With all the recent coverage given to the World Cup, interest in soccer is frequently described as reaching a "tipping point." Even President Obama has done his part to popularize the sport: taking time out from his busy schedule to watch the U.S.-Germany match, playing soccer against a robot on his recent trip to Japan, and chatting with foreign leaders about the game's finer points.

But the president appears unaware of the health risks. He has strongly warned Americans about the risks of playing football, going so far this year as saying, "I would not let my son play pro football." He hasn't offered such similar warnings about soccer.

Obama is not alone in apparently believing that soccer is less dangerous than American football. Surely the media have been all over how dangerous football is for concussions. And the lawsuits filed by NFL players have received much attention.

Unfortunately, soccer is not the benign alternative it is often portrayed as being.

Take concussions.

In college, women's soccer has a higher rate of concussions than men's football or soccer: 6.3 per 10,000 times women participate in soccer practice or a game versus 4.9 for men's soccer and 6.1 for men's football. Indeed, among college sports, women's soccer has the highest rate of concussions.

But concussions aren't the only problem. In total injuries, both men's and women's soccer exceed those of men's football. Total injuries for men's soccer are 11.14 per 10,000 practices or games and 9.7 for women's soccer. For football, the number is 9.5.

College sports are about twice as likely as high school sports to result in concussions. At the high school level, the numbers for soccer aren't quite as bad as for football. High school football is clearly the riskiest. But girls' and boys' soccer are still the second and third most dangerous sports for concussions, followed closely by girls' basketball.

There is also data showing that, while football causes a higher number of concussions, girls' and boys' high school soccer is responsible for more of the serious concussions. We can tell that from recovery time. Concussions from soccer are about twice as likely as football to require 22 or more days of recovery.

Most concussions in soccer occur for the same reason that they occur in football - collisions with other players. But in soccer there is another problem: striking one's head against a hard ball over and over again. In high school, contact with "equipment" (mostly the ball) is about nine times more likely to cause concussions in boys' soccer than in football. Soccer balls are even more dangerous for women.

Unfortunately, soccer players are much less likely than football players to recognize that they have suffered a concussion. Hence, they are less likely to take the time to rest and get treatment.

An article in the Journal of Neurology compared professional soccer players from several professional Dutch clubs with a control group of elite noncontact-sport athletes. The study found professional soccer players exhibited relatively severely impaired performances in memory, planning, and visual perceptions. How poorly they functioned was related directly to how frequently the players had "headed" the soccer ball.

Soccer might currently be the "in" sport, but parents who push their children into playing it for safety reasons are in for a rude surprise.

John R. Lott Jr. is the president of the Crime Prevention Research Center and the author of "Freedomnomics: Why the Free Market Works and Other Half-Baked Theories Don't." johnrlott@crimeresearch.org