Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 85–44–9
NIOSH REL: 6 mg/m3 (1 ppm) TWA
Current OSHA PEL: 12 mg/m3 (2 ppm) TWA
1989 OSHA PEL: 6 mg/m3 (1 ppm) TWA
1993-1994 ACGIH TLV: 6.1 mg/m3 (1 ppm) TWA
Description of substance: White solid (flake) or a clear, colorless, mobile liquid (molten) with a characteristic, acrid odor.
LEL: . . 1.7% (10% LEL, 10,500 mg/m3)
Original (SCP) IDLH: 10,000 mg/m3
Basis for original (SCP) IDLH: Because no data on acute inhalation toxicity are available on which to base an IDLH for phthalic anhydride, the chosen IDLH is based on repeated exposure data. AIHA  reported that exposure of rats and rabbits to 10,000 mg/m3 for 4 hours/day for several days produced a 25% fatality rate [Malten and Zielhuis 1964].
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal dose data:
|Adjusted LD||Derived value|
|Rat||Biofax 1970||oral||4,020||-----||28,140 mg/m3||2,814 mg/m3|
|Mouse||Izmerov et al. 1982||oral||1,520||-----||10,500 mg/m3||1,050 mg/m3|
|Cat||Marhold 1986||oral||800||-----||5,600 mg/m3||560 mg/m3|
|Rat||Patty 1963||oral||800-1,600||-----||5,600 -11,200 mg/m3||560 - 1,120 mg/m3|
|Mouse||Zhilova & Kasparov 1969||oral||2,210||-----||15,470 mg/m3||1,547 mg/m3|
Other animal data: It has been reported that exposure of rats and rabbits to 10,000 mg/m3 for 4 hours/day for several days produced a 25% fatality rate [Malten and Zielhuis 1964].
Human data: It has been reported that an exposure of 30 mg/m3 is associated with conjunctivitis, while 25 mg/m3 is associated with signs of mucous membrane irritation [Baader 1955]. It has been stated that phthalic anhydride has similar toxic effects (i.e., irritation of the skin, eyes, and upper respiratory system) as maleic anhydride, but has reduced potency [ACGIH 1991].
|Revised IDLH: 60 mg/m3
Basis for revised IDLH: Based on acute toxicity data in animals [Biofax 1970; Izmerov et al. 1982; Malten and Zielhuis 1964; Marhold 1986; Patty 1963; Zhilova and Kasparov 1969], a value between 600 and 3,000 mg/m3 would have been appropriate. However, the revised IDLH for phthalic anhydride is 60 mg/m3 (i.e., 10 times the NIOSH REL) based on acute inhalation data in humans [Baader 1955] and an analogy to maleic anhydride [ACGIH 1991] which has a revised IDLH that is 10 times its NIOSH REL. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 30 mg/m3.
1. ACGIH . Phthalic anhydride. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 1263-1264.
2. AIHA . Phthalic anhydride. In: Hygienic guide series. Am Ind Hyg Assoc J 28:395-398.
3. Baader EW . Diseases due to phthalic acid and its compounds. Arch Gewerbepath Gewerbehyg 13:419-453 (in German).
4. Biofax . Phthalic anhydride. Northbrook, IL: Biofax Industrial Bio-Test Laboratories, Inc.
5. Izmerov NF, Sanotsky IV, Sidorov KK . Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 322.
6. Malten KE, Zielhuis RL . Alkyd resins. In: Industrial toxicology and dermatology in the production and processing of plastics. Amsterdam, The Netherlands: Elsevier Publishing Company, pp. 59-70.
7. Marhold J . Prehled Prumyslove Toxikologie, Organicke Latky. Prague, Czechoslovakia: Avicenum, p. 322 (in Czechoslovakian).
8. Patty FA, ed. . Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., pp. 1822-1823.
9. Zhilova NA, Kasparov AA . Phthalic anhydride and n-nitrosodiphenylamine (Vulcalent A). Chem Abstr 71:280.