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PUBLIC HEALTH STATEMENT 

Hexachlorocyclopentadiene (HCCPD) 

CAS#: 77-47-4 

Division of Toxicology July 1999 

This Public Health Statement is the summary 

chapter from the Toxicological Profile for 

Hexachlorocyclopentadiene. 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 

hexachlorocyclopentadiene (HCCPD) and the 

effects of exposure. 

The Environmental Protection Agency (EPA) 

identifies the most serious hazardous waste sites in 

the nation. These sites make up the National 

Priorities List (NPL) and are the sites targeted for 

long-term federal cleanup activities. HCCPD has 

been found in at least 31 of the 1,467 current or 

former NPL sites. However, the total number of 

NPL sites evaluated for this substance is not known. 

As more sites are evaluated, the sites at which 

HCCPD is found may increase. This information is 

important because exposure to this substance may 

harm you and because these sites may be sources of 

exposure. 

When a substance 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. This 

release does not always lead to exposure. You are 

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 HCCPD, many factors 

determine whether you'll 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 the other chemicals you're 

exposed to and your age, sex, diet, family traits, 

lifestyle, and state of health. 

1.1 WHAT IS HCCPD? 

HCCPD is a light, lemon-yellow liquid that has a 

sharp, musty odor. It easily turns from a liquid to a 

vapor when exposed to air. The vapor looks like a 

blue haze. This chemical is also called 

percyclopentadiene, hexachloropentadiene, and hex. 

Some of its former trade names, still listed in 

chemical reference documents, are C-56, Graphlox, 

and HRS 1655. 

HCCPD is a manufactured chemical and does not 

occur naturally in the environment. It is made by 

adding chlorine to cyclopentadiene, or by removing 

chlorine from octachlorocyclopentane. HCCPD is 

used to make a group of related pesticides (aldrin, 

chlordane, dieldrin, endosulfan, endrin, heptachlor, 

isodrin, mirex, and pentac). Only two of these 

pesticides, endosulfan and pentac, are currently 

registered for use in the United States. Thus, your 

exposure to these compounds is expected to be 

limited. Endosulfan and pentac are the only two of 

these pesticides that you can buy in a store. 

HCCPD is also used to make flame retardants, 

resins that won't burn, shock-proof plastics, esters, 

ketones, fluorocarbons, and dyes. 

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 
 

 

 

 

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PUBLIC HEALTH STATEMENT 

Hexachlorocyclopentadiene (HCCPD) 

CAS#: 77-47-4 

Division of Toxicology July 1999 

Most of the HCCPD in the environment results 

from releases during its production and disposal. 

Releases can also occur as a result of the 

manufacture, use, and disposal of pesticides made 

from HCCPD. Most people can smell HCCPD in 

the air at 30 parts HCCPD per billion (ppb) parts of 

air. Most people can smell it in water when it is 

present at 1.4 ppb. The amount of HCCPD that you 

can taste in water has not been measured and the 

taste has not been described. 

1.2 WHAT HAPPENS TO HCCPD WHEN IT 

ENTERS THE ENVIRONMENT? 

HCCPD can be released to the air as a vapor during 

its production and use. However, it does not remain 

in the air very long since it is usually broken down 

to other substances by sunlight and by reaction with 

other chemicals in the air. Half of the HCCPD 

released to the air is removed in less than one day. 

When HCCPD is mixed with water at room 

temperature, only 2.1 milligrams will dissolve in a 

liter of water (2 parts per million or 2 ppm). In a 

stream or small river, the HCCPD near the surface 

will evaporate to the air. Sunlight on the water will 

cause HCCPD to change quickly into other 

chemicals. About half of the HCCPD in the water 

will be changed to other chemicals by the light in 

only four minutes. 

The HCCPD that gets into soil binds to decaying 

plant and animal matter. If the soil is sandy, the 

HCCPD can move through the soil and reach the 

water that is under the ground. When soil that 

contains HCCPD also contains solvents like 

gasoline, paint thinners, and acetone, these liquids 

will help carry the HCCPD through the soil to lakes, 

rivers, or wells. Bacteria can change HCCPD in the 

soil to other chemicals, but scientists do not know 

the nature of these compounds. About half of the 

HCCPD in the soil will be changed to other 

chemicals by bacteria in 1–2 weeks. 

HCCPD has been known to build up in fish, but 

only in very small amounts. We do not know if 

HCCPD accumulates in plants, milk, or animals 

used for food. 

1.3 HOW MIGHT I BE EXPOSED TO 

HCCPD? 

If you live near a hazardous waste site where 

HCCPD or HCCPD-derived pesticides were 

disposed, you might be exposed to HCCPD in the 

air. In one survey, levels ranging from 0.032 to 

0.053 ppb were measured in air near a hazardous 

waste site. HCCPD has not been reported in 

outdoor air in city, suburban, and rural areas. In 

most areas, the concentration of HCCPD in the air 

should be low because this chemical is not widely 

used. 

HCCPD is not commonly found in surface water. 

In one survey, it was found in less than 0.1% of 854 

water samples from various sources. The median 

concentration of HCCPD was less than 10 ppb in 

water. HCCPD in not often found in drinking 

water, so exposure by this route is unlikely. 

However, it may be formed during chlorination of 

water containing humic acid. 

HCCPD may be present in soils that have recently 

been treated with the pesticides, endosulfan or 

pentac, because it is sometimes found as an 

impurity in these pesticides. The soils near a 

landfill where these pesticides (including those no 

longer used, such as aldrin, chlordane, dieldrin, 

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 
 

 

 

 

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PUBLIC HEALTH STATEMENT 

Hexachlorocyclopentadiene (HCCPD) 

CAS#: 77-47-4 

Division of Toxicology July 1999 

endrin, heptachlor, and isodrin) or waste HCCPD 

were disposed might also contain HCCPD, but, 

since it binds to organic matter in soils, it is less 

likely to be free to affect you. 

It is highly unlikely that you will be exposed to 

HCCPD in the foods you eat, although you could be 

exposed to very small amounts if you catch and eat 

fish that lived in HCCPD-contaminated water. 

The highest exposures to HCCPD are likely to 

occur in people who are involved in the production 

or use of HCCPD, who handle pesticides made 

from it, or who treat wastes that contain it. These 

people can be exposed by breathing air 

contaminated with HCCPD, or by skin and eye 

contact with the vapors or liquid. 

Air concentrations ranging from 270 to 970 ppb 

were reported at a waste water treatment plant after 

large amounts of the compound were dumped into a 

city sewage system. Traces of HCCPD were 

present in waste water at another treatment plant 

near an industrial facility that used it as a reactant 

for making pesticides. 

1.4 HOW CAN HCCPD ENTER AND LEAVE 

MY BODY? 

There is no information available to tell us what 

happens to HCCPD once it enters the human body. 

Based on studies in animals, if you are exposed to 

HCCPD through food or drinking water, most of the 

HCCPD you eat or drink will stay bound to the food 

or water and only a small amount will enter your 

bloodstream. Thereafter, most of the HCCPD (64– 

80%) will leave your body in your feces and the rest 

will leave in your urine. 

Animal studies have shown that up to 95% of the 

HCCPD that is inhaled stays in your windpipe and 

lungs, and a small amount reaches your liver and 

kidneys. Inhaled HCCPD, therefore, causes more 

health effects in people and animals than HCCPD 

that is ingested 

If HCCPD touches your skin, it can enter your 

body. Based on studies in animals, when either 

pure HCCPD or a solution with 10% HCCPD in 

mineral oil comes in contact with your skin, a sore 

can form. The open sore will allow more HCCPD 

to enter your body. 

Most of the HCCPD that enters your body is 

changed to other chemicals, but those chemicals 

have not been identified. A small amount of 

HCCPD remains unchanged. 

1.5 HOW CAN HCCPD AFFECT MY 

HEALTH? 

To protect the public from the harmful effects of 

toxic chemicals and to find ways to treat people 

who have been harmed, scientists use many tests. 

One way to see if a chemical will hurt people is to 

learn how the chemical is absorbed, used, and 

released by the body; for some chemicals, animal 

testing may be necessary. Animal testing may also 

be used to identify health effects such as cancer or 

birth defects. Without laboratory animals, scientists 

would lose a basic method to get information 

needed to make wise decisions to protect public 

health. Scientists have the responsibility to treat 

research animals with care and compassion. Laws 

today protect the welfare of research animals, and 

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 
 

 

 

 

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PUBLIC HEALTH STATEMENT 

Hexachlorocyclopentadiene (HCCPD) 

CAS#: 77-47-4 

Division of Toxicology July 1999 

scientists must comply with strict animal care 

guidelines. 

Information on the health effects of HCCPD on 

people is limited to one incident involving shortterm exposure to HCCPD vapors (0.04–19.2 ppm). 

Exposure occurred at a waste water treatment plant 

as a result of an industrial release of HCCPD into 

the sewage system. This incident showed that the 

breathing passageways (nose, throat, lungs) in 

people are very sensitive to HCCPD. You may get 

a sore throat or have shortness of breath and chest 

discomfort if you breathe HCCPD at high levels. 

Your eyes may burn and turn red, and your skin 

may be irritated. Some people get headaches when 

they breathe high levels of HCCPD. 

Your kidneys and liver may show signs that you 

have been exposed to HCCPD. Some people who 

were exposed to HCCPD had increased amounts of 

protein in their urine and increased levels of other 

compounds in their blood. These are signs that 

kidney and liver effects may have occurred after 

exposure to HCCPD. Other people who were 

exposed did not show these effects. 

Bleeding, swelling, and fluid buildup occurred in 

the lungs of rats, mice, guinea pigs, and rabbits that 

inhaled small amounts of HCCPD vapors for two 

weeks under controlled conditions. Severe 

breathing difficulty was seen in animals exposed to 

large amounts of HCCPD for a short period of time, 

and all the animals died during or soon after 

exposure. In rats, some cells of the lung, windpipe, 

and nose contained yellow-colored or clear granules 

after exposure to a very low level (0.01 ppm) of 

HCCPD in air for a long time. In monkeys, higher 

levels (0.2 ppm) caused similar changes in those 

cells. 

When rats and rabbits swallowed HCCPD dissolved 

in corn oil or peanut oil, cells in the lungs, liver, 

kidney, brain, and heart were harmed and a sore 

formed in the stomach lining. When the doses were 

high (261–1,950 milligrams per kilogram of body 

weight [mg/kg]), most of the animals died after only 

one dose. There was damage to stomach lining and 

kidney cells in mice given a low concentration of 

HCCPD in corn oil by mouth 5 days a week for 

several months. Because these mice were also 

exposed to another chemical, hexachlorobutadiene, 

it is not clear if the cell damage in the kidneys was 

caused by HCCPD alone. 

No information is available on whether HCCPD 

affects the reproductive organs of people. 

No information is available on whether HCCPD 

causes cancer in people. The Department of Health 

and Human Services (DHHS) has determined that 

HCCPD does not cause cancer in rats and mice 

under the conditions of the study conducted by the 

National Toxicology Program. The International 

Agency for Research on Cancer (IARC) has not 

evaluated HCCPD as a possible cancer-causing 

chemical. The EPA has determined that HCCPD is 

not classifiable as to its ability to cause cancer in 

people. 

1.6 HOW CAN HCCPD AFFECT CHILDREN? 

This section discusses potential health effects from 

exposures during the period from conception to 

maturity at 18 years of age in humans. 

Children are unlikely to be exposed to HCCPD. 

There is no information on the effects of exposure 

to HCCPD in children or in adults who were 

exposed as children. We do not know whether 

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 
 

 

 

 

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PUBLIC HEALTH STATEMENT 

Hexachlorocyclopentadiene (HCCPD) 

CAS#: 77-47-4 

Division of Toxicology July 1999 

HCCPD causes birth defects in humans. Studies in 

animals indicate that exposure to HCCPD does not 

cause problems during development. HCCPD did 

not cause birth defects or impair the ability of mice 

and rabbits to produce offspring. We do not know 

whether HCCPD can cross the placenta or 

accumulate in breast milk. 

1.7 HOW CAN FAMILIES REDUCE THE 

RISK OF EXPOSURE TO HCCPD? 

If your doctor finds that you have been exposed to 

significant amounts of HCCPD, he or she can 

advise you about the potential risk of exposure to 

the rest of your family. When necessary your 

doctor may need to ask your state public health 

department to investigate. 

1.8 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO HCCPD? 

If you have been recently exposed to HCCPD, your 

blood and urine can be tested for its presence. Such 

tests are not routinely done in a doctor's office 

because special equipment is needed. Doctors often 

can collect blood or urine samples and send them to 

special laboratories to determine if you have been 

exposed to HCCPD; but these laboratories can't 

determine how much HCCPD you were exposed to, 

or whether your health will be affected. Exposure 

to HCCPD that occurred weeks or months before 

your test is not likely to be detected in either your 

blood or urine. 

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. Federal 

agencies that develop regulations for toxic 

substances include the Environmental Protection 

Agency (EPA), the Occupational Safety and Health 

Administration (OSHA), and the Food and Drug 

Administration (FDA). Recommendations provide 

valuable guidelines to protect public health but 

cannot be enforced by law. Federal organizations 

that develop recommendations for toxic substances 

include the Agency for Toxic Substances and 

Disease Registry (ATSDR) and the National 

Institute for Occupational Safety and Health 

(NIOSH). 

Regulations and recommendations can be expressed 

in not-to-exceed levels in air, water, soil, or food 

that are usually based on levels that affect animals, 

then they are adjusted to help protect people. 

Sometimes these not-to-exceed levels differ among 

federal organizations because of different exposure 

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

of different animal studies, or other factors. 

Recommendations and regulations are also 

periodically updated 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 HCCPD include the 

following: 

To protect workers who may be exposed to HCCPD 

on the job, the Occupational Safety and Health 

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 
 

 

 

 

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PUBLIC HEALTH STATEMENT 

Hexachlorocyclopentadiene (HCCPD) 

CAS#: 77-47-4 

Division of Toxicology July 1999 

Administration (OSHA) limits HCCPD exposure to 

0.01 ppm in air for an 8-hour workday over a 40-

hour workweek. The National Institute for 

Occupational Safety and Health (NIOSH) suggests 

the same limit for workplace air. 

EPA has recommended guidelines on how much 

HCCPD can be present in drinking water. The 

maximum contaminant levels (MCL) and maximum 

concentration level goal (MCLG) for drinking 

water are 50 ppb. EPA recommends that exposures 

in children should not exceed 2 ppm in water for 

10-day periods or no more than 0.7 ppb for up to 7 

years. If adults are exposed for more than 7 years, 

the EPA recommends that exposure levels should 

not exceed 50 ppb. 

HCCPD has been named a hazardous substance by 

EPA. If quantities equal to or greater than one 

pound are released to the environment, the National 

Response Center for the federal government must 

be told immediately. HCCPD has not been 

identified as a carcinogen. 

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: 

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). 1999. Toxicological profile for 

hexachloropentadiene (HCCPD). Atlanta, GA: U.S. 

Department of Health and Human Services, Public 

Health Service. 

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