PUBLIC HEALTH STATEMENT

 THALLIUM 

 CAS#: 7440-28-0 

Division of Toxicology July 1992 

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov

This Public Health Statement is the summary 

chapter from the Toxicological Profile for Thallium. 

It is one in a series of Public Health Statements 

about hazardous substances and their health effects. 

A shorter version, the ToxFAQsTM, is also 

available. This information is important because 

this substance may harm you. The effects of 

exposure to any hazardous substance depend on the 

dose, the duration, how you are exposed, personal 

traits and habits, and whether other chemicals are 

present. For more information, call the ATSDR 

Information Center at 1-888-422-8737. 

_________________________________________ 

 

This Statement was prepared to give you 

information about thallium and to emphasize the 

human health effects that may result from exposure 

to it. The Environmental Protection Agency (EPA) 

has identified 1,177 sites on its National Priorities 

List (NPL). Thallium has been found in at least 18 

of these sites. However, we do not know how many 

of the 1,177 NPL sites have been evaluated for 

thallium. As EPA evaluates more sites, the number 

of sites at which thallium is found may change. This 

information is important for you to know because 

thallium may cause harmful health effects and 

because these sites are potential or actual sources of 

human exposure to thallium. 

When a chemical is released from a large area, such 

as an industrial plant, or from a container, such as a 

drum or bottle, it enters the environment as a 

chemical emission. This emission, which is also 

called a release, does not always lead to exposure. 

You can be exposed to a chemical only when you 

come into contact with the chemical. You may be 

exposed to it in the environment by breathing, 

eating, or drinking substances containing the 

chemical or from skin contact with it.

If you are exposed to a hazardous chemical such as 

thallium, several factors will determine whether 

harmful health effects will occur and what the type 

and severity of those health effects will be. These 

factors include the dose (how much), the duration 

(how long), the route or pathway by which you are 

exposed (breathing, eating, drinking, or skin 

contact), the other chemicals to which you are 

exposed, and your individual characteristics such as 

age, sex, nutritional status, family traits, life style, 

and state of health. 

 

1.1 WHAT IS THALLIUM? 

Pure thallium is a soft, bluish-white metal that is 

widely distributed in trace amounts in the earth's 

crust. In its pure form, it is odorless and tasteless. It 

can be found in pure form or mixed with other 

metals in the form of alloys. It can also be found 

combined with other substances such as bromine, 

chlorine, fluorine, and iodine to form salts. These 

combinations may appear colorless to white or 

yellow. Thallium remains in the environment since 

it is a metal and cannot be broken down to simpler 

substances. 

Thallium exists in two chemical states (thallous and 

thallic). The thallous state is the more common and 

stable form. Thallous compounds are the most 

likely form to which you would be exposed in the 

environment. Thallium is present in air, water, and 

soil. We do not know how much time it takes for 

thallium to move from one medium to another. 

Thallium is used mostly in the manufacture of 

electronic devices, switches, and closures. It also 

has limited use in the manufacture of special glasses 
 PUBLIC HEALTH STATEMENT

 THALLIUM 

 CAS#: 7440-28-0 

Division of Toxicology July 1992 

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov

and for medical procedures that evaluate heart 

disease. Up until 1972 thallium was used as a rat 

poison, but was then banned because of its potential 

harm to man. Thallium is no longer produced in the 

United States. All the thallium used in the United 

States since 1984 has been obtained from imports 

and thallium reserves. 

1.2 HOW MIGHT I BE EXPOSED TO 

THALLIUM? 

You can be exposed to thallium in air, water, and 

food. However, the levels of thallium in air and 

water are very low. The greatest exposure occurs 

when you eat food, mostly home-grown fruits and 

green vegetables contaminated by thallium. Small 

amounts of thallium are released into the air from 

coal-burning power plants, cement factories, and 

smelting operations. This thallium falls out of the 

air onto nearby fruit and vegetable gardens. 

Thallium enters food because it is easily taken up 

by plants through the roots. Very little is known on 

how much thallium is in specific foods grown or 

eaten. Cigarette smoking is also a source of 

thallium. People who smoke have twice as much 

thallium in their bodies as do nonsmokers. Although 

fish take up thallium from water, we do not know 

whether eating fish can increase thallium levels in 

your body. It has been estimated that the average 

person eats, on a daily basis, 2 parts thallium per 

billion parts (ppb) of food. Even though rat poison 

containing thallium was banned in 1972, accidental 

poisonings from old rat poison still occur, especially 

in children. 

Thallium is produced or used in power plants, 

cement factories, and smelters. People who work in 

these places can breathe in the chemical or it may 

come in contact with their skin. Information on the 

amount of thallium in workplace air in the United 

States could not be found. Hazardous waste sites are 

also possible sources of exposure to thallium. An 

average of 23 ppb of thallium in surface water and 

11 ppb in groundwater have been found at 

hazardous waste sites. Since thallium compounds 

mix easily in water, you can be exposed if you live 

near a chemical waste site where thallium emissions 

have contaminated the water. An average of 1.7 

parts of thallium per million parts (ppm) of soil was 

found at hazardous waste sites. Since thallium sticks 

to soil, you can be exposed at hazardous waste sites 

if you swallow or touch contaminated soil. 

Thallium-contaminated dust in the air can also be 

swallowed after it is cleared from the lungs. 

Thallium is naturally found in soil at levels from 0.3 

to 0.7 ppm. 

1.3 HOW CAN THALLIUM ENTER AND 

LEAVE MY BODY? 

Thallium can enter your body when you eat food or 

drink water contaminated with thallium, breathe 

thallium in the air, and when your skin comes in 

contact with it. When thallium is swallowed most of 

it is absorbed and rapidly goes to various parts of 

your body, especially the kidney and liver. Thallium 

leaves your body slowly. Most of the thallium 

leaves your body in urine and to a lesser extent in 

feces. It can be found in urine within 1 hour after 

exposure. After 24 hours, increasing amounts are 

found in feces. It can be found in urine as long as 2 

months after exposure. About half the thallium that 

enters various parts of your body leaves them within 

3 days. 
 PUBLIC HEALTH STATEMENT

 THALLIUM 

 CAS#: 7440-28-0 

Division of Toxicology July 1992 

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov

The significant, likely routes of exposure near 

hazardous waste sites are through swallowing 

thallium-contaminated soil or dust, drinking 

contaminated water, and skin contact with 

contaminated soil. 

1.4 HOW CAN THALLIUM AFFECT MY 

HEALTH? 

Thallium can affect your nervous system, lung, 

heart, liver, and kidney if large amounts are eaten or 

drunk for short periods of time. Temporary hair 

loss, vomiting, and diarrhea can also occur and 

death may result after exposure to large amounts of 

thallium for short periods. Thallium can be fatal 

from a dose as low as 1 gram. No information was 

found on health effects in humans after exposure to 

smaller amounts of thallium for longer periods. 

Birth defects observed in children of mothers 

exposed to small amounts of thallium did not occur 

more often than would be expected in the general 

population. The length of time and the amount of 

thallium eaten by the mothers are not known 

exactly. As in humans, animal studies indicate that 

exposure to large amounts of thallium for brief 

periods of time can damage the nervous system and 

heart and can cause death. Animal reproductive 

organs, especially the testes, are damaged after 

drinking small amounts of thallium-contaminated 

water for 2 months. These effects have not been 

seen in humans. No information was found on 

effects in animals after exposure to small amounts 

of thallium for longer periods of time. No studies 

were found on whether thallium can cause cancer in 

humans or animals. 

1.5 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO THALLIUM? 

Reliable and accurate ways to measure thallium in 

the body are available. The presence of thallium in 

the urine and hair can indicate exposure to thallium. 

Tests of your urine can detect thallium up to 2 

months. The normal amount of thallium in human 

urine amounts to less than 1 ppm and 5–10 ppb in 

human hair. Although thallium can be measured in 

blood, this tissue is not a good indicator of exposure 

since thallium stays there too short a time. We do 

not know yet whether thallium levels measured in 

the body can be used to predict possible health 

effects. 

 

1.6 WHAT RECOMMENDATIONS HAS THE 

FEDERAL GOVERNMENT MADE TO 

PROTECT HUMAN HEALTH? 

The federal government has set standards and 

guidelines to protect individuals from the possible 

effects of excessive thallium exposure. The EPA 

has determined a water quality criteria level of 13 

ppb in surrounding waters to protect humans from 

the harmful effects of drinking water and eating 

food containing thallium. 

The Occupational Safety and Health Administration 

(OSHA) has established an occupational limit of 0.1 

mg of soluble thallium compounds per cubic meter 

of workplace air (mg thallium/m3/skin) for an 8-

hour workday over a 40-hour workweek. "Skin" 

indicates that measures must be taken to prevent 

skin exposure to thallium. 

 
 PUBLIC HEALTH STATEMENT

 THALLIUM 

 CAS#: 7440-28-0 

Division of Toxicology July 1992 

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov

1.7 WHERE CAN I GET MORE 

INFORMATION? 

If you have any more questions or concerns, please 

contact your community or state health or 

environmental quality department or: 

Agency for Toxic Substances and Disease Registry 

Division of Toxicology 

1600 Clifton Road NE, Mailstop F-32 

Atlanta, GA 30333 

Information line and technical assistance:

Phone: 888-422-8737 

FAX: (770)-488-4178 

ATSDR can also tell you the location of 

occupational and environmental health clinics. 

These clinics specialize in recognizing, evaluating, 

and treating illnesses resulting from exposure to 

hazardous substances. 

To order toxicological profiles, contact: 

National Technical Information Service

5285 Port Royal Road 

Springfield, VA 22161 

Phone: 800-553-6847 or 703-605-6000 

Reference 

Agency for Toxic Substances and Disease Registry 

(ATSDR). 1992 Toxicological profile for thallium. 

Atlanta, GA: U.S. Department of Health and 

Human Services, Public Health Service.