Chloroprene (aka branded 'Neoprene') is the common name for the organic compound 2-chlorobuta-1,3-diene. This colourless liquid is the monomer for the production of the polymer polychloroprene, a type of synthetic rubber.1
Polychloroprene or Chloroprene Rubber (CR), first produced in 1932, is better known as ‘Neoprene’.
‘CR was one of the first oil resistant synthetic rubbers. However, it has only moderate resistance to petroleum based oils and fuels. It can be considered as a good general-purpose rubber with an excellent balance of physical and chemical properties. It has better chemical, oil, ozone and heat resistance than natural rubber but a rather lower level of physical properties. Chloroprene tends to slowly absorb water and its electrical properties are poor. Its gas permeability is fairly low and flame resistance is excellent, chloroprene being one of the few rubbers that are self-extinguishing. Neoprene gives excellent rubber-metal bonds and good resilience.’ 2
CR is not characterised by one outstanding property, but its balance of properties is unique among the synthetic elastomers. It has:
• Good mechanical strength
• Good ozone and weather resistance
• Good aging resistance
• Low flammability
• Good resistance toward chemicals
• Moderate oil and fuel resistance
• Adhesion to many substrates
What is it used for?
CR is used in different areas, mainly in the rubber industry but is also important as a raw material for adhesives (both solvent and water-based) and has different latex applications such as moulded foam, multipurpose rubber sheeting, sound insulation, gaskets and improvement of bitumen.
Chloroprene sheeting is used to produce insulating joints and coatings for protecting environments that are in contact with oils and other chemical products. It may also be used in outdoor applications, as it has a good resistance to temperature changes, ozone action and adverse weather conditions.
Other applications in the elastomer field are widely spread, such as moulded goods, cables, transmission belts, profiles etc.
Chlorprene in the Environment
The potential for the release of chlorophene to the environment exists during its manufacture, transport, and storage, and during the manufacture of polychlorphene elastomers (eg ‘Neoprene’) and polychlorphene-containing products.
Chloroprene is ‘not readioy biodegradable’ and has a low bio- or geoaccumulation potential.
Little information is currently available regarding levels of chlorophene in the environment resulting from these processes.
Chloroprene is highly flammable. Many reactions may cause fire or explosion. Gives off irritating or toxic fumes (or gases) in a fire.
Sources and Potential Exposure
Workers may be occupationally exposed to chloroprene by inhalation or dermal exposure.
• Symptoms reported from acute human exposure to high concentrations of chloroprene include giddiness, headache, irritability, dizziness, insomnia, fatigue, respiratory irritation, cardiac palpitations, chest pains, nausea, gastrointestinal disorders, dermatitis, temporary hair loss, conjunctivitis, and corneal necrosis.
• Acute exposure may damage the liver, kidneys, and lungs; affect the circulatory system and immune system; depress the central nervous system (CNS); irritate the skin and mucous membranes; and cause dermatitis and respiratory difficulties in humans. High level exposures have affected the liver, lungs, kidneys and CNS in animals exposed by inhalation, gavage, or injection. Acute oral exposure of rats caused inflammation of the mucous membranes; damage to the lungs, liver, spleen, and kidneys; and irritation of the gastrointestinal tract.3
Chronic Effects (Noncancer):
• Symptoms of chronic exposure in workers were fatigue, chest pains, giddiness, irritability, dermatitis, and hair loss.
• One study has suggested that chronic exposure of humans to chloroprene vapor associated with neoprene production may contribute to liver function abnormalities. Disorders of the cardiovascular system and depression of the immune system have also been observed in workers chronically exposed to chloroprene. Eye irritation, nasal discharge, olfactory epithelial degeneration, restlessness, lethargy, hair loss, growth retardation, and effects to the liver, kidney, thyroid, blood, and lungs have been observed in rodents following chronic inhalation exposure. 3
Chloroprene and cancer
• EPA has classified chloroprene as a Group D, not classifiable as to human carcinogenicity, because of the absence of adequate data.
• The International Agency for Research on Cancer (IARC) has classified chloroprene as a Group 2B, possibly carcinogenic to humans.