Document Lg9D5390YZ1Q6xK1m0GB3DQpg

Federal Register / Vol. 51. No. 119 / Friday. June 20, 1986 / Rules and Regulations. 22683 Not designating a ceiling level also SelikofTs testimony that mesotheliomas corresponds to OSHA's use of have appeared in a few workers with cumulative dose models in deriving lung very short exposures and in household cancer risk and the model U9ed to derive contact with peak exposures from mesothelioma risk. Neither mode! laundering asbestos contaminated attributes additional risk to peak ceiling clothing. However the evidence relating exposures (see discussion in Section. V, dose to these diseases is limited, and Quantitative Risk Assessment, and Tr. OSHA believes it is as compatible with 6/19. p. 1-109). a cumulative dose model as with a peak Although some experts have exposure model. In addition, practical attributed elevated risk of disease to considerations rule out ceiling levels as short "very high" level asbestos low as AFL-CIO recommends. The exposures, OSHA believes the level of N10SH panel testified that using the peak exposures involved in the reference method of sampling and situations referred to far exceeded 6.0 f/ analysis, the shortest period of time one cc. the practical ceiling imposed by this could measure 0.5 f/cc would be 25 standard. Thus, at the rulemaking minutes (Tr. 6/21. p. 111-139). hearing, Or. William Nicholson, bused As to the other levels suggested by his assessment that "much of the participants, OSHA believes there is hazardous exposures come from peaks" little biological evidence in the record on evidence from that supports a dose rate response "two industries (where) the predominate exposure has been from nir concentrations that have occurred that were very high, but model utilizing peak or ceiling exposures on which to base any specific ceiling limit. As explained above, OSHA tor short duration. Insulation work is one for ' believes that practical limitations are example. Repair work is the other. And as a consequence particularly in insulation work much of the exposures, much of the disease of today has been h-om these intermittent high peaks.. . . which we have averaged over iime for the purpose of a risk assessment |Tr. 6/19. p. 1-146-147). For one of the groups, insulation work, time-weighted average exposures have .been estimated as approximately 50 f/cc (Tr. 7/12, 295). At such a high TWA exposure a 15 minute ceiling exposure would necessarily be vastly higher than the levels allowed by this final standard. Therefore-OSHA believes this record provides no evidence indicating that . peaks permitted by this standard independently elevate risk above the cumulative dose permitted by the timeweighted average PEL Other participants also pointed out the scarcity of toxicological and doseresponse data concerning an appropriate ceiling level and the resultant'difficulties of recommending.a imposed on short-term exposures by the time-weighted PEL and by the provisions under housekeeping which would require immediate clean-up of any unexpected release of asbestos fibers such as spills and containers and bags breaking. Further, the provisions on monitoring require that sampling be conducted during the periods when the highest exposures occur, which would include periods of peak exposures. Because protective requirements are triggered by the action level of 0.1 f/cc any exposure for 15 minutes above 3 f/ cc will have regulatory significance. OSHA believes that its treatment of the issue of a ceiling level reflects the evidence on this record and will protect employees against the as of yet unproven possibility that in fact very high short term exposures have . independent significance in increasing risk. 4. Paragraph (d). Exposure specific change to the 10 f/cc limit (see Monitoring. e.g.. Ex. 90-236). Section 6(b)(7) of the Act (29 U.S.C. The April proposal specifically asked 665] mandates that any'standard participants for recommendations for promulgated under section 8(b) shall, specific ceiling levels. In response, some where appropriate, "provide for participants recommended a 5 f/cc monitoring or measuring of employee ceiling limit (Exs. 92-045, 90-180]; a expoaiires at such locations and ceiling-limit equivalent to 10 times the intervals, and in such a manner as may PEL (Ex. 127J and the AFL-CIO be necessary for the protection of recommended that OSHA should lower employees." The primary purpose of the ceiling level for the asbestos monitoring is to determine the extent or standard proportionally to the reduction employee exposures to asbestos. - in the permissible exposure limit which Exposure monitoring informs the would be 0.5 f/cc, based on the AFL- employer whether the employer meets CIO recommended 0.1 f/cc time- the obligation to keep employee weighted average PEL [Ex. 335, p. 46J. exposures below the 8-hour TWA The only scientific evidence cited by the exposure limit. Exposure monitoring AFL-CIO was the statement of Dr. also permits the employer to evaluate Nicholson, discussed above, and Dr. the effectiveness of engineering and work practice controls and informs.the employer whether additional controls need to be installed. Furthermore, exposure monitoring is necessary in order to determine whether respiratory protection is required at all. and if so, which respirator is to be selected. In addition, Section 8(c)(3) of the Act (29 U.S.C. 657(c)(3)] requires employers to notify promptly any employee who has been or is being exposed to toxic materials or harmful physical agents at levels that exceed those prescribed by an applicable occupational safety or health standard. Finally, the results of exposure monitoring are part of the information that must be supplied to the physician, and these results may contribute information on the causes and prevention of occupational illness. Paragraph (d) of the final rule contains, the standard's requirements related to the monitoring of employee exposure. The final rule contains an 8-hour TWA permissible exposure limit and an action level that acts to alert employers of cases where existing exposures are approaching the PEL. There are two possible exposure situations that will determine the frequency of monitoring required. The table below lists these' two exposure situations, along with the monitoring frequency for each. Exposure scenario Required monitoring ecthrtty Betow the action level__ No monitoring required At or above the action Monitor exposure at least every 0 level, months. As is shown by the table above, the action level trigger determines whether employers must monitor employee exposure to asbestos; where the action level is reached or exceeded, the employer must monitor employee exposures. This is changed from the existing standard, which requires periodic monitoring when exposures are above the permissible exposure limits. It is OSHA's belief that this new requirement of-monitoring when levels are at or above the action level is needed to properly assess worker exposure so as to ensure the proper operation of available controls and that respirators with the appropriate protection factors are used in each regulated area. Periodic measurement is appropriate when employee exposures are at or above the action level, because relatively minor changes in the process, materials or environmental conditions might increase the airborne concentration of asbestos to levels above the standard's PEL Paragraph (d)(2)(i) requires that each employer shall perform initial' GLEASON-000931