Agent Name

Phthalic anhydride

CAS Number

85-44-9

Formula

C8-H4-O3

Major Category

Plastics & Rubber

Synonyms

1,2-Benzenedicarboxylic anhydride; PAN; Phthalic acid anhydride; [NIOSH]

Category

Acid Anhydrides, Cyclic

Description

White solid (flake) or a clear, colorless, mobile liquid (molten) with a characteristic, acrid odor; [NIOSH]

Sources/Uses

Chemical intermediate for various chemical resins, dyes, and pigments; curing agent for epoxy resins; [HSDB] Occupational asthma reported in plastic resin production workers; [Malo] Used to make alkyd resins in the production of paints; Workers may be exposed while welding on painted metals containing alkyd resin with phthalic anhydride hardener; [ACGIH]

Comments

Occupational asthma reported in plastic resin production workers; [Malo] Solid form causes first degree burns on short exposure; [CHRIS] Phthalic anhydride is a skin irritant. [Quick CPC] "Workers exhibiting dermal or respiratory symptoms (e.g., rhinitis) may benefit from early intervention to reduce or eliminate further exposure. . . . A number of human studies found that phthalic anhydride exposure can cause or is associated with sensitization, elevated IgE and IgG, occupational asthma (immediate, late or both), rhinitis, conjunctivitis, chronic bronchitis, respiratory irritation, and contact urticaria. It may also cause allergic contact dermatitis." [ACGIH] See "ACID ANHYDRIDES."

Reference Link

Phthalic anhydride-induced occupational asthma

Exposure Assessment
Skin Designation (ACGIH)

Yes

TLV (ACGIH)

0.002 mg/m3, inhalable fraction and vapor

STEL (ACGIH)

0.005 mg/m3, inhalable fraction and vapor

PEL (OSHA)

12 mg/m3

IDLH (NIOSH)

60 mg/m3

Excerpts from Documentation for IDLHs

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].

Vapor Pressure

0.000517 mm Hg

Odor Threshold Low

0.05 mg/m3

Explanatory Notes

Odor threshold from AIHA;

Reference Link

ICSC: Phthalic anhydride

Adverse Effects
Asthma

Yes

Dermatotoxin

Skin Burns

ACGIH Carcinogen

Not Classifiable

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information

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Chemical Information

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Biomedical References

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Related Information in HazMap
Diseases

Occupational diseases associated with exposure to this agent:

Processes

Industrial Processes with risk of exposure: