Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 93-76-5
NIOSH REL: 10 mg/m3 TWA
Current OSHA PEL: 10 mg/m3 TWA
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 10 mg/m3 TWA
Description of substance: Colorless to tan, odorless, crystalline solid.
LEL :. . Unknown
Original (SCP) IDLH*: Unknown [*Note: “Effective” IDLH = 5,000 mg/m3 — see discussion below.]
Basis for original (SCP) IDLH: According to ACGIH , “the toxicity of this compound appears to be similar to the somewhat better known 2,4-D. According to Rowe and Hymas , the oral LD50 values fall in a range of 300 to 1,000 mg/kg for rats, mice, guinea pigs, and rabbits. Chronic exposure is not necessarily more hazardous. Drill and Hiratzka  found that there were no deaths among dogs treated with 2, 5, or 10 mg/kg/day of 2,4,5-T (5 days/week for 13 weeks); some deaths occurred at 20 mg/kg/day. There are no reports of illness from occupational exposure. It appears that the TLV of 10 mg/m3 is justified on the basis of extrapolation from animal feeding studies and extensive use experience.” Based on the toxicological data cited above, 2,4,5-T is a relatively nontoxic compound. Because data on acute inhalation toxicology are not available for this substance and to be consistent with the IDLHs selected for similar, relatively nontoxic compounds, 5,000 mg/m3 (i.e., 500 ´ the OSHA PEL of 10 mg/m3) has been chosen as the concentration above which only the “most protective” respirators are permitted.
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal dose data:
|Adjusted LD||Derived value|
|G. pig||AAPCO 1966||oral||381||-----||2,667 mg/m3||267 mg/m3|
|Rat||Bailey & White 1965||oral||300||-----||2,100 mg/m3||210 mg/m3|
|Hamster||Grant 1979||oral||425||-----||2,975 mg/m3||298 mg/m3|
|Mouse||Senczuk & Pogorzelska 1980||oral||242||-----||1,694 mg/m3||169 mg/m3|
Other animal data: It has been reported that there were no deaths among dogs treated with 2, 5, or 10 mg/kg/day of 2,4,5-T (5 days/week for 13 weeks); some deaths occurred at 20 mg/kg/day [Drill and Hiratzka 1953].
Human data: None relevant for use in determining the revised IDLH.
|Revised IDLH: 250 mg/m3
Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for 2,4,5-T. Therefore, the revised IDLH for 2,4,5-T is 250 mg/m3 based on acute oral toxicity data in animals [AAPCO 1966; Bailey and White 1965; Grant 1979; Senczuk and Pogorzelska 1980]. This may be a conservative value due to the lack of relevant acute inhalation toxicity data for workers.
1. AAPCO . Pesticide chemicals official compendium. Topeka, KS: Association of American Pesticide Control Officials, Inc., p. 965.
2. ACGIH . 2,4,5-T (2,4,5 trichlorophenoxyacetic acid). In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 242.
3. Bailey GW, White JL . Herbicides: a compilation of their physical, chemical, and biological properties. Residue Reviews 10:97-102.
4. Drill VA, Hiratzka T . Toxicity of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichloro-phenoxyacetic acid. AMA Arch Ind Hyg Occup Med 7:61-67.
5. Grant WF . The genotoxic effects of 2,4,5-T. Mutat Res 65:83-110.
6. Rowe VK, Hymas TA . Summary of toxicological information on 2,4-D and 2,4,5-T type herbicides and an evaluation of the hazards to livestock associated with their use. Am J Vet Res 15(57):622-629.
7. Senczuk W, Pogorzelska H . Budowa chemiczna a toksykodynamiczne wlasciwosci pochodnych kwasow fenoksykarboksylowych. Roczniki Panstwowego Zakladu Higieny 31(4):373-377 (in Polish).