Occupational health services for shift and night workers

Applied

Ergonomics Vol 21, No. 1, p. 31-37. 1996 Ekvier Science Ltd Printed in Great Britain ooo3-6870/?% $10.00 + 0.00

ELSEVIER

Occupational health services for shift and night workers Margit KoXler Head of Occupat,ional and Social Hygiene Unit, Institute of Environmental Hygiene, University of Vienna, Kinderspitalgassc 15, 1095 Wien, Austria

It is important for an occupational health service to plan health supervision and measures for shift and night workers considering the biorhythmic and psychosocial desynchronisation, as well as the frequent prevalence of combined effects of adverse environmental and working conditions. The measures taken should be preventive to reduce the expected health risks rather than being rehabilitative. Both a medical surveillance and a counselling service are recommended before and during engagement in shift and night work. Sleep, digestive, metabolic and cardiovascular troubles should be noted and followed up. Medical counselling is especially necessary in the first months of shift and night work exposure and then after long-term exposure. The postulate for timed surveillance and intervention is supported by data of our epidemiologic investigations. The importance of lthe single health measures is underlined by direct reference to the relevant literature. Recommendations that should be applied in ah countries and enterprises are in accordance with the IL0 Night Work Convention 199Oa and include: (1) appropriate occupational health services provided for night and shift workers, including counselling; (2) first aid facilities during all shift hours; (3) the option of transfer to day work when certified unfit for night work for reasons of health; and (4) measures for women on night shifts, in particular special maternity protection (tranlsfer to day work, social security benefits or an extension of maternity leave). Examples of occupational health services already installed in some states for shift and night workers, and information on future developments are given. Up to now the medical service has been implemented mostly on the basis of collective agreements rather than on the basis of legal provisions. The Austrian Night Shift/Heavy Work Law Regulations of 1981, revised 1993, are cited: workers exposed to night shifts under defmed single or combined additional heavy workloads are entitled to a special health assessment, additional rest pauses, additional free time and early retirement depending on years of exposure. .Keywords:

shift work, night work, occupational health service, health surveillance, counselling, recommendations

can be superimposed upon the most varied work activities (Rutenfranz and Knauth, 1986). Thus, very frequently shift and night work is combined with adverse environmental and workplace conditions resulting in a combined effect of health hazards, even if each of the single hazards does not reach the critical exposure limit (Smolensky, 1983; Reinberg et al, 1985). Another factor which has recently come to light and which has so far been insufficiently studied is the variation in sensitivity to harmful or obnoxious influences of the working environment during the 24-hour cycle (e.g. Smolensky, 1983). This point might be of in connection with nocturnal great importance sensitivity to chemical substances, dusts or noise. The combined effects of psychobiological desynchronisation and reduced coping possibilities are not expected to result in one clear ‘occupational disease’, but, though simple causal relationships cannot easily be proven, there is general agreement that shift and night

The rationale for establishing occupational health services for shift and night workers is still under discussion. The question is open as to whether some conditions of ill health which are widely reported as shift and night work related (Smolensky et al, 1985; Rutenfranz et al, 1985a; Scott, 1990) should be declared occupational diseases or described as job related diseases (Knauth et al, 19SO; Koller, 1983; Akerstedt et al, 1984; Knutsson et al, 1988; Knutsson, 1989; Lennernas, 1993). It is doubtful whether this point will ever be agreed upon considering the multicausality of shift work related effects on wellbeing and health. Shift and night work have implications for the entire living sphere of the human being (Haider et al, 1981; Kogi, 1985; Kundi, 1989); thus, health hazards and stresses of the work itself, as well as intervening factors from outside the working life may influence and impair the state of health (Monk, 1988; Folkard, 1993). Furthermore, it must be emphasised that shift work

31

32 workers are a population at risk (Kogi et al, 1982; Corlett et al, 1988; ILO, 1990a), and that this is reason enough to plan efficient health measures for persons working shifts.

Medical supervision Medical supervision of workers who are regularly engaged in night or shift work provides an excellent opportunity for detecting certain medical indications of an inability to adjust to shift and night work, and subsequently of intolerance to this work schedule. Therefore, measures taken by the occupational health service should be preventive - that is, before the expected health risk might occur - rather than rehabilitative. However, since by the time preventive regulations and special health services are introduced adverse health effects would already be apparent in a considerable proportion of shiftworkers, special attention has to be given also to rehabilitation (see, e.g. Night Shift/Heavy Work Law, Austria, 1981). This is in accordance with the defined aim of occupational and industrial medicine, to be involved in primary or secondary prevention. A medical surveillance and a counselling service for workers are both suggested, before they are engaged in night work and during their employment. In the case of night and shift work without additional occupational health hazards, it could even turn out that counselling is much more effective than any other measure taken. In this paper, health surveillance before and during engagement, and counselling will be discussed separately. Medical preselection of night workers

Directives and papers published on this topic (Rutenfranz et al, 1985a; b; Koller, 1989) generally state that medical supervision of workers who regularly do nightwork is especially necessary before they start night work, to forecast possible intolerances. In this context, the pros and cons of a selection process of workers by the physician arise. Although tolerance to night work should not be a discriminating criterion for selecting workers, night work may be inadvisable for workers with some prevailing disorders or diseases, especially if there are additional adverse environmental, workplace or stress factors involved. For the sake of the workers, preventive medical examinations should therefore be recommended and introduced. This is also emphasised by international organisations (ILO, 1989; 1990a; 1993; EC 1990; 1991). Table 1 gives an overview of conditions under which an assignment to night work is absolutely not advisable, and also conditions aggravating adverse effects of night work. There is a need for regular timing of food intake, medications and regular sleep/wakefulness patterns, as irregularities would lead to a severe aggravation or exacerbation of symptoms. Individuals suffering from the conditions mentioned in part (a) of Table I should therefore not be assigned to night work. Workers must also be advised as to further health incompatibilities, which constitute aggravating conditions, and must be informed about possible adverse

Occupational health services for shift and night workers: M. Keller Table 1 Conditions

under which night work is not advisable

(a) Absolutely not advisable if one or more of the following conditions are present - severe gastrointestinal dysfunctions chronic hepatic and pancreas illness - diabetes, especially if insulin dependent _ severe hormonal irregularities - epilepsy and seizures of other genesis - cardiovascular high risk factors - consuming diseases - depressive or psychotic states - chronic sleep disorders

and

diseases,

including

(b) Not advisable due to a possible aggravation of adverse effects if one or more of the following conditions are present - age above 45-50 years _ unsatisfactory housing conditions, sleeping facilities - lack of social support within the family - women with small children

especially

concerning

effects of night work (part (b) of Table I). We propose, however, that the decision as to whether or not, despite these conditions, persons should actually start working night shifts should be made their own responsibility. Certainly, it may be sensible to assign primarily to night work - if possible - those persons who may be expected to encounter fewer difficulties in coping with night work on the basis of their health situation, living conditions and psychobiological characteristics. Tolerance to night work has been studied extensively in the last 15 years to evaluate the great inter-individual differences in the adaptational process to night work (e.g. Reinberg et al, 1988; Costa et al, 1989; Rosa, 1990). Harma (1993) summarised the evidence found so far and categorised the moderator variables for adaptation according to the mechanisms of circadian adjustment and sleep/wakefulness. Circadian adjustment apparently is modified by ‘morningness/eveningness’ (Kerkhof, 1985; Costa et al, 1989; Bohle and Tilley, 1989), probably also by introversion/extraversion and neuroticism. Age plays an essential role in circadian adjustment (Van Go01 and Miriam, 1986; Liebermann et al, 1989; Harma et al, 1990). Sleep/ wakefulness has been proven to be influenced by physical fitness (Harma et al, 1988). Flexibility of sleeping habits and ability to overcome drowsiness are essential moderator variables (Vidacek et al, 1987) as well as age (Miles and Dement, 1980). Standardized questionnaires and rating scales (e.g. Horne and Ostberg, 1976; Folkard et al, 1979; Torsvall and Akerstedt, 1980; Eysenck and Eysenck, 1964) can be useful to control for some of these individual factors. They should, however, be applied very carefully and, considering our present knowledge, be no basis for selection into or out of night work. Medical surveillance Health assessment. There is agreement across a number of states that health checkups for night workers are important and necessary (e.g. Portugal, 1971; France, 1977; Austria, Night shift/Heavy Work Law 1981; revision 1992 and 1993; and principally all states that

Occupational health services for shift and night workers: M. Keller

have ratified the Night Work Convention, ILO, 1990a). By definition, ‘night workers’ means an employed person whose work requires the performance of a substantial number of hours of night work which exceeds a specified limit (IL0 Convention 171, Article I, IL0 1990a). Referring to the relevant literature on health hazards of shift workers, recommendations can be given as follows:

(1) Permanent

and rotating night workers: they are generally agreed to be a population at risk and are therefore to be included in medical screening programs. (2) Shift workers being additionally exposed to workload factors, which alone or in combination with other factors and/or night work, constitute a health hazard, should be given special attention (see e.g. the revision of the Nightshift/Heavy Work Law of Austria, 1993). (3) The same applies for shift workers being exposed to a combined workload of toxic exposure and extended working hours (e.g. Hickey and Reist, 1977; Bolt and Rutenfranz, 1988). (4) It is also documented that shift workers without night work and employees with irregular working hours may suffer frorn essential psychobiological desynchronisation (Brief and Scala, 1986; Moors, 1989). Whether or not they could take advantage of the occupational health service may be discussed in terms of personnel and financial resources. (5) There is strong evidence from our earlier studies that day workers who dropped out of shift work for health reasons are a population at risk (Koller et al, 1978; 1985). From fo.llow up studies it has been shown that even several years after cessation of shift or night work the proportion of cardiovascular and circulatory problerns persisted, and that gastrointestinal and sleep disorders normalised slowly (Kundi et al, 1986; Verhaegen et al, 1981). As the expected number of workers in this group is not very high, it is recommended to include them in the special health supervision, at least up to five years after the change of work. Medical screening program. Table 2 summarises the program for periodic medical surveillances. They are intended to detect early symptoms of desynchronisation, symptoms which are most probably related to the

Table 2 Periodic medical surveillances * Health advice about sleep strategies; diet; fatigue and stress management; physical fitness to give the workers informations, suggestions and guidelines how best to cope with shift and night work

work

(which

gastrointestinal, cardiovascular, circulatory and neurohumoral system. In this connection, a screening of some indicative risk factors should be included. Data from our own studies suggest that gastrointestinal disorders are regarded as ‘normal’ in shiftwork (Koller et al, 1985) and that workers would not come to see the doctor for this reason. A recent study also indicates that the perception of ill health may be somewhat underestimated at the time of actual shift work exposure and that ex-shift workers may rapidly revise their perception of the extent of their shift work related problems (Spelten et al, 1993). Therefore, identification and assessment of risks is an essential task of the occupational health team. To control the development of risk factors for CHD it seems adequate to include at least a screening of some cardiovascular parameters (Knutsson et al, 1988) and blood lipids (Knutsson, 1989) in regular health checkups. Recent results indicate that shiftwork is associated with disturbances in nutrition intake, both with regard to the sequence and timing of meals and the composition of the food (Lennernb, 1993; Cervinka et al, 1984). Therefore, eating behaviour might be a further important risk indicator to be assessed. Angersbath et al (1980) demonstrated that smoking substantially contributed not only to cardiovascular, but also to gastrointestinal disease in shift workers. In several studies (Knutsson et al, 1988; 1989; Thelle et al, 1976) a higher prevalence of smoking was found among shift workers than among day workers. Smoking should therefore be addressed directly. Time schedule of health checkups. As to the timing of health checkups, different time schedules have been proposed by several authors (Rutenfranz et al, 1985a; Gaffuri and Costa, 1985). According to our model of health destabilisation (Haider et at, 1988; Kundi, 1989) we would suggest the following strategy (Table 3): Medical supervision is especially necessary in the first months of assignment to night and shift work, as quite a high proportion of apparently healthy workers show signs of inability to adjust to this type of working time structure. Counselling for these groups should be especially intensive, concerning health behaviour and the awareness of risk factors which may occur with a long latency. Successive health checks should be planned in shorter periods for young workers (below the age of 25), as well as for those older than 45 years and especially for elderly workers. The age dependent decrease of health in shift and night workers was investigated in our earlier studies. From medical and questionnaire information we formed an individual health index and compared age

Table 3 Schedule of health checkups First supervision no later than l-2 months after starting work - Careful monitoring during the first year (l-2 checkups)

* Medical anamnesis about gastrointestinal, cardiovascular and circulatory symptoms; obesity; drug and stimulant abuse; sleeping problems to detect early symptoms of difficulties in adjustment * Risk factor screening (ECG, RR, blood lipids) to detect signs of intolerance to shift or night require transfer to day work)

33

may

Successive health checks: - in periods of -2 years for workers ~25 years - in periods of 3-5 years for workers between 25 and 45 - in periods of -2 years for workers >45 years - in periods of -1 year for workers >60 years

night/shift

34

classes in a cross-sectional and prospective design. The analyses revealed a steep decrease in health in the first years on shiftwork, followed by a plateau over the next 15 years and another steep decrease thereafter (Kundi et al, 1986; Kundi, 1989). Analysis of follow up studies further revealed an increase in importance of sleep quality over time and the development of risk factors after a latency of 25 years on shift. These findings and supportive data from a number of studies (Foret et al, 1981; Matsumoto and Morita, 1987; Harma et al, 1990; ILO, 1990a; b) underline the strategy of a differentiated time schedule for medical surveillance. Transfer to day work when certified unfit for night work.

Where the continued employment of a night worker in a particular job is not recommendable for health reasons, the occupational health service should collaborate in efforts to find alternative (day work) employment for him/her in the undertaking, or another appropriate solution. A further important preventive measure could be the exemption from night work for transient periods relative to particular life phases, due to health impairments or severe difficulties in the family. Counselling

Before they are assigned to shift or night work, and especially in the first months of assignment, employees need guidelines on how to cope with this type of work. Workers must be aware of possible difficulties they might experience in the adaptation process, and must be informed about possible health risks. and booklets have been Several publications developed to provide a number of guiding principles for management and occupational health doctors (Corlett et al, 1988; Wallace, 1989; ILO, 1990b; 1993; Monk and Folkard, 1992; Knauth, 1993). These guidelines were specially aimed at closing the gap between researchers and practitioners. According to Wedderburn (1993) and Wedderburn and Scholarios (1993) they cannot be considered as the final version of useful guidelines for shift workers, as most of the recommendations given should be approved by testing them in the field. In a similar way, guidelines were issued to help people deal with the problems that shift and night work may bring (Monk, 1989; Wedderbum, 1991; Office of Technology Assessment, 1991; Monk and Folkard, 1992; Tepas, 1993). Again, Wedderburn (1993) emphasised that it is probable that most shift workers through their day-to-day experience and year-to-year progress have accumulated considerable wisdom about how to manage their lives against the backdrop of unusual hours of work. Maybe it will be possible in the future to take this expertise of experienced shift workers and to pass it on to the ‘newcomers’ either through information meetings or via peer groups, or by use of radio or TV.

Occupational health services for shifr and night workers: M. Koller

in relation to family, home and bedroom circumstances. Sleep times (when and for how long), naps, degree of sleep disturbances by noise and other environmental factors, and incompatibilities with sleep because of mental or emotional stress are addressed. Sleep strategies for different shifts, and the use of drugs and stimulants are discussed. (3) Another crucial point is nutrition and eating behaviour (when, where, what, how much). Overweight and eating disorders are addressed, and consultation with the doctor for persistent digestive problems recommended. (4) Physical fitness is reported to be an important positive factor to increase shiftwork tolerance and is therefore emphasised. An annual health check as a control measure is recommended. (5) Suggestions for keeping social contacts are included. Educational programmes.

Tepas (1993) discussed the concept of information versus educational programmes for shift workers. He argued that if changes in shiftworkers’ behaviour are intended, the use of educational programmes is required and not simply the dissemination of information. Many reports on general health promotion efforts show that health behaviour cannot be promoted by merely increasing the knowledge about possible health risks (e.g. Bettinghaus, 1986); it succeeds rather by attitude change and motivation. Two major further approaches are cited to strengthen the relationships between knowledge, attitude and behaviour; that taken by Fishbein and Ajzen (1975) which argues for supporting behaviour intention rather than general attitudes, and the approach of Schwarzer (1992) who emphasises the personal action control. Tepas (1993) stated that the majority of the existing educational programmes for shift workers do not appear to be adequate, and therefore proposed principles to guide the design of such programmes. Some of them are summarised below: (1) Recommendations must be relevant to the specific group(s) and work system(s) they are aimed at. There is no ‘ideal’ lifestyle applicable for all individuals. (2) Recommendations must be both practical and socially acceptable to the specific group and work. As a rule, few coping strategies seem to work well without social and domestic support (Monk, 1990). (3) Recommendations must be limited in number if they are to be remembered and used. (4) Training programmes require a high level of motivation and a significant investment of time. Longterm changes in the personal habits of adult individuals are difficult to produce and maintain. (5) Shift work educational programmes alone are not a substitute for needed improvements in work scheduling practices.

Main items addressed in guidelines for shiftworkers. As

a representative example, the main themes of the Bulletin of European Shiftwork Topics (Wedderburn, 1991) are as follows:

Recent developments in the IL0 and the EC concerning night and shift work regulations

(1) It has been made clear that coping with shiftwork is an entirely individual task. (2) Sleep is one of the important points. It is discussed

In 1990 the IL0 adopted the so-called Night Work Convention which was ratified by a large number of states. This convention includes some points which

Occupational health services for shift and night workers: M. Keller

seem an essential addition to the above recommendations for occupational hea:lth supervision (see Table 4). Some further points of the recommendations might be arbitrarily linked to the responsibilities that could be taken by the occupationail health services (Table 5). Occupational safety, training programs for workers concerning health behaviour, as well as supervision of canteens and eating facilities are postulated. They are principally acceptable tasks for the occupational health service given that adequate personnel are supplied. Finally, the convention suggests an additional advisory function for strategies promoting health and wellbeing which indeed should be taken on by occupational doctors. The coming EC Regulations (EC Draft 1990 and 1991) does not directly address the problems of night and shift work, but include postulations which will be a benefit for all employees and aim at improving working conditions in a preventive way (Table 6).

Table 4 IL0 Night work convention

(1990)

Main provisions * Right of health assessment

* * * * *

and health advice before starting night work regularly during it at any time, if workers experience health problems First aid facilities round the clock Transfer to day work if unfit for night work Protection for women before and after childbirth Right of consultation on the details of work schedules Appropriate compensation, social services

35 Health pr&otion in nightworkers: The example of Austria In Austria the approach to the problem is twofold: since there are no legal regulations set up for occupational health services regarding night workers in general, a number of plants, on the basis of collective agreements, institutionalised health services, emphasising the advisory function of the occupational health doctors. Workers exposed to night work under defined ‘single or combined additional heavy work loads’ are protected by the so-called ‘Night Shift/Heavy Work Law’ which was installed in 1981 and revised in 1993 (BGBL 53, 1993). The main regulations are as follows: if certain exposure limits are reached, workers have the right to periodic health assessments without charge, additional rest pauses during the night, additional free time depending on the number of night shifts worked per year and early retirement depending on years of exposure (Table 7). Future perspectives If legal regulations for special medical supervision of shift and night workers are to be installed in European countries, how many of the workforce will fall into legal regulations and how many occupational health doctors will be needecl.? Austrian figures stem from the last Mikrozensus (Osterr. Stat. Zentralamt, 1987) in which Table 7 Night shift/heavy revised in 1993)

work law of Austria

(installed in 1981,

Night work: from 22.00 to 06.00 for at least 6 hours, for at least 6 nights a month Table 5 The IL0 night work recommendation Concerns of the occupational

(1990)

health doctors

(I) Action possible

+ attention to occupational safety + training in health behaviour + control and improvement of f.acilities for meals, diet (II) Advice possible + + + -I+

restrictions on overtime financial versus leisure compensation rest and eating breaks social services including transport day nurseries for young children

Table 6 EC Draft 1990/1991

Heavy work: + heavy physical load, mining, heat, cold, noise, vibration, toxic chemicals, dust, VDU work + combined hazards below exposure limits + defined occupational classes without specifying certain hazards If both conditions are given, legal measures are taken: (Main points) + Additional breaks 10 min payed break during the night shift + Additional vacations limit: 60 nightshifts per year - 2 work days after 5 years on shift - 4 work days after 15 years on shift - 6 work days + Possibility of early retirement for male and female workers + Widened occupational health service increased preventive health measures + Protection against dismissal for reasons of work dependent disease

Table 8 Proportion of Austrian shiftwork (Mikrozensus, 1987)

employees

engaged

in night and

(b) shift work

z

* Occupational

(a) night work

Shift and night work [included in (a) and WI

* *

%

%

%

%

9.2 3.4

14.9 8.7

24.1 12.1

13.0 6.2

New trends and developments

* *

Health Service is introduced for all enterprises, irrespective of numbers of workers Free choice of additional preventive medical screening programs Access to all workplaces and measurement data for industrial doctors must be guaranteed by the plant Duty to inform workers about work related health risks - raising awareness of health behaviour Participation of employees concerning measures to improve working conditions

Male Female

= 500 000 employees

36

Occupational

rates of employees engaged in night work, shift work and shift work plus night shifts are published (Table 8). Thus, it seems that around 24% of male and 12% of female Austrian employees are involved in night and/or shift work, amounting to about half a million workers. The main Austrian branches where shifts are worked are, in rank order, health and social services, the textile industry, chemical and oil industries, and the metal industry (note the high proportion of shift workers in the social services). For all branches except health and social services, occupational health measures are legally installed for reasons other than shift work, namely for health hazards like toxic substances, noise, vibration, heat, etc. That means that in the majority of cases workers are traditionally included in medical screening programs, and will only need some additional surveillance and probably a lot more counselling. On the basis of the documentation of the night shift/ heavy work law we calculated the proportion of employees who are ‘only’ engaged in night and shift work without additional health hazards and came to around a quarter of the shift working population. This is around 4.5% of the total employed workforce. Another point is that up to now not all wage-earners are medically surveyed but only those in enterprises above 250 employees. These numbers will be reduced in the course of the next years. What we see, however, is that especially in small enterprises the proportion of shift and night work is high. This means that the installation of new health service regulations is especially important for night workers. The stepwise increase of occupational health doctors in relation to the number of workers under surveillance - as is planned for the next years - might help to realise the recommended supervision. The cost/effectiveness of the proposed measures still have to be estimated. Besides the preventive aspect, absenteeism rates, fluctuation and related costs, invalidity pension, etc. should be considered.

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