On afternoons across the country, kids pull on their soccer, baseball, and lacrosse uniforms and take to the field. Some come home with grass stains, but on more than 12,000 fields in the United States, kids come home with bits of rubber stuck to their shoes from crumb rubber synthetic turf infill.

Synthetic turf fields are becoming more common, in part because they tend to have greater durability and lower maintenance costs compared with grass. In North America, about 98 percent of synthetic turf fields use granulated recycled tire rubber, or crumb rubber, as infill. The granules fill in the space between synthetic blades of grass to provide cushioning, aid drainage, and help prevent injuries when athletes run, slide or take a tumble. Yet even as these fields become more common, some community members have raised questions about whether crumb rubber is safe.

On one side of the conflict are more than 70 studies and literature reviews from state health departments, universities, and other independent entities in the United States and in Europe. None of the studies say crumb rubber is a public health or environmental concern. On the other side are environmental groups and residents who worry that various chemicals in tire rubber could cause cancer or other health problems, and they are asking school boards, cities and states to ban crumb rubber infill. Tire processors and synthetic turf vendors are concerned that this fear has trumped the facts and maligned a product with real environmental benefits.

What the studies say

Over the years, numerous organizations have looked into crumb rubber’s potential health and environmental risks. Studies have examined several factors, such as how crumb rubber affects the human body when it is ingested or when athletes’ skin comes in contact with the crumbs. Other research has considered whether crumb rubber releases harmful levels of chemicals into the air.

  • A 2013 study by researchers at the Rutgers Robert Wood Johnson Medical School in New Jersey evaluated opportunities for exposure to trace metals, semi-volatile organic compounds (SVOCs), and polycyclic aromatic hydrocarbons (PAHs) from crumb rubber infill and the artificial turf fiber “grass.” The researchers found that PAHs were routinely below detection limits, and SVOCs that have environmental regulatory limits were at levels too low to quantify. Some metals were detected, but researchers said the concentrations were low and likely would not cause health problems.
  • A May 2008 literature review by TRC for the New York City Department of Health and Mental Hygiene evaluated 11 previously conducted human health risk assessments of crumb rubber in artificial turf. Each assessment looked at different crumb rubber constituent materials, but “all had a similar conclusion: exposure to [chemicals of concern] may occur, however the degree of exposure is likely to be too small through ingestion, dermal [contact], or inhalation to increase the risk for any health effect.”
  • In 2009, four Connecticut state agencies (University of Connecticut Health Center, the Connecticut Agricultural Experiment Station, the Department of Public Health, and the Department of Environmental Protection) evaluated the health and environmental impacts associated with crumb rubber turf fields in Connecticut. Researchers looked at four outdoor fields and one indoor field, asking three soccer players at each field to wear personal monitoring devices to collect samples. The study tested about 200 chemicals at each field. Researchers concluded that there were no elevated health risks from playing on the indoor and outdoor fields, but they noted that indoor fields may need ventilation because of higher levels of chemicals at the one indoor field they tested.
  • In 2013, ChemRisk in Pittsburgh conducted a literature review for the Rubber Manufacturers Association to evaluate the health and ecological risks associated with the use of recycled tire rubber on playgrounds and athletic fields. While some of the ingredients used in tire manufacturing are considered to be “potentially hazardous to human health at high doses, the potential for athlete or child exposure to these chemicals is very low” when playing on a synthetic turf field, the study says. It notes that heating during the tire manufacturing process causes physical and chemical reactions that bond potentially harmful chemicals into the material, and “the process is designed so the release of chemicals into the environment is inhibited.”

More studies in the works

Crumb rubber proponents and opponents alike are following the progress of an ongoing study from the California Office of Environmental Health Hazard Assessment (OEHHA), which aims to identify and analyze chemicals released from crumb rubber and artificial grass blades on fields, then learn if exposures pose possible health risks. The study also will sample the air above fields, evaluate how exposure could affect children differently than adults, and study the possible exposure to chemicals by swallowing the rubber or having skin contact with the material, OEHHA says. CalRecycle, which regulates recycled tires in California, commissioned the study and expects results in June 2018.

Al Garver, president of the Synthetic Turf Council, says STC supports the calls for more scientific studies and tests. The council worked with researchers from OEHHA’s study to help identify locations of several hundred fields throughout California.

“The more it’s studied, the more it will validate the fact that the rubber is inert,” Garver says.

Crumbs of concern

Despite the scientific evidence to date saying crumb rubber does not pose health or environmental concerns, some communities have opted to ban or avoid crumb rubber infill for turf fields out of caution, saying future studies still could uncover dangerous effects.

Public concern has increased in the past year after several news stories investigated the potential risk for athletes who are exposed to crumb rubber. One such story was an NBC interview with Amy Griffin, associate head coach for the University of Washington’s women’s soccer team, who says she keeps a list of young athletes who played on synthetic turf who have gotten cancer. In an NBC News investigation in 2014, Griffin says her list is not a scientific study, but it makes her wonder if there is a strong link between exposure to crumb rubber and cancer. Some critics of crumb rubber who echo Griffin’s concerns say more data are needed about specific people who have possibly developed health problems from crumb rubber: How long and how often did they spend time on the fields? And do other factors — such as a person’s age, the methods used to construct the field, or even the weather — play a role?

Crumb rubber, used inside many fields, concerns some people, although studies have not shown it to be harmful to the health of those who use the fields.
Crumb rubber, used inside many fields, concerns some people, although studies have not shown it to be harmful to the health of those who use the fields.

The concern has spread to places like Edmonds, Wash., which voted in December to put an 18-month moratorium on installing any new synthetic turf fields made with crumb rubber infill from recycled tires. The city council enacted the moratorium after residents protested the local school district’s plans to take out the aging grass field at a school campus and replace it with synthetic turf. Patrick Doherty, the city’s economic development and community services director, says field construction was already underway when residents learned the new field would have crumb rubber infill, so workers completed the project before protests could halt construction. Because of the community outcry, he says, other fields that were scheduled to get similar upgrades won’t see that happen, at least during the 18-month moratorium.

Edmonds isn’t the only community avoiding crumb rubber. On the other side of the country, Montgomery County, Md., says it will not provide public funding for crumb rubber infill when building new synthetic turf fields. In Montgomery County, the city of Gaithersburg’s first outdoor synthetic turf field, built in September 2014, was built with organic infill made of materials such as cork, rice husks, sand and coconut fibers. Officials chose the organic material because community members voiced concerns about crumb rubber’s possible environmental and health impacts, says Michele Potter, director of parks, recreation, and culture for Gaithersburg. The decision to use the organic infill was out of an abundance of caution, she says, adding that the discussions about crumb rubber versus alternative infill had more to do with possible environmental concerns than health concerns.

“My concern was for the environment. … What if in several years, the EPA says [we] have to remove all these fields?”

The case for crumb rubber

Positions such as those Edmonds and Montgomery County have taken frustrate recyclers and rubber manufacturers, who feel science is on their side and the crumb rubber fears are unfounded. More than 70 independent, peer-reviewed studies done over the past 22 years have offered enough evidence to clear crumb rubber’s name, says Institute of Scrap Recycling Industries President Robin Wiener.

“These studies have pointed to the conclusion there is no indication of negative health effects tied to crumb rubber’s use in artificial turf” based on the current information, she wrote in an Oct. 27, 2015, letter to EPA Administrator Gina McCarthy.

The letter asked the EPA to respond to the public’s concerns by highlighting the research, including the EPA’s own studies.

Some states and communities have reached the same conclusion about crumb rubber’s safety, and they say natural grass turf can have its own problems. In fact, crumb rubber supporters say research should compare artificial turf to natural turf as a baseline because some natural grass fields are maintained with fertilizers that might have toxic chemicals. Fairfax County Public Schools in Virginia has 48 synthetic turf fields with crumb rubber, and it stands by its decision to keep the fields, saying scientific research has not shown any concerns. The Virginia General Assembly in February tabled a bill that would have imposed a three-year ban on installing crumb rubber synthetic turf fields at any public or private school or in public parks near schools.

Several other communities are planning to upgrade sports fields with crumb rubber turf infill. The Jackson County, N.C., school district recently received a grant from the National Football League to help install a turf field. In an interview with The Smoky Mountain News, Superintendent Mike Murray said, “I personally think when you look at the research, [crumb rubber] does not signify a significant risk for our students.”

Mark Rannie, vice president of Emanuel Tire in Baltimore, also believes the concerns come more from fear than facts. As chair of ISRI’s Tire and Rubber Division, he has followed the issue closely. Though he says communities and organizations have a right to decide whether to use crumb rubber or an alternative on their fields, he wishes people would read the studies to help them make the decision instead of discounting crumb rubber because other communities have concerns.

“We just want the truth out there … crumb rubber is not problematic, according to the studies,” he says. “If a state agency or government agencies decide to declare a moratorium based on [fear], they are basing it on a political cause, not a scientific one.”

Rannie doesn’t expect future studies to indicate health risks, but he says the tire recycling sector welcomes the research. More information and research can help inform the public and show that there’s nothing to fear, he says. And, in the unlikely event of a problem, he says, tire recyclers have to step up and be part of the solution. “You have to put health over business,” he says.

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Editor’s Note: Earth911 partners with many industries, manufacturers and organizations to support its Recycling Directory, the largest in the nation, which is provided to consumers at no cost. Institute of Scrap Recycling Industries is one of these partners.

By Megan Quinn

Megan Quinn covers the recycling industry for Scrap, the trade magazine for the Institute of Scrap Recycling Industries. She has written about energy trends, education, crime and politics for newspapers including the Denver Post and the Boulder Daily Camera. Her work also has appeared on Colorado Public Radio. She lives in Washington D.C.