Toluene-2,4-diisocyanate

CAS number: 584–84–9

NIOSH REL: None established; NIOSH considers toluene-2,4-diisocyanate to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 0.02 ppm (0.14 mg/m³) CEILING

1989 OSHA PEL: 0.005 ppm (0.04 mg/m³) TWA, 0.02 ppm (0.15 mg/m³) STEL

1993-1994 ACGIH TLV: 0.005 ppm (0.036 mg/m³) TWA, 0.02 ppm (0.14 mg/m³) STEL

Description of substance: Colorless to pale-yellow solid or liquid (above 71°F) with a sharp, pungent odor.

LEL: . . 0.9% (10% LEL, 900 ppm)

Original (SCP) IDLH: 10 ppm

Basis for original (SCP) IDLH: For this draft technical standard, it is assumed that individuals who have developed a sensitivity to TDI will not be allowed to work in a TDI atmosphere. In these sensitized individuals, even concentrations below the OSHA PEL are capable of triggering the allergic response. Therefore, the IDLH has not been based on data obtained from the exposures of individuals or animals sensitized to TDI. The chosen IDLH is based on the 4-hour LC₅₀ values for different species of animals, ranging from 9.7 to 13.9 ppm [Duncan et al. 1962 cited by AIHA 1967 and NIOSH 1973].

Short-term exposure guidelines: None developed

ACUTE TOXICITY DATA:

Lethal concentration data:

Species	Reference	LC50 (ppm)	LCLo (ppm)	Time	Adjusted 0.5-hr LC (CF)	Derived value
Rat G. pig Mouse Rabbit	Duncan et al. 1962 Duncan et al. 1962 Duncan et al. 1962 Duncan et al. 1962	14 13.9 9.7 11	----- ----- ----- -----	4 hr 4 hr 4 hr 4 hr	28 ppm (2.0) 28 ppm (2.0) 19 ppm (2.0) 22 ppm (2.0)	2.8 ppm 2.8 ppm 1.9 ppm 2.2 ppm

Other animal data: RD₅₀ (mouse), 0.39 ppm [Alarie 1981].

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

Revised IDLH: 2.5 ppm Basis for revised IDLH: The revised IDLH for toluene-2,4-diisocyanate is 2.5 ppm based on acute inhalation toxicity data in animals [Duncan et al. 1962]. Since in sensitized individuals, even concentrations below the OSHA PEL are capable of triggering the allergic response, the revised IDLH has not been based on data obtained from the exposures of individuals or animals sensitized to TDI. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for toluene-2,4-diisocyanate at any detectable concentration.]

REFERENCES:

1. AIHA [1967]. Toluene diisocyanate. In: Hygienic guide series. Am Ind Hyg Assoc J 28:90-94.

2. Alarie Y [1981]. Dose-response analysis in animal studies: prediction of human responses. Environ Health Perspect 42:9-13.

3. Duncan B, Scheel LD, Fairchild EJ, Killens R, Graham S [1962]. Toluene diisocyanate inhalation toxicity: pathology and mortality. Am Ind Hyg Assoc J 23:447-456.

4. NIOSH [1973]. Criteria for a recommended standard: toluene diisocyanate. Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, National Institute for Occupational Safety and Health, DHEW Publication No. HSM 73-11022.