Hexachlorobutadiene, also known as HCBD, perchlorobutadiene, or Dolen-Pur, is a colourless liquid with the molecular formula C4Cl6. It has a turpentine-like odour and does not evaporate or burn easily. It is not known how it tastes or at what level people can taste it. Hexachlorobutadiene does not occur naturally in the environment. It is formed during the processing of other chemicals such as tetrachloroethylene, trichloroethylene, and carbon tetrachloride. [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][1,2]
Hexachlorobutadiene is used mainly as an intermediate in the manufacture of rubber compounds. It is also used in the production of lubricants, as a fluid for gyroscopes, as a heat transfer liquid, and in hydraulic fluids. Outside of the United States it is used to kill soil pests. 
In the Environment 
Hexachlorobutadiene is released to the environment in air, water, and soil, mainly as a result of its disposal following industrial use. Most of the hexachlorobutadiene wastes are destroyed by burning; some are released to the air in this process. It is not known what happens to hexachlorobutadiene after it enters the air. Based on the current information of similar compounds, it may be broken down by sunlight and react with gases in the atmosphere. It is not known what chemicals are formed by these reactions or if the compounds formed are harmful. Based on the properties of similar compounds, one-half of the hexachlorobutadiene in the air is expected to be broken down to other chemicals within 60 days. Hexachlorobutadiene may also be released to water during disposal of factory waste. It is not known what happens to it in water or how long it remains there. Hexachlorobutadiene that is present in water may pass into the air or soil in small amounts. Small amounts of hexachlorobutadiene may be released to soil as a result of disposal of industrial wastes containing it. It is not known what happens to hexachlorobutadiene after it contacts soil. Because hexachlorobutadiene binds to most soils, it is expected to remain there for some time. The hexachlorobutadiene present in sandy soils may move through the soil to underground water. However, no information was found on how much reaches the underground water or how long it stays in the water. Hexachlorobutadiene can build up in fish and shellfish, where waters are contaminated. It is not known if hexachlorobutadiene builds up in plants.
Sources & Routes of Exposure
Sources of Exposure 
Exposure hexachlorobutadiene can occur by breathing contaminated air, eating contaminated food, drinking contaminated water, or by direct skin contact with this chemical. People working in the industrial facilities where hexachlorobutadiene is formed or used may be exposed. Concentrations found in outside air were 2–3 parts hexachlorobutadiene per trillion parts of air (ppt). Levels were much higher in or near industrial facilities where hexachlorobutadiene is formed or used. Although hexachlorobutadiene is not very soluble in water, small amounts may be found in some public drinking water (less than 1 part hexachlorobutadiene per billion parts water [ppb]). It may also be found in underground water near hazardous waste sites. Hexachlorobutadiene has no agricultural or food chemical uses in the United States. Levels ranging from 0.1 to 4.7 milligrams per kilogram have been found in fish and shellfish because the compound is present in some surface water. Exposure at waste sites is most likely to occur from the landfill disposal of waste by-products originating from chlorinated hydrocarbon manufacture.
Routes of Exposure 
Probable routes of human exposure to hexachlorobutadiene are:
- Ingestion; and
- Dermal contact
Health Effects 
- No information is available regarding the acute (short-term) effects of hexachlorobutadiene in humans from inhalation or oral exposure.
- Animal studies have reported effects on the kidney and respiratory system from acute inhalation exposure, while oral animal studies have reported kidney effects.
- Tests involving acute oral and inhalation exposures of rats and mice have shown hexachlorobutadiene to have high acute toxicity.
- No information is available regarding the chronic (long-term) effects of hexachlorobutadiene in humans from inhalation or oral exposure.
- Animal studies have reported effects on the kidney and liver from chronic oral exposure to hexachlorobutadiene.
- EPA has not established a Reference Concentration (RfC) for hexachlorobutadiene.
- The California Environmental Protection Agency (CalEPA) has calculated a chronic inhalation reference exposure level of 0.09 milligrams per cubic metre for hexachlorobutadiene. The CalEPA reference exposure level is a concentration at or below which adverse health effects are not likely to occur.
- The Reference Dose (RfD) for hexachlorobutadiene is under review by EPA.
- EPA has calculated a provisional RfD of 0.0002 milligrams per kilogram body weight per day (mg/kg/d) based on kidney effects in mice.
- No information is available regarding the developmental or reproductive effects of hexachlorobutadiene in humans.
- One study reported that the frequency of abnormal sperm morphology did not increase significantly over controls in mice exposed to hexachlorobutadiene via inhalation. A study in rats exposed via inhalation reported no embryotoxic effects, except for a reduction in foetal body weights.
- Oral animal studies have reported reduced fertility, reduced foetal body weights, but no birth defects or other developmental effects from hexachlorobutadiene exposure.
- No information is available regarding the carcinogenic effects of hexachlorobutadiene in humans or animals from inhalation exposure.
- One study reported kidney tumours in rats exposed to hexachlorobutadiene orally.
- EPA has classified hexachlorobutadiene as a Group C, possible human carcinogen.
- EPA has calculated an oral cancer slope factor of 0.078 (mg/kg/d)-1.
First Aid Measures
- If inhaled: If breathed in, move person into fresh air. If not breathing, give artificial respiration. Consult a physician.
- In case of skin contact: Wash off with soap and plenty of water. Take victim immediately to hospital. Consult a physician.
- In case of eye contact: Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
- If swallowed: Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.
Exposure Controls & Personal Protection
- Avoid contact with skin, eyes and clothing.
- Wash hands before breaks and immediately after handling the product.
Personal Protective Equipment
The following personal protective equipment is recommended when handling hexachlorobutadiene:
- Tightly fitting safety goggles;
- Faceshield (8-inch minimum);
- Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
- Handle with gloves.
- Gloves must be inspected prior to use.
- Use proper glove removal technique (without touching glove’s outer surface) to avoid skin contact with this product.
- Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
- Wash and dry hands.
- The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it.
- Complete suit protecting against chemicals;
- The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
- Where risk assessment shows air-purifying respirators are appropriate use a full-face respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
- If the respirator is the sole means of protection, use a full-face supplied air respirator.
- Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU.)
ACGIH: The American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV) for hexachlorobutadiene is 0.02 ppm, 0.21 mg/m3 TWA (Skin); Appendix A3 (Confirmed Animal Carcinogen with Unknown Relevance to Humans)
NIOSH: The National Institute for Occupational Safety and Health has established a Recommended Exposure Limit (REL): 0.02 ppm TWA (Skin); Potential carcinogen
OSHA: The Occupational Safety and Health Administration recommends that exposure to hexachlorobutadiene not exceed 0.02 ppm for an 8- hour workday over a 40-hour workweek. This limit is not enforced by the federal government, but it is the law in at least 25 states.
EPA: The Environmental Protection Agency has recommended guidelines on how much hexachlorobutadiene can be present in drinking water for specific periods of time without causing adverse health effects in humans. EPA recommends that exposures in children should not exceed 0.3 milligrams per litre of water (mg/L) for 10-day periods, or 0.1 mg/L for more than 7 years. If adults are exposed for long periods (more than 7 years), EPA recommends that exposure levels should not exceed 0.4 mg/L.
Safe Work Australia: Safe Work Australia has established an 8 hour Time Weighted Average (TWA) concentration for hexachlorobutadiene of 0.2ppm and 0.21 mg/m3.