Health and Safety
Executive / Commission
Toxic Substances Bulletin
Welcome to the first edition of TSB for 2003 - and our 50th issue!
In the last issue we proudly announced the launch of electronic COSHH Essentials, HSE's new interactive web-based tool to help employers assess and manage the risks from hazardous substances. Available on www.coshh-essentials.org.uk, the site has had 22 707 visitors since it was launched in April 2002, resulting in 34 717 completed risk assessments. So, many thanks to those of you who logged on to use the site. As ever, we are always interested to receive any feedback through the electronic COSHH Essentials site.
In this issue, we cover issues ranging from explaining what epidemiology is to alerting you to HSE's new web pages on stress. Also included are articles on how chemicals can affect different groups of people in different ways (chemical risk assessment and individual susceptibility) and an update on negotiations on a European Commission proposal to amend the Asbestos Worker Protection Directive.
The article on Securing health together draws together all these subjects by giving an overview of Great Britain's occupational health strategy. Launched in July 2000, it has targets to stop people being made ill at work and aims to change the culture of the world of work so that rehabilitation is an option for those who do become ill. If you want to know more, this article points the way to a website address for more information.
I hope that this edition of TSB is interesting and useful. Please let us know your views. For example, is the language we use in the articles easy to understand? Are there issues which you would like us to cover? Could we change the layout to make it more readable?
In the next issue we plan to explain our plans for European Week 2003, which will have as its theme 'Dangerous substances'. Meanwhile, may we wish all our readers a happy and prosperous new year.
Carole Sullivan, Editor
The OEL framework Discussion Document (DD) examined the concerns with the present system, put forward and compared three options for a revised framework and proposed a new set of criteria for establishing the limits. The end of July 2002 was the closing date for comments and we are grateful to those readers who were among the 56 respondents.
Do you agree with these concerns about the current system?
41 respondents replied to this question; all agreed with the concerns.
Do you agree with the need for change?
39 replied, of whom 38 agreed.
Do you agree with the key objectives for a new approach?
36 replied, with 31 agreeing.
Which of the three options for a new approach do you prefer?
46 replied: 2 preferred Option 1 (maintain the present system with minor modifications to the indicative criteria);
4 did not specify between Options 2 and 2A, with 15 preferring Option 2 (good practice supported by a single limit).
The majority (25) supported Option 2A (good practice supported by a system which flags carcinogens).
The proposed approach to integrating COSHH Essentials into the OEL framework. Answers to this question were a) useful, b) not useful, c) would prefer users to be directed to a full COSHH Essentials assessment. 37 replied, with 32 considering that it would be useful. 1 answered (b) and 4 chose (c).
On 21 November 2002, ACTS considered its OEL review working group's analysis of the responses to the DD and asked
the working group to develop formal proposals for a new framework. These will be considered by ACTS and, subject to
approval by HSC, will be published in a consultative document later in 2003.
In TSB49 we set out where HSE was on proposals to amend the Control of Asbestos at Work Regulations (CAW). We are now informing readers of what has happened to the regulations and other supporting initiatives.
A Government debate on the regulations took place in the House of Commons on 24 October 2002. They were laid before Parliament on 31 October and most of the regulations came into force on 21 November 2002, apart from the two regulations which have lead-in periods. They are the new duty to manage asbestos in non-domestic premises and the requirement that employers use only accredited laboratories to analyse materials. They will come into force on 21 May 2004 and 21 November 2004 respectively.
The number of intermediaries who are helping HSE to cascade information on the new duty to manage continues to grow, with over 1500 now signed up. They receive regular updates through the campaign news letter and the web page in HSE's website, www.hse.gov.uk/asbestos/index.htm
The new Approved Code of Practice and guidance The management of asbestos in non-domestic premises (L127); the revised Approved Codes of Practice and guidance Work with asbestos insulation, asbestos coating and asbestos insulating board (L28) and Work with asbestos which does not normally require a licence (L27); a guidance book A comprehensive guide to managing asbestos in premises (HSG 227); and a revised version of the leaflet A short guide to managing asbestos in premises (INDG 223) were published on 16 December. The new HSE publications are available from HSE Books.
The European Commission has formally published its proposal to amend the Asbestos Worker Protection Directive (83/477/EEC) for a second time (http://europa.eu.int/eur-lex/en/com/pdf/2001/en_501PC0417.pdf). In the UK this is implemented by the Control of Asbestos at Work Regulations 2002 (CAW).
The intention of the Commission's latest proposal is to ensure protection for those workers who are now considered to be most at risk from exposure to asbestos, for example asbestos removal workers and maintenance workers (electricians, plumbers and decorators). Member states were concerned that the Directive, as drafted, was primarily aimed at the mining and manufacture of asbestos, and did not protect those workers who may be accidentally exposed to asbestos.
In the UK, CAW currently applies to anyone who is likely to come into contact with asbestos during a work activity. There will, however, need to be some changes to UK law as a result of the proposed amendment.
Once the Directive has been adopted, any changes to UK legislation can only be agreed following extensive stakeholder consultation, and with Health and Safety Commission and Ministerial approval. Therefore, the purpose of this article is to alert you to the key changes to the Directive and their likely impact on UK law.
1. New single control limit
2. Exemption from complying with the full requirements of the Regulations
3. Management of asbestos
4. Training requirements
Although we are close to agreeing a final Directive, the next stage in the life of the proposal is for the European Parliament (EP) to reconsider the latest text. Only when the European Council and the EP agree a text will it be an adopted Directive. So, at the moment, the text may still change.
We are likely to have an adopted Directive mid/late2003 and a revised CAW in mid/late 2006.
For further information on asbestos: www.hse.gov.uk/asbestos/index.htm
New web pages on stress at work were launched during October 2002 as part of HSE's contribution to the European Week for Health and Safety, which this year focused on psychosocial risks at work.
The site (www.hse.gov.uk/stress) is part of a new series of pages about the Health and Safety Commission's (HSC) priority programmes, designed to inform and involve the public about ongoing work and to provide guidance and support.
The pages have been developed to make them simpler and more user-friendly. The bar down the left hand side means that navigation is much easier, despite there being a lot more information available on the site than before. The pages include information on HSC/E's current plan of work, events, recent research published by HSE and useful links.
One new section aimed at employers is the stress risk assessment walk-through (www.hse.gov.uk/stress/resources.htm). Here managers will be able to work through the risk assessment process to find examples of what other people have done and also submit their own case studies to share with others. It is also possible to submit feedback about the site in this section.
The new pages place a greater emphasis on contributions from others and sharing best practice. It is hoped this will enable organisations to tackle this challenging issue and assist with meeting the targets set out in Securing health together (for information on the Government's strategy on occupational health, go to www.ohstrategy.net).
This regular article highlights recent relevant HSE publications. They are available from HSE Books, PO Box 1999, Sudbury, Suffolk CO10 2WA. Tel: 01787 881165. Fax: 01787 313995. Website: http://books.hse.gov.uk
Jobs to die for (MISC471) is a variation on HSE's previous 'fatal accident' publications. Its emphasis is not so much on the accidents themselves and the people killed but on the families and loved ones left behind.
It is meant to raise awareness of health and safety, not only among the people actually carrying out various types of work, but among those who might be in a position to exert 'emotional pressure' on them to work more safely and to take health and safety seriously. It is meant to make people think more clearly about the impact that any lack of health and safety awareness on their part might have on others, should things go wrong, and to show that accidents can happen to anyone - not just to 'others'.
As such, the target audience is potentially extremely wide and varied. The approach and tone of the publication is unlike anything else HSE has produced, and depicts real people whose loved ones have had real accidents, which have had a real negative impact on their lives.
This statistical report (MISC242) gives a comprehensive picture of work-related injury rates and the incidence of ill health over a range of different industry sectors for 2001-02. It also covers accidents and dangerous occurrences, and the activities of enforcement authorities, including HSE. It includes graphs and tables giving figures for all major aspects of occupational safety and health in recent years. It replaces the previous Statistics annual report and Statistics highlights bulletin. HSE's full and detailed statistics will be published on the HSE website.
HSE's 3Rs programme ('the right information, to the right people, in the right way') is a recent long-term risk communication research programme (the first stage of research ended in 2000). It sought to optimise the value of health and safety messages reaching the workplace by developing more effective risk messaging and delivery techniques.
Its focus was the problems of communicating in the small workplace, particularly in dry cleaning, woodworking, hairdressing, electroplating and motor vehicle repair. These industry sectors are all hard to reach, but show raised rates of chemicals-related ill health and high rates of self-reported exposure.
Although the programme looked specifically at small firms, its 11 integral projects provide an important body of evidence and analysis for all practitioners struggling to provide effective health and safety information for the workplace.
The results have surprised HSE. They have challenged our perceptions of how best to communicate with the small workplace, without any certain conclusions about how it may best be achieved. What is clear, however, is that it is going to be far more difficult than we at first thought.
The background for the programme was twofold. First, there was a strategic analysis of the probable future influences on the health of users handling chemicals. This concluded that the traditional communication route of HSE guidance, for which there was very little evidence of impact, would not answer the future challenges caused by changes in patterns of employment and increasing fragmentation of workplaces. These changes mean that it would be more difficult than ever to deliver health and safety information to workers.
This understanding coincided with the findings of a study that looked at the perception and use of occupational exposure limits but which also, peripherally, looked at the uses of hazard information in the workplaces studied. This concluded that supplier information might be a useful method of delivering health and safety information.
Because of this, the 3Rs programme's starting point was that safety data sheets (which must be supplied with the first supply of all hazardous chemicals) might be adapted to carry improved risk messages. The messages would be improved by gaining an understanding of the responses to and perceptions of risk by the workers in the industries to be studied.
The focus was on chemical users but much of the information gathered proved to be relevant to all risk communicators - not only to those seeking to communicate messages about workplace chemicals.
The 11 projects were:
The main findings were:
These results were not expected and the problem in relation to safety data sheets has meant that plans to deliver new messages through them has been abandoned. (However, the data gathered has been used to support our negotiations in Europe and secure legislative improvements to the requirements for safety data sheets information.)
But, more than this, the results have given fundamental challenge to our beliefs about the availability of an educated mediator of our messages in every workplace and, indeed, to our faith in the usefulness of written communications for much of our target group.
Much more work will now need to be done to find out how we can deliver improved messages and to find out what the best medium for those messages might be. HSE is now considering how best to carry this work forward but early evidence shows that there might be many answers and we will need to become skilled at knowing what tool to use and when.
In undertaking chemical risk assessment, there are many uncertainties surrounding our ability to accurately portray the consequences of an occupational exposure. This article deals with the uncertainties in the hazard assessment and in particular one significant aspect, that of human variability in susceptibility.
So that we could get a better grasp on the state of knowledge about individual variability and susceptibility to chemicals, HSE commissioned the Institute for Environment and Health (IEH) to hold a workshop in February 2001 on this issue. The findings have just been published.
Chemicals (or, more broadly, substances) are used widely in the workplace in a whole range of activities. We know that in some cases they can be hazardous and if people are exposed to them in sufficient quantities then this may result in harm to some of those exposed. We need, therefore, to make objective judgements of whether or not harm could occur in workers and to identify levels of exposure that are unlikely to lead to harm (eg occupational exposure limits). The way in which we do this is through the process of risk assessment, whereby a comparison is made between the available health hazard information on a substance (a hazard assessment) and the level of measured or predicted workplace exposure.
Any assessment will be constrained by the information that is available to the assessor. Information on human health hazards is rarely available from direct observations in populations that have been previously exposed to a substance (and indeed the situation of humans observed to be suffering from the ill-health effects of chemicals is just what we are trying to avoid). So, by and large, the hazard information that we do have comes from other experimental systems, extrapolating from these non-human data to the human situation until we have a position reflecting consideration of the 'average' human in a population.
Of course, though, we are not all the same and for any given substance some people in the population are more likely to be susceptible to an exposure than other people at the same level of exposure. The problem is that we do not know that much about the differences between people.
The aim of the IEH workshop was to gather together experts in this field to identify our current knowledge base and to highlight key areas for further work. The workshop programme recognised that there are some factors which are intrinsic to the individual (ie those things we are born with). These include our physical and physiological characteristics, ethnicity, age, our ability to metabolise substances foreign to the human body and of course our underlying genetic make-up which will, to greater or lesser extent, influence these other factors. Superimposed on these are acquired lifestyle factors such as tobacco and alcohol consumption as well as any pre-existing disease state (with or without the taking of medicine), nutritional and pregnancy status. The workshop also considered the possibility that, based on the changing demography, an older population will, in future, make up a greater proportion of the UK workforce.
Overall, the workshop concluded that variability and susceptibility to chemicals in the working population is unlikely to be significantly different from that in the general adult population. The workshop revealed that although our knowledge base in this area has moved forward considerably over recent years, there is still much that we do not know. For example, we have quite a large (and increasing) knowledge of how we vary in our ability to metabolise foreign compounds once they enter our bodies, but we know much less about how we vary in terms of the susceptibility to any consequential health effects.
There are some things we do know. For example, we know that the prevalence and incidence of asthma has increased two- to three-fold over the last 20 to 30 years. While this may be a consequence of improved reporting and diagnosis it probably also reflects a true increase in incidence. This means it is possible that in future years the workforce will contain a larger proportion of people with more sensitive airways.
Although we have some knowledge about the use and influence of alcohol and tobacco in workers, we know much less about how many workers may be taking medicinal (or recreational) drugs and the influence this may have on their response to exposure to substances at work. Overall, a number of recommendations were made for further work in this area.
Risk assessment is an uncertain process and risk assessors are challenged with providing the best estimate they can with very limited information of what the risk of exposure to a hazardous substance may be. For one area of uncertainty, human variability and susceptibility, the IEH workshop has helped to define more clearly what knowledge we currently possess and what some of the future directions may be to help move our understanding forward and reduce these uncertainties.
IEH Report on variability and susceptibility in human response to occupational exposure to chemicals in the UK Report R13 Institute for Environment and Health, 2002 ISBN 1 899110 36 4
An executive summary is available to download at: www.le.ac.uk/ieh/pdf/ExsumR13.pdf
Confined spaces and areas near landfill sites or underground coal strata are common locations for building, installation or maintenance work carried out by construction and utilities industries. These locations have the potential for both harmfully low oxygen levels and high carbon dioxide levels. The risk assessment for such situations may require using gas monitors to warn of significant leaks of gas. These leaks may result in an oxygen-deficient atmosphere which could lead to asphyxiation, and a toxic atmosphere due to high levels of carbon dioxide.
There appear to be conflicting views on the use of oxygen monitors for assessing the safety of atmospheres where carbon dioxide may also be present. One view is that a carbon dioxide monitor is superfluous when using an oxygen deficiency monitor because the oxygen monitor will alert the user to a low oxygen atmosphere before the carbon dioxide concentration reaches a harmful level. The other view is that a carbon dioxide monitor is required in addition to an oxygen monitor to be safer under these conditions. The following examples illustrate why in general it is better to have both oxygen and carbon dioxide monitors.
The Occupational Exposure Standards (OESs) for carbon dioxide are 5000 parts per million (ppm by volume), which is equivalent to 0.5%, for the 8-hour time-weighted average (TWA); and 15000 ppm (1.5%) for the 15-minute short-term exposure limit (STEL). Typically, oxygen deficiency alarms on gas detectors are set at 19% volume ratio (v/v). Normal air contains 20.9% oxygen.
Typical examples: fuel-burning (gas, oil, coal etc) appliances and engines; fires actually present in the confined space arising from petrol spills and/or other combustible materials, seepage from mine workings or other sources of combustible gas.
Any combusted fuel in the confined space depletes the oxygen to produce carbon dioxide and water, and possibly other products such as carbon monoxide. In this example, it is assumed that the fuel is converted to carbon dioxide.
For combustion of methane (eg arising from natural gas leakage from pipes or seepage from coal strata) the reaction is:
CH4 + 2O2 ð CO2 + 2H2O
Oxygen depletion from its normal level to 19% as a result of methane combustion could increase the carbon dioxide level to a maximum of around 0.85% (8500 ppm) depending on the original methane and oxygen concentrations and degree of combustion. In this situation the oxygen monitor would alarm before the carbon dioxide level approached the STEL. However the carbon dioxide level is above the 8-hour TWA concentration and would exceed this exposure level after 4.7 hours (8 x 5000/8500) at this concentration.
For petrol combustion, assuming petrol to be heptane, the reaction is:
C7H16 + 11O2 ð 7CO2 + 8H2O
Oxygen depletion from its normal level to 19% arising from combustion of petrol results in a maximum carbon dioxide level of 1.1% (11 000 ppm). Again this is less than the STEL but above the 8-hour TWA concentration, and would exceed the 8-hour exposure level after 3.6 hours at this concentration.
These examples illustrate how the idea of only requiring an oxygen monitor may have originated. However, this argument neglects the possibility of exceeding the 8-hour TWA which may occur for extended periods in confined space. The following examples illustrate other possibilities.
Typical examples: buildings and excavations etc near to landfill sites and dump sites; carbon dioxide gas bottles in food/drink/entertainment industry; action of acid rain on limestone/chalk in utilities industries.
Monitoring gas levels on or adjacent to a landfill site is commonly undertaken. Pure landfill gas can contain up to 35% carbon dioxide, 65% methane and no oxygen. The landfill gas then displaces the surrounding air. If the oxygen concentration in the air decreased to 19% as a result of displacement by the landfill gas (assuming it to have the above composition) then the carbon dioxide concentration would be 3.2% (32 000 ppm) [ie (100 - 19/0.209) x 0.35)]. This is over twice the STEL.
Alternatively, if the carbon dioxide level is 5000 ppm (the 8-hour TWA) in the confined space, arising from displacement of air by the carbon dioxide-containing landfill gas, then the oxygen concentration would be 20.6 % [{100 - (0.5/0.35)} x 0.209]. If the carbon dioxide level is 15 000 ppm (the 15-minute STEL) in the confined space, the oxygen concentration would be 20.0%. These are relatively small decreases in oxygen levels arising from large (OES) concentrations of carbon dioxide. They would not activate the normal oxygen alarm.
In other cases, carbon dioxide can comprise all the gas which displaces air from the confined space, eg from a carbon dioxide gas bottle. Here, if the oxygen concentration decreased to 19% then the carbon dioxide concentration would be 9.1% (91 000 ppm). This is over six times the STEL.
Alternatively, if the carbon dioxide level is 5000 ppm (0.5%) in the confined space, arising from displacement of air by 100% carbon dioxide, then the remaining oxygen concentration would be 20.8%. If the carbon dioxide level is 15 000 ppm (1.5%) in the confined space, the oxygen concentration would be 20.5%. These are even smaller decreases in normal oxygen levels arising from large (OES) concentrations of carbon dioxide. Again they would not activate the normal oxygen alarm.
There is not a general, convenient relationship between oxygen deficiency and carbon dioxide enrichment which allows the sole use of an oxygen monitor to provide warning of a oxygen deficiency and carbon dioxide hazard. It may not be obvious when entering a confined space, landfill site etc how any oxygen depletion may have occurred and whether there are potentially dangerous levels of carbon dioxide. It is therefore recommended that measurement of both oxygen and carbon dioxide is carried out in order to provide warnings of both oxygen deficiency and high carbon dioxide levels over short- and long-term exposure periods.
Musculoskeletal disorders (MSDs) are the focus of one of the priority programmes in the Health and Safety Commission's strategic plan selected to help meet the targets set out in the Revitalising health and safety strategy document.
They are being targeted because:
In order to support the MSD priority programme, HSE have recently produced the Manual handling assessment charts (MAC). The MAC is a tool to assist inspectors in the identification and assessment of high-risk manual handling activities. It comprises three flowcharts covering lifting, carrying and team handling operations. It requires an assessor to work through a sequence of risk factors, allocating a colour band and numerical score.
The tool is able to assist the identification of high-risk manual handling activities and determine where, and how urgently, remedial action is required. Currently, the MAC is available for regulatory inspectors only, and moderate quantities can be obtained by contacting HSE Books. They are due to be launched to the public during spring 2003.
According to HSE's guidance on the Manual Handling Operations Regulations (see reading list at end of article), manual handling is defined as 'any transporting or supporting of a load (including the lifting, putting down, pushing, pulling, carrying or moving thereof) by hand or by bodily force'.
More than a quarter of the accidents reported each year to the enforcing authorities are associated with manual handling. The vast majority of reported manual handling accidents result in over-three-day injury, most commonly musculoskeletal (eg a sprain or strain), often of the back. The injured do not always make a full recovery; the result can be physical impairment or even permanent disability.
The Manual Handling Operations Regulations set out a hierarchy of measures to take. Firstly you should avoid the need to perform any manual handling operations and if this cannot be avoided you should mechanise or automate the process.
Where this cannot be done you should make a 'suitable and sufficient' risk assessment of the manual handling tasks. Your risk assessment should consider the task being performed, the load being handled, the working environment and the individual capability of the person performing the task.
By following the steps in the hierarchy of measures the overall aim is to reduce the risk of injury from those operations so far as is reasonably practicable.
HSE have produced a considerable amount of literature to help with understanding and managing the risks posed by manual handling. These are available from HSE Books. Free leaflets are available to download from the HSE website.
Manual Handling. Manual Handling Operations Regulations 1992. Guidance on the RegulationsL23 (Second edition)
HSE Books 1998 ISBN 0 7176 2415 3
Getting to grips with manual handling: A short guide for employers INDG143(rev1) HSE Books 2000
Manual handling. Solutions you can handle HSG115 HSE Books 1994 ISBN 0 7176 0693 7
A pain in your workplace? Ergonomic problems and solutions (case studies of real problems and real solutions)
HSG121 HSE Books 1994 ISBN 0 7176 0668 6
Guidance on the management of risk
Health risk management: A practical guide for managers in small and medium sized enterprises (includes advice
on manual handling) HSG137 HSE Books 1995 ISBN 0 7176 0905 7
Essentials of health and safety at work (includes advice on manual handling) HSE Books 1994 ISBN 0 7176 0716
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Formula for health and safety. Guidance for small and medium-sized firms in the chemical manufacturing industry
(includes advice on manual handling) HSG166 HSE Books 1997 ISBN 0 7176 0996 0
Handle with care. Assessing musculoskeletal risk in the chemical industry HSE Books 2000 ISBN 0 7176 0689 9
There is also sector-specific manual handling guidance available including guidance for the construction industry, drinks and brewing, health services, offshore, printing industry, working with rubber and textiles and clothing etc.
Securing health together: An occupational health strategy for Great Britain is the occupational health plank of the Revitalising health and safety agenda, and was launched in July 2000. This article looks at recent developments.
The world has moved on since 2000. Although Securing health together anticipated that the need to improve rehabilitation would be important, there is now a clearer picture of how this can be developed. The Department for Work and Pensions (DWP) is leading a cross-governmental programme to provide employment-focused occupational health and rehabilitation support. What this will entail will become clearer in the next few months - but there is potential for change that will go a long way to helping us achieve the targets set by Securing health together. Programme Action Groups (PAGs) have been contributing to this development.
The targets of Securing health together go beyond HSE's traditional boundaries, so a broad range of stakeholders also contribute. One way is through the five Programme Action Groups.
These are chaired by Paul Davies, HSE's Chief Scientist; Brenda Stephens, Health Promotion Division, National Assembly for Wales; David Fisk, Chief Scientific Advisor, Office of the Deputy Prime Minister; Jane Drabble OBE, Vice-Chair, Basic Skills Agency; and Dr Ewan MacDonald, Director of Salus Occupational Health and Safety and Senior Lecturer at the University of Glasgow.
These groups consider the five areas that need to be tackled to achieve the targets: compliance with the law, continuous improvement, knowledge, skills and support.
A Partnership Board to oversee the strategy was also set up and its initial input to start the strategy was vital. However with the development of the stronger rehabilitation agenda there is a need now to find a new role for the Board. The PAGs are also reviewing their role, structure and work to build on successes and improve where lessons have been learnt.
A new version of the Securing health together website has been launched at www.ohstrategy.com/. This provides information such as publications, news and future events as well as a database describing over 40 occupational health projects. These projects show what can be done to improve occupational health and a good proportion involve big cost savings and other benefits for the organisation involved.
Further information can be obtained from Melissa Webb or Jennifer McGilvray, Securing health together Team, Rose Court, 2 Southwark Bridge, London SE1 9HS; tel: 020 7717 6198.
Like many specialist publications, TSB can fall into the trap of using jargon. This occasional series is intended to explain some terms we often use. If there are any terms that puzzle you, please use the feedback form and we will try our best to explain ourselves.
CHIP (the Chemicals (Hazard Information and Packaging for Supply) Regulations 2002) requires the suppliers of dangerous chemicals (substances and preparations) to classify them for their hazardous properties. They have to assign risk phrases (R-phrases) and safety phrases (S-phrases) to them, in accordance with detailed criteria which are set out in the Regulations themselves and in the Approved Classification and Labelling Guide.
The overall purpose of the Regulations is to enable people to protect themselves and the environment from the effects of these chemicals, and these phrases, together with the appropriate hazard symbols, appear on the label to give users an initial warning.
An R-phrase is a standard phrase which gives simple information about any hazards a chemical will present in normal use, such as flammability, toxicity etc.
S-phrases are also standard phrases; they give advice on safety precautions which may be appropriate when using the chemical, and may indicate how the product should be stored or disposed of safely.
Both R-phrases and S-phrases can be identified by means of their number. For instance, R49 is the R-phrase 'May cause cancer by inhalation' and S24 is the S-phrase 'Avoid contact with skin'.
A CHIP label is intended to be eye-catching and easy to read. When a number of R- and S-phrases are assigned to a substance or preparation, it may be necessary to choose between them. Advice on selecting R- and S-phrases can be found in the Approved classification and labelling guide. In general a maximum of six R-phrases and six S-phrases should suffice to describe the dangers and formulate the most appropriate safety advice.
The label must show the full text of each R- and S-phrase. The R- and S-phrases are listed in Part V of the Approved Supply List.
The Regulations themselves can be obtained from the Stationery Office, www.tso.co.uk
They are also available to download free from HMSO at www.opsi.gov.uk/si/si2002/20021689.htm
The related approved documents, which contain CHIP's technical detail, are:
Approved Supply List (Seventh edition) L129 HSE Books 2002 ISBN 0 7176 2368 8
Approved classification and labelling guide (Fifth edition) L131 HSE Books 2002 ISBN 0 7176 2369 6
These are available from HSE Books.
This is the first in a planned series of short articles outlining different aspects of occupational epidemiology. The idea is to give a general understanding of what epidemiology aims to do, the concepts it works with and of some of the techniques it uses to achieve its ends.
Epidemiology looks at the patterns of disease in populations and asks the question: why? Why do men have higher rates of heart disease than women? Why are rates of liver cancer so high in China? Why did rates of lung cancer increase so rapidly in the 20th century?
Occupational epidemiology directs its attention to patterns related to occupation or occupational exposures in an effort to understand the impact of working conditions on health and thereby to remove or control the risks to health from work activities.
Building this understanding is a cumulative process, and involves a number of distinct steps:
None of these three kinds of activity is straightforward and the path from first suspicion through to full understanding of a hazard rarely consists of a simple progression through these three stages. For example, the initial suspicion of a hazard may not arise from an identified pattern, but these patterns may be sought to back up suspicion generated, for example, by animal experiments or clinical observation.
Also, although certain landmark studies may often stand out as we develop our understanding of a hazard, these are invariably clearer in retrospect than they appear at the time. The accumulation of the relevant evidence will typically involve many studies and draw on expertise from many areas: toxicology, medicine, occupational hygiene, ergonomics... as well as epidemiology itself.
Epidemiological studies are essentially observational. There are very few circumstances in which an experimental approach to human health hazards is ethically possible. Nevertheless, when care is taken over the design and interpretation of studies, valid conclusions can be drawn. The range of study designs and statistical techniques available to epidemiologists has seen enormous growth over the last 50 years. This has been driven by an increasing concern to frame comparisons in the most valid way possible, and by the enormous expansion in available computing power.
But in the face of this increasing sophistication, it is important not to lose sight of the fact that the essence of any epidemiological study is the comparison of just four numbers: the sizes of an exposed and an unexposed population, and the numbers of cases of disease in each. The science and art of good epidemiology lies in the proper choice of populations and the appropriate measurement of exposure and disease. The aim is to understand the causes of disease. A good design is the simplest design that will advance this aim in the given context, taking account of the present state of knowledge and the available populations for study.
In the next article we will look at the types of study, and the purposes and circumstances they are best suited to. Future articles will discuss statistical issues such as bias (systematic - as opposed to random - effects); confounding (where the effect of one factor masks or mimics that of another) and interactions (where the level of one factor changes the effect of another); assessment of exposure and exposure response relationships and evaluation.
Ms Carole Sullivan Editor
Miss Naseem Walji Assistant Editor
Ms P Kiley Content Editor
Mr D Kyle
Dr J Groves
Mrs E Ball
Mr S Campbell
Dr R Rawbone
Ms D Llewellyn