Agent Name


Alternative Name

Thallium and soluble compounds

CAS Number

7440-28-0; varies


Tl, varies

Major Category



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


Metals, Inorganic Compounds


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


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;


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 2-4 weeks later 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. 385] 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.

Exposure Assessment
Skin Designation (ACGIH)





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;

Half Life

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

Reference Link

ATSDR - ToxFAQs - Thallium

Adverse Effects

Sensorimotor Neuropathy


Hepatotoxin, Secondary



Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information


Chemical Information

Search ChemIDplus

Biomedical References

Search PubMed

Related Information in HazMap

Occupational diseases associated with exposure to this agent:


Industrial Processes with risk of exposure: