Hexachlorobutadiene

What is Hexachlorobutadiene?

Hexachlorobutadiene, also known as HCBD, perchlorobutadiene, or dolen-pur, is a colourless liquid with the molecular formula C4Cl6. It has a turpentine-like smell 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.

What is Hexachlorobutadiene used for?

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.

Hexachlorobutadiene is used mainly as an intermediate in the manufacture of rubber compounds.

Hexachlorobutadiene Exposure

In the Environment

Hexachlorobutadiene can enter the environment through air, water, and soil, mostly from industrial waste disposal. Most of it is destroyed by burning, but some may be released into the air. It is unclear exactly what happens to it in the air, but like similar chemicals, it might break down under sunlight within about 60 days. When released into water, it may pass into the air or soil. While hexachlorobutadiene sticks to most soils, it can sometimes move through sandy soils to underground water. It can also build up in fish and shellfish where the water is contaminated, though it’s unknown if it affects plants.

Sources & Routes of Exposure

Source of Exposure

People can be exposed to hexachlorobutadiene by breathing contaminated air, drinking polluted water, eating contaminated food (especially fish and shellfish), or by touching it. The chemical is found at higher levels near industrial facilities and hazardous waste sites.

Routes of Exposure

The most likely ways people come into contact with hexachlorobutadiene are:

  • Inhalation: Breathing contaminated air.
  • Ingestion: Eating or drinking contaminated food or water.
  • Dermal contact: Touching contaminated surfaces.

Health Effects

Acute Effect

There is limited information about the immediate effects of hexachlorobutadiene on humans. However, in animals, it has been shown to cause damage to the kidneys and respiratory system when inhaled, and similar effects have been observed with oral exposure.

Chronic Effects

Long-term exposure in animals has shown effects on the kidneys and liver. The U.S. Environmental Protection Agency (EPA) and the California Environmental Protection Agency (CalEPA) have established safe exposure levels to avoid harmful health effects, though more research is still being conducted.

Reproductive/Developmental Effects

No evidence exists for reproductive or developmental effects in humans. In animals, exposure to hexachlorobutadiene has led to reduced fertility and lower fetal body weights, but no birth defects were observed.

Cancer Risk

There is no clear evidence linking hexachlorobutadiene to cancer in humans. However, studies in rats have shown an increased risk of kidney tumours when exposed orally. The EPA classifies hexachlorobutadiene as a possible human carcinogen.

Hexachlorobutadiene Safety

First Aid Measures

  • Inhalation: Move the person to fresh air. If they are not breathing, provide artificial respiration and seek medical attention.
  • Skin contact: Wash thoroughly with soap and water. Get medical help right away.
  • Eye contact: Rinse eyes with water for at least 15 minutes and consult a doctor.
  • Swallowed: Do not give anything by mouth to an unconscious person. Rinse the mouth with water and consult a doctor.

Exposure Controls & Personal Protection

Engineering Controls

  • Aoid contact with skin, eyes, and clothing.
  • Wash hands after handling the product and before breaks.

Personal Protective Equipment (PPE)

  • Eye/face protection: Use safety goggles and a face shield. Ensure the equipment meets safety standards like NIOSH (US) or EN 166 (EU).
  • Skin protection: Wear protective gloves, inspect them before use, and remove them carefully to avoid skin contact. Dispose of gloves properly. Follow regulations like EU Directive 89/686/EEC and EN 374.
  • Body protection: Wear a full suit designed for chemical protection, choosing the right gear based on the workplace’s exposure levels.
  • Respiratory protection: Use a full-face respirator with appropriate filters or cartridges. If air-purifying respirators aren’t sufficient, use a full-face supplied air respirator. Ensure respirators meet NIOSH (US) or CEN (EU) standards.

Regulations

United States

ACGIH: The American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV) for hexachlorobutadiene of 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. The 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.

Australia

Safe Work Australia: Safe Work Australia has established an 8-hour Time Weighted Average (TWA) concentration for hexachlorobutadiene of 0.2 ppm and 0.21 mg/m3.