1,3-Butadiene

CAS number. . . . . . . . . . .  106-99-0
NIOSH REL . . . . . . . . . . .  None established; NIOSH considers
                                 1,3-butadiene to be a potential occupational
                                 carcinogen as defined by the OSHA
                                 carcinogen policy [29 CFR 1990].
Current OSHA PEL. . . . . . . .  1,000 ppm (2,200 mg/m3) TWA
1989 OSHA PEL . . . . . . . . .  Same as current PEL
1993-1994 ACGIH TLV . . . . . .  10 ppm (22 mg/m3) TWA, A2
Description of Substance. . . .  Colorless gas with a mild aromatic or
                                 gasoline-like odor.
LEL . . . . . . . . . . . . . .  2.0% (10% LEL, 2,000 ppm)
Original (SCP) IDLH . . . . . .  20,000 ppm [LEL]
Basis for original (SCP) IDLH .  AIHA [1963] reported that narcosis did not
                                 occur in 2 humans inhaling 8,000 ppm during
                                 an 8-hour period [Carpenter et al. 1944].
                                 AIHA [1963] also reported that inhalation of
                                 6,700 ppm for 7.5 hours/day, 6 days/week for
                                 8 months resulted in no significant chronic
                                 effects in rats, guinea pigs, rabbits, and
                                 dogs; some growth retardation and light
                                 cloudy swelling of livers did occur
                                 [Carpenter et al. 1944].  From the data
                                 given above, acutely toxic concentrations are
                                 obviously well above the lower explosive
                                 limit (LEL) of 20,000 ppm.  For this draft
                                 technical standard, therefore, the LEL is
                                 used as the IDLH (i.e., the concentration
                                 above which only the "most protective"
                                 respirators are permitted).
Existing short-term exposure. .  1991 American Industrial Hygiene Association
guidelines                       (AIHA) Emergency Response Planning Guidelines
                                 (ERPGs):
                                      ERPG-1:      10 ppm (60-minute)
                                      ERPG-2:      50 ppm (60-minute)
                                      ERPG-3:  5,000 ppm (60-minute)

ACUTE TOXICITY DATA

Lethal concentration data:

                                                       Adjusted               
                          LC50     LCLo             0.5-hr           Derived
Species    Reference      (ppm)    (ppm)    Time       LC (CF)        Value
______________________________________________________________________________
Rabbit  Carpenter et       -----  250,000  30 min 250,000 ppm (1.0) 25,000 ppm
        al. 1944
Mouse   Dow 1941         115,111   -----    ?         ?                ?
Rat     Dow 1941   LC40: 200,000   -----   30 min 200,000 ppm (1.0) 20,000 ppm
Mouse   Dow 1941         122,000   -----    2 hr  195,200 ppm (1.6) 19,500 ppm
Rat     Shugaev 1968     126,667   -----    4 hr  253,334 ppm (2.0) 25,334 ppm
Rat     Von Oettingen    130,000   -----    4 hr  260,000 ppm (2.0) 26,000 ppm
        1940

Other animal data . . . . . . .  Exposures to 6,700 ppm for 7.5 hours/day, 6
                                 days/week for 8 months caused no progressive 
                                 injury in rats, guinea pigs, rabbits, or 1 
                                 dog [Carpenter et al. 1944].
Human data. . . . . . . . . . .  Narcosis did not occur in volunteers exposed
                                 to 8,000 ppm for
                                 8 hours [Carpenter et al. 1944].  Exposure to
                                 10,000 ppm for 5 minutes has resulted in 
                                 slight irritation and dryness of the nose
                                 and mouth with some increase in pulse rate
                                 but no effect on blood pressure or 
                                 respiration [Shugaev 1968].

Revised IDLH: 2,000 ppm [LEL]
Basis for revised IDLH: Based on health considerations and acute inhalation toxicity data in humans [Carpenter et al. 1944; von Oettingen 1940] and animals [Carpenter et al. 1944; Dow 1941; Shugaev 1968; von Oettingen 1940], a value between 10,000 and 20,000 ppm would have been appropriate. However, the revised IDLH for 1,3-butadiene is 2,000 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 2%). [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for 1,3-butadiene at any detectable concentration.]

REFERENCES:

1. AIHA [1963]. 1,3-Butadiene. In: Hygienic guide series. Am Ind Hyg Assoc J 24:91-92.
2. Carpenter CP, Shaffer CB, Weil CS, Smyth HF Jr [1944]. Studies on the inhalation of 1,3-butadiene; with a comparison of its narcotic effect with benzol, toluol, and styrene, and a note on the elimination of styrene by the human. J Ind Hyg Toxicol 26(3):69-78.
3. Dow [1941]. Research report of inhalation toxicity of 1,3-butadiene. [Unpublished research]. Midland, MI: Dow Chemical Company. [From American Industrial Hygiene Association (AIHA) 1991 Emergency Response Planning Guidelines for 1,3-Butadiene.]
4. Shugaev BB [1968]. Distribution in the organism and toxicity of aliphatic hydrocarbons. Farmakol Toxsikol 31:162-165 (translated).
5. von Oettingen WR [1940]. Toxicity and potential dangers of aliphatic and aromatic hydrocarbons. A critical review of the literature. Public Health Bulletin 255:25.