NYC-WTC_000195068

NYC 9/11 Public Portal Document

ASBESTOS MEDITEXT ® - Medical Management Page 3 of 4

5. OSHA REQUIREMENTS - OSHA has specific clinical monitoring requirements for workers exposed to asbestos. Refer to the Micromedex, Inc REGSLINK(R) Information System for more information.

4.2 RADIOGRAPHIC STUDIES

A. CHEST RADIOGRAPH 1. The sensitivity and specificity of radiographic studies for detection of plaques and asbestos-exposure are varied, because of different radiographic and patient selection criteria. False positive readings (compared to autopsy findings) ranged from 8.4 to 58 percent, and false negatives ranged from 60 to 92 percent (Gefter & Conant, 1988). a. In autopsy series, pleural plaques have been identified in approximately one-third to one-half of persons 20 years after significant asbestos exposure, and many of these plaques were not identified on antemortem x-rays (Talcott & Antman, 1988). 2. Radiographically-detected pleural plaques have been shown to correlate well with asbestos bodies on autopsy if the lung burden is more than 500 asbestos bodies/5 grams of autopsy lung tissue (Kishimoto et al, 1989). 3. The association of pleural thickening and calcification enhances diagnostic accuracy (ATSDR, 1990). There are several conditions which can mimic asbestos-related diseases, including scarring adjacent to old disease, trauma, fat or muscle shadows, healed tuberculosis, histoplasmosis, and other conditions (Reger et al, 1990). 4. Using the ILO criteria, as many as 10 to 20 percent of workers with histological evidence of asbestosis will have normal chest x-ray films (Rockoff & Schwartz, 1988). In the other extreme, positive radiographical ILO readings of pulmonary fibrosis have been found with normal lungs. 5. Variations in classifying pleural changes and inadequacy in describing features believed to be important by some readers were problems identified with the ILO 1980 International Classification of the Radiographic Appearances of Pneumoconioses (Rossiter et al, 1988). A survey found an intraobserver variation of 3.9 percent, and an interobserver variation of 18 percent (Gefter & Conant, 1988). 6. Despite the discrepancies between histologic and radiographic diagnosis, roentgenographic interpretations are still deemed useful however subjective they may be (Ducatman, 1989). 7. Because of intra- and interobserver variations in interpretations, chest x-rays are only supportive diagnostic tools (Gefter & Conant, 1988). An ILO grade of less than 1/0 implies that the diagnosis is unlikely, but diagnosis still rests on multiple clinical criteria (Gefter & Conant, 1988; Schwartz et al, 1988). 8. Reviews of smoking and roentgenographic opacities in asbestos workers suggest that parenchymal opacities alone will not reliably differentiate between the impacts of asbestos exposure and smoking in patients who have both risk factors (Blanc et al, 1988; Ducatman et al, 1990; Hnizdo & Sluis-Cremer, 1988). A cross-sectional study confirmed that smoking can be dose-related with parenchymal, but not pleural, changes (Delclos et al, 1990). 9. CT scan has been recommended as a sensitive means of differentiating asbestos-related pleural plaques from soft-tissue densities (ATSDR, 1990). 10. The strong association of both circumscribed plaques and diffuse pleural thickening with parenchymal fibrosis on high-resolution computerized tomography (HRCT) suggest that HRCT scan may be useful in identifying parenchymal injury not detected with postero- anterior chest radiographs (Schwartz et al, 1990a; Neri et al, 1996).

http://www.tomescps.com/DATA/TM/TM356-4.htm 1/4/2002

CITY_21MC100_011105068

NYC-WTC_000195086