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Stack ME, Hollman K, Mladenov N, Harper B, Pinongcos F, Sant KE, Rochman CM, Richardot W, Dodder NG, Hoh E. Micron-size tire tread particles leach organic compounds at higher rates than centimeter-size particles: Compound identification and profile comparison. Environ Pollut 2023; 334:122116. [PMID: 37394053 DOI: 10.1016/j.envpol.2023.122116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 06/12/2023] [Accepted: 06/25/2023] [Indexed: 07/04/2023]
Abstract
Tire tread particles (TTP) are environmentally prevalent microplastics and generate toxic aqueous leachate. We determined the total carbon and nitrogen leachate concentrations and chemical profiles from micron (∼32 μm) and centimeter (∼1 cm) TTP leachate over 12 days. Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were used to measure the concentration of leached compounds. Nontargeted chemical analysis by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS) was used to compare the chemical profiles of leachates. After leaching for 12 days, DOC was 4.0 times higher in the micron TTP leachate than in the centimeter TTP leachate, and TDN was 2.6 times higher. The total GC×GC/TOF-MS chromatographic feature peak area was 2.9 times greater in the micron TTP leachate than the centimeter TTP leachate, and similarly, the total relative abundance of 54 tentatively identified compounds was 3.3 times greater. We identified frequently measured tire-related chemicals, such as 6PPD, N-cyclohexyl-N'-phenylurea (CPU), and hexa(methoxymethyl)melamine (HMMM), but nearly 50% of detected chemicals were not previously reported in tire literature or lacked toxicity information. Overall, the results demonstrate that smaller TTP have a greater potential to leach chemicals into aquatic systems, but a significant portion of these chemicals are not well-studied and require further risk assessment.
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Affiliation(s)
- M E Stack
- San Diego State University Research Foundation, San Diego, CA, 92182, USA
| | - K Hollman
- Department of Civil, Construction, and Environmental Engineering, San Diego State University, San Diego, CA, 92182, USA
| | - N Mladenov
- Department of Civil, Construction, and Environmental Engineering, San Diego State University, San Diego, CA, 92182, USA
| | - B Harper
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, 97331, USA
| | - F Pinongcos
- Department of Civil, Construction, and Environmental Engineering, San Diego State University, San Diego, CA, 92182, USA
| | - K E Sant
- School of Public Health, San Diego State University, San Diego, CA, 92182, USA
| | - C M Rochman
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - W Richardot
- San Diego State University Research Foundation, San Diego, CA, 92182, USA
| | - N G Dodder
- San Diego State University Research Foundation, San Diego, CA, 92182, USA
| | - E Hoh
- School of Public Health, San Diego State University, San Diego, CA, 92182, USA.
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