GuLF Study Environmental Health Sciences (NIEHS), part of the National Institutes of Health, and aims to recruit 55,000 of the 150,000 workers who volunteered or were employed to help clean up the spill. It is led by Dale Sandler, head of the NIEHS's epidemiology branch. The "Deepwater Horizon" oil spill was the world's largest accidental marine oil spill. It began on 20 April 2010 after an explosion on the "Deepwater Horizon", a drilling rig leased by BP to drill an exploratory well. Between then and 15 July, when the well was capped, over four million barrels of oil (around 170 million US
Reactions to the Deepwater Horizon oil spill of one of the country's leading companies", to President Obama (text of letter) that expressed a concern over "double standards" compared to the sub-prime based banking crisis of 2007–2010 and over "prejudicial and personal" comments in the media. Initially BP downplayed the incident; CEO Tony Hayward called the amount of oil and dispersant "relatively tiny" in comparison with the "very big ocean." Hayward also initially stated that the environmental effect of the Gulf spill would likely be "very very modest." Later, he said that the spill was a disruption to Gulf Coast residents and himself adding, "You know, I'd like