Health consequences of the Deepwater Horizon oil spill effects, while even very low doses can cause mutagenic effects, with cancer of particular concern. The carcinogens of concern in crude oil are benzene and polycyclic aromatic hydrocarbons (PAHs), which are present in oil and in the air as a result of offshore controlled burning of crude oil. During the 2010 BP/Deepwater Horizon Gulf oil spill, an estimated one of every 20 barrels of spilled oil was deliberately burned off. Routes of exposure include contact and inhalation. The EPA obtained hundreds of air samples during the spill and a review showed that none of the samples showed concentrations of benzene
Volume and extent of the Deepwater Horizon oil spill silts and sands onshore. On 26 May 2011, the Louisiana Department of Environmental Quality extended the state of emergency related to the spill. In April 2012, oil was found dotting of Louisiana's coast. As of December 2012, of coastline remain subject to evaluation and/or cleanup operations. On 15 May 2010, researchers from the National Institute for Undersea Science and Technology, aboard the research vessel "RV Pelican", identified oil plumes in the deep waters of the Gulf of Mexico, including one as large as long, wide and thick in spots. The shallowest oil plume the group detected was at about ,