Airborne asbestos exposures associated with gasket and packing replacement: a simulation study and meta-analysis.
Exposures to airborne asbestos during the removal and installation of internal gaskets and packing associated with a valve overhaul were characterized and compared to published data according to different variables (e.g., product, equipment, task, tool, setting, duration). Personal breathing zone and area samples were collected during twelve events simulating gasket and packing replacement, clean-up and clothing handling. These samples were analyzed using PCM and TEM methods and PCM-equivalent (PCME) airborne asbestos concentrations were calculated. A meta-analysis was performed to compare these data with airborne asbestos concentrations measured in other studies involving gaskets and packing. Short-term mechanic and assistant airborne asbestos concentrations during valve work averaged 0.013f/cc and 0.008f/cc (PCME), respectively. Area samples averaged 0.008f/cc, 0.005f/cc, and 0.003f/cc (PCME) for center, bystander, and remote background, respectively. Assuming a tradesman conservatively performs 1-3 gasket and/or packing replacements daily, an average 8-h TWA was estimated to be 0.002-0.010f/cc (PCME). Combining these results in a meta-analysis of the published exposure data showed that the majority of airborne asbestos exposures during work with gaskets and packing fall within a consistent and low range. Significant differences in airborne concentrations were observed between power versus manual tools and removal versus installation tasks. Airborne asbestos concentrations resulting from gasket and packing work during a valve overhaul are consistent with historical exposure data on replacement of asbestos-containing gasket and packing materials involving multiple variables and, in nearly all plausible scenarios, result in average airborne asbestos concentrations below contemporaneous occupational exposure limits for asbestos.
Cardno ChemRisk, 130 Vantis, Suite 170, Aliso Viejo, CA 92656, United States. Electronic address: amy.madl@cardno.com.
Amy K
AK
Madl
Cardno ChemRisk, 101 2nd Street, Suite 700, San Francisco, CA 94105, United States.
Dana M
DM
Hollins
Cardno ChemRisk, 4840 Pearl East Circle, Suite 300 West, Boulder, CO 80301, United States.
Kathryn D
KD
Devlin
Cardno ChemRisk, 101 2nd Street, Suite 700, San Francisco, CA 94105, United States.
Ellen P
EP
Donovan
Cardno ChemRisk, 101 2nd Street, Suite 700, San Francisco, CA 94105, United States.
Pamela J
PJ
Dopart
Cardno ChemRisk, 20 Stanwix Street, Suite 505, Pittsburgh, PA 15222, United States.
Paul K
PK
Scott
Cardno ChemRisk, 101 2nd Street, Suite 700, San Francisco, CA 94105, United States.
Angela L
AL
Perez
D000395:Air Pollutants, Occupational / Q000737:chemistry*; D001194:Asbestos / Q000737:chemistry*; D004784:Environmental Monitoring / Q000379:methods; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis*; D016273:Occupational Exposure / Q000032:analysis*
D000395:Air Pollutants, Occupational; D001194:Asbestos
Asbestos; Equipment; Exposure; Gasket; Packing; Task; Tool; Valve