Benzidine-based Dyes (Hansard, 19 January 1981)

§ Miss Joan Lestor (Eton and Slough)
Nobody would want to cause unnecessary alarm by making allegations about possible causes of cancer without some very strong evidence to support such allegations. However, when certain evidence is available and when certain action has been taken by other countries in relation to substances in common use in this country in certain industries, particularly in the cotton and leather industries, it is the responsibility of Members of Parliament to ensure that such matters be brought before the House and that the Minister involved be asked to comment on some of the findings.
On 14 November last the American Consumer Product Safety Committee announced that it had decided to ban the use of three potentially dangerous dyes alleged to have cancer connections, particularly in relation to blood cancer. These dyes are used in this country, in America, in Japan and in many other countries in powder and liquid form and are commonly used in the two industries I have mentioned.
The evidence quoted by the United States Consumer Product Safety Committee is to the effect that the absorption of these dye substances into the human system—by inhaling the dye product itself, by contamination through the skin by placing the hands in the dyes, or in other instances by accident, as happened in Japan in the case of the Japanese kimono painters putting a paint brush between their lips in order to get a finer point—has a strong causal relationship with blood cancer.
So alarmed is the American Consumer Product Safety Committee by these findings that it has decided to impose a ban on these substances and to seek to find substitutes that do not involve such hazards. Naturally, that has alarmed the National Union of Dyers, Bleachers and Textile Workers, which has been anxious about the mounting allegations which have commanded the attention of the Cancer Prevention Society. Under the auspices of Gordon Wilson, an interesting pamphlet has been written dealing with the subject and particularly with the risk of bladder cancer from the use of these dyes.
127 Britain has not taken the action proposed by America in relation to the banning of the dyes and the search for substitutes. That is alarming since America is not at the forefront in such action until there is considerable evidence of the possible dangers. In America and other parts of the world surveys have been made of workers constantly involved with the use of such dyes. A survey of 200 bladder cancer patients in Japan demonstrated that many were involved in kimono painting and dyeing. The dyes were taken in through the lips.
Other evidence substantiates the fear that there might be a strong connection between the use of the dyes and the increase in bladder cancer. Other work has been done. Experiments and tests have been carried out among people in the wool industry in Britain. Studies have been made by Raymond Cartwright and others in Leeds and they came to different conclusions. However, the dyes are not as common in the wool industry as in the leather and cotton industries. We should conduct a full examination in those industries. Until we know for sure whether there is a connection between bladder cancer and benzidine-based dyes, there should be a ban on them.

§ Mr. Bob Cryer (Keighley)
In spite of the evidence, the National Union of Dyers, Bleachers and Textile Workers, which is concentrated in the wool and textile industry, has called for evidence on the dyes without much response from Government bodies. It is concerned about the possible cancer-causing properties of the dyes.

§ Miss Lestor
I am grateful to my hon. Friend, who has a constituency interest. The TUC has been involved with the Government and the Health and Safety Commission in trying to get action. The conclusion is that there is no doubt that there should be, and is, anxiety about the possibility of a relationship between the dyes and bladder cancer. In spite of that evidence, there is no recommendation that the dyes should be banned.
That is not good enough. I do not want to cause alarm among the thousands of people involved in the industry. However, it is not good enough, when America is taking action and other countries are expressing anxiety, for Britain to say that there is some evidence of a connection between bladder cancer and the use of benzidine-based dyes, but that until there is more evidence and proof is conclusive it will take no further action and allow the dyes to be used.
If we have any slight indication that the use of certain drugs and substances in dyes is likely to be a cancer or any other risk, unless we can produce enough safeguards to avoid it, such substances should be withdrawn until the evidence is either conclusive or can be totally and utterly repudiated.
I therefore put to the Minister, on behalf of the thousands involved, on behalf of the Cancer Research Society, the union concerned, and many other people, that unless some action similar to that taken in America is taken, the Minister must either say that America has drawn the wrong conclusions or he must justify why in this country we are seemingly still allowing these risks to be taken.

§ The Under-Secretary of State for Employment (Mr. David Waddington)
I thank the hon. Member for Eton 128 and Slough (Miss Lestor) for choosing this subject for debate. She will be aware that, not only here but in many other cases involving chemicals, difficult decisions have to be made as to what precautions are appropriate, and such decisions have often to be based on incomplete and sometimes conflicting data. The Government believe that it is important that these matters should receive the fullest consideration. There is no justification whatever for confining the debate to experts, and those involved in working with potential hazards should also be involved in the decision making process.
The hon. Member has referred in particular to the publication in this country of "Cancer at Work" by the Cancer Prevention Society, which I have read. While we welcome this valuable contribution to the debate, in that it highlights the problems, it is debatable whether all the proposals put forward in that pamphlet are wholly appropriate in the light of the evidence so far available. Before discussing benzidine-based dyes, perhaps I should say a word—so that we may have the full picture—about benzidine itself. This is the basic chemical from which benzidine-based dyes are made, and it is this chemical that has been known for very many years as a bladder carcinogen.
The manufacture and use of benzidine and substances containing benzidine was prohibited in 1967 by the Carcinogenic Substances Regulations 1967, except where any such substance contained less than 1 per cent. of free benzidine present as a by-product of a chemical reaction. At the same time, importation of benzidine and substances containing benzidine, with the same 1 per cent. exception applying, was prohibited by the Carcinogenic Substances (Prohibition of Importation) Order 1967. The effect of this legislation was to prohibit the manufacture of benzidinebased dyes from benzidine in this country, but the importation and use of the dyes was not prohibited provided they fell within the 1 per cent. exception. In fact, benzidine-based dyes are imported and used in this country but they do not contain anything like 1 per cent. of free benzidine—equivalent to 10,000 parts per million. The free benzidine content of the dyes has been measured and found generally to be less than 30 parts per milliom.
It is known that benzidine-based dyes are made in France, the United State of America and elsewhere. It is estimated that at the present time between 350 and 400 tonnes of these dyes are imported and sold in this country each year, this quantity being the equivalent of 1 per cent. of the total market for dyestuffs in Great Britain. Approximately 50 per cent. of the benzidine-based dyes imported are used in the leather industry, 45 per cent. in the textile industry—mainly in the dying of cotton and man-made fabrics—and the remaining 5 per cent. in the paper industry. Over 60 different benzidine-based dyes are imported, and these are mainly browns and blacks, the latter being used particularly in the leather industry.
The potential risk which might be expected from the use of benzidine-based dyes is that of bladder cancer. It has been accepted for many years now that benzidine itself is carcinogenic, but it is only quite recently that there has been some suspicion about the low-benzidine content dyes now used. The hon. Member was right to point to studies in the United States. After animal studies there it has been suggested that a potential carcinogenic risk may arise from the actual dyes, even if free of benzidine, due to conversion of the dyes in the body to benzidine and its metabolites. The epidemiological evidence relating to the 129 use of the dyes in Great Britain and the possibility of a raised incidence of bladder cancer in man is considered by the Health and Safety Executive to be inconclusive.
All animals so far tested have been found to metabolise benzidine-based dyes to benzidine and other derivatives. The National Cancer Institute in the United States recently reported that rats which had been fed three benzidinebased dyes, described as being widely used, developed cancer of the liver within a shorter time than would have been expected from the free benzidine content of the dyes alone. The free benzidine content of the dyes used in the experiments is not known, but in the animal feed the content was said to be less than four parts per million.
Evidence from human studies in Russia and Japan has suggested an association between the use of benzidinebased dyes and the subsequent development of pre-cancerous lesions and bladder tumours. Very few details are known about the Russian study, but, as the hon. Member mentioned, that from Japan showed a specific association in the case of kimono painters who habitually formed points on the tips of their brushes by licking, thus inadvertently consuming some of the dyes. In a study of American dye workers carried out by the National Institute of Occupational Safety and Health, benzidine or mono-acetyl benzidine was found in the urine of workers employed at four out of five factories at which tests were made. It was reported that good work practices were observed at the fifth factory, where the tests were negative. Perhaps that means—the report does not make it plain—that in the fifth factory there was more careful handling.
The hon. Member mentioned that in the middle of 1980 the United States Occupational Safety and Health Administration issued a "health hazard alert" on dyes based on benzidine. In the alert the administration concluded that benzidine-based dyes are potential human carcinogens and exposure of workers to the dyes should be reduced to the lowest feasible levels including discontinuation of use of the dyes where possible. In Great Britain there have been a number of studies involving dye workers, including a retrospective survey of men and women who died from bladder cancer in North Staffordshire between 1965 and 1970; a survey in Leeds between 1959 and 1967; and in 1975 a study on members of the National Union of Dyers, Bleachers and Textile Workers in Bradford. None of these has indicated a raised incidence of bladder cancer amongst dye users. The workers involved in the studies had been exposed to a variety of dyestuffs during the period when it is thought that benzidine-based dyes contained a higher proportion of free benzidine than is the case today.
I must make plain, however, that the Health and Safety Executive has not been idle and has taken steps to evaluate the extent of the potential problem and has investigated four possible ways in which a risk may arise from the use of benzidine-based dyes in this country. First, it commissioned work by Leeds university to investigate the residual amounts of free benzidine remaining in benzidinebased dyes used in this country. Forty-four dyes were tested, 41 of which were found to contain less than 10 parts per million of free benzidine, and the remaining three contained between 50 and 70 parts per million.
Secondly, it commissioned work by Leeds university to investigate whether benzidine-based dyes might be 130 broken down to free benzidine by a reductive chemical reaction in the operation of dye-stripping, that is, the removal of dye from fabric. Tests were carried out to measure any free benzidine in the air above stripping baths or in the bath liquor. No measurable amount of free benzidine was found in the air and a maximum concentration of 33 parts per million was found in the bath liquor.
Thirdly, the executive's employment medical advisory service investigated the possibility of the formation of benzidine and mono-acetyl benzidine following the absorption of benzidine-based dyes into the body. In 1978, tests were carried out for free benzidine or mono-acetyl benzidine in 200 urine samples from workers exposed to benzidine-based dyes. The test method was capable of detecting one part in 1,000 million of free benzidine or mono-acetyl benzidine. However, neither of those compounds was found, and the American findings were not confirmed.
Finally, in September 1980, the Health and Safety Executive commissioned research by the cancer research unit at the University of York. Two of the questions that it is hoped that this research will answer are: first, is there any evidence after application of suitable in vitro tests for biological activity, that benzidine-based dyes constitute a significant carcinogenic hazard; secondly, does any activity stem from the whole molecule or simply from the release in biological systems of the parent aromatic amine? Obviously, these studies should help to determine the potential carcinogenic hazard to man of exposure to benzidine derived dyes.
The evidence concerning the possible health effects of benzidine-based dyes as used in this country is not conclusive one way or the other. Various opinions have been expressed as to whether benzidine-based dyes are potentially human carcinogens. No doubt this controversy will continue for some time. But the most important issue is what are the appropriate steps to be taken now in the light of present evidence to ensure the health of workers exposed to these dyes. The options are prohibition, substitution and/or control.
It is the general policy of the Health and Safety Commission, expressed in its publication "guidance note EH 18—toxic substances: a precautionary policy" that dangerous materials should be substituted by safer ones. Clearly, prohibition is not a step that should be undertaken lightly and without due consideration of all the factors involved—medical, scientific, social and economic. Prohibition is a kind of mandatory substitution in that it forces industry to use alternative materials. In addition, when considering substitution, one must ensure that the substitutes proposed really are safer than the materials they replace. In the case of possible substitutes for benzidinebased dyes the risks to health have not in general been as fully investigated as those from the benzidine-based dyes themselves. Indeed, some reservations on the safety of some of the current possible alternatives have been expressed in the hazard alert to which I have referred. Whilst, therefore, every case for substitution needs to be carefully and individually considered, the Health and Safety Executive has concluded that it would be inappropriate to make specific recommendations at present, and has not done so for this reason. At the same time, it is recognised that more specific guidance on the control of exposure is necessary.
131 I should stress that it is the general policy of the Health and Safety Executive, expressed in guidance note EH 18, that exposure to all substances, including those for which there is no known limit of effect, should be kept as low as is reasonably practicable, and inspectors have been advising employers accordingly. It is generally accepted that the risk of exposure to dyes is greatest in colour stores where dyes in powder form are handled. A code of practice—"safe handling of dyestuffs in colour stores"—has recently been published by the Health and Safety Executive. The code was prepared by a committee composed of representatives of the dye manufacturers, employers and trade unions in the user industry and the Health and Safety Executive. Although the code is not intended to deal specifically with the handling of benzidine-based dyes, but rather with the handling of dyes in general, it makes recommendations which were applied in practice, greatly reduced the exposure of workers to dyestuffs, and hence reduced the extent of potential risks.
In relation to the safe use of benzidine-based dyes, the Health and Safety Executive is preparing a guidance note 132 for publication. This is currently in the course of preparation and, before being published, will be reviewed by the advisory committee on toxic substances, on which employers, trades (unions and local authorities are represented, together with independent experts.
I hope that what I have said will convince the hon. Lady that the Government are concerned to ensure that the health of employees who work with benzidine-based dyes is safeguarded. I trust that she will have formed the conclusion that this subject has been studied in great detail and that the research that has been commissioned shows that there is no complacency about it. The medical and scientific evidence will be kept under review and any new developments will be carefully considered. I am sure that the Health and Safety Executive will take careful note of what she has said tonight, but she may in any event be sure that the views of all interested parties will be fully taken into account when considering all the aspects of the matters which we have debated here tonight.