October 10, 1989
Information provided to the Occupational Safety and Health Administration (OSHA) from the United Rubber, Cork, Linoleum and Plastic Workers of America (URW) indicated their concern with a number of amine compounds (in rubber or as rubber additives) that may be nitrosated with nitrogen oxides from the air during mixing, milling, extrusion, molding, calendaring, curing, including warehousing and storage.
These amines are potent animal carcinogens, and may be close to aflatoxin in risk. There are also other health effects besides the cancer risk and they could include the target organs of the liver, kidney, lungs, skin and eyes. Individual substances may vary on symptoms such as but not limited to headache, fever, weakness, stomach upsets, enlargement of the liver and jaundice. Nearly all producers of rubber products will at some point in their manufacturing process produce some of the amine compounds listed below that the International Agency for Research on Cancer (IARC) has classified as Group 2A or Group 2B and the National Toxicology Program (NTP) has designated as an anticipated human carcinogen.
We found that the National Institute for Occupational Health's (NIOSH) literature states exposures occur in many operations in the rubber industry including, Mill Operator, Banbury Operator, Tray Compounder, Extruder Operator, Cure Heater Operator, Mold Press Operator, Press Operator, Laminator, Calendar Operator and others (see attachments).
NIOSH conducted personal sampling in a number of rubber plants and found levels that range as low as:
Other levels of nitrosamines found in the rubber and tire industries:
Currently there are no OSHA Permissible Exposure Limits (PELs) for these amine compounds. OSHA does regulate N-Nitrosodimethylamine under 29 CFR 1910.1016. Use of the OSHA General Duty Clause, 5(a)(1) of the OSHA Act may be considered if the four elements needed to support a 5(a)(1) violation are met. Any levels of employee exposure should be considered serious. (Refer to the OSHA Field Operations Manual (FOM) Chapter IV, A.2.a.)
At present, OSHA uses Thermosorb/N media or a 15 ml isopropanol bubbler for air sampling and these samples are analyzed by using the Thermal Energy Analyzer (TEA) or High Pressure Liquid Chromatography for most N-Nitrosamines. OSHA's Salt Lake City Analytical Laboratory (SLCAL) stated that in general there are no problems except for N-Nitrosophenylamine which is unstable in isopropanol used in the bubbler. Bubbler samples must be protected for light during and after sampling. Samples must be either stored in a freezer or analyzed within six days after collection. The limit of detection for most nitrosamines is as low as .02 ug per 75 liter of collected sample, according to the OSHA SLCAL.
OSHA Compliance Officers should be aware of the hazards of N-Nitroso compounds in the rubber and related industries to avoid potential exposures to themselves.
Appropriate compliance action, based on available information, should be taken to ensure that proper engineering controls, work practices, protective clothing and respirators are being utilized.
Engineering controls should include process enclosure, dilution or general ventilation and local exhaust ventilation. Isolation of the operation or equipment should also be considered.
Protective clothing, should include gloves, gowns, masks, and goggles, especially in laboratory settings, for the protection of the face, skin, eyes and other parts of the body.
At any detectable concentration, respirators should include full facepiece self-contained breathing apparatus operated in a pressure-demand or other positive pressure mode or a full facepiece supplied air respirator operated in a pressure-demand or other positive pressure mode in combination with an auxiliary self-contained breathing apparatus operated in a pressure-demand or other positive pressure mode.
Please disseminate this bulletin to all Area Offices, State Plan States and Consultation Project Officers.
The following are references on N-Nitrosamine that include specific operations in the rubber industry where significant amounts were found:
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