The W.R. Grace facility in Phoenix, Arizona, received vermiculite concentrate from the Libby, Montana, vermiculite mine. W.R. Grace Company has owned and operated the Arizona site since 1964. In 1964 W.R. Grace purchased the company that had previously occupied the site and, following the relocation of its vermiculite exfoliation furnace from Glendale, Arizona, began processing vermiculite concentrate and marketing it under the Zonolite® brand. The objective of this health consultation is to evaluate exposure pathways and potential health effects in those persons who, between 1964 and 2002, may have been exposed to Libby asbestos as a result of vermiculite concentrate processing activities and waste materials from the W.R. Grace exfoliation facility in Phoenix.

Kinder-Morgan installed monitoring wells around its Yuma Booster Station, which is surrounded by agricultural fields. Two of the monitoring wells are located on the North Gila Thomas estate property. The purpose of the monitoring wells is to provide early detection of potential contaminants associated with the pipeline running through the agricultural fields. MACTEC Engineering and Consulting, Inc. has provided laboratory data since April 2005. However, recent elevated readings of Volatile Fuel Hydrocarbons, Benzene, Toluene, Ethyl benzene, total Xylenes, and Methyl-tert-butyl Ether have caused concern. We have reviewed the groundwater sampling data collected from the two monitoring wells and conducted an assessment to evaluate whether the chemicals are at levels of public health concern.