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David Stavarek, R.G. <br /> June 29, 1998 <br /> Page 11 <br /> 8. The water intake rate PDF expressed per kilogram body weight was taken from the CaITOX <br /> model. Water intake rate is NOT a function of body weight but mainly related to factors <br /> such as physical activity, ambient temperature and relative humidity, and water content of <br /> foods. Data published in the literature as recent as last week (D. Burmaster,Risk Analysis, <br /> Vol 18,No. 2, 1998) clearly indicate that water intake does not correlate with body weight. <br /> Therefore,the data developed by McKone and used in the CaITOX model is wrong. Please <br /> use the PDF data from the USEPA Exposure Factors Handbook,August 1997. <br /> SPECIFIC COMMENTS <br /> Tables 2 and 6 <br /> 1. The soil ingestion"correction factor" shown in these tables has no basis. As discussed in(6) <br /> above, the soil ingestion rate PDF was taken from the CaITOX model, which makes use of <br /> soil ingestion normalized for body weight. Correction of this PDF [soil ingestion/body <br /> weight] would require the use of the same distribution of body weights originally used by <br /> McKone. Because two wrongs do not make a right, I recommend to please use the PDFs for <br /> soil ingestion and body weights appearing in the USEPA Exposure Factors Handbook, <br /> August 1997. <br /> SUMMARY <br /> In order to facilitate the preparation of the risk assessment document, Sierra-Pacific <br /> Groundwater may address the above comments in a letter that would be included as an <br /> Addendum to the Workplan. No revised Workplan is required by OEHHA. Further, we expect <br /> Sierra-Pacific will address the above comments in the HRA report. <br /> We appreciate the opportunity to comment on this report and look forward to assist <br /> CRWQCB in the review of the risk assessment report. <br />