Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 50–29–3
NIOSH REL: 0.5 mg/m3 TWA; NIOSH considers DDT to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].
Current OSHA PEL: TWA 1 mg/m3 TWA [skin]
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: TWA 1 mg/m3 TWA [skin]
Description of Substance: Colorless crystals or off-white powder with a slight, aromatic odor.
LEL:. . Unknown
Original (SCP) IDLH*: No Evidence [*Note: “Effective” IDLH = 500 mg/m3 — see discussion below.]
Basis for original (SCP) IDLH: The available toxicological data show no evidence that an acute exposure to a high concentration of DDT would impede escape or cause any irreversible health effects within 30 minutes. AIHA  reported that the concentration immediately hazardous to life is “probably unobtainable,” and that DDT has a low order of acute toxicity by inhalation. For this draft technical standard, therefore, respirators have been selected on the basis of the assigned protection factor afforded by each device. However, for some particulate substances for which no evidence of an IDLH exists, the determination of allowable respiratory protection based on protection factors may result in the assignment of respirators for concentrations that are not likely to be encountered in the occupational environment. Therefore, for all such particulate substances it has been arbitrarily determined that only the “most protective” respirators are permitted for use in concentrations exceeding 500 × the OSHA PEL; in the case of DDT, 500 × the OSHA PEL of 1 mg/m3 is 500 mg/m3.
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA
Lethal dose data:
Truhaut et al. 1974
Human data:Exposure of volunteers to 423 mg/m3 for periods of 1 hour/day for 6 days has been reported to only cause eye irritation [Neal et al. 1994]. It has been reported that 500 mg/kg is the lethal oral dose [Windholz 1983]. [Note: An oral dose of 500 mg/kg is equivalent to a 70-kg worker being exposed to about 23,000 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]
|Revised IDLH: 500 mg/m3
Basis for revised IDLH: The revised IDLH for DDT is 500 mg/m3 based on acute toxicity data in humans [Neal et al. 1944; Windholz 1983]. This may be a conservative value due to the lack of relevant acute toxicity data in humans exposed to concentrations above 423 mg/m3. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for DDT at concentrations above 0.5 mg/m3.]
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