{"hq_id":"hq-p-out-000076","name":"Public Playground Rubber Surface — Tire Crumb Infill (6PPD-Quinone, Lead, PAH Exposure from Recycled Tire Rubber)","category":{"primary":"outdoor_environment","secondary":"playground_surface","tags":["tire crumb","rubber infill","6PPD-quinone","lead","PAH","playground","children","recycled tire","ground rubber"]},"product_tier":"OUT","overall_risk_level":"moderate","description":"Recycled tire crumb rubber is used as shock-absorbing infill in approximately 40,000 US playgrounds and athletic fields. The rubber granules release a complex mixture of chemicals including 6PPD-quinone (a transformation product of the antiozonant 6PPD that is acutely toxic to coho salmon at sub-microgram-per-liter concentrations), polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (a known human carcinogen), and heavy metals including lead (from tire manufacturing additives) and zinc (from vulcanization). Children playing on tire crumb surfaces experience dermal contact, hand-to-mouth ingestion of granules, and inhalation of volatile organic compounds off-gassing from heated rubber — surface temperatures on black crumb rubber can exceed 60C (140F) on sunny days, dramatically increasing VOC release. EPA's 2019 Federal Research Action Plan on Recycled Tire Crumb studied exposure pathways but stopped short of health-based regulation, concluding that while chemical exposures were detectable, cancer risk was low at population level. Environmental concerns are mounting: 6PPD-quinone washes off fields during rain events at concentrations lethal to Pacific salmon, prompting Washington State to ban 6PPD in tires by 2030.","synthesis":{"derived_risk_level":"moderate","synthesis_confidence":0.879,"synthesis_method":"compound_composition","context_used":"human_child","context_source":"product_users","exposure_modifier":1,"vulnerability_escalated":true,"escalation_reason":"Child exposure group","compounds_resolved":3,"compounds_total":3,"synthesis_date":"2026-03-27","synthesis_version":"1.0.0"},"hazard_summary":{"sensitive_populations":"children (hand-to-mouth ingestion, developing systems, prolonged playground exposure), coho salmon and aquatic invertebrates (6PPD-quinone lethality), athletes on synthetic turf","overall_risk":"moderate","primary_concerns":["Children ingest tire crumb granules via hand-to-mouth transfer during playground activity","6PPD-quinone runoff is acutely lethal to Pacific salmon at sub-ppb concentrations","PAH exposure increases dramatically when black rubber surfaces heat above 60C on sunny days","Lead and zinc leach from tire-derived rubber into soil and groundwater"],"exposure_routes":"Dermal (direct skin contact with rubber granules). Ingestion (hand-to-mouth transfer of crumb rubber, especially in young children). Inhalation (volatile PAHs and benzothiazole from heated surfaces). Environmental (stormwater runoff carrying 6PPD-quinone and metals)."},"exposure":{"routes":["dermal","ingestion","inhalation"],"contact_types":["dermal_direct","ingestion_hand_to_mouth","inhalation_incidental"],"users":["child","adult","aquatic_organism"],"duration":"chronic","frequency":"weekly","scenarios":["Child: dermal contact with crumb rubber granules during playground activity; hand-to-mouth ingestion of loose granules","Child: inhalation of volatile PAHs and benzothiazole from heat-expanded rubber on sunny days (surface temps >60C)","Athlete: prolonged sliding/diving contact on synthetic turf with crumb rubber infill","Environment: 6PPD-quinone runoff from fields during rain events entering waterways at salmon-lethal concentrations"],"notes":"EPA Federal Research Action Plan (FRAP, 2019): studied tire crumb exposure at 40 synthetic turf fields and playgrounds. Found detectable levels of PAHs, benzothiazole, 4-tert-octylphenol, and metals in air, surface wipes, and biological samples. Concluded cancer risk was low for typical exposure but acknowledged data gaps for children. 6PPD-quinone: discovered in 2020 (Tian et al., Science) as the causative agent of coho salmon urban runoff mortality syndrome. Washington State HB 1085 (2024): first US ban on 6PPD in tires, effective 2030. EU ECHA restriction proposal for PAHs in granular infill: limit of 20 mg/kg total PAHs (Regulation 2021/1199)."},"consumer_guidance":{"usage_warning":"Wash children's hands and exposed skin thoroughly after playing on crumb rubber surfaces. Avoid playgrounds with tire crumb infill on hot sunny days when VOC off-gassing is highest. Discourage children from picking up or mouthing rubber granules. Check shoes and clothing for embedded granules before entering homes. Advocate for municipal adoption of safer infill alternatives.","safer_alternatives":["Poured-in-place rubber (bound rubber — reduced loose granule exposure)","Engineered wood fiber (EWF) playground surfacing","Cork-based synthetic turf infill (PFAS-free, lower chemical leaching)","Coconut coir or rice husk infill alternatives","Sand or pea gravel for younger children's play areas"]},"regulatory":{"applicable_regulations":[{"jurisdiction":"USA","regulation":"EPA Federal Research Action Plan on Recycled Tire Crumb (FRAP)","citation":"EPA 600/R-19/051 (2019); Washington State HB 1085 (2024)","requirements":"EPA FRAP studied exposure but did not establish regulatory limits for tire crumb chemicals on playgrounds. EU Regulation 2021/1199 limits total PAHs in granular infill to 20 mg/kg. Washington State banned 6PPD in tires effective 2030 — first US jurisdiction. No federal playground surface chemical standards exist. CPSC regulates fall height and impact attenuation only.","compliance_status":null,"effective_date":"2019-07-25","enforcing_agency":"EPA Office of Research and Development; Washington State Department of Ecology","penalties":null,"source_ref":null}],"certifications":[],"labeling":{"required_disclosures":[],"prop65_warning":{"required":null,"chemicals":[],"endpoint":null,"notes":null},"ghs_labeling":{"required":null,"signal_word":null,"pictograms":[],"hazard_statements":[],"notes":null},"hidden_ingredients":{"trade_secret_protected":null,"categories_hidden":[],"estimated_count":null,"known_concerns":null,"notes":null},"notes":null},"recalls":[],"regulatory_gap":null,"notes":null},"lifecycle":{"recyclable":false,"disposal_guidance":"Spent crumb rubber infill should be disposed of at permitted solid waste facilities. Do not dump in waterways or storm drains due to 6PPD-quinone and metal leaching.","hazardous_waste":false,"expected_lifespan":"8-12 years before infill replacement needed; chemical leaching continues throughout lifespan"},"formulation":{"form":"varies","key_ingredients":[],"certifications":[]},"materials":{"common":[],"concerning":[],"preferred":[]},"compound_composition":[{"hq_id":"hq-c-org-002083","compound_name":null,"role":"transformation_product","typical_concentration":"6PPD-quinone leaches from tire rubber; acutely lethal to coho salmon at 0.8 ug/L; detected in playground runoff"},{"hq_id":"hq-c-ino-000001","compound_name":null,"role":"contaminant","typical_concentration":"lead from tire manufacturing additives; concentrations 2-50 ppm in crumb rubber samples (EPA FRAP 2019)"},{"hq_id":"hq-c-org-000005","compound_name":null,"role":"contaminant","typical_concentration":"PAHs including benzo[a]pyrene from carbon black and petroleum-derived rubber components; surface heat increases volatilization"}],"identifiers":{"common_names":["public playground rubber surface — tire crumb infill (6ppd-quinone, lead, pah exposure from recycled tire rubber)"],"aliases":[],"manufacturer":null,"brands":[]},"brand_examples":[],"sources":[{"type":"expert_curation","name":"ALETHEIA Safety Database","date":"2026-03-26"}],"meta":{"schema_version":"4.0.0","last_updated":"2026-03-26","timestamp":"2026-05-01T14:24:55.474Z"}}