Zinc oxide

CAS number: 1314–13–2

NIOSH REL: Fume: 5 mg/m³ TWA, 10 mg/m³ STEL;

Dust: 5 mg/m³ TWA, 15 mg/m³ CEILING

Current OSHA PEL: Fume: 5 mg/m³ TWA;

Dust: 15 mg/m³ (total dust) TWA,

5 mg/m³ (respirable dust) TWA

1989 OSHA PEL: Fume: 5 mg/m³ TWA, 10 mg/m³ STEL;

Dust: 10 mg/m³ (total dust) TWA,

5 mg/m³ (respirable dust) TWA

1993-1994 ACGIH TLV: Fume: 5 mg/m³ TWA, 10 mg/m³ STEL;

Dust: 10 mg/m³ TWA

Description of substance: White, odorless solid.

LEL: . . Noncombustible Solid

Original (SCP) IDLH*: No Evidence* [*Note: "Effective" IDLH = 2,500 mg/m³) -- see discussion below.]

Basis for original (SCP) IDLH: The available toxicological data contains no evidence that an acute exposure to a high concentration of zinc oxide fume would impede escape within 30 minutes or cause any irreversible health effects. For this draft technical standard, therefore, respirators have been selected on the basis of the assigned protection factor afforded by each device. However, for some particulate substances for which no evidence of an IDLH exists, the determination of allowable respiratory protection based on protection factors may result in the assignment of respirators for concentrations that are not likely to be encountered in the occupational environment. Therefore, for all such particulate substances it has been arbitrarily determined that only the "most protective" respirators are permitted for use in concentrations exceeding 500 ´ the OSHA PEL of 5 mg/m³ (i.e., 2,500 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
Mouse	Takahashi 1976	2,500 mg/m3	-----	?	?	?
G. pig	Turner & Thompson 1926	-----	2,500 mg/m3	3-4 hr	4,500-5,000 mg/m3 (1.8/2.0)	450-500 mg/m3

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Mouse	Gig Sanit 1986	oral	7,950	-----	55,650 mg/m3	5,565 mg/m3

Human data: Workers exposed to zinc concentrations between 320 to 580 mg/m³ for 1-3 hours have experienced nausea on the job, and chills, shortness of breath, and severe chest pains 2 to 12 hours later [Hammond 1944]. Two men exposed to about 600 mg/m³ for 10.5 to 12 minutes experienced headaches, chills, and fever with cough and a decrease in vital capacity which persisted for 15 hours after exposure [Sturgis and Thompson 1927]. When air concentrations approach 600 mg/m³, it has been reported that visibility is occluded [Turner and Thompson 1926]. The lethal oral dose has been reported to be 500 mg/kg [Gekkan Yakuji 1980]. [Note: An oral dose of 500 mg/kg is equivalent to a 70-kg worker being

exposed to about 23,300 mg/m³ for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]

Revised IDLH: 500 mg/m3 Basis for revised IDLH: The revised IDLH for zinc oxide is 500 mg/m3 based on acute inhalation toxicity data in humans [Hammond 1944; Sturgis and Thompson 1927].

REFERENCES:

1. Gekkan Yakuji (Pharmaceuticals Monthly) [1980]; 22:291-298 (in Japanese).

2. Gig Sanit [1986]; 51(4):89-90 (in Russian).

3. Hammond JW [1944]. Metal fume fever in the crushed stone industry. J Ind Hyg Toxicol 26(4):117-119.

4. Sturgis CC, Thompson PD [1927]. Metal fume fever: I. Clinical observations on the effect of the experimental inhalation of zinc oxide by two apparently normal persons. J Ind Hyg 9(3):88-97.

5. Takahashi A [1976]. Problems of hygiene maintenance for food coming into contact with rubber and plastics products. Int Polymer Sci Tech 3(1):93-105.

6. Turner JA, Thompson LR [1926]. Health hazards of brass foundries. Section II. Laboratory studies relating to pathology of brass foundrymen's ague. Public Health Bulletin 157:35-75.