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Motorcycle accident–related fatalities account for 1 in every 8 deaths on the road. And a new study suggests that blacks are at higher risk than whites: for every two white motorcyclists who die in accidents, three of their African-American counterparts do not survive.

Johns Hopkins researchers analyzed 68,840 motorcycle accidents recorded by the National Trauma Data Bank between 2002 and 2006. The data show that black riders were 50% more likely to die than white riders, despite the fact that African Americans were more likely to be wearing helmets at the time of the crash. The disparity held up even after controlling for the severity of the accident, the biker’s gender and insurance status. White bikers not wearing helmets were still less likely to die in a crash than black bikers wearing helmets; the highest risk group were blacks riding without protective head gear. (More on Time.com: How Kids Get Clobbered by Racial Discrimination)

The study published in the American Journal of Surgery suggests that safety interventions, like helmet laws, don’t help everyone equally. “Helmet for helmet, African Americans have more lethal injuries,” said Adil Haider, senior author and assistant professor of surgery at the Johns Hopkins University School of Medicine, in a statement.

The authors hypothesize that the disparity may be due to differences in levels of health care before and after the accidents: lack of health insurance, less access to or poorer quality of critical care, and a higher rate of pre-existing conditions may make recovery after a crash more complicated for blacks.

It’s also possible that black motorcyclists prefer wearing less-protective helmets or riding more dangerous bikes. Researchers won’t know without further study.

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