Occupational exposure to asbestos, vermiculite

Limited data are available on the levels of LA in the air at the plant during the years Libby vermiculite was exfoliated at the site. From 1967 through 1991, Vermiculite Northwest/W.R. Grace received shipments of 193,112.78 tons (386,225,563 lbs.) of Libby vermiculite that were exfoliated at the site.

Workers were potentially exposed to LA during the various stages of vermiculite processing, including the unloading of vermiculite from rail cars, during transfer of vermiculite to the furnace, and during the bagging of exfoliated material. Pollution control equipment and dust suppression measures varied over time, being minimal until later in the history of the facility (1970s and 1980s), although they complied with the pollution control requirements at the time.

Review of air monitoring data collected for industrial hygiene studies during the late 1970s reveals that fibers were present at levels often exceeding both the current occupational exposure standard and the less restrictive occupational standard that existed at the time. Data from plant productions in 1950s and 1960s, when dust controls were likely minimal, is not available. The past occupational exposure pathway is a complete pathway and is the most significant exposure pathway at Vermiculite Northwest. This pathway is considered a "past public health hazard."

Workers employed in businesses renting the remainder of the facility during the years W.R. Grace occupied a portion of the building may have been exposed to asbestos. Facility operations in one part of the building would likely ensure that fibers were present in other parts of the building. Not enough information is available to determine the extent of exposure for this group of workers. Exposure to contaminated dust at the site for workers in collocated businesses from 1950 to 1980 is an "indeterminate public health hazard."

Workers employed in businesses occupying the facility subsequent to its sale by W.R. Grace may have been exposed to asbestos. EPA and ODEQ conducted an investigation in April 2000 and found asbestos to be present in soil and dust samples at the facility. These results prompted an investigation by Oregon OSHA, which determined that employees of businesses located in the building after Vermiculite Northwest vacated the premises might have been exposed to asbestos fibers remaining in the building.

Although the exposure would have been much less than for the vermiculite processing workers, the actual level of exposure is unknown. Exposure to contaminated dust at the site from 1994 to present is considered an "indeterminate public health hazard for workers."