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

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

CAS number: 26140–60–3 (mixed isomers)

NIOSH REL: 5 mg/m3 (0.5 ppm) CEILING

Current OSHA PEL: 9 mg/m3 (1 ppm) CEILING

1989 OSHA PEL: 5 mg/m3 (0.5 ppm) CEILING

1993-1994 ACGIH TLV: 5 mg/m3 (0.53 ppm) CEILING

Description of substance: Colorless or light-yellow solid.

LEL : . Unknown

Original (SCP) IDLH*: Unknown [*Note: “Effective” IDLH = 900 mg/m3 — see discussion below.]

Basis for original (SCP) IDLH: According to Testa and Masi [1964], workers have been exposed to 280 mg/m3 without adverse effect. For this draft technical standard, however, respirators have been selected on the basis of the assigned protection factor afforded by each device up to 100 ´ the OSHA PEL of 9 mg/m3 (i.e., 900 mg/m3); only the “most protective” respirators are permitted for use in concentrations exceeding 900 mg/m3. This is a concentration unlikely to occur because of its low vapor pressure.

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived value
Mixed isomers Mouse Zhenjiang & Gengliang 1986 oral 13,200 —– 92,400 mg/m3 9,240 mg/m3
o-Isomer Rat Cornish et al. 1962 oral 1,900 —– 13,300 mg/m3 1,330 mg/m3
m-Isomer Rat Cornish et al. 1962 oral 2,400 —– 16,800 mg/m3 1,680 mg/m3
p-Isomer Rat Cornish et al. 1962 oral >10,000 —– >70,000 mg/m3 >7,000 mg/m3
p-Isomer Rat NRC 1953 oral —– 500 3,500 mg/m3 350 mg/m3

Other animal data: In 30-day feeding studies involving doses of 250 or 500 mg/kg/day, rats fed o-terphenyl showed elevated liver and kidney weight ratios, rats fed m-terphenyl showed elevated kidney weight ratios only, and rats fed p-terphenyl showed no elevation in liver or kidney weight ratios [Cornish et al. 1962].

Human data: It has been reported that workers have been exposed to 280 mg/m3 without adverse effect [Testa and Masi 1964].


1. Cornish HH, Bahor RE, Ryan RC [1962]. Toxicity and metabolism of ortho-, meta-, and para-terphenyls. Am Ind Hyg Assoc J 23:372-378.

2. NRC [1953]. Relationship between chemical structure and toxic action on rats. National Academy of Sciences, National Research Council, Chemical-Biological Coordination Center, Review 5:26.

3. Testa C, Masi G [1964]. Determination of polyphenyls in working environments of organic reactors by spectrophotometric methods. Anal Chem 36(12):2284-2287.

4. Zhenjiang L, Gengliang W [1986]. Development of hydroterphenyl for use as high temperature organic heat carrier. Shiyou Huagong (Petrochemical Technology) 15:305-308 (in Chinese).

Page last reviewed: December 4, 2014