2. Academic Validation
  3. Screening p-Phenylenediamine Antioxidants, Their Transformation Products, and Industrial Chemical Additives in Crumb Rubber and Elastomeric Consumer Products

Screening p-Phenylenediamine Antioxidants, Their Transformation Products, and Industrial Chemical Additives in Crumb Rubber and Elastomeric Consumer Products

  • Environ Sci Technol. 2023 Feb 21;57(7):2779-2791. doi: 10.1021/acs.est.2c07014.
Haoqi Nina Zhao 1 2,  Ximin Hu 1 2,  Melissa Gonzalez 2,  Craig A Rideout 2,  Grant C Hobby 3,  Matthew F Fisher 3,  Carter J McCormick 3,  Michael C Dodd 1,  Kelly E Kim 3,  Zhenyu Tian 2 3 4,  Edward P Kolodziej 1 2 3
Affiliations

Affiliations

  • 1 Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington 98195, USA.
  • 2 Center for Urban Waters, Tacoma, Washington 98421, USA.
  • 3 Interdisciplinary Arts and Sciences, University of Washington Tacoma, Tacoma, Washington 98421, USA.
  • 4 Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, USA.
PMID: 36758188 DOI: 10.1021/acs.est.2c07014
Abstract

Recently, roadway releases of N,N'-substituted p-phenylenediamine (PPD) Antioxidants and their transformation products (TPs) received significant attention due to the highly toxic 6PPD-quinone. However, the occurrence of PPDs and TPs in recycled tire rubber products remains uncharacterized. Here, we analyzed tire wear particles (TWPs), recycled rubber doormats, and turf-field crumb rubbers for seven PPD Antioxidants, five PPD-quinones (PPDQs), and five Other 6PPD TPs using liquid chromatography-tandem mass spectrometry. PPD Antioxidants, PPDQs, and Other TPs were present in all samples with chemical profiles dominated by 6PPD, DTPD, DPPD, and their corresponding PPDQs. Interestingly, the individual [PPDQ]/[PPD] and [TP]/[PPD] ratios significantly increased as total concentrations of the PPD-derived chemical decreased, indicating that TPs (including PPDQs) dominated the PPD-derived compounds with increased environmental weathering. Furthermore, we quantified 15 Other industrial rubber additives (including bonding agents, vulcanization accelerators, benzotriazole and benzothiazole derivatives, and diphenylamine Antioxidants), observing that PPD-derived chemical concentrations were 0.5-6 times higher than these often-studied additives. We also screened various Other elastomeric consumer products, consistently detecting PPD-derived compounds in lab stoppers, sneaker soles, and rubber garden hose samples. These data emphasize that PPD Antioxidants, PPDQs, and related TPs are important, previously overlooked contaminant classes in tire rubbers and elastomeric consumer products.

Keywords

PPD antioxidants; PPD-quinones; crumb rubber; elastomeric consumer products; environmental contaminants; weathering.

Figures
Products
  • Cat. No.
    Product Name
    Description
    Target
    Research Area
  • HY-176747
    99.1%, Antioxidant