Vinyl Chloride (Hansard, 8 April 1974)

§ Mr. Harold Walker

There are no prescribed limits of exposure to vinyl chloride in the United Kingdom. In general the Factories Act 1961 requires protective measures to prevent injury to health from all dust and fume and an acceptable standard of hygiene control is assessed in the light of current medical knowledge and of threshold limit values as published in my Department's Technical Data Note No. 2.

The published threshold limit value for vinyl chloride is 200 parts per million. This was set when acro-osteolysis was recognised as the main specific hazard from exposure but it is not now thought 25W appropriate because wider risks including carcinogenicity have very recently been identified as associated with the industrial use of vinyl chloride. The experiments which first drew attention to these greater risks have been negative at 50 parts per million but further consideration is necessary before this figure could be put forward as a hygiene standard.

Medical advisers of my Department have started work on an epidemiological study among those who have worked with vinyl chloride in this country and are in close touch with those conducting a similar study in the United States of America. In the United Kingdom only one worker exposed has been identified as having suffered the rare form of liver tumour associated with vinyl chloride, although the substance has been widely used for some 30 years. Further experiments are in progress and medical advisers are being kept informed of their results.

Inspectors of factories have made extensive inquiries at the six factories where vinyl chloride is processed in this country. They report very great activity by these firms in making improvements in environmental control, and this progress indicates that 50 parts per million is an attainable level in existing plant.

I am satisfied that the Factories Act 1961 provides sufficient powers to enforce suitable control measures for this substance.