Relationship between vapor intrusion and human exposure to trichloroethylene

Abstract

Trichloroethylene (TCE) in groundwater has the potential to volatilize through soil into indoor air where it can be inhaled. The purpose of this study was to determine whether individuals living above TCE-contaminated groundwater are exposed to TCE through vapor intrusion. We examined associations between TCE concentrations in various environmental media and TCE concentrations in residents. For this assessment, indoor air, outdoor air, soil gas, and tap water samples were collected in and around 36 randomly selected homes; blood samples were collected from 63 residents of these homes. Additionally, a completed exposure survey was collected from each participant. Environmental and blood samples were analyzed for TCE. Mixed model multiple linear regression analyses were performed to determine associations between TCE in residents' blood and TCE in indoor air, outdoor air, and soil gas. Blood TCE concentrations were above the limit of quantitation (LOQ; ≥ 0.012 µg L⁻¹) in 17.5% of the blood samples. Of the 36 homes, 54.3%, 47.2%, and >84% had detectable concentrations of TCE in indoor air, outdoor air, and soil gas, respectively. Both indoor air and soil gas concentrations were statistically significantly positively associated with participants' blood concentrations (P = 0.0002 and P = 0.04, respectively). Geometric mean blood concentrations of residents from homes with indoor air concentrations of >1.6 µg m⁻³ were approximately 50 times higher than geometric mean blood TCE concentrations in participants from homes with no detectable TCE in indoor air (P < .0001; 95% CI 10.4–236.4). This study confirms the occurrence of vapor intrusion and demonstrates the magnitude of exposure from vapor intrusion of TCE in a residential setting.

Keywords:

• Groundwater plume
• indoor air exposure
• soil gas exposure
• trichloroethylene
• vapor intrusion
• volatile organic compounds

Acknowledgments

The findings and conclusions of this report are those of the authors and do not necessarily represent the views of the Agency for Toxic Substances and Disease Registry or the Centers for Disease Control and Prevention. The authors would also like to thank Tina Walker, Tom Ellerbee, Nancy Ingram, David Rivera, Maria Smith, Linda Williams, Susan Prosperie, Jennifer Lyke, Matthew Jordan, Heather Powell, Joseph “Kip” Haney, Mike Aplin, Bret Kendrick, Greg Fife, and Rick Ehrhart for their contributions to this investigation.

Funding

Funding for this investigation was provided by the Texas Environmental Health Institute (TEHI) and ATSDR.