The Health Basis of Asbestos Exposure Measurement

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					The Health Basis of Asbestos
  Exposure Measurement


     OSC Readiness Training Program
                Novemeber, 19 2002

                  Region 8 and the
      National Enforcement Investigation Center
                     Denver, CO
Basic Respiratory Anatomy
Fiber Deposition in the Lung




             Tremolite
Fibers Impact on Bronchial Lining
 due to Aerodynamics and Mass
Mechansisms of Particle
 Deposition in the Lung
Bundle of Libby amphibole asbestos fibrils
View of slide mount from air filter
ASBESTOS DISEASE
 – Asbestosis -Scarring of the lung tissue.
  Severity ranges from mild impairment to
  disabling and eventually fatal.
 – Malignant mesothelioma-Fatal cancer of
  the lung pleural (outside lining). Virtually all
  cases attributable to asbestos exposure.
 – Lung cancer Asbestos exposure increases
  risk of all lung cancer, especially when
  combined with smoking.
     • Latency -The time between exposure to asbestos and the
       onset of disease typically 10 to 40 years.
Pleural Cavity and Asbestos
Radiograph of the pleural lining
Microscopic and Macroscopic Lung
Abnormalities Caused by fibers
                                    Radiograph of
                                    Pleural plaques




‘asbestos bodies’                   Anatomy of
                                    Pleural plaques
             ‘ferruginous bodies’
Site Concept Model
Center for Asbestos Disease
         Libby, MT
Radiology as a Measure of
   Asbestos Exposure
                                                                                          Size Distribution
                                                                      (based on ISO 10312 and AHERA counts)




Fiber size distributions                                                                                                                              40



                                                                                                                                                     35



                                                                                                                                                     30



                                                                                                                                                     25



                                                                                                                                                     20    Count

                                                                                                                                                 15




 Analysis of fiber size                         0

                                                    2
                                                                                                                                                 10


                                                                                                                                                 5



 Distribution Indicates
                                                        5
                                           Length
                                                            10                                                                                   0

                                                                                                                                     0.1   0
                                                                 15                                                          0.2



 that only 30%
                                                                                                                 0.4   0.3
                                                                                                 0.75    0.5
                                                                                   1.25     1
                                                                         1.5                                    Width



 Fall within the regulated                                                                 Size Distribution

 range.
                                                                      (based on ISO 10312 and AHERA counts)
                                                                                                                                                              0


                                                                                                                                                              1

                                   Count
                                                                                                                                                              2

 EPA risk assessments              35-40
                                   30-35                                                                                                                      3.5


 Use only regulated                25-30
                                   20-25                                                                                                                      5
                                                                                                                                                                     Length
                                   15-20
 (or PCME) fibers                  10-15
                                   5-10
                                                                                                                                                              7.5


                                                                                                                                                              10

  to calculate risks.              0-5
                                                                                                                                                              12.5


                                                                                                                                                              15

                             PCME Fibers                                                                                                                      17.5
                                                    1.5           1.25         1          0.75    0.5          0.4     0.3         0.2     0.1            0
                                                                                                        Width
               Summary
• Fiber toxicity is dependent upon:
  – Fiber Shape (length, width, aspect ratio)
  – Fiber Chemistry (solubility and possibly
    electrochemistry)
• Recording human exposure and risk
  requires detailed pathway analysis and
  careful fiber characterization.

				
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