Coal tar pitch volatiles

CAS number: 65996–93–2

NIOSH REL: 0.1 mg/m³ (cyclohexane-extractable fraction) TWA; NIOSH considers coal tar pitch volatiles to be potential occupational carcinogens as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 0.2 mg/m³ (benzene-soluble fraction) TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.2 mg/m³ (benzene-soluble fraction) TWA, A1

Description of Substance: Black or dark-brown amorphous residue.

LEL: . . Unknown

Original (SCP) IDLH: 700 mg/m³ [*Note: "Effective" IDLH = 400 mg/m³ -- see discussion below.]

Basis for original (SCP) IDLH: Redmond et al. [1972] have shown that the major health effects resulting from long-term repeated exposure to coal tar pitch volatiles (CTPV) are cancer of the lung, kidney, and skin; however, no studies have been made on carcinogenic effects by any route from single short-term exposure to CTPV that could relate to a 30-minute IDLH. Therefore, reliance must be placed on comparative data of single versus repeated carcinogenic doses of benzo(a)pyrene [B(a)P], a known component of CTPV. Bingham [1971] reported that B(a)P applied in a single dose of 2 mg to the skin of mice yielded tumors in 10% to 20% of the animals whereas 0.01 mg B(a)P applied in a noncarcinogenic solvent applied to the skin 3 times/week for 50 weeks yielded tumors in 50% of the animals. Thus, a single dose producing about 1/3 the number of tumors was 200 times the repeated 3 times/week dose. Using this factor and the value of 0.6 mg/m³ CTPV reported by Mazumdar et al. [1975] as safe for coke oven workers, a total dose IDLH of 120 mg CTPV (as benzene solubles) is calculated; by using 7.5 liters as the minute volume of coke oven workers and a 75% lung retention of CTPV a 30-minute IDLH is calculated to be about 700 mg/m³ (as benzene solubles). However, because of the assigned protection factor afforded by each device, 400 mg/m³ (i.e., 2,000 × the PEL) is the concentration above which only the "most protective" respirators are permitted.

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
Pyrene Rat	Potapova et al. 1971	170 mg/m3	-----	?	?	?

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Pyrene Rat Mouse	Potapova et al. 1971 Potapova et al. 1971	oral oral	2,700 800	----- -----	18,900 mg/m3 5,600 mg/m3	1,890 mg/m3 560 mg/m3
Anthracene Mouse	Nogochy 1969	oral	-----	>17,000	>119,000 mg/m3	>11,900 mg/m3
Phenanthrene Mouse	Rakhmanina 1964	oral	700	-----	4,900 mg/m3	490 mg/m3

Other animal data: The major health effects resulting from long-term repeated exposure to coal tar pitch volatiles (CTPV) are cancer of the lung, kidney, and skin [Redmond et al. 1972]; however, no studies have been made on carcinogenic effects by any route from single short-term exposure to CTPV that could relate to a 30-minute IDLH. Therefore, reliance must be placed on comparative data of single versus repeated carcinogenic doses of benzo(a)pyrene [B(a)P], a known component of CTPV. It has been reported that B(a)P applied in a single dose of 2 mg to the skin of mice yielded tumors in 10% to 20% of the animals whereas 0.01 mg B(a)P applied in a noncarcinogenic solvent applied to the skin 3 times/week for 50 weeks yielded tumors in 50% of the animals [Bingham 1971]. Thus, a single dose producing about 1/3 the number of tumors was 200 times the repeated 3 times/week dose. Using this factor and the value of 0.6 mg/m³ CTPV reported as safe for coke oven workers [Mazumdar et al. 1975], a total dose IDLH of 120 mg CTPV (as benzene solubles) is calculated; by using 50 liters as the minute volume of workers and 100% lung retention of CTPV, a 30-minute IDLH is calculated to be about 80 mg/m³ (as benzene solubles).

Human data: None relevant for use in determining the revised IDLH.

Revised IDLH: 80 mg/m3 (as the benzene-soluble fraction) Basis for revised IDLH: The revised IDLH for coal tar pitch volatiles is 80 mg/m3 (as the benzene-soluble fraction) based on toxicity data in animals [Bingham 1971; Mazumdar et al. 1975; Redmond et al. 1972] (see discussion above). [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for coal tar pitch volatiles at concentrations above 0.1 mg/m3 (cyclohexane-extractable fraction).]

REFERENCES:

1. Bingham E [1971]. Thresholds in cancer inductions. If they do exist, do they shift? Arch Environ Health 22:692-695.

2. Mazumdar S, Redmond C, Sollecito W, Sussman N [1975]. An epidemiological study of exposure to coal tar pitch volatiles among coke oven workers. J Air Pollut Control Assoc 25(4):382-389.

3. Nagochy PA [1969]. Comparative study of the toxicity of pure and technical anthracene. Gig Tr Prof Zabol 13(5):59 (in Russian).

4. Potapova AN, Kapitulsky VB, et al. [1971]. Toxicological evaluation of pyrene. Gig Tr Prof Zabol 15(2):59 (in Russian).

5. Rakhmanina NL [1964]. Establishing standards for the phenanthrene and pyrene contents in water bodies. Gig Sanit 29(6):19-23 (translated).

6. Redmond CK, Ciocco A, Lloyd JW, Rush HW [1972]. Long-term mortality study of steel workers. VI. Mortality from malignant neoplasms among coke oven workers. J Occup Med 14(8):621-629.