title: Addressing Emerging Risks: Scientific and Regulatory Challenges Associated with Environmentally Persistent Free Radicals.
abstract: Airborne fine and ultrafine particulate matter (PM) are often generated through widely-used thermal processes such as the combustion of fuels or the thermal decomposition of waste. Residents near Superfund sites are exposed to PM through the inhalation of windblown dust, ingestion of soil and sediments, and inhalation of emissions from the on-site thermal treatment of contaminated soils. Epidemiological evidence supports a link between exposure to airborne PM and an increased risk of cardiovascular and pulmonary diseases. It is well-known that during combustion processes, incomplete combustion can lead to the production of organic pollutants that can adsorb to the surface of PM. Recent studies have demonstrated that their interaction with metal centers can lead to the generation of a surface stabilized metal-radical complex capable of redox cycling to produce ROS. Moreover, these free radicals can persist in the environment, hence their designation as Environmentally Persistent Free Radicals (EPFR). EPFR has been demonstrated in both ambient air PM2.5 (diameter < 2.5 µm) and in PM from a variety of combustion sources. Thus, low-temperature, thermal treatment of soils can potentially increase the concentration of EPFR in areas in and around Superfund sites. In this review, we will outline the evidence to date supporting EPFR formation and its environmental significance. Furthermore, we will address the lack of methodologies for specifically addressing its risk assessment and challenges associated with regulating this new, emerging contaminant.
authors.affiliation: Department of Comparative Biomedical Sciences, LSU School of Veterinary Medicine, Baton Rouge, LA 70803, USA. tammydugas@lsu.edu.
authors.forename: Tammy R
authors.initials: TR
authors.lastname: Dugas
authors.affiliation: Department of Environmental Sciences, Louisiana State University and A &amp; M College, Baton Rouge, LA 70803, USA. slomni1@lsu.edu.
authors.forename: Slawomir
authors.initials: S
authors.lastname: Lomnicki
authors.affiliation: Department of Pediatrics, University of Tennessee Health Sciences Center and Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN 38103, USA. scormier@uthsc.edu.
authors.forename: Stephania A
authors.initials: SA
authors.lastname: Cormier
authors.affiliation: Department of Chemistry, Louisiana State University and A &amp; M College, Baton Rouge, LA 70803, USA. barryd@lsu.edu.
authors.forename: Barry
authors.initials: B
authors.lastname: Dellinger
authors.affiliation: Department of Environmental Sciences, Louisiana State University and A &amp; M College, Baton Rouge, LA 70803, USA. mreams@lsu.edu.
authors.forename: Margaret
authors.initials: M
authors.lastname: Reams
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D004781:Environmental Exposure / Q000009:adverse effects; D005609:Free Radicals / Q000633:toxicity*; D033161:Government Regulation; D006256:Hazardous Waste; D006801:Humans; D017745:Incineration; D052638:Particulate Matter / Q000633:toxicity*; D018570:Risk Assessment
chemical_list: D000393:Air Pollutants; D005609:Free Radicals; D006256:Hazardous Waste; D052638:Particulate Matter
keywords: PM2.5; combustion; free radicals; incineration; particulate matter; superfund sites