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

CAS number: 8003–34–7

NIOSH REL: 5 mg/m3 TWA

Current OSHA PEL: 5 mg/m3 TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 5 mg/m3 TWA

Description of substance: Brown, viscous oil or solid.

LEL :. . Unknown

Original (SCP) IDLH: 5,000 mg/m3

Basis for original (SCP) IDLH: The chosen IDLH has been estimated from the rat oral LD50 of 820 mg/kg [Carpenter et al. 1950 cited by ACGIH 1971]. In addition, ACGIH [1971] reported that rats experienced moderate lung congestion when exposed for 30 minutes to 6,000 mg/m3 pyrethrum in peanut oil [Carpenter et al. 1950].

Short-term exposure guidelines: None developed


Lethal dose data:

Species Reference Route LD50




Adjusted LD Derived value
Rat Carpenter et al. 1950 oral 820 ----- 5,740 mg/m3 574 mg/m3
Rat Hayes 1982 oral 200-1,870 ----- 1,400-13,090 mg/m3 140-1,309 mg/m3
Rat Malone & Brown 1968 oral 273- 796 ----- 1,911- 5,572 mg/m3 191- 557 mg/m3
Mouse Miyamoto 1976 oral 370 ----- 2,590 mg/m3 259 mg/m3
G. pig Shimkin & Anderson 1936 oral ----- 1,000 7,000 mg/m3 700 mg/m3

Other animal data: It has been reported that rats experienced moderate lung congestion when exposed for 30 minutes to 6,000 mg/m3 pyrethrum in peanut oil [Carpenter et al. 1950].

Human data: It has been estimated that the fatal human dose might be between 1 and 2 g/kg [Gosselin et al. 1984; Lehman 1949]. [Note: An oral dose of 1 to 2 g/kg is equivalent to a 70-kg worker being exposed to about 47,000 to 93,000 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]

Revised IDLH: 5,000 mg/m3 [Unchanged]

Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for pyrethrum. Therefore, based on acute oral toxicity data in humans [Gosselin et al. 1984; Lehman 1949], the original IDLH for pyrethrum (5,000 mg/m3) is not being revised at this time.


1. ACGIH [1971]. Pyrethrum. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 219-220.

2. Carpenter CP, Weil CS, Pozzani UC, Smyth HF Jr [1950]. Comparative acute and subacute toxicities of allethrin and pyrethrins. AMA Arch Ind Hyg Occup Med 2:420-432.

3. Gosselin RE, Smith HP, Hodge HC [1984]. Clinical toxicology of commercial products. 5th ed. Section III. Therapeutics Index. Baltimore, MD: Williams & Wilkins Company, pp. 352-355.

4. Hayes WJ Jr [1982]. Pesticides studied in man. Baltimore, MD: Williams & Wilkins Company, pp. 75-80.

5. Lehman AJ [1949]. Pharmacological considerations of insecticides. Q Bulletin Assoc Food Drug Off U.S. 13(2):65-70.

6. Malone JC, Brown NC [1968]. Toxicity of various grades of pyrethrum to laboratory animals. Pyrethrum Post 9:3-8.

7. Miyamoto J [1976]. Degradation, metabolism and toxicity of synthetic pyrethroids. Environ Health Perspect 14:15-28.

8. Shimkin MB, Anderson HH [1936]. Acute toxicities of rotenone and mixed pyrethrins in mammals. Proc Soc Exp Biol Med 34:135-138.

Page last reviewed: December 4, 2014