Commonwealth of Australia 2000

11.2Hazards

Acrylonitrile is a highly volatile, flammable and explosive liquid. It reacts violently with many other chemicals and may undergo spontaneous, explosive self-polymerisation unless stabilised by a chemical inhibitor and/or water.

In both laboratory animals and humans, acrylonitrile is readily absorbed by ingestion, by inhalation and through the skin. It is acutely toxic by all routes of exposure, causing convulsions followed by paralysis and respiratory failure. It is acutely irritating to the skin and eyes and may cause allergic contact dermatitis. Repeated exposure of workers to airborne acrylonitrile has been associated with respiratory tract irritation and functional disturbances of the CNS. Acrylonitrile is mutagenic in vitro and a potent multi-organ carcinogen in rats. Epidemiological studies involving large numbers of exposed workers and extensive follow-up periods have neither established nor ruled out a causal relationship between acrylonitrile exposure and cancer in humans.

Acrylonitrile is included in the NOHSC List of Designated Hazardous Chemicals based on the classification in EC Council Directive 96/54/EC. It is classified as highly flammable; toxic by inhalation, in contact with skin and if swallowed; a skin irritant; and a carcinogen in Group 2 (substances regarded as if they are carcinogenic to humans). In March 1999, the EC agreed to amend their original classification of acrylonitrile to include risk phrases for irritation of the respiratory tract, serious damage to the eyes, and skin sensitisation. Australia will adopt this amended classification via the NOHSC hazardous substances regulatory process.

The available environment data indicate that acrylonitrile can be characterised as exhibiting slight to moderate acute and slight chronic toxicity to aquatic vertebrates and aquatic invertebrates. Similarly, for algae and aquatic plants, results for effects on biomass suggest that acrylonitrile is moderately toxic, while results for effects on reproduction are indicative of slight toxicity.

11.3Occupational controls

In Victoria and New South Wales, almost all of the national provisions pertaining to acrylonitrile have been embodied in State legislation relating to occupational health and safety, drugs and poisons, or dangerous goods. The corresponding regulations are enforced through a system of permits, licences and warrants. These are issued on the condition that the holder supplies detailed information about health and safety control measures and can be withdrawn if it is found that the approved control plans are not adhered to in practice.

In the workplace, the principal method employed to control exposure to acrylonitrile is full enclosure and isolation together with engineering controls to minimise emissions, waste streams and leaks from the closed system. Access to areas where acrylonitrile is handled is limited to a minimum of people whose presence is absolutely necessary. In addition, all workers wear eye and skin protection. Respiratory protective equipment is used during the making and breaking of enclosed pipelines during ship to shore transfer and loading and unloading of the road tanker that transports acrylonitrile to the sites where it is processed.

In situations where isolation cannot be maintained because of emergencies or the need to enter the closed system to carry out sampling or maintenance, PPE deployed includes chemical goggles, a protective suit, rubber gloves and rubber boots. In addition, respiratory protection is mandatory in all situations where the breathing zone concentration (measured by grab sampling) is >1 ppm or unknown.

In laboratories handling neat acrylonitrile the main control measures are standard operating procedures and the confinement of all manipulations to a fume cupboard.

All sites storing bulk acrylonitrile have implemented control measures aimed at reducing the likelihood and impact of fires, explosions, spills and other accidents. These include isolation, chemical inhibition to prevent spontaneous polymerisation, nitrogen blanketing and bunding of storage tanks, the equipment of storage tanks and reactors with high temperature and high pressure alarms and deluge systems, and detailed on-site emergency plans.

Hazard communication includes MSDS, the labelling of containers of hazardous chemicals, and education and training of workers. Deficiencies were found in some of the MSDS provided for assessment. All companies handling the chemical in bulk provide training programs in acrylonitrile-related hazards and safety procedures.

Personal full-shift and/or task monitoring of potentially exposed workers is conducted by all companies that handle bulk acrylonitrile, although the exposure monitoring programs vary considerably from site to site. There was no indication of a consistent approach to strategic issues such as the selection of workers for personal monitoring, definition of sample sizes, data analysis or determination of the frequency of monitoring. The monitoring data provided for assessment indicate that the number of samples obtained for each similar exposure group has declined over the last decade. In recent years, several sites have relied on small samples, sometimes not exceeding 1-2 per assessment. This may not suffice to determine the level of exposure with a reasonable degree of confidence.