PUBLIC HEALTH STATEMENT 

 Hydrogen Sulfide CAS#: 7783-06-4 

Division of Toxicology and Environmental Medicine July 2006

__________________________________________________________________________________________

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 

Hydrogen Sulfide. 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 public health statement tells you about 

hydrogen sulfide and the effects of exposure to it. 

The Environmental Protection Agency (EPA) 

identifies the most serious hazardous waste sites in 

the nation. These sites are then placed on the 

National Priorities List (NPL) and are targeted for 

long-term federal clean-up activities. Hydrogen 

sulfide has been found in at least 35 of the 

1,689 current or former NPL sites. Although the 

total number of NPL sites evaluated for this 

substance is not known, the possibility exists that 

the number of sites at which hydrogen sulfide is 

found may increase in the future as more sites are 

evaluated. This information is important because 

these sites may be sources of exposure and exposure 

to this substance may harm you. 

When a substance is released either from a large 

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

such as a drum or bottle, it enters the environment. 

Such a release does not always lead to exposure. 

You can be exposed to a substance only when you 

come in contact with it. You may be exposed by 

breathing, eating, or drinking the substance, or by 

skin contact. 

If you are exposed to hydrogen sulfide, many 

factors will determine whether you will be harmed. 

These factors include the dose (how much), the 

duration (how long), and how you come in contact 

with it. You must also consider any other chemicals 

you are exposed to and your age, sex, diet, family 

traits, lifestyle, and state of health. 

1.1 WHAT IS HYDROGEN SULFIDE? 

Hydrogen sulfide (H2S) is a poisonous, flammable, 

colorless gas with a characteristic odor of rotten 

eggs. Other names for hydrogen sulfide include 

hydrosulfuric acid, sewer gas, hydrogen sulphide, 

and stink damp. People usually can smell hydrogen 

sulfide at low concentrations in air, ranging from 

0.0005 to 0.3 parts per million (ppm) (0.0005–

0.3 parts of hydrogen sulfide in 1 million parts of 

air); however, at high concentrations, a person 

might lose their ability to smell it. This can make 

hydrogen sulfide very dangerous. 

Hydrogen sulfide occurs both naturally and from 

human-made processes. It is in the gases from 

volcanoes, sulfur springs, undersea vents, swamps, 

and stagnant bodies of water and in crude petroleum 

and natural gas. Hydrogen sulfide also is associated 

with municipal sewers and sewage treatment plants, 

swine containment and manure-handling operations, 

and pulp and paper operations. Industrial sources of 

hydrogen sulfide include petroleum refineries, 

natural gas plants, petrochemical plants, coke oven 

plants, food processing plants, and tanneries. 

Bacteria found in your mouth and gastrointestinal 
 PUBLIC HEALTH STATEMENT 

 Hydrogen Sulfide CAS#: 7783-06-4 

Division of Toxicology and Environmental Medicine July 2006

__________________________________________________________________________________________

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 

tract produce hydrogen sulfide during the digestion 

of food containing vegetable or animal proteins. 

Hydrogen sulfide is one of the principal 

components in the natural sulfur cycle. 

1.2 WHAT HAPPENS TO HYDROGEN 

SULFIDE WHEN IT ENTERS THE 

ENVIRONMENT? 

Hydrogen sulfide is released primarily as a gas and 

spreads in the air. However, in some instances, it 

may be released in the liquid waste of an industrial 

facility or as the result of a natural event. When 

hydrogen sulfide is released as a gas, it remains in 

the atmosphere for an average of 18 hours. During 

this time, hydrogen sulfide can change into sulfur 

dioxide and sulfuric acid. Hydrogen sulfide is 

soluble in water, and is a weak acid in water. 

1.3 HOW MIGHT I BE EXPOSED TO 

HYDROGEN SULFIDE? 

Your body makes small amounts of hydrogen 

sulfide. Hydrogen sulfide is produced by the 

natural bacteria in your mouth and is a component 

of bad breath (halitosis). Breakdown of sulfurcontaining proteins by bacteria in the human 

intestinal tract also produces hydrogen sulfide. The 

levels of hydrogen sulfide in air and water are 

typically low. The amount of hydrogen sulfide in 

the air in the United States is 0.11–0.33 parts per 

billion (ppb) (one thousandth of a ppm). In 

undeveloped areas of the United States, 

concentrations have been reported at 0.02–0.07 ppb. 

The amount of hydrogen sulfide in surface water is 

low because hydrogen sulfide readily evaporates 

from water. Groundwater concentrations of 

hydrogen sulfide generally are less than 1 ppm; 

however, measured sulfur concentrations in surface 

and waste waters have ranged from slightly less 

than 1 to 5 ppm. Household exposures to hydrogen 

sulfide can occur through misuse of drain cleaning 

materials. Hydrogen sulfide can be found in well 

water and formed in hot water heaters, giving tap 

water a rotten egg odor. Cigarette smoke and 

emissions from gasoline vehicles contain hydrogen 

sulfide. The general population can be exposed to 

lower levels from accidental or deliberate release of 

emissions from pulp and paper mills; from natural 

gas drilling and refining operations; and from areas 

of high geothermal activity, such as hot springs. 

People who work in certain industries can be 

exposed to higher levels of hydrogen sulfide than 

the general population. These industries include 

rayon textiles manufacturing, pulp and paper mills, 

petroleum and natural gas drilling operations, and 

waste water treatment plants. Workers on farms 

with manure storage pits or landfills can also be 

exposed to higher levels of hydrogen sulfide than 

the general population. As a member of the general 

public, you might be exposed to higher-than-normal 

levels of hydrogen sulfide if you live near a waste 

water treatment plant, a gas and oil drilling 

operation, a farm with manure storage or livestock 

confinement facilities, or a landfill. Exposure from 

these sources is mainly from breathing air that 

contains hydrogen sulfide. 
 PUBLIC HEALTH STATEMENT 

 Hydrogen Sulfide CAS#: 7783-06-4 

Division of Toxicology and Environmental Medicine July 2006

__________________________________________________________________________________________

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 

1.4 HOW CAN HYDROGEN SULFIDE 

ENTER AND LEAVE MY BODY? 

Hydrogen sulfide enters your body primarily 

through the air you breathe. Much smaller amounts 

can enter your body through the skin. Hydrogen 

sulfide is a gas, so you would not likely be exposed 

to it by ingestion. When you breathe air containing 

hydrogen sulfide or when hydrogen sulfide comes 

into contact with skin, it is absorbed into the blood 

stream and distributed throughout the body. In the 

body, hydrogen sulfide is primarily converted to 

sulfate and is excreted in the urine. Hydrogen 

sulfide is rapidly removed from the body. 

1.5 HOW CAN HYDROGEN SULFIDE 

AFFECT MY HEALTH? 

Scientists use many tests to protect the public from 

harmful effects of toxic chemicals and to find ways 

for treating persons who have been harmed. 

One way to learn whether a chemical will harm 

people is to determine how the body absorbs, uses, 

and releases the chemical. For some chemicals, 

animal testing may be necessary. Animal testing 

may also help identify health effects such as cancer 

or birth defects. Without laboratory animals, 

scientists would lose a basic method for getting 

information needed to make wise decisions that 

protect public health. Scientists have the 

responsibility to treat research animals with care 

and compassion. Scientists must comply with strict 

animal care guidelines because laws today protect 

the welfare of research animals. 

Exposure to low concentrations of hydrogen sulfide 

may cause irritation to the eyes, nose, or throat. It 

may also cause difficulty in breathing for some 

asthmatics. Brief exposures to high concentrations 

of hydrogen sulfide (greater than 500 ppm) can 

cause a loss of consciousness. In most cases, the 

person appears to regain consciousness without any 

other effects. However, in some individuals, there 

may be permanent or long-term effects such as 

headaches, poor attention span, poor memory, and 

poor motor function. No health effects have been 

found in humans exposed to typical environmental 

concentrations of hydrogen sulfide (0.00011–

0.00033 ppm). Deaths due to breathing in large 

amounts of hydrogen sulfide have been reported in 

a variety of different work settings, including 

sewers, animal processing plants, waste dumps, 

sludge plants, oil and gas well drilling sites, and 

tanks and cesspools. 

Very little information is available about health 

problems that could occur from drinking or eating 

something with hydrogen sulfide in it. Scientists 

have no reports of people poisoned by such 

exposures. Pigs that ate feed containing hydrogen 

sulfide experienced diarrhea for a few days and lost 

weight after about 105 days. 

Scientists have little information about what 

happens when you are exposed to hydrogen sulfide 

by getting it on your skin, although they know that 

care must be taken with the compressed liquefied 

product to avoid frostbite. Hydrogen sulfide will 

irritate your eyes if you are exposed to the gas. 

These types of exposures are more common in 

certain kinds of jobs. 

Hydrogen sulfide has not been shown to cause 

cancer in humans, and its possible ability to cause 
 PUBLIC HEALTH STATEMENT 

 Hydrogen Sulfide CAS#: 7783-06-4 

Division of Toxicology and Environmental Medicine July 2006

__________________________________________________________________________________________

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 

cancer in animals has not been studied thoroughly. 

Hydrogen sulfide has not been classified for its 

ability to cause or not cause cancer. 

1.6 HOW CAN HYDROGEN SULFIDE 

AFFECT CHILDREN? 

This section discusses potential health effects in 

humans from exposures during the period from 

conception to maturity at 18 years of age. 

Children are likely to be exposed to hydrogen 

sulfide in the same manner as adults, except for 

adults at work. However, because hydrogen sulfide 

is heavier than air and because children are shorter 

than adults, children sometimes are exposed to more 

hydrogen sulfide than adults. There is very little 

information on possible health problems in children 

who have been exposed to hydrogen sulfide. 

Exposed children probably will experience effects 

similar to those experienced by exposed adults. 

Whether children are more sensitive to hydrogen 

sulfide exposure than adults or whether hydrogen 

sulfide causes birth defects in people is not known. 

The results of studies in animals suggest that 

exposure to low concentrations of hydrogen sulfide 

during pregnancy does not cause birth defects. 

1.7 HOW CAN FAMILIES REDUCE THE 

RISK OF EXPOSURE TO HYDROGEN 

SULFIDE? 

If your doctor finds that you have been exposed to 

substantial amounts of hydrogen sulfide, ask 

whether your children might also have been 

exposed. Your doctor might need to ask your state 

health department to investigate. 

Hydrogen sulfide is part of the natural environment; 

the general population will have some exposure to 

hydrogen sulfide. Families can be exposed to more 

hydrogen sulfide than the general population if they 

live near natural or industrial sources of hydrogen 

sulfide, such as hot springs, manure holding tanks, 

or pulp and paper mills. However, their exposure 

levels are unlikely to approach those that sicken 

people exposed at work. Families can reduce their 

exposure to hydrogen sulfide by avoiding areas that 

are sources of hydrogen sulfide. For example, 

individuals of families that live on farms can avoid 

manure storage areas where high concentrations of 

hydrogen sulfide may be found. 

1.8 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO HYDROGEN SULFIDE? 

Hydrogen sulfide can be measured in exhaled air, 

but samples must be taken within 2 hours after 

exposure to be useful. A more reliable test to 

determine if you have been exposed to hydrogen 

sulfide is the measurement of increased thiosulfate 

levels in urine. This test must be done within 

12 hours of exposure. Both tests require special 

equipment, which is not routinely available in a 

doctor’s office. Samples can be sent to a special 

laboratory for the tests. These tests can tell whether 

you have been exposed to hydrogen sulfide, but 

they cannot determine exactly how much hydrogen 

sulfide you have been exposed to or whether 

harmful effects will occur. 
 PUBLIC HEALTH STATEMENT 

 Hydrogen Sulfide CAS#: 7783-06-4 

Division of Toxicology and Environmental Medicine July 2006

__________________________________________________________________________________________

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 

1.9 WHAT RECOMMENDATIONS HAS THE 

FEDERAL GOVERNMENT MADE TO 

PROTECT HUMAN HEALTH? 

The federal government develops regulations and 

recommendations to protect public health. 

Regulations can be enforced by law. The EPA, the 

Occupational Safety and Health Administration 

(OSHA), and the Food and Drug Administration 

(FDA) are some federal agencies that develop 

regulations for toxic substances. Recommendations 

provide valuable guidelines to protect public health, 

but cannot be enforced by law. The Agency for 

Toxic Substances and Disease Registry (ATSDR) 

and the National Institute for Occupational Safety 

and Health (NIOSH) are two federal organizations 

that develop recommendations for toxic substances. 

Regulations and recommendations can be expressed 

as “not-to-exceed” levels, that is, levels of a toxic 

substance in air, water, soil, or food that do not 

exceed a critical value that is usually based on 

levels that affect animals; they are then adjusted to 

levels that will help protect humans. Sometimes 

these not-to-exceed levels differ among federal 

organizations because they used different exposure 

times (an 8-hour workday or a 24-hour day), 

different animal studies, or other factors. 

Recommendations and regulations are also updated 

periodically as more information becomes available. 

For the most current information, check with the 

federal agency or organization that provides it. 

Some regulations and recommendations for 

hydrogen sulfide include the following: 

OSHA has established an acceptable ceiling 

concentration of 20 ppm for hydrogen sulfide in the 

workplace, with a maximum level of 50 ppm 

allowed for 10 minutes maximum duration if no 

other measurable exposure occurs. NIOSH has set 

a maximum Recommended Exposure Limit (REL) 

ceiling value of 10 ppm for 10 minutes maximum 

duration. 

1.10 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 contact 

ATSDR at the address and phone number below. 

ATSDR can also tell you the location of 

occupational and environmental health clinics. 

These clinics specialize in recognizing, evaluating, 

and treating illnesses that result from exposure to 

hazardous substances. 

Toxicological profiles are also available on-line at 

www.atsdr.cdc.gov and on CD-ROM. You may 

request a copy of the ATSDR ToxProfilesTM CDROM by calling the toll-free information and 

technical assistance number at 1-888-42ATSDR 

(1-888-422-8737), by e-mail at atsdric@cdc.gov, or 

by writing to: 

Agency for Toxic Substances and Disease Registry 

Division of Toxicology and Environmental 

Medicine 

1600 Clifton Road NE 

Mailstop F-32 

Atlanta, GA 30333 

Fax: 1-770-488-4178 
 PUBLIC HEALTH STATEMENT 

 Hydrogen Sulfide CAS#: 7783-06-4 

Division of Toxicology and Environmental Medicine July 2006

__________________________________________________________________________________________

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 

Organizations for-profit may request copies of final 

Toxicological Profiles from the following: 

National Technical Information Service (NTIS) 

5285 Port Royal Road 

Springfield, VA 22161 

Phone: 1-800-553-6847 or 1-703-605-6000 

Web site: http://www.ntis.gov/