The Environmental Protection Agency (EPA) asked the Agency for Toxic Substances and Disease Registry (ATSDR) to comment on the public health implications of contaminants present at the Washington Natural Gas Seattle Plant (Gas Works Park) [1]. EPA recently released the Expanded Site Investigation (ESI) [2].

Gas Works Park is a former coal gasification plant. It is now a city park. Past environmental sampling identified polycyclic aromatic hydrocarbons (PAHs) as the principal contaminants of concern [2]. Some volatile organic compounds (VOCs) were also identified as a potential threat to public health [2,3].

Since the mid 1980s, local and federal agencies have periodically asked representatives of the Public Health Service to comment on the contamination. In 1984, the Centers for Disease Control (CDC) recommended that measures be taken to reduce or eliminate exposure to PAH contamination at the park [2]. Those recommendations were based on data indicating that PAHs were present in certain soils and sediments at concentrations over 10,000 parts per million (ppm). ATSDR commented on the contaminants present on site in 1986 [3], 1993 [4], and 1995 [5]. ATSDR comments were based on the data that CDC had reviewed and on more recent data collected after some remediation activities. Some of the data that ATSDR used in 1995 were part of the ESI recently released by EPA.

The ESI and the other data collected over the years confirm that PAHs are still present in accessible soil and sediments at concentrations greater than 1000 ppm. The data also indicate that VOCs are present at concentrations greater than 0.10 ppm in water seeping from the site. The contamination affects soil in the park, sediments along the shoreline of the park and Lake Union, and water seeping from beneath the park into Lake Union.

Discussion

As the ESI concludes, it is apparent from the recent sampling that no significant change in sediment contamination has occurred since the surveys completed in the mid 1980s [2]. ATSDR concurs with this conclusion and believes that site conditions are not substantially different from those which existed when ATSDR's 1986, 1993, and 1995 reviews took place. For this reason, ATSDR believes that the conclusions and recommendations made at those times are still relevant.

Previous ATSDR conclusions and recommendations about the contamination at Gas Works Park may be summarized as follows:

1. Direct contact with highly contaminated soil or sediment is the main exposure pathway of concern at the park [3];
2. Short-term exposure to the contamination may result in some dermal effects [3-5];
3. Long-term human exposure to the contamination seems unlikely [3-5];
4. Anyone digging in park soil or sediment may be exposed to high transient concentrations of VOCs; and
5. Further consideration should be given to preventing human contact with highly contaminated soil and sediments [3].

Conclusions

The conclusions and recommendations previously made by ATSDR and CDC, as summarized in the discussion section above, are still appropriate for Gas Works Park.

Recommendations

Human contact with highly contaminated soil and sediments should be prevented. No new recommendations are necessary at this time.

If further clarification is required or if additional information becomes available for review, please do not hesitate to contact this office at (206) 553-2632.

Steven J. Haness, Ph.D

References

1. Electronic mail message from David Bennett, EPA Region 10, to Greg Thomas, ATSDR.
2. Letter from David M. Bennett, EPA Region 10, to Robin Kordik, Seattle Department of Parks and Recreation. January 26, 1996. Expanded Site Investigation, November 28, 1995, is attached to the letter.
3. Memorandum: Health Assessment, Gas Works Park. June 5, 1986. From Jeffrey A. Lybarger, ATSDR, to Joel Mulder, ATSDR.
4. ATSDR Record of Activity. Seattle Gas Works. April 21, 1993. Steve Haness (scientist), Raymond Grissom (concurrence); to Greg Thomas, (ATSDR Regional Representative).
5. ATSDR Record of Activity. Gas Works Park. June 29, 1995. Ken Orloff (scientist) to Greg Thomas (ATSDR Regional Representative).