Asbestos Sources of Exposure

We are all exposed to asbestos at some level as a part of the natural background. That exposure is normally very low but in some areas, the natural exposure may exceed industrial limits. There are areas in the Cascades and Sierra Nevada Mountain Ranges were dirt roads and trails emit what would be a high exposure within the industrial exposure guidelines. In California, many of these areas are posted as hazardous. Many streams and stream banks are laden with asbestos. There does not seem to be an increase in asbestos-related diseases for people living in these areas unless mining or milling operations are involved.



Asbestos is a group of naturally occurring minerals that have a fibrous form. There are basically five (six if Actinolite and Tremolite are counted separately) natural fibers that are specified as “ Asbestos” in Federal Regulations.

Chrysotile Asbestos Home

Chrysotile Asbestos

Chrysotile is the most common of all the asbestos minerals. It is also the least hazardous.

Amosite Asbestos Hazardous

Amosite Asbestos Hazardous

Amosite is the next most common of all the asbestos minerals. It is used extensively, often with chrysotile, for boiler and acoustic insulation.

Crocidolite Asbestos Fibers

Crocidolite Asbestos Fibers

Crocidolite is the blue asbestos. It made the blue ceramic water pipe blue. It also was used for boiler insulation.

Anthophyllite Asbestos In Talc

Anthophyllite Asbestos In Talc

Actinolite Asbestos Hazardous

Actinolite Asbestos Hazardous

Tremolite Asbestos In Tiles

Tremolite Asbestos In Tiles

Anthophyllite, Actinolite, and Tremolite are the least common commercial asbestos minerals. they are occasionally found as contaminants in Talc and Vermiculite.



Method of Analysis

Each Sample is analyzed using polarized light microscopy with dispersion staining, the PLM-DS method. This is the method recommended by the Environmental Protection Agency (EPA), the National Institute of Science and Technology (NIST), and is detailed in the Code of Federal Regulations, 40CFR Part 763, Subpart F, Appendix A.


Other Hazardous Mineral Fiber

There are many hundreds of natural fibrous minerals. Many are closely related mineralogically to the asbestos minerals and are presumably just as hazardous. These include richterite and winchite, which are a part of the Actinolite-Tremolite family. Another example would be arfvedsonite which is closely related to crocidolite. Other hazardous fibers belong to the Zeolite family of minerals. Fibrous forms of Talc are also suspect. See the Photogallery under Fibers-Minerals.

Winchite-Richterite are fibrous minerals associated with Actinolite-Tremolite asbestos in some Vermiculite deposits.

Arfvedsonite is closely related to Crocidolite asbestos.

Erionite is a fibrous Zeolite that has been implicated as a carcinogen similar to the asbestos fibers.

Fibrous Talc has a structure similar to Anthophyllite asbestos. Commercial Talcs sold now are generally low in fiber content.



 Friable Material

e.g. Insulation Acoustic and Popcorn Ceiling

Same Day ……………………….$55.00

24 Hour …………………………..$45.00

5 Working Days………………..$35.00

Non-Friable Material

e.g. Vinyl Flooring, Tile, Roofing, Glues, etc.

Same Day ……………………….$65.00

24 Hour …………………………..$55.00

5 Working Days………………..$45.00

Deposit each Sample in separate plastic sandwich bags. Label each sample according to where it was taken. Please remember to include your name and e-mail or home address.

More Information
  • MicrolabNW Photomicrograph Gallery
  • U.S. Environmental Protection Agency
  • Wikipedia-Asbestos Definition, Types, and Images
  • Center for Disease Control and Prevention-NIOSH Publications on Asbestos