Since 2004, 34 deaths reported to the U.S. Food and Drug Administration (FDA) have been linked to energy drinks, according to the Center for Science in the Public Interest.

The non-profit education organization and a lawyer representing the parents of a deceased teenager, Anais Fournier, obtained the documents under the Freedom of Information Act. Fournier’s parents sued Monster Beverage Corp. for wrongful death, though the energy company has blamed her death on a preexisting medical condition.

Fournier’s case is just one of dozens of fatalities tied to an energy drink sector under close watch by consumer advocates, regulators and lawmakers.

Twenty two deaths have been linked to 5-Hour Energy, 11 fatalities have been linked to Monster, and one death has been linked to Rockstar, according to CSPI in a June 25 press release. CSPI revealed 17 previously unreported deaths linked to energy drinks since late 2012.

"As I see in my medical practice, energy drinks are clearly causing symptomatic arrhythmias," said Dr. Stacy Fisher, director of complex heart diseases at University of Maryland School of Medicine, in the release. "These new reports of deaths and other injuries raise the level of concern about the adverse effects of energy drinks."

According to the results of the public records request, FDA received 276 adverse event reports (AERs) connected to energy drinks between Jan. 1, 2004 and March 10, 2014. Of the non-fatalities, 42 involved life-threatening injuries while 115 incidents resulted in hospitalization, CSPI said.

5-Hour Energy and Rockstar did not respond to requests for comment. Monster referred an inquiry to the American Beverage Association, which also did not respond to a request for comment. 

The adverse event reports (AERs) don’t prove the energy drinks actually caused the events, FDA representatives have consistently said. 

“FDA has and continues to investigate every one of these reports to try to determine whether the product caused or contributed to the event," said FDA spokesman Arthur Whitmore. “Frequently there are other complicating factors, such as existing disease or medications the person may have been taking. Often, despite our best efforts, we are unable to get more information, either because of a lack of medical records or contact information."

Whitmore said the agency has been studying energy drinks for years to determine if they pose an increased risk to consumers other than the caffeine in the products that must be declared on the label.

In a letter Wednesday to FDA Commissioner Margaret Hamburg, CSPI asked the agency to start a rulemaking in order to require warning labels on energy drinks to let consumers know about the potential risks of a convulsion, heart attack or other adverse side effects.

Many substances found in energy drinks—including caffeine, guarana, taurine, glucuronolactone, and ginseng—may produce harmful effects, CSPI warned in the letter. “As far as we can tell, the FDA has not examined some of those ingredients for safety, effectiveness, purity, or interactions with other energy-drink ingredients," the organization said.