Radon reviewed

Radon reviewed

865 Noticeboard Watching brief on medical devices The US Food and Drug Administration has put forward proposals for implementing the law that require...

362KB Sizes 0 Downloads 80 Views

865

Noticeboard Watching brief on medical devices The US Food and Drug Administration has put forward proposals for implementing the law that requires manufacturers of medical devices such as heart valves, breast implants, and

defibrillators to adopt effective systems for tracking their products from the manufacturer through the distribution chain to the patient. The requirement is limited to permanent implants and to life-sustaining or life-supporting devices. So far thirty-five types of devices from more than 370 manufacturers will be affected by the proposed regulation, which was mandated by the Safe Medical Devices Act of 1990. Of these, thirty met the statutory criteria for tracking; the other five have been included by the FDA because of the potential risk to the public health if they should fail. Manufacturers will be required to design a system appropriate to their products and that will ensure that patients and devices can be traced and reported to the FDA within three working days. The data and the functioning of the system will have to be audited every six months. The FDA expects that often more than one means of data collection will be necessary to ensure effective tracking. For example, pre-addressed postcards given to patients to be returned to the manufacturer would have to be supplemented by means of following up patients for changes in names or addresses. The proposal has been published in the US Federal Register and the public has 60 days to comment on the proposal. Comments will be considered carefully when the final regulation is prepared. If no comments are received by May 28, 1992, the Safe Medical Devices Act provides that the proposal automatically will become final. In an earlier move this week, Representative John D. Dingell’s Congressional Subcommittee on Oversight and Investigations found out that the FDA was negligent in its inspection of many factories that make medical devices. Congressional investigators said the agency does not even know how many manufacturers it is supposed to be inspecting. On March 25, the committee looked at two products. One is a synthetic jelly, Orcolon, manufactured by Optical Radiation Corporation, which is injected into the eye to hold it steady for surgery. It noted that the jelly was associated with many adverse reactions, including blindness. More than 270 adverse reactions had been reported to the FDA. The company withdrew the product from the market last year. The other product encompasses several devices that beam radiation at cancers. Defective software meant that patients have died from the high doses given. The manufacturer, Theratronics International, has stopped making them but continues to provide spare parts to keep the machines in running condition. Dr James S. Benson, director of the FDA’s Center for Devices and Radiological Health told the committee that the agency would try to do better and was already becoming more aggressive in reviewing the safety of medical devices.

Japan’s wait for low-dose "pill" According to a press leak on March 18, plans to license the low-oestrogen-dose oral contraceptive pill for use in Japan by this summer have been shelved for the time being by the Central Council on New Drugs. The reason for the decision as cited by the press reports was concern that availability of the pill might contribute to the spread of human immunodeficiency virus (HIV) infection in Japan. So far the Government has made no official statement. "Regrettably, this is not unusual. The Japanese Government seems to neglect people’s right to know", says Ms Yuriko Ashino, deputy executive director of the Family Planning Federation of Japan. Middle/high-dose pills are available on prescription for the treatment of menstrual disorders but are prescribed by doctors for use as a contraceptive. Condoms, though, are the main type of contraceptive used; 80% of married couples rely on them. Obstetric and family planning groups have been pressing for low-dose oral contraceptives to be licensed. In December, 1986, a government

study group on the medical evaluation of the pill set out guidelines for clinical tials, which were conducted between 1987 and 1990. The safety and efficacy revealed in these trials (5000 women, 65 000 menstrual cycles) led several pharmaceutical companies to start applying, since mid-1990, for a licence. Prof Shoichi Sakamoto, president of the Japan Association of Maternal Welfare and of the International Federation of Fertility Studies, believes that the leaks might have stemmed from routine communications from the chairman of the subcommittee on combination drugs to the nine applicants for product licences. Professor Sakamoto thinks that the subcommittee’s view that the increasing numbers of cases of AID S in Japan ought to be taken into consideration in setting indications for use of low-dose oral contraceptives might have been a reflection of concern raised in the Ministry of Health and Welfare by non-medical scientists. He has been assured by a member of the subcommittee that they are quite clear that their duty is to judge safety of drugs and not to draw up policy on public health. According to Professor Sakamoto, who in 1988 chaired a committee on the prevention of vertical transmission of HIV infection, a joint conference of government ministers and an AIDS surveillance committee had been held on March 17, at which only general issues were discussed and an expert committee for AIDS control set up; the relation between low-dose oral contraceptives and AIDS was not discussed. His view is that the growing incidence of AIDS makes some delay in product licensing understandable. However, he believes that the authorities should press ahead with approval of the low-dose pill, for several reasons-it would be ethically desirable for the women who have taken part in the trials and those who wish to use oral contraceptives not to have to be put on middle/high-dose pills; abortions among teenagers are on the rise, even though the total number of abortions has approximately halved since 1960; the birth rate is rising slightly (by 3% in the past year); and no study has shown a relation between the use of low-dose oral contraceptive pills and the spread of AIDS. He has put his views to officials concerned and has also suggested that they explain reasons for their decisions to the public, to prevent misunderstandings. "Many groups are preparing their protest documents. If the officials of the ministry do not pay attention to my suggestion, there will be a big public outcry."

Radon reviewed Parts of Devon and Cornwall in the UK, and regions of many other countries, have indoor levels of ionising radiation higher than those in some areas in the path of the nuclear fallout from the Chernobyl explosion. This radiation comes from radon gas, a natural breakdown product of uranium in soil, which is the single largest contributor to radiation exposure, and which is responsible for about 50% of the average annual radiation dose to man. The health problems associated with radon and means of reducing exposure were discussed at a conference, organised by the National Radiological Protection Board, in London, UK, on March 26-27. Radon gas seeps from the soil and accumulates in houses and other buildings where the free flow of air is restricted--eg, offices and schools. In Britain, Sweden, and the USA radon ranks after tobacco as the leading contributor to deaths from lung cancer. At the average annual exposure to radiation from radon in the UK (20 Bq/m3), the lifetime risk of death from lung cancer due to radon is 3-3 5/1000 of population, and, because together radon and tobacco have an enhancing effect, in smokers this risk is increased to 1 in 100. At the "action level" for radon in the UK (200 Bq/m3), lifetime risk of death from lung cancer due to radon is estimated to be 3 in 100 in non-smokers and 10 in 100 in smokers. Actions levels have been set by many governments, and are recommended limits at which remedial action should be taken to reduce radon exposure; however, there is no consensus on what the action level should be. The Commission of the European Communities (EC) has recommended 400 Bq/m3 for existing buildings and 200 Bq/m3 for new constructions. In individual EC countries the action level is 200 Bq/m3 in the UK and Ireland, 250 Bq/m3 in Germany, and 400 Bq/m3 for existing buildings and 100 Bq/m3 for new buildings in Denmark; there are no recommendations in the remaining EC countries. Sweden has set an action level of 200 Bq/m3 for existing

866

buildings and 70 Bq/m3 for new buildings, whereas the USA limit is

150 Bq/m3. Speakers

from Britain, Sweden, and the USA described their respective national radon action programmes. These countries have mounted campaigns to publicise the dangers of radon in highexposure areas and radon testing can be requested by householders (free in Britain and Sweden, a nominal cost in the USA). Advice is given on how to mitigate radon exposure in homes found to be above the action levels. Remedial actions are voluntary in the UK and USA, but in Sweden houses found to be above the action level can be declared insanitary and owners forced to take action. Unfortunately, because of public apathy on the subject of radon, only a fraction of at-risk homes in each country have been tested (from about a tenth in Britain to about a third in Sweden). The general public do not consider radon a serious environmental risk to health. In the USA, the public perception is that hazardous waste and nuclear power are the biggest environmental threats to health, with radon at the botton of the list, whereas the scientific consensus is that radon is the greatest threat and nuclear power the least. In Devon and Cornwall, a survey showed that people were much more worried about the possibility of a radiation leak from a proposed nuclear power station than about existing high levels of radiation from radon. Because radon is seen as a natural threat to which individual deaths cannot be-attributed, there is a general denial of the risk. Perhaps the greatest challenge faced by radon protection programmes is overcoming public inertia.

Neuronal

generation

Since undifferentiated cells from the brain of embryonic mice can be induced by epidermal growth factor (EGF) to proliferate and differentiate in culture into neurons, and since adult central nervous tissue contains EGF receptors, will brain cells from adult mice not behave likewise? Reynolds and Weiss decided to conduct their study with striatal cells from adult mice. These cells proliferated, acquired the morphological and antigenic features of neurons, and were immunoreactive for y-aminobutyric acid and substance P, two of the major neurotransmitters present in the striatum. One possible reason why the newly generated cells did not contain three other neurotransmitters found in the striatum-methionine-enkephalin, neuropeptide Y, or somatostatin-is that EGF-responsive progenitor cells are limited in the type of cell that they can produce. Another is that the other phenotypes may appear at different times or under different conditions. Reynolds and Weiss also found that poly-L-ornithine inhibited EGF-induced proliferation in vitro. Could the inability of stemcells to proliferate in vivo be due to the inhibitory influence of adult central nervous tissue and, if so, could poly-L-ornithine be one of these influences? Whatever the answers, Reynolds and Weiss’ work carries two, albeit long-term, implications. One is that if the substances that induce or inhibit neuronal proliferation and differentiation can be identified, there is the possibility that they can be used for the repair of central nervous system damage. The other is the possibility of using the newly generated cells for

transplantation. 1.

Reynolds BA, Weiss S. Generation of neurons and astrocytes from isolated cells of the adult mammalian central

nervous

system. Science 1992; 255: 1707-10.

Spinal cord monitoring To reduce the risk of paraplegia after spinal surgery surgeons (neurological and orthopaedic) often monitor spinal cord function by means of somatosensory-evoked potentials (SEPs).1 But postoperative paraplegia has been reported despite preserved SEPs. One explanation is that motor pathways might be more susceptible than sensory pathways to damage. If so, monitoring of both sensory and motor function seems desirable. However, spinal motor-evoked potentials (MEPs) are technically more difficult to elicit than SEPs, and they are affected by anaesthesia and muscle relaxants. Taylor2 reporting at the British Scoliosis Society meeting last week, records success with dual monitoring of SEPs and MEPs in all 40 patients studied. Two key factors contributed to the success with the MEP

technique. One was anaesthesia with propofol, which did not, unlike nitrous oxide and isoflurane, abolish MEPs (muscle relaxants, he found, could also be used). The other was to give, for stimuli applied in the upper thoracic region, two electrical pulses with an interstimulus interval of 1-2 ms to obtain, by temporal summation, a measurable response in the tibialis anterior. Enhancement of response in this way is necessary because of the synapses that the stimuli travelling down the cord have to cross. When applied at the lumbar region, only one pulse is necessary. The ease with which a response is obtained as stimuli are applied progressively down the cord increases sharply after about T8. This change suggests the presence of a polysynaptic pathway at this region, which might in turn account for the sensitivity of the cord to intraoperative injury at this level. The spinal MEP technique has been successfully adapted for use in monitoring cord function during surgery in two children with scoliosis due to hereditary sensory motor neuropathy (Charcot-Marie-Tooth disease)Poor conduction of afferent impulses along impaired peripheral nerves in this disorder makes SEPs difficult to obtain, but the intact central nervous system enables a good motor response to be evoked. 1. Editorial. Scoliosis: spinal cord monitoring during surgery. Lancet 1991; 338: 219-20. Taylor B. The method, rationale and results of spinal motor evoked potential (SMEP) spinal cord monitoring in scoliosis surgery.J Bone Joint Surg (Br) (in press). 3. Taylor BA, Fennelly M The spinal motor evoked potential allows intraoperative monitoring in sensorimotor neuropathy.J Bone Joint Surg (Br) (in press). 2.

Attack

on

health-care fraud

The US Department of Justice is marshalling resources to strengthen its attack on health-care fraud. It cites a General Accounting Office estimate that health-care fraud and abuse costs

Americans

more

than$50 billion

a

year. 50 Federal Bureau of

Investigation counterintelligence agents will be transferred to units specialising in health-care cases; they join the 46 other agents and 100 assistant US attorneys already working on such cases. Other agencies that are also allocating resources to combat health-care fraud include the Drug Enforcement Administration, the Postal Inspection Service, and the Department of Labor’s Inspector General. The initiative is being concentrated on twelve cities, and work will be coordinated by a new Health Care Fraud Unit, to which the Department of Justice has assigned six attorneys. So who will be the likely recipients of unwelcome attention from the fraud squad, whose strength has been increased not only in numbers but also by the availability of modem surveillance methods? They include those who sell unnecessary home medical equipment to elderly citizens and then bill Medicare; those who receive illegal kickbacks (in the past 3 years over$1 million has been recovered from 400 doctors in these schemes); those who take part in price-fixing schemes; and also those who resort to fraud in drug licensing applications.

Drugs and Therapeutics Bulletin Dr Andrew Herxheimer, who founded the Bulletin in 1962, has retired after 30 years as editor. The Bulletin, which started as the British edition of the American Medical Letter on Drugs and Therapeutics, is distributed free by government health departments to final year medical students and to doctors in most of the UK and in southern Ireland. It serves as source material for drug bulletins in many countries and is translated into Spanish for wide circulation in Central South America. Dr Joe Collier, formerly the deputy editor, has taken over as editor.

International

Diary

8th international symposium entitled Radionuclides in Nephrourology will be held in Chester, UK, on May 6-8: Mr P. H. O’Reilly, Department of Urology, Stepping Hill Hospital, Stockport, Cheshire SK2 7JE, UK

(061-419 5484). International workshop on Immunology of Human Papillomavirus Infections is to be held in Amsterdam, Netherlands, on May 7-8: Joke van Dam, Organising Secretary, Bureau PAOG, Tafelbergweg 25, 1105 BC Amsterdam, Netherlands (31 20-566 4801).