{"hq_id":"hq-p-out-000102","name":"Tire Recycling Crumb Rubber — PAHs and Heavy Metals in Playground Surfaces and Artificial Turf (Benzo[a]pyrene, Lead, Zinc, Children's Exposure)","category":{"primary":"waste_management","secondary":"tire_recycling","tags":["crumb rubber","tire recycling","PAH","benzo[a]pyrene","lead","zinc","playground","artificial turf","children","6PPD-quinone"]},"product_tier":"OUT","overall_risk_level":"moderate","description":"Recycled tire crumb rubber — ground from the 300 million scrap tires generated annually in the United States — is used as infill in 12,000-13,000 synthetic turf athletic fields and as surfacing material in thousands of playground fall zones. This creates direct, prolonged exposure of children and athletes to a complex mixture of chemicals inherent to tire composition: polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (IARC Group 1 carcinogen), heavy metals including lead (50-100 mg/kg), zinc (8,000-20,000 mg/kg — leaches at acutely toxic levels to aquatic organisms), cadmium, and the recently identified tire-derived chemical 6PPD-quinone — a transformation product of the rubber antioxidant 6PPD that is acutely lethal to coho salmon at 0.8 ug/L (discovered 2020). Children playing on crumb rubber surfaces ingest particles through hand-to-mouth behavior, inhale volatilized PAHs during hot weather (surface temperatures of crumb rubber turf reach 60-80C/140-175F — 30-40C above natural grass), and experience dermal contact with rubber particulate embedded in skin abrasions ('turf burn'). The EPA/CDC/CPSC Federal Research Action Plan on Recycled Tire Crumb (2016-2019) found that while individual chemical concentrations in crumb rubber were generally below levels of concern, the cumulative multi-pathway exposure assessment and the presence of 6PPD-quinone (identified after the study) warrant continued investigation. Multiple European countries and US states have proposed or enacted restrictions on crumb rubber use, with the EU ECHA restriction proposal limiting PAH content to 20 mg/kg (sum of 8 PAHs) in granular infill materials.","synthesis":{"derived_risk_level":"moderate_to_high","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":2,"compounds_total":2,"synthesis_date":"2026-03-27","synthesis_version":"1.0.0"},"hazard_summary":{"sensitive_populations":"children on playgrounds (highest hand-to-mouth ingestion rate), young athletes on crumb rubber turf fields (dermal exposure through turf burns, inhalation during exercise), coho salmon and aquatic organisms (6PPD-quinone acute toxicity at 0.8 ug/L)","overall_risk":"moderate","primary_concerns":["PAHs including benzo[a]pyrene (IARC Group 1 carcinogen) volatilize from crumb rubber at elevated surface temperatures","6PPD-quinone: acutely lethal to coho salmon at 0.8 ug/L — ubiquitous in urban tire-derived runoff","Zinc leaching at 8,000-20,000 mg/kg — acutely toxic to aquatic organisms in stormwater runoff","Surface temperatures of crumb rubber reach 60-80C — 30-40C hotter than natural grass, increasing chemical volatilization"],"exposure_routes":"Ingestion (hand-to-mouth transfer of crumb rubber particles — primary route for children). Inhalation (volatilized PAHs at elevated surface temperatures). Dermal (embedded particles in turf burn abrasions, skin contact with hot surface). Aquatic (stormwater leaching of zinc and 6PPD-quinone)."},"exposure":{"routes":["ingestion","inhalation","dermal"],"contact_types":["ingestion_hand_to_mouth","inhalation_vapor","dermal_contact","dermal_abrasion"],"users":["child","athlete","aquatic_ecosystem"],"duration":"chronic","frequency":"weekly_to_daily","scenarios":["Child plays on crumb rubber playground surface — hand-to-mouth ingestion of rubber particles containing PAHs and lead","Soccer player slides on crumb rubber turf field on 35C day — 'turf burn' abrasion embeds rubber particles in open wound; surface temperature reaches 70C","Stormwater runoff from crumb rubber turf field carries zinc and 6PPD-quinone to urban stream — coho salmon acute mortality at 0.8 ug/L 6PPD-quinone","Hot weather volatilization: PAH vapor concentration above crumb rubber surface increases 3-5x at 60-80C surface temperatures vs ambient"],"notes":"Crumb rubber composition: natural rubber 20-30%, synthetic rubber (SBR) 25-35%, carbon black 25-30%, zinc oxide 1-2%, sulfur and accelerators 1-2%, processing oils (high PAH). Annual US scrap tire generation: ~300 million (4 million tonnes). Crumb rubber turf fields: 12,000-13,000 in US. Playground surfacing: thousands of installations meeting ASTM F1292 fall impact. 6PPD-quinone: Tian et al. (2021, Science) — transformation product of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine; LC50 coho salmon 0.8 ug/L; ubiquitous in urban runoff. EPA/CDC/CPSC FRAP (2016-2019): Tire Crumb Rubber Characterization study — individual chemicals below concern levels but cumulative assessment warranted. EU ECHA restriction proposal: limit sum of 8 PAHs to 20 mg/kg in infill granules (from current limit of 100 mg/kg under REACH Entry 50). Washington state: first to ban 6PPD in tires (SB 5931, 2024 — phased ban by 2035)."},"consumer_guidance":{"usage_warning":"If your children play on crumb rubber playgrounds or artificial turf fields, ensure they wash hands thoroughly before eating. Avoid hot-weather use when surface temperatures exceed 60C (check with infrared thermometer — crumb rubber surfaces routinely reach 70C+ on sunny days when air temperature exceeds 30C). If your child sustains a 'turf burn' abrasion, clean the wound thoroughly to remove embedded rubber particles. Support transitions to safer infill alternatives when your municipality or school district resurfaces turf fields.","safer_alternatives":["Cork infill for artificial turf (Amorim, Shaw Sports) — natural, no PAHs or 6PPD","Coconut fiber/husk infill — organic, biodegradable, no tire-derived chemicals","EPDM virgin rubber infill — lower PAH content than recycled tire crumb","Natural grass fields maintained for athletic use","Wood fiber or engineered wood fiber (EWF) for playground surfacing"]},"regulatory":{"applicable_regulations":[{"jurisdiction":"USA","regulation":"EPA/CDC/CPSC Federal Research Action Plan on Recycled Tire Crumb and State Restrictions","citation":"EPA FRAP Tire Crumb Study (2016-2019); Washington SB 5931 (6PPD ban, 2024); EU ECHA REACH Entry 50 PAH restriction proposal for infill","requirements":"No federal ban or restriction on crumb rubber infill in US. EPA FRAP study (2019) concluded further research needed. Washington state SB 5931: first-in-nation ban on 6PPD in tires (phased implementation by 2035). California AB 1423 (2021): requires disclosure of chemicals in artificial turf. EU ECHA: proposed restriction limiting sum of 8 PAHs to 20 mg/kg in infill (current REACH Entry 50 limit 100 mg/kg).","compliance_status":null,"effective_date":null,"enforcing_agency":"EPA / State environmental agencies / ECHA","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":true,"disposal_guidance":"End-of-life crumb rubber infill from turf field replacement should be collected and managed as special waste — not spread on landscapes or dumped. Some tire-derived fuel facilities accept spent crumb rubber. Stormwater treatment at crumb rubber turf installations recommended to capture zinc and 6PPD-quinone before waterway discharge.","hazardous_waste":false,"expected_lifespan":"Crumb rubber turf field: 8-12 year surface life; crumb rubber persists in environment indefinitely; 6PPD-quinone generated continuously from tire wear"},"formulation":{"form":"varies","key_ingredients":[],"certifications":[]},"materials":{"common":[],"concerning":[],"preferred":[]},"compound_composition":[{"hq_id":"hq-c-org-000005","compound_name":null,"role":"tire_component","typical_concentration":"benzo[a]pyrene in crumb rubber: 1-20 mg/kg; IARC Group 1 carcinogen; volatilizes at elevated surface temperatures (60-80C on hot days)"},{"hq_id":"hq-c-ino-000001","compound_name":null,"role":"tire_contaminant","typical_concentration":"lead in crumb rubber: 50-100 mg/kg; zinc 8,000-20,000 mg/kg (leaches to levels acutely toxic to aquatic life)"}],"identifiers":{"common_names":["tire recycling crumb rubber — pahs and heavy metals in playground surfaces and artificial turf (benzo[a]pyrene, lead, zinc, children's exposure)"],"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":"2026-05-01T14:23:42.878Z"}}