A member of her Staten Island, New York, high school track team, Newman used popular over-the-counter drugs like Icy Hot and Bengay to relieve pain – ointments which contain methyl salicylate.
The medical examiner told Arielle's mother her daughter used an excessive amount of those ointments which led to a toxic build up.
"She told me the normal levels or the safe levels, and then she told me hers was a level that six times that amount," said her mother, Alice Newman.
But, as CBS News correspondent Randall Pinkston reports, Newman's mother doesn't believe her daughter was using any more of the over-the-counter drugs than anyone else on the track team.
"They all have it in their sports bags," she said. "If you go to a track meet, you smell it everywhere."
The early warning signs of salicylate poisoning can be easily missed. They include ringing in the ears, difficulty breathing and a fast heart rate.
All the norm for someone who runs track, according to sports medicine specialist dr. Steve Weinfeld.
"When someone's exercising their metabolic and their exertion rate is significantly increased," he said.
That means that Arielle's body was likely to be absorbing more salicylate because of strenuous exercise.
"The one thing we don't know in this case – that I'm not aware of – is whether this child was taking oral medications such as aspirin, which also contains salycilic acid," Weinfeld said.
The combination of oral aspirin plus the ointment could have led to toxic poisoning. Her mother said Arielle had recently sought a doctor's help because it was taking her a long time to recover between races.
"She was getting frustrated," her mother said. "She was saying 'I don't know why it's taking so long to run the next race,' and the coach brought it to my attention, and that's when I took her to the doctor."
Medical experts describe Newman's death as baffling. Bengay's manufacture, Johnson & Johnson, insists its product is safe if used as directed. A company spokesman told CBS News that they are checking to see if there have been any other fatalities.