As the vanguard and pinnacle of the game, the National Football League faces continual legal scrutiny regarding the long-term safety of its players, as some allege culpability for devastating brain injuries among retired players.

Now, a new study points to safety concerns earlier in the pipeline. Every year, a dozen or so high school and college football players die on the field during practices or games, according to researchers analyzing data from the National Center for Catastrophic Sports Injury Research.

Two-hundred forty-three student athletes died on the field between July 1990 and June 2010, succumbing to heart failure, brain injury and heat-related illness. One-hundred of the deaths came from an underlying heart condition with 62 caused by a brain injury, such as a subdural hematoma, and 38 from heat-related causes. Eleven African American players with sickle cell disease - a genetic trait leaving them susceptible to dehydration and low oxygen - died during intense practice sessions.

Many of the fatalities occurred in the South during preseason play, when programs typically hold twice-daily practices, researchers reported in The American Journal of Sports Medicine. The number of heat-related deaths alone is quite alarming, said Kelly Dougherty, an assistant professor of pediatrics at the University of Pennsylvania's Perelman School of Medicine.

"These are preventable deaths," said Dougherty, who was not involved in the study. "This article highlights the urgent need for future research studies that would investigate children's and especially football players' body temperature responses during practice [and] during games," she told media.

"We have so few data to guide policy, to guide recommendations, and we really don't have a good idea of body temperature responses in the field."

Presently, the American Academy of Pediatrics recommends that teenagers and adolescents ease into such high-intensity activities during hot days, taking more water breaks and expending less energy. Although some tests may predict susceptibility to sudden heart-related deaths, such screenings remain unpopular because of a high rate of false positives.

The deaths represent one of every 100,000 high school and college football player in America.

The National Collegiate Athletic Association, which provides funding for the Center, told media its "health and safety committee" planned to review its study.

"Through this data the NCAA has made recent policy changes in several important areas, including football preseason practice, medical examinations, safety training for coaches, concussion management plans and sickle cell trait," the representative said. "The problem of football fatalities is real and needs to be addressed by continued surveillance and rule changes when applicable to further reduce the incidence."