title: Managing risks of noncancer health effects at hazardous waste sites: A case study using the Reference Concentration (RfC) of trichloroethylene (TCE).
abstract: A method for determining a safety range for non-cancer risks is proposed, similar in concept to the range used for cancer in the management of waste sites. This safety range brings transparency to the chemical specific Reference Dose or Concentration by replacing their "order of magnitude" definitions with a scientifically-based range. EPA's multiple RfCs for trichloroethylene (TCE) were evaluated as a case study. For TCE, a multi-endpoint safety range was judged to be 3 μg/m(3) to 30 μg/m,(3) based on a review of kidney effects found in NTP (1988), thymus effects found in Keil et al. (2009) and cardiac effects found in the Johnson et al. (2003) study. This multi-endpoint safety range is derived from studies for which the appropriate averaging time corresponds to different exposure durations, and, therefore, can be applied to both long- and short-term exposures with appropriate consideration of exposure averaging times. For shorter-term exposures, averaging time should be based on the time of cardiac development in humans during fetal growth, an average of approximately 20-25 days.
authors.affiliation: Toxicology Excellence for Risk Assessment (TERA) Center, University of Cincinnati, OH, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Dourson
authors.affiliation: Toxicology Excellence for Risk Assessment (TERA) Center, University of Cincinnati, OH, USA. Electronic address: gadagbbd@ucmail.uc.edu.
authors.forename: Bernard K
authors.initials: BK
authors.lastname: Gadagbui
authors.affiliation: Risk Options, Indianapolis, IN, USA.
authors.forename: Rod B
authors.initials: RB
authors.lastname: Thompson
authors.affiliation: Hull & Associates, Inc., Dublin, OH, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Pfau
authors.affiliation: CH2M, Spokane, WA, USA.
authors.forename: John
authors.initials: J
authors.lastname: Lowe
mesh_terms: D000818:Animals; D003661:Decision Support Techniques; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring / Q000379:methods* / Q000592:standards; D004785:Environmental Pollutants / Q000009:adverse effects* / Q000032:analysis; D006256:Hazardous Waste / Q000009:adverse effects* / Q000032:analysis; D064371:Hazardous Waste Sites; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects; D012016:Reference Values; D018570:Risk Assessment; D017751:Safety Management; D013997:Time Factors; D018675:Toxicity Tests; D014241:Trichloroethylene / Q000009:adverse effects* / Q000032:analysis
chemical_list: D004785:Environmental Pollutants; D006256:Hazardous Waste; D014241:Trichloroethylene
keywords: Indoor air; Non-cancer hazard; Reference dose/concentration; Risk management; Safety range; Sensitive subpopulation; Short-term exposure; Trichloroethylene; Uncertainty factor; Vapor intrusion