Ingestion of Tyre Crumb Rubber and Uptake of Associated Contaminants in Marine Invertebrates (Pandalus borealis) and Fish (Cyclopterus lumpus) – An Experimental Exposure Study

Abstract

Crumb rubber (CR) produced from end of life vehicle tires is widely used on artificial sports fields and to create urban artificial surfaces. It is also used as a surrogate for tyre wear particles in experimental studies simulating the behaviour and effects of car tyre particles in the environment. It is known to contain a wide range of organic chemicals and metals, some of which are only just being identified and assessed. Weathering of such artificial surfaces releases both particles and the chemicals they contain into the environment, where they may be bioavailable and affect biota. N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) has been identified as a chemical marker for CR and tyre wear particles. Both 6PPD and its transformation product, 6PPD-quinone, have been shown to be toxic to a number of different freshwater and marine organisms. The current study examines the ingestion of CR (1 - 2.8; < 1.2 mm) by a marine invertebrate and fish, the gut retention time of ingested CR, and the tissue burden of tire-derived chemicals. Lumpfish (Cyclopterus lumpus) and Northern shrimp (Pandalus borealis) were exposed to CR in laboratory experiments for 21 days; 7 days of exposure to CR followed by 14 days of depuration. The stomach contents have been analyzed for ingested CR and selected tissues (Lumpfish liver and blood; Northern shrimp hepatopancreas and muscle) have been characterized for tire-associated chemicals and metals. Analytical chemical techniques involved ICP-MS, pyrolysis GC-MS, GC-MS/MS and HRGC-HRMS (ThermoFisher, Orbitrap). CR were found in 76% of exposed Lumpfish stomachs (n=90), where the number of CR particles in the stomach increased during the exposure and peaked around day 8 followed by a decrease throughout the depuration. Ingested CR was still found in some Lumpfish stomachs at the end of the experiment (day 21). Ingestion by Northern shrimp was analyzed by pyrolysis-GC/MS but. Analysis by HRGC/HRMS (ThermoFisher, Orbitrap) detected 6PPD up to 700 pg/g in blood from exposed Lumpfish, 6PPD was found both at the end of the exposure and at the end of depuration. ICP-MS analysis of metals did not show increased concentrations of metals in any of the tissues for exposed individuals or over time for either Lumpfish or Northern shrimp. The current results suggest that ingested CR can stay in the digestive system of Lumpfish longer than 14 days and that the particles may be leaching 6PPD during this period, suggesting bioavailability of both CR particles and associated chemicals to ecologically and commercially important marine organisms.