Laserfiche WebLink
" Jim Allen • <br /> Memo, Page 2 <br /> June 8, 1987 <br /> with a disposable trowel. Samples were sent to HML for heavy metals <br /> analysis. No water samples were taken. <br /> Laboratory Analysis <br /> A copy of the laboratory reports is enclosed, along with a memo from Robert <br /> Schlag to me summarizing them. Arsenic, chromium, copper and zinc were <br /> found in several samples at levels well above background and California <br /> Administrative Code levels. Although analyses for hexavalent chromium were <br /> requested, these were not performed because of exceedences of holding times. <br /> Toxicological Analysis <br /> Because of the magnitude of the levels found in some samples, and the <br /> accessibility of these areas to people, I asked David Morry of the ESSS <br /> Hazardous Waste Unit to do a toxicological assessment of risks posed by <br /> potential exposures to this soil for nearby residents, particularly <br /> children. A memo describing his assessment is attached. To summarize, it <br /> appears that there are potential concerns about this soil because of: <br /> (1) potential acute toxicity from eating 10 grams of soil due to high <br /> levels of copper; <br /> (2) potential chronic toxicity from a lifetime of exposure to chromium <br /> if all the soil (0.71 grams a day) to which area residents are exposed <br /> has levels of chromium comparable to the highest levels found (which is <br /> unlikely) and depending on the amount of chromium present as hexavalent <br /> chromium; and <br /> (3) potential excess cancer risk from exposure to the arsenic and <br /> chromium found in the soil. Again, assuming that all soil exposures in <br /> a lifetime were to soil at the highest levels of arsenic contamination, <br /> this excess risk was quite high (4 X 10-5) , but it is more likely that <br /> much of the soil in the area is much less contaminated than that. <br /> Estimation of cancer risk attributable to excess chromium is difficult <br /> because we do not know how much of the chromium was in hexavalent form. <br /> When we assume it was all in hexavalent form (which is unlikely) there <br /> is an extremely high excess lifetime cancer risk calculated (5 X 10-1) . <br /> Dr. Morry did not consider these numbers to be very realistic, because <br /> of the assumptions about hexavalent chromium. <br /> Conclusions and Recommendations: <br /> In interpreting these analyses, it is important to keep in mind that these <br /> samples constitute a "worse case" picture of the levels of offsite <br /> contamination, and were not intended to be a random sample representative of <br /> the entire area. However, if they had been negative, the sampling would <br /> have provided reassurance that there had not been past or current runoff <br /> from the site. The toxicological analyses were also done using "worse case" <br /> assumptions. Although such an analysis cannot "prove" , it does indicate <br /> that there is potential for toxic exposures to residents around the Marley <br /> Cooling Towers site, from soil contamination with chromium, arsenic and <br />