumped at a slow rate of approximately 2 barrels (320 L) per minute into the well-head. Pumping continued for eight hours, at the end of which time the well was declared to be "in a static condition." On 4 August, BP began pumping cement from the top, sealing that part of the flow channel permanently.
On 3 September the 300-ton failed blowout preventer was removed from the well and a replacement blowout preventer was installed. On 16 September, the relief well reached its destination and pumping of cement to seal the well began. On 19 September, National Incident Commander Thad Allen declared the well "effectively dead" and said that it posed no further threat to the Gulf.
Recurrent or continued leakage
Oil slicks were reported in March and August 2011, in March and October 2012, and in January 2013. Repeated scientific analyses confirmed that the sheen was a chemical match for oil from Macondo well. The USCG initially said the oil was too dispersed to recover and posed no threat to the coastline, but later warned BP and Transocean that they might be held financially responsible for cleaning up the new oil. USGS director Marcia McNutt stated that the riser pipe could hold at most 1,000 barrels (160 m3) because it is open on both ends, making it unlikely to hold the amount of oil being observed.
In October 2012, BP reported that they had found and plugged leaking oil from the failed containment dome, now abandoned about 1,500 feet (460 m) from the main well. In December 2012, the USCG conducted a subsea survey; no oil coming from the wells or the wreckage was found and its source remains unknown. In addition, white, milky substance was observed seeping from the wreckage. According to BP and the USCG it is "not oil and it's not harmful."
Oceanographer Ian MacDonald said, "It's possible that the wreckage in 2010 somehow opened up a new fault on the seafloor." In May 2010, BP admitted they had "discovered things that were broken in the sub-surface" during the "top kill" effort.
Containment, collection and use of dispersants
The fundamental strategies for addressing the spill were containment, dispersal and removal. In summer 2010, approximately 47,000 people and 7,000 vessels were involved in the project. By 3 October 2012, federal response costs amounted to $850 million, mostly reimbursed by BP. As of January 2013, 935 personnel were still involved. By that time cleanup had cost BP over $14 billion.
It was estimated with plus or minus 10% uncertainty that 4.9 million barrels (780,000 m3) of oil was released from the well; 4.1 million barrels (650×103 m3) of oil went into the Gulf. The report led by the Department of the Interior and the NOAA said that of "75% [of oil] has been cleaned up by Man or Mother Nature", however only about 25% of released oil was collected or removed while about 75% of oil remained in the environment in one form or another. In 2012, Markus Huettel, a benthic ecologist at FSU, maintained that while much of BP's oil was degraded or evaporated, at least 60% remains unaccounted for.
Containment booms stretching over 4,200,000 feet (1,300 km) were deployed, either to corral the oil or as a barrier to protect a marsh, mangrove, shrimp/crab/oyster ranch or other ecologically sensitive area. Booms extend 18–48 inches (0.46–1.2 m) above and below the water surface and were effective only in relatively calm and slow-moving waters. Including one-time use sorbent booms, a total of 13,300,000 feet (4,100 km) of booms were deployed. Booms were criticized for washing up on the shore with the oil, allowing oil to escape above or below the boom and for ineffectiveness in more than three to four foot waves.
The Louisiana barrier island plan was developed to construct barrier islands to protect the coast of Louisiana. The plan was criticised for its expense and poor results. Critics allege that the decision to pursue the project was political with little scientific input. The EPA expressed concern that the berms would threaten wildlife.
The spill was also notable for the volume of Corexit oil dispersant used and for application methods that were "purely experimental". Altogether, 1.84 million US gallons (7,000 m3) of dispersants were used; of this 771,000 US gallons (2,920 m3) were released at the wellhead. Subsea injection had never previously been tried but due to the spill's unprecedented nature BP together with USCG and EPA decided to use it. Over 400 sorties were flown to release the product. Although usage of dispersants was described as "the most effective and fast moving tool for minimizing shoreline impact", the approach continues to be investigated.
A 2011 analysis conducted by Earthjustice and Toxipedia showed that the dispersant could contain cancer-causing agents, hazardous toxins and endocrine-disrupting chemicals. Environmental scientists expressed concerns that the dispersants add to the toxicity of a spill, increasing the threat to sea turtles and bluefin tuna. The dangers are even greater when poured into the source of a spill, because they are picked up by the current and wash through the Gulf. According to BP and federal officials dispersant use stopped after the cap was in place; however, marine toxicologist Riki Ott claimed that dispersant use continued after that date.
Corexit EC9500A and Corexit EC9527A were the principal variants. The two formulations are neither the least toxic, nor the most effective, among EPA's approved dispersants but BP said it chose to use Corexit because it was available the week of the rig explosion. On 19 May, the EPA gave BP 24 hours to choose less toxic alternatives to Corexit from the National Contingency Plan Product Schedule and begin applying them within 72 hours of EPA approval or provide a detailed reasoning why no approved products met the standards. On 20 May, BP determined that none of the alternative products met all three criteria of availability, non-toxicity and effectiveness. On 24 May, EPA Administrator Lisa P. Jackson ordered EPA to conduct its own evaluation of alternatives and ordered BP to reduce dispersant use by 75%. BP reduced Corexit use by 25,689 to 23,250 US gallons (97,240 to 88,000 l; 21,391 to 19,360 imp gal) per day, a 9% decline. On 2 August 2010, the EPA said dispersants did no more harm to the environment than the oil itself and that they stopped a large amount of oil from reaching the coast by breaking it down faster. However, some independent scientists and EPA's own experts continue to voice concerns about the approach.
Underwater injection of Corexit into the leak may have created the oil plumes discovered below the surface. Because the dispersants were applied at depth, much of the oil never rose to the surface. One plume was 22 miles (35 km) long, more than a mile wide and 650 feet (200 m) tall. In a major study on the plume, experts found the most worrisome part to be the slow pace at which the oil was breaking down in the cold, 40 °F (4 °C) water at depths of 3,000 feet (910 m).
The three basic approaches for removing the oil from the water were: combustion, offshore filtration, and collection for later processing. USCG said 33 million US gallons (120,000 m3) of tainted water was recovered, including 5 million US gallons (19,000 m3) of oil. BP said 826,800 barrels (131,450 m3) had been recovered or flared. It is calculated that about 5% of leaked oil was burned at the surface and 3% was skimmed. On the most demanding day 47,849 people were assigned on the response works.
From April to mid-July 2010 411 controlled in-situ fires remediated approximately 265,000 barrels (11,100,000 US gal; 42,100 m3). The fires released small amounts of toxins, including cancer-causing dioxins. According to EPA's report the released amount is not enough to pose an added cancer risk to workers and coastal residents, while a second research team concluded that there was only a small added risk.
Oil was collected from water by using skimmers. In total 2,063 various skimmers were used. For offshore, more than 60 open-water skimmers were deployed, including 12 purpose-built vehicles. EPA regulations prohibited skimmers that left more than 15 parts per million (ppm) of oil in the water. Many large-scale skimmers exceeded the limit. Due to use of Corexit the oil was too dispersed to collect, according to a spokesperson for shipowner TMT. In mid June 2010, BP ordered 32 machines that separate oil and water, with each machine capable of extracting up to 2,000 barrels per day (320 m3/d). After one week of testing, BP began to proceed and by 28 June, had removed 890,000 barrels (141,000 m3).
After the well was captured, the cleanup of shore became the main task of the response works. Two main type of affected coast were sandy beaches and marshes. On beaches the main techniques were sifting sand, removing tar balls and digging out tar mats manually or by using mechanical devices. For marshes techniques like vacuum and pumping, low-pressure flush, vegetation cutting, and bioremediation were used.
Dispersants are said to facilitate the digestion of the oil by microbes. Mixing dispersants with oil at the wellhead would keep some oil below the surface and in theory, allow microbes to digest the oil before it reached the surface. Various risks were identified and evaluated, in particular that an increase in microbial activity might reduce subsea oxygen levels, threatening fish and other animals.
Several studies suggest that microbes successfully consumed part of the oil. By mid-September, other research claimed that microbes mainly digested natural gas rather than oil. David L. Valentine, a professor of microbial geochemistry at UC Santa Barbara, said that their oil-gobbling properties had been grossly overstated.
Some experts suggested that the bacteria may have caused health issues for Gulf residents, such as an outbreak of skin rashes. Genetically modified Alcanivorax borkumensis was added to the waters to speed digestion.
The first video images were released May 12, and further video images were released by members of Congress who had been given access to them by BP.
During the spill response operations, the Federal Aviation Administration (FAA) implemented was by a request of the Coast Guard a 900-square-mile (2,300 km2) temporary flight restriction zone over the operations area. Restrictions were explained by necessity to prevent civilian air traffic from interfering with aircraft assisting the response effort. All flights in the operations' area were prohibited except, except flight authorized by air traffic control, routine flights supporting offshore oil operations, federal, state, local and military flight operations supporting spill response, and air ambulance and law enforcement operations. Exceptions for these restrictions were granted on a case-by-case basis dependent safety issues, operational requirements, weather conditions, and traffic volume. No flights, except aircraft conducting aerial chemical dispersing operations, or for landing and takeoff, were allowed below 1,000 metres (3,300 ft). Notwithstanding restrictions, there were 800 to 1,000 flights per day during the operations.
Local and federal authorities citing BP's authority denied access to members of the press attempting to document the spill from the air, from boats, and on the ground, even blocking access to areas that were open to the public. In some cases photographers were granted access only with BP officials escorting them on BP-contracted boats and aircraft. In one example, the U.S. Coast Guard stopped Jean-Michel Cousteau's boat and allowed it to proceed only after the Coast Guard was assured that no journalists were present onboard. In another example, a CBS News crew was denied access to the oil-covered beaches of the spill area. The CBS crew was told by the authorities: "this is BP's rules, not ours," when trying to film the area.  Some members of Congress were also critical of the restrictions placed on access by journalists.
The FAA denied that BP employees or contractors took decision for access saying that those decision were made by the FAA and Coast Guard. The FAA acknowledge that media access was limited by hired planes or helicopters, but was arranged through the Coast Guard. The Coast Guard and BP denied having a policy of restricting journalists and noted that members of the media had been embedded with the authorities and allowed thus to cover response efforts since the beginning of the response, with more than 400 embeds aboard boats and aircraft to date. They also claimed that they wanted to provide access to the information while maintaining safety.
The greatest impact was on marine species. The spill area hosted 8,332 species, including more than 1,200 fish, 200 birds, 1,400 molluscs, 1,500 crustaceans, 4 sea turtles and 29 marine mammals. In addition to the 14 species under federal protection, the spill threatened 39 more ranging from "whale sharks to seagrass". Damage to the ocean floor especially endangered the Louisiana pancake batfish whose range is entirely contained within the spill-affected area. The oil contained approximately 40% methane by weight, compared to about 5% found in typical oil deposits. Methane can potentially suffocate marine life and create "dead zones" where oxygen is depleted. During a January 2013 flyover, former NASA physicist Bonny Schumaker noted a "dearth of marine life" in a radius 30 to 50 miles (48 to 80 km) around the well. In March 2012, a definitive link was found between the death of a Gulf coral community and the spill.
The spill waters contained 40 times more Polycyclic aromatic hydrocarbons (PAH) than before the spill. PAH is often linked to oil spills and includes carcinogens and chemicals that pose various human health risks. The PAHs were most concentrated near the Louisiana Coast, but levels also jumped 2-3 fold in areas off Alabama, Mississippi and Florida. PAHs can harm marine species directly and microbes used to consume the oil would reduce marine oxygen levels. Estimates state that only 2% of the carcasses of killed mammals were recovered. In the first birthing season for dolphins after the spill, dead baby dolphins washed up along Mississippi and Alabama shorelines at about 10 times the normal number. Oil was discovered on dead dolphins along the Gulf Coast. Fifteen of the 406 dolphins that washed ashore in the first 14 months had oil on their bodies; the oil found on eight was linked to the spill. A NOAA/BP study in the summer of 2011 found that "many of the 32 dolphins studied were underweight, anemic and suffering from lung and liver disease, while nearly half had low levels of a hormone that helps the mammals deal with stress as well as regulating their metabolism and immune systems". Other conditions included drastically low weight and low blood sugar.
The oil and dispersant mixture, including PAHs, permeated the food chain through zooplankton. Signs of an oil-and-dispersant mix were found under the shells of tiny blue crab larvae. The use of dispersant made oil sink faster and more deeply into beaches, and possibly groundwater supplies. Corexit allowed the PAHs to permeate sand where, due to a lack of sunlight, degradation is slowed. Some types of spiders and other insects became far less numerous. Migratory birds carried chemicals from the spill as far as Minnesota. The vast majority of a small sample of Pelican eggs tested contained "petroleum compounds and Corexit".
In the summer of 2010, scientists reported immense underwater plumes of dissolved oil in addition to an 80-square-mile (210 km2) "kill zone" surrounding the blown well. Fish with oozing sores and lesions were first noted by fishermen in November 2010. Dispersant and PAHs from oil are believed to have caused "disturbing numbers" of mutated fish that scientists and commercial fishers began seeing in 2012, including 50% of shrimp found lacking eyes and eye sockets. Prior to the spill, approximately 1/10 of 1% of Gulf fish had lesions or sores. A report from the University of Florida said that many locations showed 20% of fish with lesions, while later estimates reach 50%. NOAA stated that dolphins and whales were dying at twice the normal rate in 2011. Scientists in 2012 reported finding "alarming numbers" of mutated crab, shrimp and fish resulting from chemicals released during the spill.
Environmental impacts continue, and research is ongoing. Two years after the spill began, tar balls continued to wash up along the Gulf coast. After Hurricane Issac hit the Gulf in September 2012, about 565,000 pounds (256,000 kg) of oiled material traced to the spill was brought to land. Huge tar mats were uncovered during the storm, prompting beach closures. In 2013, researchers found that oil on the bottom of the seafloor does not seem to be degrading, and observed a phenomenon called "dirty blizzard": oil caused deep ocean sediments to clump together, falling to the ocean floor at ten times the normal rate in an "underwater rain of oily particles." The result could have long-term effects on both human and marine life because oil could remain in the food chain for generations. The same research suggested that as much as one-third of the oil remains in the Gulf.
By 21 June, 143 spill exposure cases had been reported to the Louisiana Department of Health and Hospitals (DHH); 108 of those cases involved workers in the clean-up efforts, while 35 were reported by gulf residents. Chemicals from the oil and dispersant are believed to be the cause of these illnesses as the addition of dispersants created an even more toxic substance (PAHs) when mixed with crude oil. Mike Robicheux, a Louisiana physician who has been treating people sick from exposure to toxic chemicals, described it as the biggest public health crisis from a chemical poisoning in the history of this country" In addition, the increased risk of mental disorders and stress-related health problems were noted shortly after the spill.
A survey of the health effects of the spill on cleanup workers reported "eye, nose and throat irritation; respiratory problems; blood in urine, vomit and rectal bleeding; seizures; nausea and violent vomiting episodes that last for hours; skin irritation, burning and lesions; short-term memory loss and confusion; liver and kidney damage; central nervous system effects and nervous system damage; hypertension; and miscarriages". Dr. James Diaz, writing for the American Journal of Disaster Medicine, said these ailments appearing in the Gulf reflected those reported after previous oil spills, like the Exxon Valdez. Diaz warned that "chronic adverse health effects, including cancers, liver and kidney disease, mental health disorders, birth defects and developmental disorders should be anticipated among sensitive populations and those most heavily exposed". Diaz also believes neurological disorders should be expected.
After testing the blood of BP cleanup workers and residents in Louisiana, Mississippi, Alabama, and Florida for Volatile Organic Compounds (VOC's), found in BP's oil and in Corexit, environmental scientist Wilma Subra says she is "finding amounts 5 to 10 times in excess of the 95th percentile." Subra explains the "presence of these chemicals in the blood indicates exposure." Two years after the spill, a study intitiated by the National Institute for Occupational Safety and Health found biomarkers matching the oil from the spill in the bodies of cleanup workers. Other studies have reported a variety of mental health issues, skin problems, breathing issues, coughing, and headaches. In 2013, during the three-day "Gulf of Mexico Oil Spill & Ecosystem Science Conference", findings discussed included a '"significant percentage" of Gulf residents reporting mental health problems like anxiety, depression and PTSD. These studies also showed that the bodies of former spill cleanup workers carry biomarkers of "many chemicals contained in the oil".
Growing concerns regarding the latent effects of exposure, prompted the National Institute of Health (NIH) to launch a 10 year longitudinal study to track health outcomes associated with the cleanup. The principal goal of the Gulf Long-term Follow up Study (GuLF STUDY) is to identify links between response workers’ physical and mental health symptoms and exposure to oil and dispersants used in the cleanup. Presently, response workers, volunteers and controls not involved in the cleanup are being actively recruited to participate. The case-control study will commence with an initial in-home visit, during which vitals will be recorded and specimens collected. Participants will then be asked to complete subsequent questionnaires every 2 years to track changes in their health. The information collected in this study will provide invaluable insight into the effects of exposures to oil and cleanup dispersants at an unprecedented level. Additionally, the study’s findings may be used to help influence policy decisions on healthcare and health services in the affected region.
However, the interpretation of the outcomes from observational epidemiologic studies, such as the GuLF STUDY, is subject to limitations. First, these study designs do not have rigorous control over external variables that may influence the results; and therefore, they can only provide limited information regarding cause. In fact in a comment to the AFP, BP suggested that many of the health problems suffered by response workers did not deviate significantly from those expected among a workforce of similar size under normal conditions. Another limitation of epidemiologic studies is that it is often difficult to directly measure exposures. For instance, health outcomes for response workers are likely to vary substantially based on the concentration of exposure and method of absorption. Many worked in different areas at different times of the cleanup, so their exposure would have fluctuated making it hard to assign a level of exposure to a particular outcome. Additionally, because exposure pathways differed depending on a worker’s task, establishing an outcome related dose also presents a challenge. Also no initial baseline measures were collected from workers before they were exposed, which makes it difficult to assess the impact of exposure. This isn’t to say there is no value in the information these studies provide, one just needs to exercise prudence in drawing specific conclusions from the results.
Main article: Economic and political consequences of the Deepwater Horizon disasterThe spill had a strong economic impact to BP as also the Gulf Coast's economy sectors such as offshore drilling, fishing and tourism. On BP's expenditures on the spill included the cost of the spill response, containment, relief well drilling, grants to the Gulf states, claims paid, and federal costs, including fines and penalties. As of March 2012, BP estimated the company's total spill-related expenses do not exceed $37.2 billion. However, by some estimations penalties that BP may be required to pay have reached as high as $90 billion. In addition, in November 2012 the EPA announced that BP will be temporarily banned from seeking new contracts with the US government. Due to the loss of the market value, BP had dropped from the second to the fourth largest of the four major oil companies by 2013. During the crisis, BP gas stations in the United States reported sales off between 10 and 40% due to backlash against the company.
Local officials in Louisiana expressed concern that the offshore drilling moratorium imposed in response to the spill would further harm the economies of coastal communities as the oil industry employs about 58,000 Louisiana residents and has created another 260,000 oil-related jobs, accounting for about 17% of all Louisiana jobs. NOAA had closed 86,985 square miles (225,290 km2), or approximately 36% of Federal waters in the Gulf of Mexico, for commercial fishing causing $2.5 billion cost for the fishing industry. The U.S. Travel Association estimated that the economic impact of the oil spill on tourism across the Gulf Coast over a three-year period could exceed approximately $23 billion, in a region that supports over 400,000 travel industry jobs generating $34 billion in revenue annually.
Offshore drilling policies
Main articles: United States offshore drilling debate and 2010 United States deepwater drilling moratoriumSee also: Hornbeck Offshore Services LLC v. SalazarOn 30 April 2010 President Barack Obama ordered the federal government to hold the issuing of new offshore drilling leases and authorized investigation of 29 oil rigs in the Gulf in an effort to determine the cause of the disaster. Later a six-month offshore drilling (below 500 feet (150 m) of water) moratorium was enforced by the United States Department of the Interior. The moratorium suspended work on 33 rigs. On 22 June, a United States federal judge on the United States District Court for the Eastern District of Louisiana Martin Leach-Cross Feldman when ruling in the case Hornbeck Offshore Services LLC v. Salazar, lifted the moratorium finding it too broad, arbitrary and not adequately justified. The ban was lifted in October 2010.
On 28 April 2010, the National Energy Board of Canada, which regulates offshore drilling in the Canadian Arctic and along the British Columbia Coast, issued a letter to oil companies asking them to explain their argument against safety rules which require same-season relief wells. On 3 May California Governor Arnold Schwarzenegger withdrew his support for a proposed plan to allow expanded offshore drilling projects in California. On 8 July, Florida Governor Charlie Crist called for a special session of the state legislature to draft an amendment to the state constitution banning offshore drilling in state waters, which the legislature rejected on 20 July.