Boosters called Houston’s Astrodome the “Eighth Wonder of the World” when the first domed sports stadium opened in 1965. But one feature wasn’t so wondrous: baseball players couldn’t see fly balls in the glare from the plastic skylights. To fix this problem the panes were painted grey, which improved visibility but made the interior dimmer. Over several months the Astrodome’s grass withered and died.
In response, stadium managers tried a new option: they resurfaced the field with Chemgrass, a carpet of half-inch thermoplastic fibers attached to a rubber mat and laid on top of an asphalt base. Chemstrand, the Monsanto subsidiary that had developed the synthetic turf, saw a marketing opportunity and renamed it AstroTurf.
The new surface was hard, smooth, and fast. Astros manager Grady Hatton bragged that it made the Astrodome “a real Utopia for baseball. No wind, no sun, no rain, no heat, no cold, and now no bad bounces.” Others had doubts. “If baseball was meant to be played on that rubber mat, I’m crazy,” said renowned infielder and manager Leo Durocher, who had just come out of retirement to steer the Chicago Cubs. “Imagine that—a $45 million ballpark and a 10-cent infield.”
Today Americans play football, soccer, lacrosse, and other sports on more than 11,000 synthetic-turf fields across the nation. Advocates praise synthetic turf’s durability and say it is more affordable than grass. Critics, including many professional athletes, argue that more injuries occur on such turf than on natural grass.
Ironically, artificial turf was designed to make people healthier. The idea came from the Educational Facilities Laboratory, a nonprofit corporation established by the Ford Foundation in 1958 to help schools modernize and create environments that supported learning. Spurred by research showing that military recruits from rural areas were more physically fit than their urban counterparts, lab director Harold Gores urged Monsanto to create a grasslike surface that could be laid down on city lots to provide more places to play. Chemgrass was the result.
Stadium groundskeepers saw promise in synthetic turf when it debuted at the Astrodome. The new surface could be installed more quickly than sod and did not get soggy in rainstorms. Over the next decade artificial turf was installed at major-league ballparks in Chicago, San Francisco, St. Louis, Cincinnati, Pittsburgh, Philadelphia, Kansas City, Montreal, Seattle, and Toronto. The new surface changed the pace of baseball: it offered less resistance than grass, so ground balls traveled farther. The Kansas City Royals in the 1970s and the St. Louis Cardinals in the 1980s won championships with rosters of speedy “slap hitters” who didn’t belt many home runs but could bang out line drives and steal bases on their home parks’ synthetic fields.
Many players complained that artificial turf was hard on their legs and backs and caused more injuries than grass. “If you dived for a ball, you’d have one tremendous rug burn,” said former Astros outfielder Bob Watson. “They never heal.” (This summer, players in the 2015 Women’s World Cup soccer tournament raised the same issues, publishing photographs of their badly grazed legs from playing on artificial turf.)
Synthetic turf made even bigger inroads at football stadiums, where surfaces took more punishment. By 1984, 17 out of 28 National Football League (NFL) teams were playing on artificial turf. Many NFL players argued that these surfaces caused more strains, abrasions, and concussions than playing on grass. They also contended that artificial-turf abrasions exposed them to staph infections.
In the 1970s the NFL Players Association repeatedly called for moratoriums on the installation of synthetic turf until these issues were addressed. A 1973 study commissioned by the NFL from the Stanford Research Institute found no significant difference in the total number of injuries that occurred on synthetic turf compared with natural grass. Another study, published in 1992, concluded that linemen were more likely to suffer knee sprains during passing plays on AstroTurf than on grass.
Baseball stadiums, which had a longer historical association with grass, started converting back to natural surfaces. A wave of retro-style ballparks were built in the 1990s, all with grass fields, including Camden Yards in Baltimore, Coors Field in Denver, and Safeco Field in Seattle. Today only two major-league ballparks have artificial turf: Tampa’s Tropicana Field and Toronto’s Rogers Centre, where owners of the Toronto Blue Jays hope to convert to grass by 2018.
But synthetic-turf manufacturers had their eyes on larger markets: minor league, college, and high-school fields. In the 1990s manufacturers introduced a new generation of synthetic turf designed to provide a safer, more comfortable playing surface. These products used longer “grass” fibers with infill materials spread between the fibers to provide cushioning and better traction. The infill typically consisted of “crumb rubber”—rubber from used tires, ground into particles about 1 millimeter across—often mixed with sand.
Reusing scrap tires on sports fields helped solve a major waste headache. Many states had banned scrap tires from landfills in the 1960s and 1970s because the tires did not decompose readily. As a result millions of tires had accumulated in open-air dumps that harbored rats and mosquitoes and were prone to catching fire. The dumps also were pollution sources: rainwater flowing through them leached chemicals from the tires into the ground.
According to industry estimates, covering a single football field with synthetic turf consumed the infill equivalent of 20,000 to 40,000 tires. But using crumb rubber to cushion playing surfaces raised new concerns. Tire manufacturers add oils that contain hazardous chemicals, such as polycyclic aromatic hydrocarbons to make the rubber stronger and more pliable, and treat the rubber with zinc oxide (which can contain lead and cadmium compounds) during vulcanization to make it more elastic and durable.
As cities and counties across the United States converted playing fields to artificial turf in the late 1990s and early 2000s, some parents noticed loose crumb-rubber particles clinging to their children’s clothes, hair, and skin after football and soccer games. Many students called the particles “turf bugs.” Public-health researchers worried about athletes diving onto the turf and driving crumb rubber into their skin or inhaling crumb-rubber dust.
In 2009 the U.S. Environmental Protection Agency (EPA) field-tested methods for monitoring particulate matter, volatile organic compounds, and metals at synthetic-turf fields and playgrounds and concluded that concentrations of these materials were below levels of concern. Public Employees for Environmental Responsibility, a nonprofit watchdog group that works with government employees who manage environmental resources, challenged the EPA’s findings, which were based on air and surface samples from three athletic fields and one playground, and did not consider the role of heat in crumb-rubber emissions. (Temperatures above synthetic-turf fields can rise to 150°F or higher on hot, sunny days.) In 2013 the EPA acknowledged that its findings were too limited to apply beyond the four sample sites and called for more studies.
In October 2013 NBC News aired an investigative report that sparked public concerns about the health risks of crumb rubber. The report featured Amy Griffin, an assistant women’s soccer coach at the University of Washington who had compiled an anecdotal list of 38 U.S. soccer players diagnosed with cancer since 2009. Many of the players had blood cancers, such as lymphoma and leukemia, and most were goalkeepers who regularly dived onto artificial turf. The report found no consensus among experts over health risks associated with crumb rubber, but it led to a wave of media stories about possible links between crumb rubber and cancer.
Many communities see synthetic turf as a good investment. Although it costs roughly twice as much to install as a grass field, manufacturers say that artificial turf costs less to maintain and provides more hours of playing time, which adds up to greater cost savings over time. According to the Synthetic Turf Council, an industry group, more than 1,200 synthetic-turf playing fields were installed in the United States in 2013.
Natural-grass advocates argue that improved strains of grass need less water, fertilizer, pesticides, and mowing than sods did 10 or 20 years ago, reducing maintenance costs. They also point out that natural grass absorbs rain, reducing storm-water runoff, and transpires water, which cools playing surfaces. Some synthetic-turf manufacturers are introducing alternative fill materials, such as coated sand, ground cork, coconut fiber, and rice husks, in response to health and environmental concerns about crumb rubber.
No independent agency has produced an authoritative life-cycle analysis of the costs and impacts of artificial turf, which leaves local governments wrestling with conflicting information. Most municipalities conclude that synthetic turf will provide more playing time and so is a good investment.
But some communities have bucked the trend. Since 2007 more than a dozen towns in Massachusetts have voted against installing artificial-turf fields. The Los Angeles Unified School District, the New York City Department of Parks and Recreation, and Montgomery County, Maryland, all ban the use of crumb rubber in any fields built going forward. Although artificial turf looked like a winner when it was introduced, the contest between synthetic and grass fields has become a hard-fought race.