Chloroprene

Chloropreneis the common name for theorganic compound2-chlorobuta-1,3-diene, which has the chemical formulaC4H5Cl. [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] It is a halogenated alkene that exists at room temperature as a clear colourless liquid with a pungent ether-like odour. Chloroprene is practically insoluble in water, soluble in alcohol, and miscible with acetone, benzene, and ethyl ether. It is highly flammable and polymerises on standing, making it unstable in the environment. [2]

 

Uses [2]

 

The only commercial use identified for chloroprene is as a monomer in the production of the elastomer polychloroprene (neoprene), a synthetic rubber used in the production of automotive and mechanical rubber goods, adhesives, caulks, flame-resistant cushioning, construction materials, fabric coatings, fibre binding, and footwear. Other uses of this polymer include applications requiring chemical, oil, or weather resistance or high gum strength. The United States Food and Drug Administration permits the use of chloroprene as a component of adhesives used in food packaging and also permits the use of polychloroprene in products intended for use with food.

 

Sources & Routes of Exposure

 

Sources of Exposure [3]

 

  • Workers may be occupationally exposed to chloroprene by inhalation or dermal exposure.
  • The release of chloroprene to the environment may occur during its manufacture, transport, and storage and during the manufacture of polychloroprene elastomers and polychloroprene-containing products.

 

Routes of Exposure [2]

 

The routes of human exposure to chloroprene are:

  • Inhalation;
  • Ingestion; and
  • Dermal contact.

 

Health Effects [3]

 

Acute Effects

 

  • 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.
  • Acute animal tests in rats and mice, have demonstrated chloroprene to have moderate acute toxicity by inhalation and high acute toxicity from ingestion. (5)

 

Chronic Effects

 

  • 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 vapour 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.
  • EPA has calculated a provisional Reference Concentration (RfC) of 0.007 milligrams per cubic metre (mg/m3) for chloroprene based on respiratory effects in rats.
  • EPA has calculated a provisional Reference Dose (RfD) of 0.02 milligrams per kilogram body weight per day (mg/kg/d) for chloroprene.

 

Reproductive/Developmental Effects

 

  • A study reported functional disturbances in spermatogenesis in workers exposed to chloroprene and increased spontaneous abortions in the wives of exposed workers. However, insufficient details are available in the reports to adequately evaluate the results.
  • Reproductive effects including a decreased number of spermatogonia, a decline in sperm motility, an increased number of dead sperm, and degeneration of the testes have been observed in male rats exposed by inhalation or dermal contact.
  • Increased embryonal mortality and decreased foetal weight were reported in rats exposed by inhalation; contamination may have occurred during this study. No effects on embryonic or foetal survival nor incidence of soft tissue or skeletal defects were observed in other studies of rats exposed by inhalation.

 

Cancer Risk

 

  • Epidemiological studies of rubber workers in the Soviet Union have indicated a possible association between exposure to chloroprene and skin and lung cancer. However, levels of exposure causing symptoms have not been well defined and these studies have major methodological deficiencies. An increased incidence of lung cancer was not reported in another study of American workers occupationally exposed to chloroprene during the manufacture of neoprene.
  • An inhalation bioassay by the NTP showed clear evidence of carcinogenic activity in both rats and mice, based on increased incidences of neoplasms of the oral cavity, thyroid gland, lung, kidney, liver, skin, mammary glands, and other organs.
  • 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.

 

Safety [4]

 

First Aid Measures

 

  • Eye: Non corrosive to eyes. In the case of entering into eyes, please wash them with copious amounts of water.
  • Skin: The compound is not likely to be hazardous by skin contact but cleansing the skin with soap and water after use is advisable. If molten material gets on skin, cool rapidly with cold water. Do not attempt to remove material from skin. Obtain medical treatment for thermal burn.
  • Inhalation: Irritating fumes occurred only in the heating process. If too many fumes inhaled, please move patient to fresh air or administer oxygen and assist ventilation as required.
  • Ingestion: Ingestion is not a probable route of exposure. Chloroprene rubber is not considered a serious threat for human health, for which is low toxicity.

 

Exposure Controls & Personal Protection

 

Engineering Controls

 

  • Local exhaust ventilation may be necessary to control air contaminants from hot processing. The use of local ventilation is recommended to control emissions near the source.
  • Provide mechanical ventilation for confined spaces.
  • Facilities storing or utilising this material should be equipped with an eyewash facility and a safety shower.

 

Personal Protective Equipment (PPE)

 

The following personal protective equipment is recommended when handling chloroprene:

  • Eye/Face Protection: In the heating process, wear safety glasses when possibility exists for eye and face contact due to splashing or spraying of molten material. Have eye-wash stations available where eye contact can occur.
  • Skin Protection: Wear gloves impervious to the heating conditions of use. Additional protection may be necessary to prevent skin contact including use of face shield, boots or full body protection. A safety shower should be located in the work area.
  • Respirators: In the heating process, air purifying respirator with an organic vapour cartridge with a dust/mist filter may be permissible under certain circumstances where airborne concentrations are expected to exceed exposure limits.
  • Protective Clothing: If there is potential contact with hot/molten material, wear heat resistant clothing and footwear.

Regulation

 

United States [5]

 

OSHA: The Occupational Safety & Health Administration has set the following Permissible Exposure Limits (PEL)for chloroprene:

 

ACGIH: The American Conference of Governmental Industrial Hygienists has established a Threshold Limit Value (TLV) for chloroprene of 10 ppm, 36 mg/m3TWA; Skin

 

NIOSH: The National Institute for Occupational Safety and Health has set a Recommended Exposure Limit (REL) for chloroprene of 1 ppm, 3.6 mg/m3Ceiling (15 minutes);Appendix A– NIOSH Potential Occupational Carcinogens

 

Australia [6]

 

Safe Work Australia: Safe Work Australia has set a Time Weighted Average (TWA) concentration for chloroprene of 10ppm or 36mg/m3 for a 40 hour work week.

 

References

 

  1. http://en.wikipedia.org/wiki/Chloroprene
  2. https://ntp.niehs.nih.gov/ntp/roc/content/profiles/chloroprene.pdf
  3. http://www.epa.gov/ttn/atw/hlthef/chloropr.html
  4. http://dhard.ucp-is.com/docs/Regulatory/MSDS/MSDS.SN.grades.en.pdf
  5. https://www.osha.gov/dts/chemicalsampling/data/CH_228000.html
  6. http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documents/772/Workplace-exposure-standards-airborne-contaminants.pdf

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