Limit, short term hoods

In mostresearch laboratory situations, it would be unusual to find an airborne radioactivity area on otherthan a short-term basis. If there is any possibility ofan approach to the limits while working on an open bench, the use of radioactive materials should be restricted to a hood, or in a glove box or hot cell. In a facility with a broad license, it is recommended that at least some ofthe more active individuals using radioisotopes should be included in a bioassay program for the same reason that others weara personal monitoring device, to ensure and document that no one is receiving an internal dose over the limits. 

Formaldehyde is listed as a suspected human carcinogen and has a 0.3 ppm short-term exposure limit (STEL). Fortunately this very low exposure limit can be met since the use of formaldehyde in chemical synthesis processes involve closed systems which minimize worker exposures. Laboratory use of formaldehyde solutions must be conducted in hoods with efficient ventilation. 

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