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.

The Stoneridge subdivision is a growing rural community with approximately 5,000 residents. The Prescott Valley Water Company (Prescott Valley, AZ) provides drinking water for residents in this area. A resident in the community indicated that there is a “paint thinner” type odor coming from the tap water. The Prescott Valley Water Company sampled the water due to request of the resident. On July 27, 2004, the resident called the Arizona Department of Health Services to express his/her concern regarding the analytical results of benzene in tap water samples collected from faucets inside the house. As a result, the Arizona Department of Health Services completed a health consultation to evaluate if benzene and other volatile organic compounds in the water supplied by the Prescott Valley Water Company pose any adverse health effects.