The popularity of Poured-in-Place (PIP) surfaces in kids' play zones stems from their soft rubber cushioning for falls and their role in recycling scrap car and truck tires. Playgrounds and sports fields often feature recycled tire crumb rubber loaded with polycyclic aromatic hydrocarbons, or PAHs, which can include carcinogenic ones. A new study warns this material may leach harmful chemicals. PAHs resist rapid degradation, lingering in soil and water long-term, threatening ecosystems and stirring concerns for human exposure risks.
Exposure happens through direct skin absorption, ingestion of crumb particles, and inhalation of released vapors or dust, amplified on hot days. This repeated contact during play heightens potential chronic health risks.
The study team examined granulate made from discarded vehicle tires, evaluating total PAH content and the bioavailable portion that dissolves in water for organism uptake. The smallest tested particles had over twice the contamination, and because they're more reactive, they release a larger fraction of toxins into the environment.
To mimic environmental threats, the team exposed soil springtails, garden cress, and marine bacteria to rubber granulate and soaked water. Springtails suffered the worst. The tiniest rubber particles killed 70% outright, and survivors couldn't reproduce at all. Even the biggest chunks killed a third and cut reproduction by over half.
The study identified potentially harmful metals including zinc and copper leaching into water from the granulate, with some concentrations above drinking-water limits, intensifying toxicity concerns.
While affirming tire recycling as an important eco-goal, the researchers cautioned that recycled products aren't always safe by default. This work highlights the need to rethink assessment protocols and usage guidelines for recycled tire granulate.
To view the original scientific study click below:
Toxicity and polycyclic aromatic hydrocarbons bioavailability in recycled tire rubber granulate of varying particle sizes
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