Skip directly to local search Skip directly to A to Z list Skip directly to navigation Skip directly to site content Skip directly to page options
CDC Home
May 1994

Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)


CAS number: 100–00–5

NIOSH REL: None established; NIOSH considers p-nitrochlorobenzene to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990] that may be absorbed through the skin.

Current OSHA PEL: 1 mg/m3 TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.64 mg/m3 (0.1 ppm) TWA [skin]

Description of substance: Yellow, crystalline solid with a sweet odor.

LEL: . . . Unknown

Original (SCP) IDLH: 1,000 mg/m3

Basis for original (SCP) IDLH: No data on acute inhalation toxicity are available on which to base an IDLH for p-nitrochlorobenzene. The chosen IDLH, therefore, is based on an analogy with nitrobenzene, which has an IDLH of 200 ppm. [Note: A concentration of 200 ppm nitrobenzene is equivalent to about 1,000 mg/m3 p-nitrochlorobenzene.]

Short-term exposure guidelines: None developed


Lethal concentration data:


SpeciesReferenceLC50 LCLoTimeAdjusted 0.5-hr


Derived value
CatWatrous & Schultz 1950 164 mg/m3-----7 hr393 mg/m3 (2.4)39 mg/m3

Lethal dose data:






Adjusted LDDerived value
RatBack et al. 1972oral812-----5,684 mg/m3 568 mg/m3
MouseBack et al. 1972 oral1,414-----9,898 mg/m3990 mg/m3
MouseIzmerov et al. 1982 oral440-----3,080 mg/m3308 mg/m3
RatSziza & Magos 1959 oral420 ----- 2,940 mg/m3 294 mg/m3

Other animal data: Exposures of cats and guinea pigs to 87 mg/m3 for 8 hours/day for 6 weeks resulted in methemoglobinemia and slight anemia [Watrous and Schultz 1950].

Human data: Workers exposed intermittently for 0.5 to 1 hour over many months to concentrations ranging from 7 to 400 mg/m3 (average of 90 mg/m3) had only vague complaints of tiredness, loss of appetite, headache, and afternoon fatigue [Watrous and Schultz 1950]. Because of the strong and disagreeable odor, these workers voluntarily wore respiratory protection when exposed to the higher concentrations [Watrous and Schultz 1950].


Revised IDLH: 100 mg/m3

Basis for revised IDLH: The revised IDLH for p-nitrochlorobenzene is 100 mg/m3 based on subchronic inhalation toxicity data in workers [Watrous and Schultz 1950] and animals [Watrous and Schultz 1950]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 100 mg/m3. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for p-nitrochlorobenzene at any detectable concentration.]


1. Back KC, Thomas AA, MacEwen JD [1972]. Reclassification of materials listed as transportation health hazards. Wright-Patterson Air Force Base, OH: 6570th Aerospace Medical Research Laboratory, Report No. TSA-20-72-3, pp. A-270 to A-271.

2. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 92.

3. Sziza M, Magos I [1959]. Toxikologische untersuchung einiger in der ungarischen industrie zur anwendung gelangenden aromatischen nitroverbindungen. Arch Gewerbepath Gewerbehyg 17:217-226 (in German).

4. Watrous RM, Schultz HN [1950]. Cyclohexylamine, p-chloronitrobenzene, 2-aminopyridine: toxic effects in industrial use. Ind Med Surg 19:317-320.

Contact Us: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Road Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO