The more states allow people to ride motorcycles without helmets, the more people die, according to a study discussed in TheDetroitBureau.com today.

The report, released by FairWarning.org, outlines how for the past 30 years, states have begun to loosen helmet restrictions on bikers and deaths have climbed, even as automotive deaths have dropped to historic lows. In 1972, 47 states required riders to wear helmets. In 2012, only 19 states have laws requiring every rider don protective headgear.

Meanwhile, deaths on motorcycles has more than doubled from 1997 to 2010, from 2,116 to 4,502, according to NHTSA.

"We call it the organ donor enhancement act," a doctor told TheDetroitBureau.com. "We've always had a shortage of donors but expect to see the numbers go way up. "