Isophorone

CAS number: 78–59–1

NIOSH REL: 4 ppm (23 mg/m³) TWA

Current OSHA PEL: 25 ppm (140 mg/m³) TWA

1989 OSHA PEL: 4 ppm (23 mg/m³) TWA

1993-1994 ACGIH TLV: 5 ppm (28 mg/m³) CEILING

Description of substance: Colorless to white liquid with a peppermint-like odor.

LEL:. . 0.8% (10% LEL, 800 ppm)

Original (SCP) IDLH: 800 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the UCC [1971] report that exposure of animals for 1 hour to 880 ppm caused serious organ damage; only 1 of 6 animals died from an 8-hour exposure to air saturated with isophorone (approximately 525 ppm at 77°F).

Short-term exposure guidelines: None developed

ACUTE TOXICITY DATA:

Lethal concentration data:

Species	Reference	LC50 (ppm)	LCLo (ppm)	Time	Adjusted 0.5-hr LC (CF)	Derived value
Rat	ATSDR 1989	-----	885	6 hr	2,036 ppm (2.3)	204 ppm
G. pig	Marhold 1986	4,600	-----	8 hr	11,500 ppm (2.5)	1,150 ppm
Rat	Smyth & Seaton 1940	-----	1,840	4 hr	3,680 ppm (2.0)	368 ppm
Mammal	UCC 1971	LC17: 525	-----	8 hr	1,316 ppm (2.5)	132 ppm

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Rat	Smyth et al. 1970	oral	2,330	-----	2,841 ppm	284 ppm
Mouse	Smyth et al. 1970	oral	2,690	-----	3,280 ppm	328 ppm

Other animal data: RD₅₀ (mouse), 27.8 ppm [DeCeaurriz et al. 1981]. It has been reported that exposure of animals for 1 hour to 880 ppm caused serious organ damage [UCC 1971].

Human data: A few of the 11 or 12 volunteers exposed for a few minutes to 200 or 400 ppm complained of nausea, headache, dizziness, faintness, inebriation, and a feeling of suffocation [Smyth and Seaton 1940].

Revised IDLH: 200 ppm Basis for revised IDLH: The revised IDLH for isophorone is 200 ppm based on acute inhalation toxicity data in humans [Smyth and Seaton 1940] and animals [ATSDR 1989].

REFERENCES:

1. ATSDR [1989]. Toxicological profile for isophorone. Atlanta, GA: Agency for Toxic Substances and Disease Registry, ATSDR/TP-89/15.

2. DeCeaurriz JC, Micillino JC, Bonnet P, Guenier JP [1981]. Sensory irritation caused by various industrial airborne chemicals. Toxicol Lett 9:137-147.

3. Marhold J [1986]. Prehled Prumyslove Toxikologie, Organicke Latky. Prague, Czechoslovakia: Avicenum, p. 290 (in Czechoslovakian).

4. Smyth HF Jr, Seaton J [1940]. Acute response of guinea pigs and rats to inhalation of the vapors of isophorone. J Ind Hyg Toxicol 22(10):477-483.

5. Smyth HF Jr, Weil CS, West JS, Carpenter CP [1970]. An exploration of joint toxic action. II. Equitoxic versus equivolume mixtures. Toxicol Appl Pharmacol 17:498-503.

6. UCC [1971]. Toxicology studies: isophorone. New York, NY: Union Carbide Corporation.