The U.S. National Institutes of Health said on Tuesday it would use $10 million from BP to start a multiyear study to look at the potential health effects from the oil spill in the Gulf of Mexico.

The NIH has already designated another $10 million to begin the study, which will look at the health effects on clean-up workers from oil and dispersants, including respiratory, neurobehavioral, carcinogenic, and immune conditions.

The study will also include mental health concerns and other spill-related problems such as job loss, family disruption and financial uncertainty.

"It was clear to us that we need to begin immediately studying the health of the workers most directly involved in responding to this crisis," NIH director Dr. Francis Collins said in a statement.

"The donation from BP will help speed our work with centers for disease control and prevention, environmental protection agency and other federal  agencies, academia, as well as state and local partners to carry out this important study." The U.S. government said on Saturday BP's ruptured oil well is secure with no threat of spewing crude.

The Macondo well failed on April 20, leading to an explosion aboard the Deepwater Horizon drilling rig which killed 11 crew members. The well spewed more than 4 million barrels of oil into the Gulf for nearly three months until BP sealed it by pumping in mud and cement from the top on Aug. 5.

"Clean-up workers are likely to be the most heavily exposed of all population groups in the Gulf Coast region," said Dale Sandler of the NIH's National Institute of Environmental Health Services, which will lead the study.

"For example, we hope to recruit workers involved in oil burning, skimming and booming, equipment decontamination, wildlife cleanup, and also those with lower exposure such as shoreline clean-up workers."

Workers who were trained but who never did any clean-up work will act as control for the study, Sandler said in a statement. "What we learn from this study may help us prepare for future incidents that put clean-up workers at risk."

Prior oil spills have shown contact with oil and chemicals can affect the lungs, kidneys, and liver, and the mental strain can boost rates of anxiety, depression and post traumatic stress as many as six years later.

A survey done a year after the Exxon Valdez spill found local residents 3.6 times more likely to have an anxiety disorder, 2.9 times more likely to have  post-traumatic stress disorder and 2.1 times more likely to show signs of depression.