Thallium

Synonyms

Thallium, elemental; Thallium metal; Thallium compouinds; Thallous oxide; Thallium nitrate; Thallium acetate; Thallium sulfate; Thallium carbonate; [ACGIH] Thallium and soluble compounds;

Category

Metals, Inorganic Compounds

Description

Appearance and odor vary depending upon the specific soluble thallium compound. [NIOSH]

Sources/Uses

Coal-burning and smelting emissions are the major sources of release of thallium into the environment. [ATSDR ToxProfiles] METALLURGY: Alloy production; MANUFACTURING: Rodenticides, Electronic components, Optical lenses, Costume jewelry; USING OR DISPOSING: Grind or machine thallium-containing alloys; Clean fossil fuel furnaces or flues;

Comments

Chronic poisoning can cause peripheral neuropathy, liver injury, and hair loss (alopecia). Occupational exposure may occur through alloy production, machining thallium-containing alloys, or manufacturing of rodenticides, electronic components, optical lenses, or costume jewelry. It is used as an alloy with mercury to make switches in the semiconductor industry. "A urine thallium concentration of 100 ug/L corresponds to a 40-hour/week exposure to 0.1 mg/m3." Most reported cases of thallium poisoning follow ingestion. Occupational cases have been reported after skin absorption. [ACGIH] Thallous acetate and thallic chloride are slightly more toxic than the less soluble thallic oxide and thallous iodide. Symptoms are usually delayed for 12-14 hours after ingestion and include gastroenteritis (sometimes hemorrhagic) and shock. Chronic symptoms appear after 2-4 weeks in patients who survive--painful paresthesias and later hair loss. Urinary thallium levels of >20 mcg/L suggests excessive exposure. Thallium is radiopaque and may be detected in plain x-rays. [Olson, p. 433-4] After thallium poisoning by ingestion, patients may develop acute renal failure. [Rosenstock, p. 575] "The toxicological significance of thallium is mainly restricted to some inorganic and organic salts of Tl+ such as TlCl, Tl2SO4 (used as a rodenticide), and thallium acetate. Intoxications by elemental thallium are comparatively rare." [Ullmann] Cases of occupational poisoning from skin contact in workers manufacturing rodenticides were described in the 1950s. Symptoms included vague ill health, paresthesias, and some hair loss. [Nordberg, p. 1236]

Thallium rodenticides were banned in the U.S. in 1972.

Biomedical References

Yes

Yes

0.02 mg/m3, inhalable fraction, as Tl (Tl and soluble cmpnds)

0.1 mg/m3, as Tl (Tl and soluble cmpnds)

15 mg/m3, as Tl (soluble cmpnds)

Excerpts from Documentation for IDLHs

Human data: Lethal oral doses ranging from 0.9 to 9.4 mg/kg have been reported [Gekkan Yakuji 1980; Tanaka et al. 1978; Venugopal and Luckey 1978; Yakkyoku 1977]. [Note: An oral dose ranging from 0.9 to 9.4 mg/kg is equivalent to a 70-kg worker being exposed to concentrations ranging from about 40 to 450 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]

Explanatory Notes

Melting Point = 577 degrees F;

Whole body: 22 days; [TDR, p. 1129]

Reference Link #2

Sensorimotor

Hepatoxic (a) from occupational exposure (secondary effect) or (b) in animal studies or in humans after ingestion

Yes

Diseases

Occupational diseases associated with exposure to this agent:

• Neuropathy, toxic

Processes

Industrial Processes with risk of exposure:

• Cleaning Furnaces or Flues
• Metal Extraction and Refining
• Metal Machining
• Semiconductor Manufacturing