WASHINGTON » Direct costs from deaths and injuries due to motorcycle crashes were $16 billion in 2010, but the full cost is likely higher because long-term medical expenses are difficult to measure, a government report said.

Motorcyclists are involved in fatal crashes at higher rates than drivers of other types of vehicles, and are 30 times more likely to die in a traffic crash than passenger car occupants, according to the Government Accountability Office report.

In 2010, 82,000 motorcyclists were injured and 4,502 were killed in crashes, the report said. The average cost for a fatal crash was estimated at $1.2 million, while the cost for injuries ranged from $2,500 to $1.4 million depending upon the severity.

It’s difficult to determine the full costs with accuracy because some types of costs are difficult to measure, the report said. For example, treating serious injuries can be long and expensive, but follow-up analyses of costs are conducted only for a few years. Also, other consequences of long-term injuries such as changes in employment and living status can’t be fully measured, the report said.

Laws requiring all motorcyclists to wear helmets are the only strategy proven effective in reducing fatalities and injuries, the report said. Several studies have estimated helmets reduce the risk of death by as much as 39 percent, the report said. The National Highway Traffic Safety Administration has estimated helmets saved the lives of 1,550 motorcyclists in 2010.

However, there has been strong opposition from motorcycle groups to "universal" helmet laws, and only 19 states have them. Another 28 states have "partial" helmet laws that require only some motorcyclists to wear helmets, usually riders under age 21 or under age 18.

Three states have no helmet laws: Illinois, Iowa and New Hampshire.

Earlier this year, Michigan legislators repealed that state’s helmet requirement for motorcyclists over 21. Other proposals to repeal mandatory helmet laws were considered in California, Maryland, Missouri and Tennessee.

While many motorcycle groups endorse the use of helmets, they also oppose mandatory helmet laws as infringements on personal liberties and their right to assume the risk of riding without a helmet, the report said. Instead, motorcycle groups have backed better safety education as a means to prevent accidents.

The Motorcycle Riders Foundation didn’t immediately respond to a request for comment.

"Education is not a substitute for wearing a helmet," said Jackie Gillan, president of Advocates for Highway and Auto Safety, which supports mandatory helmet laws. "It’s like saying if you take a driver’s ed class, you don’t have to wear your seat belt. Now how silly is that?"

Partial helmet laws are also difficult to enforce because it’s hard for police to tell the age of motorcyclists as they go whizzing by, she said.

The National Transportation Safety Board dropped mandatory helmet laws from their list of ten "most wanted" safety improvements earlier this month, angering some safety advocates.