Seven NFL stadiums are installing grass fields to comply with FIFA regulations for this summer's World Cup, and one of the league's biggest stars is calling out the hypocrisy.Half the league’s stadiums use turf, despite NFLPA Executive Director Lloyd Howell saying that 92% of the league’s players prefer grass.The common speculation, though, is that turf is cheaper to use and easier to maintain than grass, considering the stadiums host plenty more events year-round.CLICK HERE FOR MORE SPORTS COVERAGE ON FOXNEWS.COMWell, as the group stage reaches its final days, San Francisco 49ers tight end George Kittle called the NFL out for ignoring players' requests but bending the knee to FIFA."We’ve made it clear that we prefer grass fields. We know it’s better on our bodies. And clearly, we know it’s possible based on everything that went into putting down grass fields for the World Cup in each stadium," Kittle said in a statement the NFLPA posted on social media.WORLD CUP ANNOUNCER SAYS FIFA'S GRASS MANDATE WILL BE A 'HUGE CONVERSATION' REGARDING NFL'S TURF FIELDS"At this point, it comes down to the NFL making it a priority and choosing to invest in us as players, because our bodies are our business, which they get to capitalize on!"Kittle is recovering from a torn Achilles which he suffered on grass in Philadelphia.Former offensive lineman Andrew Whitworth recently told Fox News Digital he "would absolutely be" frustrated with the NFL if he were in Kittle's shoes."I don't think there's any doubt about it, only because we've voiced so much that we'd love to have it..." Whitworth admitted, but did say he understood the turf argument. "The reality is everyone wants to play on grass because you feel better."It was announced late last year that each NFL team will be provided with "a library of approved and accredited NFL fields" before the 2026 season begins. Any new field will immediately have to meet those standards, and all teams will have two years to achieve them.Both grass and synthetic turf fields will be subject to the new standards, but the NFL has no plans to require natural grass fields.The league’s chief medical officer, Dr. Allen Sills, said there are no "statistically significant differences" in lower-extremity injuries or concussions that can be attributed to the type of playing surface or a specific surface. That is despite widespread preferences by players for grass fields and complaints about surfaces such as the one at MetLife Stadium, where the New York Giants and Jets play and where the World Cup final will be held on July 19.Fox News' Chantz Martin contributed to this report.Follow Fox News Digital’s sports coverage on X, and subscribe to the Fox News Sports Huddle newsletter.