An estimated 18.22 million viewers watched in awe Sunday as Silvestre Valera's header forged a tie for Portugal in its World Cup match against the United States. But former U.S. women's star Brandi Chastain says that headers are more dangerous than just breaking the hearts of American soccer fans.

Kids are particularly susceptible to injuries that result from heading the ball because their brains are still forming.

“I believe that the benefits of developing heading skills as children are not worth the thousands of additional concussions that youth soccer players will suffer," Chastain said. "As a parent, I won't allow my children to head the ball before high school, and as a coach I would prefer my players focused solely on foot skills as they develop their love of the game. I believe this change will create better and safer soccer."

Chastain is part of the Parents and Pros for Safer Soccer (PASS) campaign, which is fighting to prohibit heading for players under 14.

Heading is taught as one of the fundaments of the game, but young soccer players and their parents are often unaware of the consequences that come with heading a soccer ball. Heading is the leading cause of serious injuries, like concussions, according to the New York Times.

World Cup hype has captivated millions of U.S. soccer fans, including wide-eyed children who dream of emulating a header like Valera's. Chastain said this newfound popularity adds urgency to the campaign.

"I would love for U.S. Soccer to take this on, because it will only help kids stay healthy," Chastain said. "Why not protect our kids for as long as we can?"

The U.S. Senate held a hearing Wednesday on the long-term effects of sports-related brain injuries. Chastain and PASS can only hope their heading prohibition rule will take off as quickly as America's interest in the World Cup.

Dr. Robert Cantu, an expert in the study of athletes' brain, told the New York Times, "If we were to take a pillow and slam it as hard as we could against a child's head, again and again, we would be charged with child abuse. But that's exactly what it’s like when a player is hit in the head with a ball from pretty close."