title: Approaches for describing and communicating overall uncertainty in toxicity characterizations: U.S. Environmental Protection Agency's Integrated Risk Information System (IRIS) as a case study.
abstract: Single point estimates of human health hazard/toxicity values such as a reference dose (RfD) are generally used in chemical hazard and risk assessment programs for assessing potential risks associated with site- or use-specific exposures. The resulting point estimates are often used by risk managers for regulatory decision-making, including standard setting, determination of emission controls, and mitigation of exposures to chemical substances. Risk managers, as well as stakeholders (interested and affected parties), often have limited information regarding assumptions and uncertainty factors in numerical estimates of both hazards and risks. Further, the use of different approaches for addressing uncertainty, which vary in transparency, can lead to a lack of confidence in the scientific underpinning of regulatory decision-making. The overarching goal of this paper, which was developed from an invited participant workshop, is to offer five approaches for presenting toxicity values in a transparent manner in order to improve the understanding, consideration, and informed use of uncertainty by risk assessors, risk managers, and stakeholders. The five approaches for improving the presentation and communication of uncertainty are described using U.S. Environmental Protection Agency's (EPA's) Integrated Risk Information System (IRIS) as a case study. These approaches will ensure transparency in the documentation, development, and use of toxicity values at EPA, the Agency for Toxic Substances and Disease Registry (ATSDR), and other similar assessment programs in the public and private sector. Further empirical testing will help to inform the approaches that will work best for specific audiences and situations.
authors.affiliation: American Chemistry Council, 700 2nd St NE, Washington, DC 20002, United States. Electronic address: nancy_beck@americanchemistry.com.
authors.forename: Nancy B
authors.initials: NB
authors.lastname: Beck
authors.affiliation: American Chemistry Council, 700 2nd St NE, Washington, DC 20002, United States. Electronic address: rick_becker@americanchemistry.com.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Becker
authors.affiliation: Texas Commission on Environmental Quality, PO Box 13087, Austin, TX 78711, United States. Electronic address: Neeraja_Erraguntla@americanchemistry.com.
authors.forename: Neeraja
authors.initials: N
authors.lastname: Erraguntla
authors.affiliation: Colorado State University, 135 Physiology (1680 Campus Delivery), Fort Collins, CO 80523, United States. Electronic address: William.Farland@ColoState.edu.
authors.forename: William H
authors.initials: WH
authors.lastname: Farland
authors.affiliation: Texas Commission on Environmental Quality, PO Box 13087, Austin, TX 78711, United States. Electronic address: robertagrant1357@gmail.com.
authors.forename: Roberta L
authors.initials: RL
authors.lastname: Grant
authors.affiliation: Milken Institute School of Public Health, George Washington University,950 New Hampshire Ave, NW, Washington, DC 20051, United States. Electronic address: gmgray@gwu.edu.
authors.forename: George
authors.initials: G
authors.lastname: Gray
authors.affiliation: Summit Toxicology LLP, 29449 Pike Drive, Orange Village, OH 44022, United States. Electronic address: ckirman@summittoxicology.com.
authors.forename: Christopher
authors.initials: C
authors.lastname: Kirman
authors.affiliation: LaKind Associates, LLC; Department of Epidemiology and Public Health, University of Maryland School of Medicine, Milton S. Hershey Medical Center, 106 Oakdale Ave. Catonsville, MD 21228, United States; Department of Pediatrics, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, 106 Oakdale Ave., Catonsville, MD 21228, United States. Electronic address: lakindassoc@gmail.com.
authors.forename: Judy S
authors.initials: JS
authors.lastname: LaKind
authors.affiliation: ExxonMobil Biomedical Sciences, 1545 US Highway 22 East, Annandale, NJ 08801, United States. Electronic address: r.jeffrey.lewis@exxonmobil.com.
authors.forename: R
authors.initials: R
authors.lastname: Jeffrey Lewis
authors.affiliation: Toxicology Excellence for Risk Assessment (TERA) Center, Department of Environmental Health College of Medicine, University of Cincinnati, 160 Panzeca Way, Kettering Laboratory, Room G24, Cincinnati, OH 45267, United States. Electronic address: patricia.nance@uc.edu.
authors.forename: Patricia
authors.initials: P
authors.lastname: Nance
authors.affiliation: The Dow Chemical Company, Toxicology and Environmental Research and Consulting, Midland, MI 48674, United States.
authors.forename: Lynn H
authors.initials: LH
authors.lastname: Pottenger
authors.affiliation: FOCUS GROUP Risk Communication and Environmental Management Consultants, 29 Welgate Rd., Medford, MA 02155, United States. Electronic address: ssantos.focusgroup@comcast.net.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Santos
authors.affiliation: Texas Commission on Environmental Quality, PO Box 13087, Austin, TX 78711, United States. Electronic address: stephanieharkeyshirley@gmail.com.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Shirley
authors.affiliation: Ted Simon LLC, 4184 Johnston Rd, Winston, GA 30187, United States. Electronic address: ted@tedsimon-toxicology.com.
authors.forename: Ted
authors.initials: T
authors.lastname: Simon
authors.affiliation: Toxicology Excellence for Risk Assessment (TERA) Center, Department of Environmental Health College of Medicine, University of Cincinnati, 160 Panzeca Way, Kettering Laboratory, Room G24, Cincinnati, OH 45267, United States. Electronic address: michael.dourson@uc.edu.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Dourson
mesh_terms: D003657:Decision Making; D015386:Hazardous Substances / Q000633:toxicity*; D006801:Humans; D007255:Information Services / Q000458:organization & administration* / Q000706:statistics & numerical data; D018570:Risk Assessment; D035501:Uncertainty; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D015386:Hazardous Substances
keywords: Hazard; Hazard communication; Risk assessment; Risk communication; Toxicity characterization; Uncertainty