Memo regarding comments on the draft risk assessment for the Tutu Wells Site
c Memorandum DATE: September 21, 1994 SUBJECT: Comments Re: Draft Risk Assessment for the Tutu Wells Site FROM: Mark Maddaloni , //^/'l TO: Caroline Kwan General Comments The risk assessment performed by COM Inc. for the Tutu Well site is, for the most part, consistent with the appropriate EPA guidance. The single greatest concern with this report involves the amount of data, rather than how those data were handled. Most of the individualized exposure areas identified for evaluation suffered from poor characterization (i.e., paucity of soil sampling points) . Additional comments are listed below. Specific Comments \ 1 -.J ••^ Page 4 Sampling data dating back to 1988 and 1989 were employed ^ _>° in the risk assessment. Are those results indicative of current site conditions? Page 8 Although reference to it is made later in the text, the following should be included as a reference document: Dermal Exposure Assessment; Principals and Applications (ORD 1/92) . Page 14 The Health Effects Assessment Summary Tables (HEAST. 1993) were referenced as a source of toxicity values. …
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c Memorandum DATE: September 21, 1994 SUBJECT: Comments Re: Draft Risk Assessment for the Tutu Wells Site FROM: Mark Maddaloni , //^/'l TO: Caroline Kwan General Comments The risk assessment performed by COM Inc. for the Tutu Well site is, for the most part, consistent with the appropriate EPA guidance. The single greatest concern with this report involves the amount of data, rather than how those data were handled. Most of the individualized exposure areas identified for evaluation suffered from poor characterization (i.e., paucity of soil sampling points) . Additional comments are listed below. Specific Comments \ 1 -.J ••^ Page 4 Sampling data dating back to 1988 and 1989 were employed ^ _>° in the risk assessment. Are those results indicative of current site conditions? Page 8 Although reference to it is made later in the text, the following should be included as a reference document: Dermal Exposure Assessment; Principals and Applications (ORD 1/92) . Page 14 The Health Effects Assessment Summary Tables (HEAST. 1993) were referenced as a source of toxicity values. The 1994 HEAST is available. Page 98 Region IV guidance (1992) is referenced for PAH toxicity equivalency factors (TEFs) . The most appropriate TEF guidance is: Provisional Guidance for Quantitative Risk Assessment of PAHs (ORD 7/93) . Page 100 The text states that some metals were found in the sample blanks. This statement should be qualified by including the relative concentration (i.e., > or < than 5 times the sampled amount) of the contaminant. Page 114 The evaluation and subsequent dismissal of tentatively identified compounds appears rather cursory. _- - JI.IT O06 I OO3 *64659* 64659 The text utilizes sub-chronic toxicity values for childhood exposure scenarios (6 year duration). Sub-chronic toxicity is technically defined as 2 weeks to 7 years; however,a 6 year exposure duration is at the upper bound of sub-chronicity, consequently, an argument could be made for applying (chronic j,^i> toxicity values in this situation. ^=———-~" References Casarett & Doull's Toxicology; The basic Science of Poisoning is currently in its fourth edition (1990). The text lists the third edition (1986). Appendix C Manganese has two (water and food) RfDs. The food RfD was used to evaluate soil. This may sound intuitively^correct, but the food RfD is intended to evaluate (-djTetary sourc^ of Mn, while the water RfD is intended for non-dietary—envlronmental sources; therefore, it would be more appropriate to utilize the water RfD for evaluating soil. Appendix C-32 The text used two liters as the daily ingestion/ \* rate (childhood) for water. RAGS recommends one liter a day. cc: Vince Pitruzzello Mel Hauptman TUT OO6 1.004