STILLWATER INDUSTRIAL PARK
December 1, 1997
Exposure Investigation and Consultation Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
BACKGROUND AND STATEMENT OF ISSUES
A private citizen asked the Agency for Toxic Substances and DiseaseRegistry (ATSDR) to assess the health hazard posed by ambient aircontamination in and around the Stillwater Industrial Park. TheStillwater Industrial Park contains six major industrialfacilities, but only one, Moore Document Solutions, had anemissions inventory that showed significant emissions oftetrachloroethylene (PCE).
Between June 23-29, 1997, a contractor for the Oklahoma Departmentof Environmental Quality conducted ambient air monitoring for PCEaround the property of Moore Document Solutions. Using Tenaxtubes, the contractor collected 24-hour ambient air samples at twodownwind and one upwind location. The sampling locations were justbeyond the Moore Document Solutions property line. It rained onJune 26, 27, and 29; on these days, the air sampling tubes wereturned upside down to avoid collecting moisture, to the extentpossible.
Analysis of two of the samples revealed peak splitting and lowinternal standard recoveries due to high moisture in the tubes(these samples were collected on a rain day). Because of thisQA/QC problem, ATSDR did not include these two samples in itsanalysis of the data. In the remaining 19 samples, PCEconcentrations ranged from 0.037 µg/m3 to 5.365 µg/m3. In general,the concentrations of PCE at the downwind stations exceeded theconcentrations at the upwind station.
Human exposure to high concentrations of PCE can affectneurological function, as evidenced by an increase in reaction time. To protect against such adverse effects, ATSDR developed achronic Minimal Risk Level of 40 parts per billion (ppb) or about270 µg/m3. This concentration is 50 times higher than the maximumconcentration of PCE detected in ambient air samples from the site. Therefore, the reported levels of PCE in ambient air does not posea significant risk of non-cancer toxic effects.
Experimental studies have demonstrated that inhalation exposure tohigh concentrations of PCE may increase the rate of some cancers inlaboratory animals. However, a number of epidemiological studiesof men and women who were occupationally exposed to highconcentrations PCE have not identified a statistically significantincrease in the prevalence of cancer . ATSDR concluded that,"Conclusive proof of the carcinogenic potential oftetrachloroethylene in humans is lacking ." Therefore, based onavailable evidence, potential human exposure to the low levels ofPCE detected in ambient air at the Stillwater Industrial Park wouldnot be expected to pose a significant cancer risk.
|(1)||The concentrations of tetrachloroethylene detected in ambient air near the Moore Document Solutions property do not pose a public health hazard.|
|Kenneth G. Orloff, Ph.D. |
|(1)||Agency for Toxic Substances and Disease Registry; Toxicological Profile for Tetrachloroethylene (Draft Update); August 1995. |
|(2)||Agency for Toxic Substances and Disease Registry; ATSDR Case Studies in Environmental Medicine: Tetrachloroethylene Toxicity; June 1990.|