OSHA formerly had a limit of 50 mppcf (approximately 15 mg/m3) for Portland cement containing less than 1 percent crystalline silica. The ACGIH has a TLV-TWA of 10 mg/m3 for Portland cement as total dust containing less than 1 percent quartz. The proposed PEL was 10 mg/m3, measured as total particulate, and this is the limit established in the final rule; the 5-mg/m3 respirable fraction limit is retained. Portland cement refers to a class of hydraulic cements that are odorless gray powders containing less than 1 percent crystalline silica. Portland cement is insoluble in water and contains tri- and dicalcium silicate, in addition to varying amounts of alumina, tricalcium aluminate, and iron oxide.
Intraperitoneal injection of Portland cement in guinea pigs produced an absorptive reaction, which is an effect typical of inert particulates. Portland cement is eventually eliminated from the tissue and is generally not considered harmful when ingested (Miller and Sayers 1941/Ex. 1-595).
In a study of industrial exposures, Gardner and associates (1939/Ex. 1-589) found no evidence of Portland-cement-related pneumoconiosis in 2,278 workers who had been heavily exposed to this substance for prolonged periods of time (Gardner, Durkan, Brumfiel, and Sampson 1939/Ex. 1-589). Conflicting reports of pneumoconiosis (Parmeggiani 1951, as cited in ACGIH 1986/ Ex. 1-3, p. 494; Prosperi and Barsi 1957/Ex. 1-1093) are attributed to the presence of silica in the inhaled dust rather than to exposure to Portland cement itself (ACGIH 1986/Ex. 1-3, p. 494). Cement dermatitis does occur among exposed workers, however, as a consequence of the alkaline, abrasive, and hygroscopic properties of the wet cement, which cause irritation of the skin (Schwartz, Tulipan, and Birmingham 1957a/Ex. 1-1168). NIOSH, the only commenter on this substance, reported that it has not thoroughly reviewed the health effects for Portland cement (Ex. 8-47, Table N4).
OSHA is establishing 8-hour TWA PELs of 10 mg/m3 (total particulate) and 5 mg/m3 (respirable fraction) for Portland cement containing less than 1 percent quartz. The Agency concludes that these limits will protect workers against the significant risks associated with on-the-job exposures to Portland cement dust. These risks include eye, skin, and mucous membrane irritation, and may include more severe respiratory effects, all of which constitute material health impairments. In addition, revising the total particulate limit to 10 mg/m3 as an 8-hour TWA will simplify employee exposure monitoring for Portland cement, since gravimetric rather than impinger methods can then be used.