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Crumb rubber toxicity in coastal marine systems

Halsband-Lenk, Claudia; Herzke, Dorte; Sørensen, Lisbet; Booth, Andy

Publication details

Event: SETAC Europe 30th Annual Meeting (Online)

Date: May 3rd 2020 – May 7th 2020

Crumb rubber granulate (CRG) produced from end of life tires (ELTs) is commonly applied on indoor and outdoor synthetic turf pitches (STPs), playgrounds, safety surfaces and walkways. In addition to fillers, stabilizers, cross-linking agents and secondary components (e.g. pigments, oils, resins, fibers), ELTs contain high levels of organic additive compounds and heavy metals. While previous environmental studies have focused on terrestrial soil and freshwater ecosystems, in Norway many sites applying CRG are coastal. In the current study, the organic chemical and metal content of 'fresh' and 'weathered' CRG and their seawater leachates was investigated, and the uptake of crumb rubber by the brown crab (Cancer pagurus) was studied as an example of an exposure route for CRG to coastal marine organisms. A combination of pyrolysis gas chromatography mass spectrometry (py-GC-MS) and chemical extraction followed by GC-MS analysis revealed similar organic chemical profiles for pristine and weathered CRG, including additives such as benzothiazole, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine and a range of polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds (e.g. bisphenols). ICP-MS analysis indicated g/kg quantities of Zn and mg/kg quantities of Fe, Mn, Cu, Co, Cr, Pb and Ni in the CRG. A mixture of organic additives, metals and other inorganic compounds readily leached from the CRG into seawater. Benzothiazole was the organic compound with highest concentration (average of 136 mg/L), while PAHs (ranging from <LOD to 0.58 mg/L) and phenolic compounds (e.g. 2,4-bisphenol F and 4,4’-bisphenol F at 0.012 and 0.006 mg/L, respectively) were present in low abundance. Zn was the most abundant metal in the leachates (23.8 mg/L) followed by Fe (0.08 mg/L) and Co (0.06 mg/L). While organic chemical concentrations in the leachates stabilized within days, metals continued to leach out over the 30 day period. Brown crabs were exposed to two concentrations of CRG (0.5 and 0.05 g/L) in two size fractions (5 mm and 250 µm diameter) for 24 hours. Ingestion of the rubber and subsequent gut evacuation were studied over 5 days. Image analysis of filtered stomach contents confirmed uptake of rubber particles in different sizes, but also efficient gut evacuation upon transfer to clean water. We discuss the implications of CRG and leachate toxicity in acute and long-term exposure scenarios for marine coastal ecosystems.