Release of Zinc and Polycyclic Aromatic Hydrocarbons From Tire Crumb Rubber and Toxicity of Leachate to Daphnia magna: Effects of Tire Source and Photoaging

Tire crumb rubber (TCR) has been widely used in artificial turf fields, however, the potential environmental risk of TCR and the effect of sunlight exposure are scarcely studied. Here, we evaluated leachability of Zn and polycyclic aromatic hydrocarbons (PAHs) in four types of TCRs and acute toxicity of leachates to Daphnia magna. The results showed that all types of TCRs tested released Zn (0.20-1.3 mu g/g) and PAHs (9.4-17 mu g/g) but only two were lethal to D. magna (mortality 73%). Notably, ultraviolet (UV) irradiation induced TCR to generate acidic leachate (pH similar to 4.8), which contained 24- and 1.2-fold higher concentrations of Zn and PAHs and therefore was more toxic to D. magna than that in the absence of UV treatment. These findings demonstrate source-dependent toxicity of TCR and highlight the need to consider the effect of photoaging when evaluating the environmental risks of TCR.

Automated summary

The study found that tire crumb rubber (TCR) poses potential environmental risks, especially when exposed to sunlight. UV irradiation can induce TCR to generate more toxic acidic leachate, causing more severe impacts on Daphnia magna. Therefore, the effect of photoaging should be considered when evaluating the environmental risks of TCR.