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Filters: Author is Kelly Moran  [Clear All Filters]
2024
Mayer, P.; Moran, K.; Miller, E.; Brander, S.; Harper, S.; Garcia-Jaramillo, M.; Carrasco-Navarro, V.; Ho, K. T.; Burgess, R. M.; Hampton, L. M. Thornto; et al. 2024. Where the rubber meets the road: Emerging environmental impacts of tire wear particles and their chemical cocktails. Science of the Total Environment 927.

About 3 billion new tires are produced each year and about 800 million tires become waste annually. Global dependence upon tires produced from natural rubber and petroleum-based compounds represents a persistent and complex environmental problem with only partial and often-times, ineffective solutions. Tire emissions may be in the form of whole tires, tire particles, and chemical compounds, each of which is transported through various atmospheric, terrestrial, and aquatic routes in the natural and built environments. Production and use of tires generates multiple heavy metals, plastics, PAH's, and other compounds that can be toxic alone or as chemical cocktails. Used tires require storage space, are energy intensive to recycle, and generally have few post-wear uses that are not also potential sources of pollutants (e.g., crumb rubber, pavements, burning). Tire particles emitted during use are a major component of microplastics in urban runoff and a source of unique and highly potent toxic substances. Thus, tires represent a ubiquitous and complex pollutant that requires a comprehensive examination to develop effective management and remediation. We approach the issue of tire pollution holistically by examining the life cycle of tires across production, emissions, recycling, and disposal. In this paper, we synthesize recent research and data about the environmental and human health risks associated with the production, use, and disposal of tires and discuss gaps in our knowledge about fate and transport, as well as the toxicology of tire particles and chemical leachates. We examine potential management and remediation approaches for addressing exposure risks across the life cycle of tires. We consider tires as pollutants across three levels: tires in their whole state, as particulates, and as a mixture of chemical cocktails. Finally, we discuss information gaps in our understanding of tires as a pollutant and outline key questions to improve our knowledge and ability to manage and remediate tire pollution.

 (4.66 MB)
2023
Moran, K.; Gilbreath, A.; Méndez, M.; Lin, D.; Sutton, R. 2023. Tire Wear: Emissions Estimates and Market Insights to Inform Monitoring Design. SFEI Contribution No. 1109. San Francisco Estuary Institute: Richmond, CA.

Every vehicle on the road sheds tiny particles from its rubber tires into the environment. Tire wear is one of the top sources of microplastic releases to the environment. Tire wear also disperses tire-related chemicals into the environment. SFEI studies supported by the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) and others have found tire wear particles and tire-related chemicals in San Francisco Bay and its small tributaries, which drain the Bay watershed’s local urban areas. The RMP has developed a short-term multi-year plan of potential special studies (“Tires Strategy”) that responds to recent data revealing the magnitude of tire particle and chemical emissions and their potential toxicity to aquatic organisms.

This article is available upon request. Please message [email protected] for the materials.

2022
Moran, K.; Askevold, R. 2022. Microplastics from Tire Particles in San Francisco Bay Factsheet. SFEI Contribution No. 1074. San Francisco Estuary Institute: Richmond, CA.

As we drive our cars, our tires shed tiny particles

When it rains, stormwater runoff carries tire particles—and the toxic chemicals they contain—from city streets and highways to storm drains and fish habitat in creeks and estuaries like San Francisco Bay. Stormwater washes trillions of tire particles into the Bay each year.

How do tires affect wildlife?

A recent study found a highly toxic chemical (“6PPD-quinone”) derived from vehicle tires in Bay Area stormwater at levels that are lethal to coho salmon. New data indicate that steelhead, a salmon species still migrating through the Bay to surrounding watersheds, are also sensitive to this chemical.

 (1.38 MB)
2021
Moran, K.; Miller, E.; Mendez, M.; Moore, S.; Gilbreath, A.; Sutton, R.; Lin, D. 2021. A Synthesis of Microplastic Sources and Pathways to Urban Runoff. SFEI Contribution No. 1049. San Francisco Estuary Institute: Richmond, CA.

California Senate Bill 1263 (2018) tasks the Ocean Protection Council (OPC) with leading statewide efforts to address microplastic pollution, and requires the OPC to adopt and implement a Statewide Microplastics Strategy related to microplastic materials that pose an emerging concern for ocean health. Key questions remain about the sources and pathways of microplastics, particularly to urban runoff, to inform an effective statewide microplastics management strategy. The OPC funded this work to inform these microplastics efforts. The purpose of this project was to build conceptual models that synthesize and integrate our current understanding of microplastic sources and pathways to urban runoff in order to provide future research priorities that will inform how best to mitigate microplastic pollution. Specifically, we developed conceptual models for cigarette butts and associated cellulose acetate fibers (Section 2), fibers other than cellulose acetate (Section 3), single-use plastic foodware and related microplastics (Section 4), and tire particles (Section 5), which were prioritized based on findings from the recent urban stormwater monitoring of microplastics in the San Francisco Bay region. Conceptual models specific to each of these particle types are valuable tools to refine source identification and elucidate potential source-specific data gaps and management options.

 (9.17 MB)
2019
Sutton, R.; Xie, Y.; Moran, K. D.; Teerlink, J. 2019. Occurrence and Sources of Pesticides to Urban Wastewater and the Environment. In Pesticides in Surface Water: Monitoring, Modeling, Risk Assessment, and Management. Pesticides in Surface Water: Monitoring, Modeling, Risk Assessment, and Management. American Chemical Society: Washington, DC. pp 63-88.

Municipal wastewater has not been extensively examined as a pathway by which pesticides contaminate surface water, particularly relative to the well-recognized pathways of agricultural and urban runoff. A state-of-the-science review of the occurrence and fate of current-use pesticides in wastewater, both before and after treatment, indicates this pathway is significant and should not be overlooked. A comprehensive conceptual model is presented to establish all relevant pesticide-use patterns with the potential for both direct and indirect down-the-drain transport. Review of available studies from the United States indicates 42 pesticides in current use. While pesticides and pesticide degradates have been identified in wastewater, many more have never been examined in this matrix. Conventional wastewater treatment technologies are generally ineffective at removing pesticides from wastewater, with high removal efficiency only observed in the case of highly hydrophobic compounds, such as pyrethroids. Aquatic life reference values can be exceeded in undiluted effluents. For example, seven compounds, including three pyrethroids, carbaryl, fipronil and its sulfone degradate, and imidacloprid, were detected in treated wastewater effluent at levels exceeding U.S. Environmental Protection Agency (US EPA) aquatic life benchmarks for chronic exposure to invertebrates. Pesticides passing through wastewater treatment plants (WWTPs) merit prioritization for additional study to identify sources and appropriate pollution-prevention strategies. Two case studies, diazinon and chlorpyrifos in household pesticide products, and fipronil and imidacloprid in pet flea control products, highlight the importance of identifying neglected sources of environmental contamination via the wastewater pathway. Additional monitoring and modeling studies are needed to inform source control and prevention of undesirable alternative solutions.

2017
Sadaria, A. M.; Sutton, R.; Moran, K. D.; Teerlink, J.; Brown, J. V.; Halden, R. U. 2017. Passage of fiproles and imidacloprid from urban pest control uses through wastewater treatment plants in northern California. Environmental Toxicology and Chemistry 36, 1473-1482 . SFEI Contribution No. 783.

Urban pest control insecticides, specifically fipronil and its four major degradates (fipronil sulfone, sulfide, desulfinyl, and amide) and imidacloprid, were monitored during drought conditions in eight San Francisco Bay wastewater treatment plants (WWTPs). In influent and effluent, ubiquitous detections were obtained in units of ng/L for fipronil (13-88), fipronil sulfone (1-28), fipronil sulfide (1-5) and imidacloprid (58-306). In influent, 100% of imidacloprid and 62 ± 9% of total fiproles (fipronil and degradates) were present in the dissolved state, with the balance being bound to filter-removable particulates. Targeted insecticides persisted during wastewater treatment, regardless of treatment technology utilized (imidacloprid: 93 ± 17%; total fiproles: 65 ± 11%), with partitioning into sludge (3.7-151.1 μg/kg dry weight as fipronil) accounting for minor losses of total fiproles entering WWTPs. The load of total fiproles was fairly consistent across the facilities but fiprole speciation varied. This first regional study on fiprole and imidacloprid occurrences in raw and treated California sewage revealed ubiquity and marked persistence to conventional treatment of both phenylpyrazole and neonicotinoid compounds. Flea and tick control agents for pets are identified as potential sources of pesticides in sewage meriting further investigation and inclusion in chemical-specific risk assessments.