Paper No. 84-10
Presentation Time: 9:00 AM-1:00 PM
EXPLORING NATURALLY OCCURRING ASBESTOS IN ROAD SEDIMENT FROM BOULDER CITY, NEVADA
Road sediment is an inherent and useful medium that records both anthropogenic and geogenic contributions. Some regions may be more prone to having naturally occurring asbestos minerals (NOA) in road sediment than others. One region that has a potential high probability of having NOA in road sediment is southern Nevada. This includes Las Vegas, North Las Vegas, Henderson, and Boulder City, some of the most highly populated cities in the state. Previous studies have determined that there is extensive NOA exposed within geologic deposits in southeastern Nevada suggesting a high probability of NOA fibers and/or particles being present in road sediments in this area. Because Boulder City is the southeastern-most city of the study area, it is closest to the exposed geologic deposits containing NOA within the McCullough Range. Ten street sediment samples were collected from Boulder City as well as 36 samples from the other listed areas. Preliminary Scanning Electron Microscopy (SEM) data has shown that there are large, non-asbestiform actinolite particles and fragments in the samples from Boulder City. Road sediment processes such as abrasion and grinding appear to reduce these particles to fragments that conform to WHO and OSHA’s definition for asbestiform fiber characteristics. Energy dispersive spectrometry (EDS) has shown that the chemical compositions of these large fibers are similar to the NOA exposed within the local bedrock, particularly similar to fibrous actinolite (Ca2
) and magnesio-hornblende.
It is well-known that exposure to asbestos fibers can lead to disease, including mesothelioma, a form of cancer that tends to affect the respiratory system, abdomen, and other organs. Previous studies have shown that there are higher mesothelioma rates in southern Nevada, particularly in women and young adults, indicating environmental exposure to asbestos rather than occupational. Further research on this topic is needed as well as more detailed analyses of road sediment. Preliminary results have been obtained using the SEM and powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) will provide more details and indicate the nature of asbestos minerals in each sample.