TETRAETHYL LEAD
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: 78-00-2; Chemical Formula: (C2H5)4Pb
OSHA’s current 8-hour limit for tetraethyl lead is 0.075 mg/m3, measured as lead, with a skin notation; NIOSH has no REL for this substance. The ACGIH is now recommending that worker exposures to TEL not exceed 0.1 mg/m3 TWA; the ACGIH also recommends a skin notation. Tetraethyl lead is a colorless liquid, which may be dyed red, orange, or blue, and has a slightly musty odor.
The previous TLV of 0.075 mg/m3 was based almost exclusively on a personal communication from the Medical Department of the Ethyl Corporation, which stated that a level of 0.075 mg/m3 “is a good guideline for an allowable air concentration of TEL” (ACGIH 1966/Ex. 1-13). The ACGIH documentation for the 0.075 mg/m3 TLV also pointed out that the ability of tetraethyl lead to penetrate the skin “makes reliance on the airborne concentration impractical in many situations,” and that urinary lead levels are a more reliable indicator of exposure than blood lead levels (ACGIH 1966/Ex. 1-13).
In its documentation for the 0.1 mg/m3 TLV, the ACGIH (1986/Ex. 1-3, p. 563) again cited the communication from the Ethyl Corporation. In addition, the organization cited a personal communication from Linch (1968, as cited in ACGIH 1986/Ex. 1-3, p. 563), who reported that an improved analytical procedure for measuring airborne concentrations of tetraethyl lead had been used to determine the relationship between airborne tetraethyl lead levels and urinary lead levels. He reported that urinary lead concentration was not significantly elevated “above a high normal” value (0.15 mg/L) when the airborne TEL level was 121 ug/m3 (ACGIH 1986/Ex. 1-3, p. 563). As a result of this communication, the ACGIH adopted a revised TLV of 0.1 mg/m3 in 1970.
NIOSH (Ex. 8-47, Table N1) concurs that OSHA should retain its existing limit for TEL; no other comments on this substance were submitted.
OSHA does not find the evidence presented by the ACGIH to be sufficiently comprehensive or detailed to permit significant risk to be ruled out at the 0.1 ppm level. The Agency is also reluctant to increase the PEL for TEL in light of this substance’s ability to be absorbed percutaneously. OSHA is therefore retaining the existing PEL of 0.075 mg/m3, measured as Pb and with a skin notation, for tetraethyl lead.