he new cancer threat

avid Hendrey ehre was every reason for the consternation Ised within the plastics industry and el irkiiiere at the beginning of this year. when ,sable evidence linked vinyl chloride

ohier, the key chemical for PVC

lfacture, with a rare cancer of the liver. hs the latest and most disturbing confirma

Of the hazard to health involved for

ers in' twentieth-century industry. lore; the common initial for .polyvinylr'h'de, was first manufactured about forty ; ago and is now ubiquitous. Worldwide "tIction of the plastic totalled 7.7 million

last year, 400,000 tons being used in Bri

r such diverse products as pipes, eleceeables, floor tiles, packaging foils and Ls, gramophone records, shoe soles — the n'eeois endless. By any yardstick, therefore,

is an important material.

e itself is not cancer-forming, but in a ti me form can contain a certain amount of 0 Verted vinyl chloride monomer, which t;eased during further processing. Workers 0, Litlfacturing and processing PVC are f eght to be at risk to this cancer threat, but , ktent remains an unanswered question. Week the Department of Employment „ Unced plans for a Code of Practice, y!tled to minimise workers' exposure to i„ chloride monomer. The Factories Ins'urate, TUC, CBI and Chemical Industries tiation have all agreed that the Code of 0ce should be drawn up as soon as postven so, it is unlikely to appear for !I months. Two working parties will e,'gate medical aspects and occupational 4"e in relation to this new cancer threat, the expected to begin reporting their findTi a main working group in August. In '"earitime, PVC workers have been etZ."` of the risk they face and the officially maximum for vinyl chloride lI0er in air is reduced from 200 parts per lit to 50. To the plastics industry's credit, e "ler level was reached in most factories v`rhie ago. hinad Wider context, however, the story E'lit" how vinyl chloride monomer was Y recognised as a potential occupai.gealth hazard is somewhat disturbing. Ink between this chemical and liver

cancer would never have been discovered but for two extraordinary strokes of luck. The first came as a result of basic research by cancer scientists in Rome. For twelve months they had exposed rats to a massive 300,000 ppm of vinyl chloride monomer, which caused cancers in the skin, lungs and bones of these animals. Most other cancer scientists were suspicious of this finding. The familiar saying that any chemical will cause cancer if given in large enough doses might well have been applicable in this case. The finding could not, however, be ignored, so PVC manufacturers in Europe sponsored fuller research. Professor Maltoni of Bologna's Institute of Oncology agreed to carry out the research, which was expected to take about three years to complete. This was in 1971 and not long after, the Department of Employment in Britain began an epidemiology study of the workers in a major PVC works.

The study at first found no increase in any sort of cancer. It was rather like looking for a needle in a haystack, until Professor Maltoni in Bologna learned from early results of his research that vinyl chloride monomer can cause a rare cancer of the liver called angiosarcoma. This was the second stroke of luck. If this chemical instead caused cancer in tissues like the lung, where cancers are caused by numerous agents, then it would have been impossible to associate the cancer with a particular occupational health hazard. Any given case of lung cancer might be blamed on smoking, rather than on an industrial chemical.

In tne middle of 1973 epidemiology studies were begun in the United States with angiosarcoma in mind. This is an extremely rare cancer in the population generally, each year seeing only twenty to twenty-five cases throughout the entire United States. Dr John Creech, physician to the American PVC manufacturers, B. F. Goodrich and Company, was therefore surprised to find that two workers died of angiosarcoma at the same factory within two years. The alarm was raised in January of this year and so far the identified cases among PVC workers now total twelve in the United States, one in Britain and possibly five in Europe.

To put the problem in some sort of perspective, it must be pointed out that all these workers carried out for an average of twenty years certain procedures in PVC manufacture which exposed them to very large amounts of vinyl chloride monomer. This is converted to PVC by mixing with water, a plasticiser and a catalyst, and then reacting the mixture under pressure in an autoclave. Workers are maximally exposed to vinyl chloride monomer when the autoclave doors are reopened and its inside cleaned. The single British case of angiosarcome occurred in a worker who actually got inside the autoclave for cleaning. What cannot be estimated is how many more cases of angiosarcoma will be revealed in the future. Pehaps the optimism of a British Medical Journal editorial will prove justified: "The past three decades have seen both great advances in chemical engineering technique and an increasing awareness of the undesirability of exposing men to noxious vapours, so that the exposure to vinyl chloride monomer today may be only a fraction of what has occurred in earlier years." It is to be hoped so.

Indeed, improved ventilation around the autoclaves and elsewhere in PVC works, together with the use of high-pressure hoses for cleaning, has considerably reduced exposure. But there remains the possibility that the few cases known now are only the tip of an angiosarcoma iceberg. Could it be that exposure to lesser amounts of vinyl chloride monomer also causes cancer after, say, thirty or forty years? This is the big question that has to be in the minds of the working group as they formulate the new Code of Practice.

And a fundamental issue is how the usefulness to society of a material like PVC, not to mention the profits derived from its manufacture, can be weighed against a suspected occupational health hazard in its manufacture and processing. Between 1970 and 1972 an official committee of inquiry, headed by Lord Robens, investigated the whole problem of safety and health at work. The committee had stong views on the outcome of occupational health hazards: "For humanitarian and economic reasons, no society can accept with complacency that such levels of death, injury, disease and waste must be regarded as the inevitable price of meeting its needs for goods and services."

Apathy, concluded the committee, is the most important single reason for occupational hazards: "This attitude will not be cured so long as people are encouraged to think that safety and health at work can be ensured by an ever-expanding body of legal regulations enforced by an ever-increasing army of inspectors. The primary responsibility for doing something about the present levels of occupational accidents and disease lies with those who create the risks and those who work with them." (The committee's italics.) The Robens report paved the way for the Health and Safety at Work Bill which is presently going through Parliament. There is a clause which makes this responsibility a duty, as far as potentially hazardous chemicals are concerned:

Clause 5 (5) It shall be the duty of any person who undertakes the manufacture of any substance for use at work to carry out or arrange for the carrying•

any necessary research with a view to the and, so far as is reasonably practicable, ganination or minimisation of any risks to or safety to which the substance may give e danger of not doing what this legal says should be done was put in more ye language by Bryan Harvey, Chief tor of Factories in his annual report 1970, before the vinyl chloride monomer at became known: "Cancer-producing lea's share with asbestos and other genic dusts a latent period before the e is manifest. Any failure at the present to bring these risks under control can Ltherefore be reaped as a bitter harvest, °Y us but by the next generation." "Sing the onus of research on the ;Ilacturer seems at first sight to be a ";_le move. But are the tests presently able adequate for detecting cancereirig chemicals before they are used in scale operations? The use of animals for Chemicals is constantly improving, but tests are very lengthy affairs and coneritly very expensive. Many cancer tists are trying to develop simple and nsive tests using micro-organisms and le), cultures. These tests could make it ,,le to check out not only new chemicals, "o'so established ones like vinyl chloride mriler, which might be unsuspected health "8 to workers. 81itish Medical Journal editorial writer s out the present uncertainty: "Until eetests can be brought to a high degree of rtion and are used systematically by inWe may expect many more rude „Ilings to possible industrial car Hendrey is director of Janis, the (1st medicine and biology news agency.