ALLYL PROPYL DISULFIDE
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: 2179-59-1; Chemical Formula: CH2 = CHCH2S2C3H7
The previous OSHA PEL for allyl propyl disulfide was 2 ppm (12 mg/m3) as an 8-hour TWA. OSHA proposed to supplement this limit with a 3-ppm (18-mg/m3) 15-minute STEL, and NIOSH (Ex. 8-47, Table N1) concurred with this proposal. The final rule establishes a 2-ppm TWA limit and 3-ppm STEL for this substance; these limits are the same as those recommended by the ACGIH (1986/Ex. 1-3). Allyl propyl disulfide is a liquid with a pungent, irritating odor.
Nearly all exposures to allyl propyl disulfide, the primary constituent in onion oil, occur in the processing of onions and onion products. Allyl propyl disulfide’s irritative effects on the human eye, nose, and upper respiratory tract are well recognized. The most severe irritation effects have occurred when workers were exposed to allyl propyl disulfide in the vicinity of onion slicing machines, where average concentrations of 3.4 ppm have been measured (Feiner, Burke, and Baliff 1946/Ex. 1-604).
No rulemaking participants other than NIOSH commented on the addition of a STEL to the current TWA limit for allyl propyl disulfide. OSHA concludes that, in the absence of a STEL, the 2-ppm TWA limit would not prevent employees from being exposed to short-term concentrations of sufficient magnitude to cause acute irritant effects. The Agency considers this effect to constitute material impairment of health and functional capacity. Accordingly, OSHA finds that a limit on short-term exposure is necessary to protect workers from significant acute irritation and is supplementing its current 2-ppm TWA limit with a 3-ppm 15-minute STEL in the final rule.