ALUMINUM (PYRO POWDERS)

OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.

CAS: 7429-90-5; Chemical Formula: Al

OSHA previously had no permissible exposure limit for aluminum pyro powders. The ACGIH has an 8-hour TLV-TWA of 5 mg/m³. The proposed and final rules have a PEL of 5 mg/m³ for the aluminum pyro powders; NIOSH (Ex. 8-47, Table N1) concurs with this limit. Powders and flake aluminum are flammable and can form explosive mixtures in air.

Aluminum pyro powders have a higher reported toxicity than aluminum metal dusts (Stokinger 1981a/Ex. 1-1133). Several British studies have examined the effects of exposure to this finely flaked aluminum on workers in paints and pyrotechnics plants. Their findings revealed that pulmonary fibrosis may result from exposure to pyro powders, although epidemiologic evidence indicates that additives used to prevent oxidation and agglomeration may have contributed to the incidence and nature of the disease (Edling 1961/Ex. 1-733; Jordan 1961/Ex. 1-559; Mitchell, Manning, Molyneux, and Lane 1961/Ex. 1-564). Exposures that have previously caused lung changes in workers are presumed to have been extremely high (ACGIH 1986/Ex. 1-3, p. 22). No comments, other than NIOSH’s, were received on these powders.

OSHA concludes that the permissible exposure limit of 5 mg/m³ TWA for aluminum pyro powders will prevent the significant risk of lung changes in workers exposed at the concentrations formerly permitted by the absence of an OSHA limit. The Agency has determined that these lung changes constitute material impairment of health.