Supplementary Exposure Limits

However, the limited studies to date indicate that these substances have chemical reactivity and mutagenicity similar to acetaldehyde and malonaldehyde. Therefore, NIOSH recommends that careful consideration should be given to reducing exposures to these nine related aldehydes. Further information can be found in NIOSH Current Intelligence Bulletin 55 Carcinogenicity of Acetaldehyde and Malonaldehyde, and Mutagenicity of Related Low-Molecular-Weiglit Aldehydes [DHHS (NIOSH) Publication No. 91-112]. This document is available on the NIOSH Web site (http //www.cdc.gov/niosh/91112 55.html). 

As found in 29 CFR 1910.1001, the OSHA PEL for asbestos fibers (i.e., actinolite asbestos, amosite, anthophyllite asbestos, chrysotile, crocidolite, and tremolite asbestos) is an 8-hour TWA airborne concentration of 0.1 fiber (longer than 5 micrometers and having a length to diameter ratio of at least 3 to 1) per cubic centimeter of air (0.1 fiber/cm ), as determined by the membrane filter method at approximately 400X magnification with phase contrast illumination. No worker should be exposed in excess of 1 fiber/cm (excursion limit) as averaged over a sampling period of 30 minutes. 

The recommendations provided below are from Health Effects of Occupational Exposure to Asphalt [DHHS (NIOSH) Publication No. 2001-110] (http //www.cdc.gov/niosh/01-110pd.html). 

Occupational exposure to asphalt fumes shall be controlled so that employees are not 

The available data indicate that although not all asphalt-based paint formulations may exert genotoxicity, some are genotoxic and carcinogenic in animals. No published data examine the carcinogenic potential of asphalt-based paints in humans, but NIOSH concludes that asphalt-based paints are potential occupational carcinogens. 

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The use of personal protection equipment (PPE) is not allowed as a permanent measure. It should not be a substitute for necessary technical improvements to reach the state of the art In practice, in most cases it is used as an additional supplementary protection measure to give protection against unexpected or accidental incidents, e. g., a sudden leakage. In the case of exceeding the occupational exposure limit or a risk of dermal exposure, personal protection equipment (PPE) must be used. The duration of this must be restricted to the period of necessity. 

If very low systemic exposure is found in animals relative to that of the human, consideration should be given as to whether the toxicity studies are valid and whether supplementary work needs to be done. If the exposure is such that measurable levels of the compound cannot be found in the conceptus, then some means of increasing the exposure (within reasonable limits) should be devised otherwise the potential for effects remains unknown. Any course of action should be justified. 

The basis for assignment of exposures is limited by the supplementary information included in the database. The OSHA data set, for example, contains information on job and industry but not tasks or other determinants. Proposals for broadening the data contained in these administrative databases could make them useful for determinants of exposure studies, with the promise and caveats stated above (Rajan et al, 1997). 

The SCOEL evaluates the scientific dossier and the supplementary data for the identification of the critical health effects and then proposes a recommendation for a health-based limit value in a summary document, which in addition to the recommendation for an OEL, also contains further information on the basic data, a description of the critical effect, the extrapolation techniques used, and any data on possible risks to human health. The technical feasibility of monitoring exposure is also noted. Furthermore the SCOEL identifies important gaps in the data and the need for more research. Once the Committee agrees the summary document the Commission makes it public to interested parties with the request for health based scientific comments and eventually further data. After a period of about six months allowed for comments, the SCOEL rediscusses the document in the light of the comments received and adopts the final version, which is then published by the Commission. 

The available database to assess the safety of ASC and its residues chlorite and chlorate has limitations, and few of the studies have been conducted to the current standards expected for regulatory submissions. The studies on ASC related to a germicidal product, and some of these involved parenteral administration. The Committee considered that although not directly relevant to oral exposure, these studies provided useful supplementary information that did not raise concern about the use of acidified chlorite as a processing aid. In many of the studies in which chlorite or chlorate was administered in drinking-water, the information provided was insufficient to derive an accurate estimation of the dose received by the animals. 

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