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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
ACUTE TOXICITY DATA:
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].
| Revised IDLH: 500 mg/m3Basis for revised IDLH: Based on health considerations and acute toxicity data in animals [NRC 1953], a value of about 2,000 mg/m3 would have been appropriate for terphenyl. However, the revised IDLH for terphenyl is 500 mg/m3 based on being 100 times the NIOSH REL of 5 mg/m3 (100 is an assigned protection factor for respirators and was used during the Standards Completion Program for deciding when the “most protective” respirators should be used for terphenyl). |
REFERENCES:
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).