Crumb rubber infill: what the federal research found, and why home lawns rarely use it

01Why does artificial turf have rubber pellets?

Because a sports field needs weight and cushion between the blades, and ground-up tires supply both.

• What it is. EPA describes tire crumb rubber as scrap tires reduced to size, with “99 percent or more of the steel and fabric” removed (EPA Q&A). The Toxics Use Reduction Institute at UMass Lowell says recycled tire rubber, also called SBR, is the most commonly used artificial turf infill (TURI).
• What it does. The federal exposure report says the crumb, “sometimes mixed with sand or other raw materials,” goes in “for ballast, support for the synthetic grass blades, and as cushioning for field users” (EPA and CDC/ATSDR, 2024).
• How common it is. The same report, citing the Synthetic Turf Council, counts 18,000 to 19,000 synthetic turf fields in the United States and 1,200 to 1,500 new installations a year, about half of them replacements.

Windsor turned two Chimney Park baseball fields from grass to artificial turf in spring 2026 (Town of Windsor), and Weld RE-4 replaced the Windsor High School stadium turf in 2023 (Weld RE-4). Neither public page says what infill went down. How synthetic and grass fields compare for a school or club is in synthetic or natural grass sports fields.

02What did the EPA and CDC research find?

That chemicals are in the crumb and players can be exposed, but likely to a limited degree. EPA and CDC/ATSDR, with the Consumer Product Safety Commission, began in February 2016, and EPA calls it the largest tire crumb rubber study done in the United States (EPA). They sampled crumb from 40 indoor and outdoor fields and nine tire recycling plants, then reported in two parts: Part 1 in 2019 on what is in the material, and Part 2 in April 2024 on how people using the fields are exposed.

The agencies sum it up this way: “although chemicals are present (as expected) in the tire crumb rubber and exposures can occur, they are likely limited.” The report is as plain about its limits: neither part “constitutes an assessment of the risks” of playing on these fields, and the study was not designed, and is not enough on its own, to answer health-risk questions directly.

Heat is the local wrinkle. The Greeley UNC weather station averages 58.3 days a year at or above 90°F (NOAA 1991–2020 normals), and Mead High’s football coach told the maker of the school’s new field that “We’ve recorded temperatures of 130 degrees on our old turf field” (FieldTurf, 2021). Surface temperatures, and what cools them, are in how hot artificial turf gets.

03Do turf fields cause cancer?

No study so far has shown that they do, and the investigation built around that fear found less cancer than expected. None has ruled the risk out, either.

• Washington’s investigation. After several goalies developed blood cancers, a University of Washington soccer coach began listing players with cancer; by 2016 her list had 53 names. The state health department and the university found less cancer among the soccer players on the list than expected for Washington residents of the same ages, and no increased cancer rate among the state’s soccer players. The department adds that the investigation “was not designed to determine” whether crumb rubber raises the risk for soccer players in general (Washington State Department of Health). Its word to parents: “Parents should be aware, but not concerned.”
• Other reviews. The federal report quotes the Netherlands’ RIVM calling the health risk of playing on these fields “virtually negligible,” and the European Chemicals Agency finding “a very low level of concern.” It also quotes the National Toxicology Program: mice that ingested crumb rubber showed no toxicity, but in human-cell tests under conditions such as high heat, crumb rubber leached chemicals, some of which killed cells.
• Europe capped it anyway. EU regulators treat eight PAHs found in tire rubber as carcinogens for which “a dose without a theoretical cancer risk cannot be derived.” Since 10 August 2022, EU law has barred rubber or polymer granules and mulches holding more than 20 mg/kg of those eight combined from turf pitches and playgrounds; infill already in place could stay (Regulation (EU) 2021/1199). The EU’s risk committee said that figure “is not based upon the estimated risk” but aims to avoid very high PAH concentrations.

04Why do home lawns rarely use crumb rubber?

The federal researchers left homes out of their study for exactly that reason: residential turf “does not typically include tire crumb rubber.” Local rules that name infill point the same way.

• Firestone. The town’s code requires infill to be “a non-toxic anti-microbial material such as silica sand or acrylic coated sand” and says “Crumb rubber filler shall be prohibited” (Firestone Development Code 16.6.4). In Barefoot Lakes, the metro district’s guidelines call for infill such as silica sand or Envirofill, a coated sand, in kid and pet areas (St. Vrain Lakes Metropolitan Districts). It depends on your lot and the infill you pick; ask Firestone Planning. Not legal advice.
• Frederick’s parks. Its design standards for playground turf say “Rubber infill is not permitted” and call for coated silica sand (Town of Frederick). They govern park projects, not home yards.
• Longmont’s Dry Creek fields. The city picked antibacterial-coated sand over rubber, and its FAQ credits sand with less chemical exposure and lower heat retention (City of Longmont).

Each town’s turf rules are in artificial turf rules in Northern Colorado; an HOA or metro district can add its own.

What goes in instead? Besides sand, the main route is plant infill such as cork or coconut, and an engineer writing for field owners says some of it must be kept at a set moisture content, which the plains’ “low relative humidity” works against (Colorado Climate Center). Our infill types guide compares how each holds up here. No option is free of questions: Washington’s health department notes that plant-based infills had the fewest chemicals of concern in some studies but can bring mold, allergens and fibers to breathe, and that TURI’s alternatives assessment named only organically managed natural grass as a safer alternative to tire crumb (Washington State Department of Health).

Europe is also ending sales of synthetic-polymer granular infill for sports surfaces from 17 October 2031 under its microplastics rules (Regulation (EU) 2023/2055). What turf sheds into water here is in artificial turf and microplastics.

05What should parents ask a school or park about its field?

• What infill is in this field? A good answer names the product: tire crumb, coated sand, EPDM or TPE granules, or a plant-based blend. For a Windsor field, ask the Town’s parks department or Weld RE-4, since their project pages don’t say.
• Is it indoor or outdoor? The federal work found exposure may be higher on indoor fields.
• What happens on hot days? Washington’s health department says field managers “should regularly monitor surface level temperatures and set guidelines for when to alert users to avoid field use.” A good answer names who checks and at what temperature play moves.
• Are there food and hand-washing rules? Thompson School District already bars food and drinks other than water on its synthetic turf field (Thompson School District).
• When is the field due for replacement, and what infill will the new one use? That choice is made at bid time, and Frederick and Longmont show sand is an option. A good answer includes the infill’s test results, such as its PAH content against the EU’s 20 mg/kg cap.

At home, Washington’s health department suggests washing hands after play and before eating, not eating or drinking on the turf, taking off cleats, gear and dirty uniforms outside, brushing crumbs out of children’s clothes, and spitting out any pellets that end up in a mouth.

For a district or park weighing a new field, see commercial turf; under swings and climbers, see playground turf and what goes under a swing set.