Xylene (o-, m-, p-isomers)

May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS numbers: 95-47-6 (o-isomer), 108-38-3 (m-isomer), 106-42-3 (p-isomer)

NIOSH REL: 100 ppm (435 mg/m3) TWA, 150 ppm (655 mg/m3) STEL

Current OSHA PEL: 100 ppm (435 mg/m3) TWA

1989 OSHA PEL: 100 ppm (435 mg/m3) TWA, 150 ppm (655 mg/m3) STEL

1993-1994 ACGIH TLV: 100 ppm (434 mg/m3) TWA, 150 ppm (651 mg/m3) STEL

Description of substance: Colorless liquid with an aromatic odor.

LEL: . . 0.9-1.1% (10% LEL, 900-1,100 ppm)

Original (SCP) IDLH: 1,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the following statements by ANSI [1971]. “Exposure at 1,000 ppm for 5 minutes or less will probably allow self-rescue with no irreversible injury. Higher concentrations or longer exposure periods can cause eye and respiratory tract irritation, and the beginning of narcotic effects which may limit self-rescue ability. This information is based on human experience and extrapolation from animal data.”

Existing short-term exposure guidelines: National Research Council [NRC 1984] Emergency Exposure Guidance Levels (EEGLs):

1-hour EEGL: 200 ppm

24-hour EEGL: 100 ppm


Lethal concentration data:

Species Reference LC50




Time Adjusted 0.5-hr


Derived value
o-Xylene Rat Cameron et al. 1938 ----- 6,125 12 hr 73,500 ppm (2.9) 7,350 ppm
o-Xylene Human Gekkan Yakuji 1980 ----- 6,125 12 hr 73,500 ppm (2.9) 7,350 ppm
m-Xylene Mouse Cameron et al. 1938 ----- 2,010 24 hr 7,236 ppm (3.6) 724 ppm
m-Xylene Rat Smyth et al. 1962 ----- 8,000 4 hr 16,000 ppm (2.0) 1,600 ppm
p-Xylene Mouse Arch Exp Pathol Pharmacol 1929 ----- 3,401 ? ? ?
p-Xylene Rat Harper et al. 1977 4,550 ----- 4 hr 9,100 ppm (2.0) 910 ppm
Xylene Human Morley et al. 1970 ----- 10,000 18 hr 33,000 ppm (3.3) 3,300 ppm
Xylene Rat NPIRI 1974 5,000 ----- 4 hr 10,000 ppm (2.0) 1,000 ppm
Xylene G. pig Smyth and Smyth 1928 ----- 450 ? ? ?

Other animal data: RD50 (mouse): 1,467 ppm [DeCeaurriz et al. 1981].

Other human data: It has been reported that 1,000 ppm for 5 minutes or less will probably allow self-rescue with no irreversible injury [ANSI 1971]. Volunteers found 200 ppm to be definitely irritating to the eyes, nose, and throat [Nelson et al. 1943]. Reaction time was not affected in 23 volunteers exposed to 100 or 200 ppm for 3 to 7 hours [Ogata et al. 1970]. No noticeable changes in reaction time or short-term memory tests were seen in 15 volunteers exposed to 100 or 300 ppm for 70 minutes [Gamberale et al. 1978].

Revised IDLH: 900 ppm

Basis for revised IDLH: The revised IDLH is 900 ppm based on acute inhalation toxicity data in animals [Cameron et al. 1938; DeCeaurriz et al. 1981; Harper et al. 1977; NPIRI 1974]. Although this may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 300 ppm, this value would have otherwise been selected for safety considerations (i.e., being 10% of the lower explosive limit of 0.9% for o-xylene).


1. Arch Exp Pathol Pharmakol [1929]. Toxicity of various hydrocarbon vapors; 143:223-233 (in German).

2. ANSI [1971]. American national standard, acceptable concentrations of xylene (dimethyl benzene). New York, NY: American National Standards Institute, Inc., ANSI Z37.10-1971, p. 7.

3. Cameron GR, Paterson JLH, de Saram GSW, Thomas JC [1938]. The toxicity of some methyl derivatives of benzene with special reference to pseudocumene and heavy coal tar naphtha. J Pathol Bacteriol 46:95-107.

4. DeCeaurriz JC, Micillino JC, Bonnet P, Guenier JP [1981]. Sensory irritation caused by various industrial airborne chemicals. Toxicol Lett 9(2):137-143.

5. Gamberale F, Annwall G, Hultengren M [1978]. Exposure to xylene and ethylbenzene. III. Effects on central nervous functions. Scand J Work Environ Health 4:204-211.

6. Gekkan Yakuji (Pharmaceuticals Monthly) [1980]; 22(5):883-889 (in Japanese).

7. Harper C, Drew RT, Fouts JR [1977]. Benzene and p-xylene: a comparison of inhalation toxicities and in vitro hydroxylations. In: Biological reactive intermediates, formulation, toxicity, and inactivation. Proceedings of the International Conference, Twiku, Finland, 1975. New York, NY: Plenum Publishing Corporation, pp. 302-311.

8. Morley R, Eccleston DW, Douglas CP, Greville WEJ, Scott DJ, Anderson J [1970]. Xylene poisoning: a report on one fatal case and two cases of recovery after prolonged unconsciousness. Br Med J 3:442-443.

9. Nelson KW, Ege JF, Ross M, Woodman LE, Silverman L [1943]. Sensory response to certain industrial solvent vapors. J Ind Hyg Toxicol 25(7):282-285.

10. NPIRI [1974]. Raw materials data handbook, physical and chemical properties, fire hazard and health hazard data. Vol. 1. Organic solvents. Bethlehem, PA: National Printing Ink Research Institute, p. 123.

11. NRC [1984]. Emergency and continuous exposure limits for selected airborne contaminants. Vol. 2. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 113-123.

12. Ogata M, Tomokuni K, Tatatsuka Y [1970]. Urinary excretion of hippuric acid and m- or p-methylhippuric acid in the urine of persons exposed to vapours of toluene and m- and p-xylene as a test of exposure. Br J Ind Med 27:43-50.

13. Smyth HF, Smyth HF Jr [1928]. Inhalation experiments with certain lacquer solvents. J Ind Hyg 10(8):261-271.

14. Smyth HF, Carpenter CP, Weil CS, Pozzani UC, Striegel JA [1962]. Range-finding toxicity data: list VI. Am Ind Hyg Assoc J 23:95-107.

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