Release of Nitrosamines and Nitrosamine Precursors from Scrap Tires

Abstract

Materials used during manufacturing of tires can be a source of nitrosamines and/or their precursors. Here, we examined the leaching of nitrosamines and nitrosamine precursors from scrap tires under different test conditions. Tire chips of different sizes and crumb rubber were exposed to leaching solutions with pH values ranging from 4.0 to 10.0. Leachates collected from tires were analyzed for nitrosamines. Leachates were oxidized with chloramine, ozone, or ozone followed by chloramine to quantify the amount of nitrosamine precursors. While N-nitrosodimethylamine (NDMA) and N-nitrosomorpholine (NMOR) constituted more than 90% of nitrosamines, N-nitrosodibutylamine and N-nitrosopyrrolidine were also detected in the leachates. Chloramination of the leachate was found to form additional NDMA, NMOR, and other nitrosamines. While ozonation alone did not lead to formation of NDMA or NMOR, lower levels of formation of NDMA and NMOR were observed when ozonation was followed by chloramination as compared to those...