Ample room for improvement in the approach to ADHD

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1 1 March 2001 Advice on RSI Page 3 The medical syndrome RSI gives rise to many problems, especially among the working population. It often substantially undermines people s quality of life and sometimes even makes it impossible for them to take part in the work process. Little is known about the causes of RSI or about effective means of preventing and treating this condition. In nearly every case a complex of risk factors is involved. Prescribing absolute rest to an RSI patient is not to be recommended. Having identified an urgent need for scientific research in this area, the Health Council gives this advice to the State Secretary for Social Affairs and Employment and the Minister of Health, Welfare and Sport in a report published on 27 November Ample room for improvement in the approach to ADHD Page 4 The identification and treatment of children with ADHD could be improved. These children are persistently and pervasively restless, hyperactive, impulsive and lack concentration - most of them from early age. They pose major problems both to themselves and to those around them and in many cases their development may be threatened. Often there are also other problems. Careful diagnosis is needed in order to ensure that child and family receive the right care. There are two effective modes of treatment: medication and intensive behavioural therapy via the parents and teachers. In practice, the results of both approaches leave room for improvement. Guidelines are urgently needed for paediatricians, behavioural scientists and GPs. This is the advice given by the Health Council in a report to the Minister of Health, Welfare and Sport published on 13 November Preventing high blood pressure Page 9 Using salt sparingly is good for the blood pressure. Restraint is also desirable when salt is used in the industrial preparation of food products. Eating plenty of vegetables and fruit and low-fat dairy produce also appears to help. Being overweight, consuming large amounts of alcohol and physical inactivity are risk factors that deserve attention. This is the advice given by the Health Council in a report to the Minister of Health, Welfare and Sport published on 18 October 2000.

2 Content Page Advice on RSI 3 Ample room for improvement in the approach to ADHD 4 Caution needed over variant CJD 5 Use of gastric acid inhibitors often unnessary 6 Screening for colorectal cancer 7 Care needed with folic acid fortification 8 Preventing high blood pressure 9 Committee on the safety assessment of Novel Foods 10 Room for darkness 11 Toxic substances at the workplace 12 Available reports 14

3 More research and more physical exercise Advice on RSI The medical syndrome RSI gives rise to many problems, especially among the working population. It often substantially undermines people s quality of life and sometimes even makes it impossible for them to take part in the work process. Little is known about the causes of RSI or about effective means of preventing and treating this condition. In nearly every case a complex of risk factors is involved. Prescribing absolute rest to an RSI patient is not to be recommended. Having identified an urgent need for scientific research in this area, the Health Council gives this advice to the State Secretary for Social Affairs and Employment and the Minister of Health, Welfare and Sport in a report published on 27 November The name Repetitive Strain Injury (RSI) denotes a syndrome characterized by pain or discomfort in the neck, upper back, shoulder, upper or lower arm, elbow, wrist or hand, which leads to impairments and participation problems. The clinical picture reflects a disturbance in the balance between load and physical capacity, which arises following activities that involve repeated movements or, conversely, maintenance of a static position. Little is still known about the physiological mechanisms that cause RSI. Possible causes are overloading of muscles, tendons or nerves. Prevalence If the seriousness and the duration of the complaints are disregarded, it is estimated that between 20 and 40% of working people experience some sort of RSI problem every year. For complaints that cause impairments affecting everyday activities, the estimated annual prevalences are approximately 10% (neck/shoulder/upper back) and 5% (elbow/wrist/hand), respectively. Risk factors for RSI are excessive use of force and work that is either performed in uncomfortable positions or constantly in the same position, or else involves repetitive movements. Secondary factors (work pressure, work stress, work rate, inadequate supervision, etc) can increase the risk of complaints. Prevention and treatment Various steps are taken in companies and institutions to prevent RSI. There is, however, still absolutely no scientific evidence of the effectiveness of these efforts. If prevention is to be at all effective, it is extremely important that the approach adopted should, somehow or other, not merely be limited to just one of the possible risk factors. As in the case of prevention, very little is also known about the effectiveness of therapeutic measures. An RSI patient will still frequently undergo all manner of treatments without any satisfactory outcome. This causes a great deal of concern, uncertainty and additional distress. The first-line advice that is given to patients must be consistent. It is important that the right information is provided. The first step in any treatment must consist of reducing the exposure to the presumed risk factors and increasing the body s ability to cope with strain. The latter is possible by encouraging physical exercise. According to the advisory report, absolute rest is altogether misguided. In the letter of presentation to the State Secretary, Health Council Vice-President Professor J.A. Knottnerus wrote: In view of the need to prevent RSI complaints, various companies and institutions are introducing preventive measures. In order to be able to investigate the effectiveness of those measures, it is ex-

4 tremely important that companies and institutions, acting in consultation with occupational health services, should link the introduction of such measures to a systematic framework of assessment. In the interests of early recognition and prompt treatment of RSI complaints, it is also important that the outcomes of the therapeutic measures adopted by occupational health services should be systematically monitored and evaluated. Diagnosis and treatment under scrutiny Ample room for improvement in the approach to ADHD The identification and treatment of children with ADHD could be improved. These children are persistently and pervasively restless, hyperactive, impulsive and lack concentration - most of them from early age. They pose major problems both to themselves and to those around them and in many cases their development may be threatened. Often there are also other problems. Careful diagnosis is needed in order to ensure that child and family receive the right care. There are two effective modes of treatment: medication and intensive behavioural therapy via the parents and teachers. In practice, the results of both approaches leave room for improvement. Guidelines are urgently needed for paediatricians, behavioural scientists and GPs. This is the advice given by the Health Council in a report to the Minister of Health, Welfare and Sport published on 13 November ADHD (attention deficit hyperactivity disorder) is regarded in psychiatry as a disorder which demands treatment due to the major burden and handicap that it represents for child and family alike and due to the threat that it poses for the child s further development. Frequently these children also have developmental problems with speech, motor control or social skills, or else there is a specific learning disorder. More than half of the children with ADHD have an additional psychiatric condition, such as an anxiety disorder, depression or (most commonly) defiant and aggressive behaviour. The last-named combination in particular carries a poor prognosis. Partly because of the accompanying symptoms, ADHD carries an increased risk of the child dropping out of school prematurely, problems with work and social contacts, addiction, accidents and crime. Behavioural problems in children can have a variety of causes. Precise diagnosis demands information from parents and teachers. Medical and psychosocial expertise is essential and a thorough investigation of the possible existence of accompanying conditions is required. Treatment of a child with ADHD must always begin with psycho-education of the parents (i.e. informing them about the nature of the disorder and how to deal with it). Treatment Medication with methylphenidate (Ritalin) has a beneficial effect in the majority of children as long as the drug is, in fact, taken. Its effectiveness is enhanced by systematic provision of the appropriate information, supervision and evaluation. The safety of this medication has been tested and verified for use during a period of nearly two years, but the safety of prolonged use and its long-term health implications are unknown. Research into these issues is urgently required. Behavioural therapy programmes are principally provided by the children s mental healthcare services 1 and seek to ensure a consistent approach from parents and teachers. They can be sufficiently effective (especially in milder cases) providing certain requirements are met with regard to their content, intensity, duration and structure. If, after a period 1 The Jeugd-GGZ, formerly the children s branch of the Regional Institute for Outpatient Mental Health Care (RIAGG-Jeugd)

5 not exceeding six months, these programmes prove insufficiently effective, then medication needs to be considered. Use of Ritalin has risen sharply since In 1999 there were around 30,000 users in the Netherlands aged 19 years and under. The duration of use ranges from a few months to several years. It is impossible to determine the degree of appropriateness in the prescription of the medication. According to an American study, a substantial proportion of the children with ADHD do not receive any medication, whereas in more than half of the cases in which medication is prescribed, the child in question is not, strictly speaking, suffering from ADHD but from ADHD-like behavioural characteristics. Although medication is not necessarily misplaced in such cases, there is nevertheless a risk of the indication being extended inappropriately. The Health Council believes that the same situation applies in the Netherlands and calls for thorough research into current practice. Guidelines Ritalin therapy is initiated by a paediatrician in roughly 50% of cases, and by a child psychiatrist in about 20%. GPs are principally involved in early identification of the condition, referral, supervision and maintenance therapy. The Netherlands Psychiatric Association (NVP) has drawn up guidelines. It is highly desirable that complementary guidelines should be produced that are specifically designed for paediatricians, for behavioural therapists and for GPs. Youth Welfare Agencies and organisations for education, parenting support and school healthcare can help considerably in the identification and care of children with behavioural problems or ADHD. However, certain conditions must be met with regard to expertise, availability and cooperation. Health Council urges universal leukodepletion and more donor selection Caution needed over variant CJD It is highly probable that the agent that causes mad cow disease is also responsible for a variant of Creutzfeldt-Jakob disease in humans. We cannot rule out the possibility that this pathogen is transmitted via blood transfusion. The current level of knowledge offers no reliable means of preventing this route of Precautionary measures Various measures adopted in recent years have substantially reduced the risk of the BSE agent being transmitted from animals to human beings. Nevertheless, it is still not possible to completely rule out such transmission in the Netherlands. Very little is known about the possibility of variant CJD being transmitted from one human being to another via blood or blood products. Until a method of detecting the pathogen in blood is available, it is impossitransmission in the Netherlands. Removal of the white blood cells from blood products is advisable, as is the exclusion of donors who have received a transfusion since This is the advice given by the Health Council in a report to the Minister of Health, Welfare and Sport published on 1st February There is firm evidence to suggest that a single agent - here in referred to as the BSE agent - is responsible for the epidemic of the prion disease bovine spongiform encephalopathy (BSE or mad cow disease ) in the United Kingdom, as well as for a variant of the already known Creutzfeldt-Jakob disease (CJD) in humans. This variant (designated as variant CJD) is also a fatal disease of the central nervous system. First reported in 1996, it has to date been almost exclusively confined to the UK. More than 90 victims of the disease have been diagnosed, virtually all of whom have since died.

6 ble to be certain that donoted blood is not infected. In variant CJD patients, the BSE agent has been detected in the lymphoid tissues, which contain large numbers of white blood cells. As a precautionary measure, the Health Council is therefore advocating a policy of universal leukodepletion that is to say removal of the white blood cells from blood products. As a further precaution, the Council argues that individuals who have received cellular blood products via transfusion since 1985 should be excluded as blood donors (despite the drawbacks of such a policy). Exceptions should only be made in the presence of compelling medical reasons. A further possible precautionary measure would be to exclude blood donors who have spent a certain period of time in the United Kingdom. According to the advisory report, however, the Health Council anticipates that the benefit of such a measure would be so minimal that it sees no reason for recommendation. The Health Council highlights not only the severe lack of scientific data in this area, but also the fact that the transfusion of blood or blood products will always involve some degree of risk. Because the measures which are now being advocated are of a precautionary nature, they need to be reviewed as soon as more data become available. With a view to maintaining international exchangeability of blood and blood products, the Council considers it important that there should be European harmonisation of such measures. Advisory report on the management of dyspepsia Use of gastric acid inhibitors often unnessary The management of dyspepsia could be more efficient if compliance with existing guidelines were to be improved. Many patients get long-term gastric acid inhibitors without sufficient evidence of benefit. Furthermore, endoscopic examination of the oesophagus and stomach an invasive procedure is not always necessary. On the other hand, some patients do not receive appropriate diagnosis and treatment from which they would benefit. These are some of the conclusions formulated by the Health Council in an advisory report to the Minister of Health, Welfare and Sport, published on 12th December Every year well over 350,000 people in the Netherlands consult their GP every year because of dyspepsia. In around 60 percent of cases, no anatomical abnormalities can be found. Many patients not only have to contend with physical complaints, but also with the fear of a malignant disease. In most cases that fear is unwarrented, especially if there are no other, specific symptoms. Major advance Little is known about the causes of dyspepsia. However, the discovery some 15 years ago that gastric ulcers are usually caused by the bacterium Helicobacter pylori (Hp) marked a major advance in the field of gastroenterology. Certain drugs can also cause gastric ulcers for example, those used against rheumatism and pain associated with joint disease. Less clear-cut but possibly important is the influence of hereditary factors, smoking, stress, alcohol, diet or overweight. The natural course of stomach complaints is generally favourable. Consequently, extensive diagnostic investigation is not necessary for a patient with first-time symptoms. When treatment of the symptoms does not bring about a lasting improvement, then an endoscopic investigation is advisable to detect a possible anatomical abnormality. Because endoscopy is stressful for the patient, it is advisable to test first of all for Hp infection. Given a favourable test outcome, there may be no immediate need for endoscopy. If the symptoms persist, however, endoscopy should still be performed.

7 Shortcomings Hp infection and hence a gastric ulce can be successfully treated with modern drugs. Various gastric acid inhibitors are available for patients with heartburn, but the Health Council believes that these compounds are overused. Prolonged use of such treatment is seldom appropriate. Because these compounds tend to promote dependency, however, it is difficult to discontinue medication once it has been started. Patients without demonstrable anatomical abnormalities need to be taken seriously and given reassurance. It has not been irrefutably established that any of the drugs widely used in this patient group has a beneficial effect. There is a serious need for further research in this area. The Health Council agrees with the general thrust of the existing guidelines of the Netherlands College of General Medical Practitioners (NHG), but concludes that, in practice, compliance is less than adequate. The shortcomings specifically apply to the following recommendations: treatment should begin with drugs that are relatively simple and safe; additional check ups should be conducted into persistent or recurrent complaints which require the long-term use of gastric acid inhibitors; and patients with a previously detected gastric ulcer should receive treatment for Hp infection. The Health Council notes that worthwhile initiatives have been carried out in some general practice groups to improve implementation of the NHG guidelines. Health Council highlights new possibilities Screening for colorectal cancer In an advisory report released on 19th January 2001, the Health Council alerted the Minister of Health, Welfare and Sport to new scientific developments in the field of colorectal cancer screening. Colorectal cancer is second only to lung cancer as a cause of mortality due to malignant neoplasms. According to the Health Council, serious consideration needs to be given to the introduction of nationwide screening for colorectal cancer. The advisory report includes a solution-oriented review of the remaining obstacles to be negotiated in achieving this goal. Every year around 4,400 people in the Netherlands die from colorectal cancer. Recent research from abroad has shown that mortality can be reduced by faecal occult blood testing. A further highly promising approach is a technique known as flexible sigmoidoscopy, which permits inspection of the rectum and the lower portion of the colon for the presence of polyps. This technique should help to alleviate the burden of disease as well as reduce mortality. A third possibility is colonoscopic examination of the entire colon and in particular the less invasive virtual variant of this procedure. All things considered, various techniques are now so well advanced that serious consideration needs to be given to the introduction of nationwide screening for colorectal cancer. Questions The cost-effectiveness ratios of the various screening techniques look favourable, but merit further investigation. There is a need for empirical and model-based studies to answer important questions regarding such issues as the selection of a screening strategy, the anticipated level of participation, the programme design, the surveillance of individuals in whom abnormalities are detected and, finally, the requirements in terms of manpower and services. The Health Council finds it important that in policy development attention should not be confined exclusively to curbing mortality. Also at issue is the quality of life for the participants in a potential screening programme. In addition, we need to examine the broader implications for healthcare as a whole.

8 Folic acid supplements preferable Care needed with folic acid fortification If a woman receives insufficient folic acid during the weeks preceding and following conception, there is an increased risk of spina bifida, hydrocephalus or some other neural tube defect occurring in the embryo. It is therefore desirable to take a folic acid supplement during this period, but this practice is still insufficiently widespread in the Netherlands. The availability of food products containing added folic acid could help to rectify this problem. In an advisory report to the Minister of Health, Welfare and Sport (published on 15 November 2000), however, the Health Council urges caution. Folic acid is a B vitamin which plays an important role in the protein metabolism and DNA synthesis within the body. It occurs naturally especially in green vegetables and citrus fruits. The synthetic form that is incorporated in vitamin preparations is known as PMG (pteroylglutamic acid). An adequate supply of folic acid is extremely important for women in the weeks preceding and following conception. Should there be a shortfall in this supply, there is a risk that the embryo in the mother s womb may develop a neural tube defect (the most notorious of these being spina bifida and hydrocephalus). Neurological risk For some years now, women wishing to become pregnant have been recommended to take 400 micrograms of PMG daily via a folic acid supplement. In practice, however, this recommendation has proved insufficient. Consequently, in some countries standard food products are being brought onto the market which contain added PMG. This practice of folic acid fortification is not permitted in the Netherlands. According to the Health Council, we cannot be absolutely certain that a high intake of PMG does not induce or exacerbate neurological abnormalities. Daily intake must therefore not exceed one milligram. For people with an marginal supply of vitamin B12, the risk of neurological damage may be even higher. Our current level of knowledge does not allow us to determine a safe upper limit for PMG intake for this group, which includes many elderly people. Tighter controls preferable Until more data becomes available, the Health Council would like to see folic acid fortification of foodstuffs confined to products which are specifically aimed at women who wish to become pregnant. Information and labelling must be used to help prevent daily PMG intake exceeding one milligram as a result of combined use of folic acid supplements and fortified food products. Post-marketing surveillance must then be conducted to investigate the extent to which the fortified products are, in fact, only reaching the target group and whether undesirable side-effects are, nevertheless, still occurring. In the letter of presentation which accompanies its advisory report to the Minister, the Health Council argues that more information about and tighter controls over the use of folic acid supplements are preferable to the addition of PMG to food products.

9 Plea for sparing use of salt Preventing high blood pressure Using salt sparingly is good for the blood pressure. Restraint is also desirable when salt is used in the industrial preparation of food products. Eating plenty of vegetables and fruit and low-fat dairy produce also appears to help. Being overweight, consuming large amounts of alcohol and physical inactivity are risk factors that deserve attention. This is the advice given by the Health Council in a report to the Minister of Health, Welfare and Sport published on 18 October It is an established fact that sodium in food raises the blood pressure. Cooking and table salt are our most important source of sodium. At approximately nine grams per person per day, the average consumption of salt in the Netherlands is virtually identical to that of neighbouring countries. Around 15 per cent of the population have excessively high blood pressure. For several decades now we have been asking ourselves whether general measures to restrict the consumption of salt help to prevent high blood pressure. Salt sensitivity It appears from extensive scientific research that a fairly sharp reduction in average sodium intake (say by a quarter) brings about a relatively small fall in the average blood pressure. It has also been shown that such a reduction demands massive effort and is virtually or completely impossible to maintain. Furthermore, there is a growing suspicion in scientific circles that salt sensitivity varies from person to person: cutting one s salt intake has a far more beneficial effect on blood pressure in some individuals than it does in others. Mineral mixtures According to the advisory report, it is desirable that attention should continue to be focused on the need to lower the use of salt both in the home and in the food industry as one possible way of keeping blood pressure in check. Combating overweight and excessive alcohol use are other measures that should be recommended. Taking sufficient physical exercise also helps. Moreover, there is an increasing body of evidence to suggest that eating plenty of vegetables and fruit and low-fat dairy produce is good for the blood pressure, as is avoidance of saturated fat. It has meanwhile emerged that low-sodium salt-substitute mineral mixtures can be effective in individuals with hypertension. The domestic use of these mixtures is still debatable, however, partly because we appear to be more extravagant in our use of these products than we are with salt. In this advisory report the Health Council does not focus on the medical treatment of hypertensive patients. Recommending the adoption of a low-sodium diet or the use of saltsubstitute mineral mixtures can be important, depending on the attending physician s view of the patient s salt sensitivity (among other factors).

10 Safety assessment of novel foods Committee on the safety assessment of Novel Foods In the context of the European Regulation concerning Novel Foods and Novel Food Ingredients, a producer submits a safety dossier in one member state before marketing a novel food. This member state carries out what is known as the initial assessment. Based on the dossier and the initial assessment, the remaining member states carry out a second assessment. All of the member states discuss the application for placing a novel food on the market and the safety assessments in the Standing Committee for Food. There then follows a European decision on whether or not the novel food is to be authorised. In the Netherlands, the Committee that makes the initial and second assessments on the safety of novel foods (VNV), was established within the Health Council in The VNV Committee is currently consider- ing six dossiers for initial assessment. Four of them are for foods containing ingredients from genetically modified sources, sugar beets and maize. The other two concern arachidonic acid-enriched oil derived from a micro-organism and restructured fat as an ingredient for clinical nutrition. The Minister of Health also seeks the Committee s advice if new information emerges which might be of relevance to the safety of novel foods already on the market. This is the case with a specific GMO soya variant (containing extra DNA fragments), phytosterol esters (increased cholesterol metabolites in the gut) and phytostanol esters (post marketing surveillance). As far as the second assessments are concerned, two requests for advice are under consideration regarding the safety of using phytosterols in sausage and cheese and in bakery products. Trehalose At the end of last year a second assessment was issued on a new formulation of trehalose, a disaccharide of glucose (2000/05VNV) for use in bakery products, beverages, confectionery, jam, breakfast cereals, rice and pasta. The initial assessment was made by the UK Advisory Committee on Novel Foods and Processes (ACNFP), which judged trehalose to be safe for use as a food ingredient providing the specifications stipulated by the WHO/FAO Joint Expert Committee on Food Additives (JECFA) are satisfied and providing the use is confined to the foods specified in the dossier. The Committee on the safety assessment of Novel Foods (VNV) emphasises the condition stipulated by the initial assessment body that diabetics must be informed via the customary channels about trehalose being a source of glucose (it is not described as a sugar on the label). The two most important enzymes used in the production process have been tested for mutagenicity and acute toxicity, but they have not been fully tested in accordance with JECFA standards for the general use of enzymes in foodstuffs. The VNV Committee concurs with the initial assessment body s recommendation that these tests should be performed. The Committee has no supplementary questions or comments on the dossier and endorses the initial assessment as issued by the ACNFP.

11 Health Council highlights primordial quality of the living environment Room for darkness In an advisory report presented to the Minister of Housing, Spatial Planning and the Environment, the Minister of Transport, Public Works and Water Management and the Minister of Agriculture, Nature Management and Fisheries on 30 November, the Health Council draws attention to the importance of evening and night-time darkness as a primordial quality of the living environment of man and animals. The Council calls for the issue of light nuisance to be explicitly included in environmental policy. Existing legislation needs to be extended and there is room for improvement in the monitoring of compliance, it adds. Evening and night-time darkness is increasingly being lost as a result of urbanization, motor traffic, more flexible working hours, sports events, glasshouse horticulture, the illumination of buildings, advertising displays, etc. No data is yet available with regard to the detrimental impact which the combined effect of the shortening of the evening and night and the influence of other stress factors associated with our hectic 24-hour society might conceivably have on health. Research conducted into light nuisance and perceptions concerning our living environment shows that many people attach importance to the onset of darkness and the sight of a starry sky. Threat Artificial light at night-time can also influence the behaviour and life cycle of animals in many ways, particularly since it is often accompanied by other disturbing or alienating factors such as the impact of road traffic. In birds, insects and amphibians manifestations of disorientation, attraction and repulsion have been observed. Such effects generally increase the chances of exhaustion and death, posing a particular threat to small, isolated populations. Legislation is either in place or else in preparation which aims to combat light nuisance in the residential environment caused by the illumination of sports complexes and assimilation lighting in glasshouses. There would, however, be a need to tighten up controls on compliance with those regulations. There are also still no guidelines for illuminated advertising and floodlights. Light abatement areas Despite the lack of empirical research into the ecological consequences of artificial light at night and in the evening, there are sufficient grounds for supporting the implementation of a general prohibition with certain exceptions. This is the approach currently adopted by the Department of Public Works and Water Management with regard to street lighting in nature conservation areas. However, government policy on public lighting would need to be incorporated into an integrated, nation-wide strategy designed to protect and improve the quality of the natural environment. One possibility might be the designation of light abatement areas in analogy to the existing noise abatement areas. The explicit inclusion of light nuisance as an integral part of environmental policy will stimulate the carry-over of measures to other government bodies.

12 Toxic substances at the workplace Three committees advise the Ministers of Social Affairs and Employment on the health hazard of occupational exposure to toxic substances in the air: the Dutch Expert Committee on Occupational Standards (the WGD Committee also known by its English acronym, DECOS), the Committee on Compounds Toxic to Reproduction and the Committee on Updating Occupational Exposure Limits. The Committee on Compounds Toxic to Reproduction has issued an advisory report on chromium VI and chromium VIcompounds. The Committee on the Committee on Updating Occupational Exposure Limits has also published a series of advisory reports. The Dutch Expert Committee on Occupational Standards has issued an advisory report on benzotriazole. Reproductive toxicity of chromium VI and chromium VI-compounds (Advisory report; 25th January 2001) Hexavalent chromium referred to as chromium VI and its compounds are released during such procedures as pigment production and welding operations. The Committee does not consider that there is sufficient evidence that exposure to the substances in question impairs fertility, but does see grounds for concern. As far as the criterion effects on fertility is concerned, it therefore recommends that these substances be classified in category 3 ( substances which cause concern on account of their possible harmful effects on human fertility ). Additionally, the Committee states that there is sufficient evidence for strong suspicion that exposure to these substances causes developmental disorders in human beings. As far as the criterion harmful to progeny is concerned, this means classification in category 2 ( substances which should be regarded as if they cause developmental disorders in humans ). Re-evaluation of Old MAC values (18 advisory reports; 14th December 2000) For practical reasons, the Dutch government has in the past adopted MAC (Maximum Allowable Concentration) values for several hundred substances from foreign lists. It gradually became apparent that these figures were too high and therefore delivered insufficient health protection. At the request of the State Secretary for Social Affairs and Employment, an international committee specially created under the aegis of the Health Council has since 1997 been testing these old MAC values against the current level of knowledge with a view to proposing health-based recommended occupational exposure limits where possible. On 14 December 2000 the first 18 in a series of around 160 English-language advisory reports were published. The Committee proposes health-based recommended occupational exposure limits for diborane, phenyl phosphine and methylcyclohexanol. In the Committee s opinion, currently available toxicological data are insufficient to permit such proposals for the following substances: cesium hydroxide, cyclopentane, dimethoxymethane, dipropyl ketone, germanium tetrahydride, hexachloronaphthalene, methane thiol, methyl isopropyl ketone, mica, sodium hydroxide, octachloronaphthalene, silane, tetrachloronaphthalene, yttrium and yttrium compounds. Occupational exposure to 1,2,3-benzotriazole (advisory report; 22 November 2000) 1,2,3-benzotriazole is an odourless, white or light-brown crystalline powder which is used in industry as an anti-corrosive, as a stabilizer for plastics and as an intermediary agent in the synthesis of various chemical compounds. In the workplace, benzotriazole principally occurs in the form of dust. According to the advisory report, we cannot be absolutely certain that occupational exposure to benzotriazole does not lead to sensitization and irritation of the eyes or respiratory tract, even at workplace concentrations below the substance standard that is applied in relation to industrial hygiene.

13 There are also grounds for concern about the possible carcinogenicity of benzotriazole. The acute lack of research results has prompted the Committee to rule that the substance is a suspected carcinogen in humans. It is not clear to what extent a genotoxic mechanism of action may be involved here. No further data is available on the consequences of prolonged exposure to benzotriazole. The advisory report concludes by stating that, given the present lack of scientific data, it is not possible to derive a health-based recommended occupational exposure limit for occupational exposure to 1,2,3-benzotriazole. New requests On 11 October 2000 the Committee on Updating Occupational Exposure Limits was requested to establish a health-based exposure limit for water-soluble molybdenum compounds.

14 Available reports Translated integrally into English IVF-related research. 1998/08E DNA diagnostics. 1998/11E Antimicrobial growth promotors. 1998/15E Pertussis: a critical appraisal. 1998/16 Laser pointers held up to he light. 1999/03E Hormone disruptors in ecosystems. 1999/13E Public health impact of large airports. 1999/14E Azathioprine. 1999/04 OSH ß-Butyrolactone. 1999/05 OSH Carbadox. 1999/06 OSH 1,2-Dibromoethane.1999/07 OSH Diethylsulphate. 1999/08 OSH Diglycidyl resorcinol ether. 1999/09OSH 2-Methylaziridine (propylene imine). 1999/10 OSH Metronidazole. 1999/11 OSH N-Nitrosodimethylamine (NDMA). 1999/12 OSH 2-Nitropropane. 1999/13 OSH Procarbazine hydrochloride. 1999/14 OSH Vinylbromide. 1999/15 OSH Exposure to electromagnetic fields (0 Hz - 10 MHz) 2000/06E Field research for the authorisation of pesticides. 2000/07E Screening and treatment of adolescents with schizophrenia. 2000/08E GSM base stations. 2000/16E From implementing to learning; the importance of a dialogue between practice and science in health care. 2000/18E. Ethanol. 2000/01OSH. Halothane. 2000/02OSH Nitrous oxide. 2000/03OSH Cadmium and its compounds.2000/04osh Mercury and its compounds. 2000/05OSH Lithiumcarbonate and lithiumchloride. 2000/06OSH Chloroform. 2000/07OSH Hardwood and softdust:evaluation of the carcinogenicity and genotoxicity. 2000/08OSH 4,4'-Methylene bis (2-Chloroaniline). 2000/09OSH Epicholorohydrin (1-Chloro-2,3-epoxypropane). 2000/10OSH 4,4'-Methylene dianiline. 2000/11OSH Urethane (ethyl carbamate). 2000/12OSH Aziridine (ethyle imine). 2000/13OSH 1,2,3-Benotriazole. 2000/14OSH Workprogramme for A2000/03E Reports can be downloaded from the website (www. gr.nl) or ordered from the Health Council of the Netherlands (address and telephone number on page 2).

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