The U.S. Army's surgeon general has declared on Thursday that a new survey reveals 30 percent of troops have developed mental health problems due to stress.

The survey was carried out on 1,000 troops stationed overseas, in Iraq

A study published in the American Journal of Public Health, found that immigrants accounted for 10.4 percent of the U.S. population but only 7.9 percent of total health spending and 8 percent of government health spending.

"Our study lays to rest the myth that expensive care for immigrants is responsible for our nation's high health costs. The truth is, immigrants get far less care than other Americans," Dr. Sarita Mohanty, who led the study while she was at Harvard University and who is now at the University of Southern California, said in a statement

Professor, Sir Richard Doll, the epidemiologist and former Regius Professor of Medicine at Oxford University, has died at the age of 92.

Sir Richard, along with Professor Austin Bradford Hill, of the Medical Research Council were the first two scientists to link smoking with lung cancer

The Centers for Disease Control and Prevention says Americans today have lower levels of potentially dangerous substances in their blood than ten years ago.

Such substances include lead and byproducts of secondhand smoke

The Centers for Disease Control and Prevention says Americans today have lower levels of potentially dangerous substances in their blood than ten years ago.

Such substances include lead and byproducts of secondhand smoke