Di-sec octyl phthalate

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

CAS number: 117–81–7

NIOSH REL: 5 mg/m3 TWA, 10 mg/m3 STEL; NIOSH considers di-sec octyl phthalate to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 5 mg/m3 TWA

1989 OSHA PEL: 5 mg/m3 TWA, 10 mg/m3 STEL

1993-1994 ACGIH TLV: 5 mg/m3 TWA, 10 mg/m3 STEL

Description of Substance: Colorless, oily liquid with a slight odor.

LEL(@474 F): 0.3% (10% LEL(@474 F), 8,600 mg/m3)

Original (SCP) IDLH*: Unknown [*Note: “Effective” IDLH = 5,000 mg/m3 — see discussion below.]

Basis for original (SCP) IDLH: Patty [1963] made the statement that inhalation of the vapor-mist mixture produced by bubbling air through a column of plasticizer maintained at 170 C could be tolerated for 2 hours without producing fatalities. In a 4-hour period, however, all rats had succumbed. On the basis of these experiments, the hazard to exposed workers should be very low under ordinary circumstances. Because di-sec octyl phthalate has such a low toxicity, respirators have been selected on the basis of the assigned protection factor afforded by each device up to 1,000 × the OSHA PEL of 5 mg/m3 (i.e., 5,000 mg/m3); only the “most protective” respirators are permitted for use in concentrations exceeding 5,000 mg/m3.

Short-term exposure guidelines: None developed


Lethal dose data:







Adjusted LD

Derived value

G. pig



Autian 1973

Autian 1973

Shibko and Blumenthal 1973

Yagi et al. 1976













238,000 mg/m3

182,000 mg/m3

214,200 mg/m3

210,000 mg/m3

23,800 mg/m3

18,200 mg/m3

21,420 mg/m3

21,000 mg/m3

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

Revised IDLH: 5,000 mg/m3

Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for di-sec octyl phthalate. Since the acute oral toxicity data in animals [Autian 1973; Shibko and Blumenthal 1973; Yagi et al. 1976] indicates that di-sec octyl phthalate has low acute toxicity, the revised IDLH for di-sec octyl phthalate is 5,000 mg/m3 based on being 1,000 times the OSHA PEL of 5 mg/m3 (1,000 is an assigned protection factor for respirators and was used during the Standards Completion Program for deciding when the "most protective" respirators should be used for di-sec octyl phthalate). [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for di-sec octyl phthalate at concentrations above 5 mg/m3.]



1. Autian J [1973]. Toxicity and health threats of phthalate esters: review of the literature. Environ Health Perspect 4:3-26.

2. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1909.

3. Shibko SI, Blumenthal H [1973]. Toxicology of phthalic acid esters used in food-packaging material. Environ Health Perspect 3:131-137.

4. Yagi Y, Tutikawa K, Shimoi N [1976]. Teratogenicity and mutagenicity of a phthalate ester. Int J Abnorm Develop 14(2):259 [Abstract].

Page last reviewed: December 4, 2014