City Council; I reviewed the Millenium Consultants study of the Hillview Turf and the review by PES Environmental. I have 40 years of experience in environmental chemistry and risk assessment. I am not a toxicologist. I have a few observations that I hope will be helpful. * Millenium's chemical analysis approach is standard for an exposure and risk evaluation that one would perform for an industrial site cleanup. The list of volatile and semivolatile chemicals that the lab analyzed for were those identified as toxic or carcinogenic under EPA RCRA regulations. Those chemical lists were developed many years ago and miss many common hazardous chemicals. Since the purpose of this study is to evaluate risk to children, rather than to check off some regulatory requirement, the VOC and SVOC analyses should have included "Tentatively Identified Chemicals (TICs). If that is specified to the lab, they will activate a software routine in the gas chromatogram/mass spectrometer to search a library of chemical spectra for likely matches for every large unidentified peak in the chromatogram. Without looking at TICs, a toxic substance can be present in huge quantities, but not be reported. If the laboratory kept the extracts of the turf samples, a TIC analysis can still be ordered, at less than the cost of repeating the work on a new sample. However, be aware that the level of effort to evaluate the risk of TICs could be much greater, as some may not have toxicity factors. * The failure to analyze vapor inhalation risks is understandable given the low VOC/SVOC concentrations detected in the crumb rubber; however, there are more accurate ways to estimate inhalation of vapors. One approach is to place a plastic dome over the surface and collect a vapor sample for analysis. If this were done on the turf field on a hot day, that would give a more accurate estimate of maximum exposure than extracting the turf particles. Also, that approach would avoid focusing only on the crumb rubber, as that ignores any chemicals emitted by the plastic turf and underlayer. * The particle ingestion rate used in the risk assessment is the highly conservative value that EPA uses based on children that have pica - i.e., that eat soil. The risk assessment doesn't address inhalation of particles - a toxicologist will need to weigh in on whether risks from inhaling particles are more than from eating them. Again, the risk assessment can only evaluate what the lab tested for. If there are toxic or carcinogenic chemicals not reported, the resulting risk won't account for them. Naomi Goodman MSPH Environmental Chemistry 897 Woodland Menlo Park Received on Sat Nov 18 2017 - 10:50:46 PST
