Is rubber mulch toxic for kids on a playground?

The short answer

Rubber mulch is not toxic in any way the measurements so far have shown. Parents hear both answers because two facts are true at once. Shredded tires do contain PAHs, metals and other chemicals; every study that looked found them. Very little of that leaves the rubber; every study that measured release found small fractions.

The "toxic" claim rests on the first fact, the "perfectly safe" claim on the second. No US agency has finished a playground risk assessment: the CPSC knows of "no specific chemical hazards from recycled tires in playground surfacing" and is still evaluating the federal data³. The one playground estimate, from California, came out low. What remains is the child who puts the surfacing in their mouth, and that decides who should skip it.

What has actually been measured

Five pieces of work cover almost everything said on this question, and they test different things.

The lab studies tell you what is in the material, the federal study how much reached real people, and the CPSC survey how small children actually use loose fill. Only California put a risk number on playground use.

The California numbers, read properly

California's Office of Environmental Health Hazard Assessment (OEHHA) ran the 2007 study, summarized in its 2026 synthetic turf report⁵. It modeled two scenarios.

The first was a single swallow of 10 grams of tire shreds, digested in a simulated stomach. For a three year old, the added lifetime cancer risk came out at 3.7 in 100 million, below the de minimis level of one in a million, which the report glosses as "too trivial or minor for consideration." The same calculation gave an acute hazard index of 2.2 for the shred chemicals combined, which the 2026 summary reports without further comment.

The second was the everyday route: hands on the surface, then hands in the mouth. Wipes from playground and track surfaces picked up zinc and four PAHs. For zinc, fluoranthene and pyrene, the estimated doses were 200 to 8,000 times lower than the dietary allowance or reference doses, and the authors "concluded no adverse health concerns." For chrysene, regular contact from age 1 through 12 gave an added cancer risk of 2.9 in a million.

How much comes out of the rubber

The federal research effort run by the EPA and CDC, with the CPSC handling playgrounds, found "a range of metals, semivolatile organic compounds, volatile organic compounds and bacteria" in tire crumb². Its 2024 exposure report then measured release: metals dissolving into simulated biological fluids averaged about 3% in stomach fluid and under 1% in saliva and in sweat, against a default risk assessment assumption of 100%¹.

The biomonitoring held up the same way. In the larger study of 161 players, urine PAH markers changed by similar amounts before and after practice whether people played on tire crumb or on natural grass, and blood metals in the pilot group matched the general population, apart from selenium, which was not found above detection limits in the tire crumb¹. The report's conclusion is that exposures "are likely limited." It is equally explicit that the work "is not intended to be a risk assessment"¹.

Two limits matter for playgrounds. The participants were 11 to 21, not toddlers, and they played on turf fields, not on a bed of loose nuggets. The CPSC is still evaluating what the field results mean for playgrounds³.

PAH levels against the only legal limit

The European Union is the one jurisdiction in these sources with a number for this material. Since August 10, 2022, granules or mulches sold there for loose use on playgrounds may contain no more than 20 mg/kg of eight listed PAHs combined, and each batch must be marked with an identification number⁸.

This is why old and new studies disagree. The 2021 authors found total PAHs lower than in earlier studies, including the 2013 paver work, and attribute it to EU rules against PAH-rich extender oils in tires made after January 2010⁶. Most of their surfaces met the 20 mg/kg limit; the two exceptions were commercial tiles from one supplier. They still argued the limit should be tightened toward the consumer product and toy levels⁶. A sand sample contained none of the compounds they targeted.

Indoor samples ran higher than outdoor ones, matching the federal finding of more chemicals in indoor field air¹. For soft play rooms, indoor play surfacing covers the alternatives.

Mouthing is the exposure that matters

The CPSC survey measures the behavior every risk model has to guess at. Of the 1,266 parents who answered the mouthing question, 26% said their child puts pieces of the loose material in their mouth at least sometimes, and about 11% said once a visit or more⁴. Over a third said their child picks pieces up more than once a visit. The question covered all loose material, not rubber alone, so wood fiber gets mouthed too, but wood fiber is not a tire.

The CPSC's advice follows from that³: avoid mouth contact with surfacing, "including mouthing, chewing, or swallowing playground rubber"; no eating or drinking on the surface; wash hands and exposed skin after the visit; clean toys used there; and limit time at the playground on extremely hot days.

The heat point has a chemical side: in the federal tests, emissions of most semivolatile and many volatile compounds were low at 25 C but higher for some at 60 C¹. Surface burns are the more immediate summer hazard, covered in heat and burn risk. The hand-washing routine is the one that applies to old CCA-treated playsets, and cleaning and sanitizing covers toys and surfaces.

Who should choose something else

For a school-age child who washes their hands after play, the measurements give no reason to stay away. Three settings change that.

Poured-in-place rubber and rubber tiles are not something a child can pick up and chew, though the two over-limit samples in the 2021 study were both tiles. Sand has its own label question, covered in is play sand safe, and sand and pea gravel covers fall performance.

Where this answer stops

The California figures come from a 2007 pilot study, described through OEHHA's own 2026 summary⁵. The federal biomonitoring involved sports players, not small children¹. The lab studies came from a Spanish university team, and the 2021 authors note that crumb from tires made outside the EU has been found to carry more PAHs⁶. No source here tested a US brand of rubber mulch or followed children over years. The CPSC says further playground work "will depend on availability of resources and agency priorities"³.

What to do next

If you already have rubber mulch on a playground for school-age children, keep it, wash hands after play and keep food off the surface. If you are buying, ask for a PAH result against the EU 20 mg/kg basis with the impact report. For toddlers, childcare or indoors, price an alternative.

The main rubber mulch page covers depth, cost and the wire question, and can rubber mulch catch fire? covers the other risk people ask about. To compare materials over their whole life, use the surfacing cost comparison, and check depth against fall height in the depth and fall height chart.