p-Phenylene diamine

May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 106–50–3

NIOSH REL: 0.1 mg/m3 TWA [skin]

Current OSHA PEL: 0.1 mg/m3 TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.1 mg/m3 TWA

Description of substance: White to slightly red, crystalline solid.

LEL: . . Unknown

Original (SCP) IDLH*: Unknown [*Note: “Effective” IDLH = 25 mg/m3 — see discussion below.]

Basis for original (SCP) IDLH: ACGIH [1971] reported that the TLV for this chemical is believed to be sufficiently low to minimize the number of persons who become sensitized, but the limit is not low enough to prevent exacerbation of asthma in those already sensitized to p-phenylene diamine. Because sensitized workers may be endangered by concentrations far below the TLV, this cannot be used to set an IDLH. Therefore, in the absence of other toxicological data and noting that Patty [1963] reported systemic poisoning from industrial exposure to be unknown [Reichel 1934], for this draft technical standard the respirators have been selected on the basis of the assigned protection factor afforded by each device up to the saturated concentration at 20°C (approximately 29.1 mg/m3) rounded down to 25 mg/m3; only the “most protective” respirators are permitted for use in concentrations exceeding 25 mg/m3.

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50 (mg/kg) LDLo (mg/kg) Adjusted LD Derived value




G. pig

Burnett et al. 1977

Hanzlik 1923

Hanzlik 1923

Lloyd et al. 1977

Sheftel 1988
















560 mg/m3

1,750 mg/m3

700 mg/m3

686 mg/m3

1,015 mg/m3

56 mg/m3

175 mg/m3

70 mg/m3

69 mg/m3

102 mg/m3

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

Revised IDLH: 25 mg/m3

Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for p-phenylene diamine. Therefore, based on health considerations and acute oral toxicity data in animals [Burnett et al. 1977; Hanzlik 1923; Lloyd et al. 1977], a value of about 50 mg/m3 would have been appropriate. However, the revised IDLH for p-phenylene diamine is 25 mg/m3 based on the concentration recommended originally in the Standards Completion Program for deciding when the "most protective" respirators should be used. Because sensitized workers may be affected by concentrations far below occupational exposure limits, exacerbation of asthma cannot be used to set an IDLH.


1. ACGIH [1971]. p-Phenylenediamine. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 205.

2. Burnett C, Loehr R, Corbett J [1977]. Dominant lethal mutagenicity study on hair dyes. J Toxicol Environ Health 2:657-662.

3. Hanzlik PJ [1923]. The pharmacology of some phenylenediamines. J Ind Hyg 4:386-409, 448, 462.

4. Lloyd GK, Ligget MP, Kynoch SR, Davies RE [1977]. Assessment of the acute toxicity and potential irritancy of hair dye constituents. Food Cosmet Toxicol 15(6):607-610.

5. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 2121.

6. Reichel H [1934]. Vergifungsfallen 5:A21 (in German).

7. Sheftel VO [1988]. Toxic properties of phenylene diamine. Gig Sanit 53(7):62-63 (in Russian).

Page last reviewed: December 4, 2014