HEALTH CONSULTATION
STILLWATER INDUSTRIAL PARK
STILLWATER, OKLAHOMA
December 1, 1997
Prepared by:
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 Disease Registry (ATSDR) to assess the health hazard posed by ambient air contamination in and around the Stillwater Industrial Park. The Stillwater Industrial Park contains six major industrial facilities, but only one, Moore Document Solutions, had an emissions inventory that showed significant emissions of tetrachloroethylene (PCE).
Between June 23-29, 1997, a contractor for the Oklahoma Department of Environmental Quality conducted ambient air monitoring for PCE around the property of Moore Document Solutions. Using Tenax tubes, the contractor collected 24-hour ambient air samples at two downwind and one upwind location. The sampling locations were just beyond the Moore Document Solutions property line. It rained on June 26, 27, and 29; on these days, the air sampling tubes were turned upside down to avoid collecting moisture, to the extent possible.
Analysis of two of the samples revealed peak splitting and low
internal standard recoveries due to high moisture in the tubes
(these samples were collected on a rain day). Because of this
QA/QC problem, ATSDR did not include these two samples in its
analysis of the data. In the remaining 19 samples, PCE
concentrations ranged from 0.037 µg/m3 to 5.365 µg/m3. In general,
the concentrations of PCE at the downwind stations exceeded the
concentrations at the upwind station.
DISCUSSION
Human exposure to high concentrations of PCE can affect neurological function, as evidenced by an increase in reaction time [1]. To protect against such adverse effects, ATSDR developed a chronic Minimal Risk Level of 40 parts per billion (ppb) or about 270 µg/m3. This concentration is 50 times higher than the maximum concentration of PCE detected in ambient air samples from the site. Therefore, the reported levels of PCE in ambient air does not pose a significant risk of non-cancer toxic effects.
Experimental studies have demonstrated that inhalation exposure to
high concentrations of PCE may increase the rate of some cancers in
laboratory animals. However, a number of epidemiological studies
of men and women who were occupationally exposed to high
concentrations PCE have not identified a statistically significant
increase in the prevalence of cancer [1]. ATSDR concluded that,
"Conclusive proof of the carcinogenic potential of
tetrachloroethylene in humans is lacking [2]." Therefore, based on
available evidence, potential human exposure to the low levels of
PCE detected in ambient air at the Stillwater Industrial Park would
not be expected to pose a significant cancer risk.
CONCLUSIONS
| (1) | The concentrations of tetrachloroethylene detected in ambient air near the Moore Document Solutions property do not pose a public health hazard. |
RECOMMENDATIONS
| (1) | None |
| Kenneth G. Orloff, Ph.D. Senior Toxicologist |
REFERENCES
| (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. |
