Methylene bisphenyl isocyanate (MDI)
May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 101–68–8
NIOSH REL: 0.05 mg/m3 (0.005 ppm) TWA,
0.2 mg/m3 (0.020 ppm) 10-minute CEILING
Current OSHA PEL: 0.2 mg/m3 (0.02 ppm) CEILING
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 0.051 mg/m3 (0.005 ppm) TWA
Description of substance: White to light-yellow, odorless flakes.
LEL: . . Unknown
Original (SCP) IDLH: 100 mg/m3
Basis for original (SCP) IDLH: The chosen IDLH is based on an analogy with toluene diisocyanate, which has an IDLH of 10 ppm. [Note: A concentration of 10 ppm methylene bisphenyl isocyanate is equivalent to about 100 mg/m3.]
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal concentration data:
| Species | Reference | LC50 | LCLo | Time | Adjusted 0.5-hr LC (CF) | Derived value |
| Rat | Bunge et al. 1977 | 369 mg/m3 | ----- | 4 hr | 738 mg/m3 (2.0) | 74 mg/m3 |
| Rat | Bunge et al. 1977 | 380 mg/m3 | ----- | 4 hr | 760 mg/m3 (2.0) | 76 mg/m3 |
| Rat | Woolrich 1982 | 178 mg/m3 | ----- | ? | ? | ? |
Lethal dose data:
| Species | Reference | Route | LD50 (mg/kg) | LDLo (mg/kg) | Adjusted LD | Derived value |
| Mouse | Izmerov et al. 1982 | oral | 2,200 | ----- | 15,400 mg/m3 | 1,540 mg/m3 |
| Rat | Woolrich 1982 | oral | ----- | 31,690 | 221,830 mg/m3 | 22,183 mg/m3 |
Human data: None relevant for use in determining the revised IDLH.
Revised IDLH: 75 mg/m3 Basis for revised IDLH: The revised IDLH for methylene bisphenyl isocyanate is 75 mg/m3 based on acute inhalation toxicity data in animals [Bunge et al. 1977]. |
REFERENCES:
1. Bunge W, Ehrlicher H, Kimmerle G [1977]. Medical aspects of work with surface coating systems using the spraying technique. Zentralbl Arbeitsmed Arbeitsschutz Prophylaxe 4(spec. ed.):1-46 (in German). [From ACGIH [1991]. Methylene bisphenyl isocyanate. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 978-980.]
2. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 63.
3. Woolrich PF [1982]. Industrial hygiene and medical control of TDI, MDI and PMPPI. Am Ind Hyg Assoc J 43(2):89-97.