Terphenyl (o-, m-, p­isomers)

IDLH Documentation
CAS number: 26140­60­3 (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

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

Description of substance: Colorless or light­yellow 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.

Short­term 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 MouseZhenjiang & Gengliang 1986
oral
13,200
-----
92,400 mg/m3
9,240 mg/m3
o-Isomer RatCornish et al. 1962
oral
1,900
-----
13,300 mg/m3
1,330 mg/m3
m-Isomer RatCornish et al. 1962
oral
2,400
-----
16,800 mg/m3
1,680 mg/m3
p-Isomer RatCornish et al. 1962
oral
>10,000
-----
>70,000 mg/m3
>7,000 mg/m3
p-Isomer RatNRC 1953
oral
-----
500
3,500 mg/m3
350 mg/m3

Other animal data: In 30­day feeding studies involving doses of 250 or 500 mg/kg/day, rats fed o­terphenyl showed elevated liver and kidney weight ratios, rats fed m­terphenyl showed elevated kidney weight ratios only, and rats fed p­terphenyl 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/m3

Basis 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 para­terphenyls. Am Ind Hyg Assoc J 23:372­378.

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):2284­2287.

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

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