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Vinyl chloride

DESIGNATIONS

CAS No.: 75-01-4
Registry name: Vinyl chloride
Chemical name: Chloroethene
Synonyms, Trade names: Monochloroethene, ethene monochloride, VC, VCM, Freon 1140
Chemical name (German): Vinylchlorid
Chemical name (French): Chlorure de vinyle
Appearance: colourless gas with slightly sweet odour; it is transported only in stabilised condition (using phenol and its derivatives) in pressurised cylinders.

BASIC CHEMICAL AND PHYSICAL DATA

ORIGIN AND USE

Usage:
96-98% of vinyl chloride is used to make polyvinyl chloride (PVC) with the remaining 2-4% being utilised in the manufacture of specific chlorinated hydrocarbons such as 1,1,1-trichloroethane, 1,1,2-trichloroethane and vinylidene chloride. VC is used on a large scale to make polymers (ATRI, 1985). About 25% of the world's total chlorine production is required for the production of VC.

Origin/derivation:
Production is by way of the addition of hydrogen chloride to acetylene or by way of the decomposition of 1,2-dichloroethane with the formation of hydrogen chloride as a by-product. The polymer of vinyl chloride is polyvinyl chloride (PVC).

Production figures:

Toxicity

Note:
¹⁾ Inhalation, 4h, 12th-18th day after conception

Characteristic effects:

Humans/mammals: This flammable, toxic and narcotic gas irritates the eyes, the skin and the respiratory tract. Repeated exposure damages the liver, kidneys and spleen; malignant tumours may occur. Toxic concentrations in air may occur without producing an alarming odour. VC is definitely carcinogenic and teratogenic (deformities and skeletal changes on inhalation) as revealed both by animal experiments and human exposure.

Thermal decomposition produces acidic gases which irritate the eyes, the nose and the throat.

ENVIRONMENTAL BEHAVIOUR

Water:
Vinyl chloride is persistent in water, if not evaporating. However, there are no known cases of damage to aquatic organisms (UBA, 1986). Accumulation in the aquatic food chain is unlikely (BUA, 1989).

Air:
On expansion, the pressurised gas forms cold mists which are denser than air. They evaporate easily and form toxic, explosive mixtures. Accumulation in the atmosphere is likely because of the physical and chemical properties of vinyl chloride.

Half-life:
Under normal environmental conditions, vinyl chloride is extremely persistent. Under anaerobic conditions its half-life in soil is more than 2 years. Aerobic degradation in sewage treatment plants and surface water in an isolated bacteria culture with 20-120 mg/l requires at least 5 weeks (UBA, 1986). OH radicals reduce the half-life to 66 h. The hydrolytic half-life is less than 10 years (calculated, 25°C) (RIPPEN, 1991). The half-life in the troposphere is eleven weeks (abiotic degradation) (ATRI, 1985). An average half-life between 2.2 and 2.7 days is reported by the BUA (1989).

Degradation, decomposition products:
Photochemical oxidation results in the formation of HCl, CO and formyl chloride as well as formaldehyde. There is no photolysis of 10 mg/l in water at 300 nm over 90 hours. Biotic mineralisation is extremely slow.

Combination effects:
Vinyl chloride reacts with acetylene, chlorine, fluorine, oxidising agents and peroxides with considerable amounts of heat being generated. Polymers are formed. Light, heat and hydrogen sulphide act as polymerisation initiators.

ENVIRONMENTAL STANDARDS

Notes:

¹⁾ Sum of all chlorinated hydrocarbons except pesticides
²⁾ 4 day average for special synthetics industry, direct introduction
³⁾ Applies to existing installations
⁴⁾ Clearly carcinogenic
⁵⁾ Ambient air, California

Within the framework of the specifications governing the handling of carcinogens, there is a special regulation in Germany for vinyl chloride. Accordingly, the concentration in workplace air must not exceed 3 ppm, marking and mandatory investigation are regulated, personal protection equipment defined and cleaning measures described (VGB 113, 1982, Appendix, 1 vinyl chloride). Furthermore, the Appendix to the BAT list (DFG, 1989) describes the relationship between the substance concentration in workplace air and the substance/metabolite concentration in biological material (EKA values) for vinyl chloride as a carcinogenic substance. The following accordingly applies:

Air vinyl chloride Sample: urine at end of shift/end of exposure

The Order Governing Vinyl Chloride Consumer Goods (1983) in Germany bans the marketing of articles with a monomeric vinyl-chloride content of > 1 mg/kg. No risk from foodstuffs is assumed as long as the detectable monomeric vinyl-chloride level does not exceed 0.01 mg/kg.

On the basis of the Order Banning PCB (superseded regulations enforced since 1978 in 1990) vinyl chloride cannot be used in the Federal Republic of Germany as a propellant for aerosols.

Vinyl chloride is a substance hazardous to water for which approval must be granted in line with §19a of the WHG if they are to be conveyed in pipelines.

Comparison/reference values

Assessment/comments

The use of vinyl chloride must be avoided as far as possible because of its definite carcinogenic effect and its high persistence. Waste incineration is inadequate since incomplete combustion produces highly toxic pollutants (e.g. hydrochloric acid and TCDD). Special sources: ATRI (1985); DRAFT (1988). Polyvinyl chloride (PVC) should be substituted by other (non-chlorinated) materials wherever possible.

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