Chapter Two.

Published Works Relating to Supermarket Checkout Safety

The Supermarket Checkout has been the subject of an immense amount of study over the last twenty years. Such studies have reviewed the design and operation of the checkstand from a number of perspectives ranging from operational efficiency through ergonomic assessment, and biomechanical analysis to customer perception.

This chapter attempts to provide an overview of this research, by theme. Firstly it identifies the typical designs of checkouts and their advantages and disadvantages. Then it looks at the range of health and safety issues which have been linked to checkout work. It considers researchers’ early concerns - primarily welfare linked, and looks in detail at more specific medical conditions which have been identified. It concludes with evidence from recent Health & Safety Executive research.

 

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It is suggested that this chapter is read in conjunction with Appendix One which further charts the progress of research in this field, and contains critiques of significant published works listed chronologically to illustrate how research has evolved.

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2.1 The Development of Supermarket Checkouts

Although considerable thought no doubt was put into the development of the original checkouts, designers had no ergonomic, biomechanical or epidemiological data on which to base their layouts. Accordingly early checkouts were of a very basic construction, a simple structure . They were functional, designed to house very heavy mechanical cash registers such as the one shown below which was from the early 1970s.

 

 

Figure 1 Typical Mechanical Cash Register Manufactured by Sweda C.1972

 

 

In the mid 1970s the Mechanical Cash Register began to be replaced by the new electronic cash register. This device required the operator to apply less pressure to the keys and was heralded as a means of increasing checkout speeds by in the region of 20%.

Little consideration had been given to worker welfare up until this point. The checkout task was known to be highly repetitive, and often physically demanding, however, the "risks" were seen as negligible. Such jobs were necessary and unavoidable.

Developments in computing power and the breakthrough of scanning technology were seen to have almost no drawbacks. The introduction of ‘Electronic Point of Sale Systems’ (EPOS) changed the face of retailing.

Scanning was first used in the UK around 1981 according to Wilson & Grey (1984). The task of routinely keying in price data was almost eliminated and the role of the checkout operator was de-skilled. Such changes were initially perceived as having only positive benefits for the operators who would find the task easier and would need to concentrate less. Employers were clearly enthusiastic to promote this development.

Despite the high initial capital investment required by EPOS and scanning systems it was perceived that staff costs could be reduced which could be equivalent to a 25% rise in the stores profitability (Anon 1979). Supporting the changes Hoffman & Cramer (1981) argued that it reduced both the cognitive and performance workload on operators.

A report by ICL suggested that such systems could have the following benefits:

 

Table 2. The Benefits of using EPOS systems.

w Reduced Human Error

w Increased Productivity

w Decreased Absenteeism due to Work Related Illnesses

w Decreased Labour Turnover

w Decreased Direct Cost of Recruitment and Training

w Decreased Risk of Accidents

w Improved Staff Well-being

w Improved Staff Attitudes

w Improved Company Image

w Satisfied Customers

From Grey, Norris & Wilson, 1987, Ergonomics in the Electronic Retail Environment. pp 2.

 

By the early 1980s it was acknowledged that checkouts had frequently changed to accommodate new equipment - but the stand itself changed only slightly. Wallersteiner, (1981 pp79), noted:

"the lack of change in check-stand design, combined with progressive innovations in work methods, has contributed significantly to health complaints of cashiers"

 

 

2.2 The Design of Supermarket Checkouts

There are numerous different designs of checkouts. They will contain different equipment, be of different ages, and will be adapted to the particular retailer’s physical needs and ‘house style’. To understand their possible impact on worker health and safety it is necessary to understand their design.

In studies of supermarket checkout designs Rodrigues and Flynn (1988) identified that most consisted of five key elements, in different configurations. The elements they identified were:

a. The feeder belt to the scanner,

b. The Scanner - which may be of a horizontal

or vertical beam type,

c. Produce scales / display / key-pad and cash drawer,

d. The bagging platform,

e. The bagging belt (to carry away scanned items).

 

Rodrigues (1989) recognised three typical component configurations, which were named according to the position of the worker relative to the flow of the items. Grant et. al. (1993) classified a further three types. The following table indicates the generic types classified.

 

 

Table 3. Basic Types of Checkouts Identified by Researchers

Checkout Type Rodrigues (1989) Grant et. al.(1993)
Side Facing Checkout ü ü
Front Facing Checkout ü ü
Right Hand Take-Away Checkout ü ü
Over The Counter Checkout ü  
Over The End Checkout ü  

Side Facing Checkout (With no take away belt)

ü  
"Checkout Type" descriptor taken from phraseology used by Grant et. al.(1993) Rodrigues, citing Hoffman refers to an 'Over The End Checkout' which Grant terms 'Right Hand Take-Away Checkout'.

This section now briefly looks at each of these design types in turn and identifies their merits and disadvantages according to published research.

2.2.1 Side Facing Checkout

In this design the operator stands (or sits) in line with the customer, typically with a key-pad and cash drawer to their right, slightly behind them, and the scanning device (of a vertical scanning type) in line with the input belt. The design is elongated, yet relatively compact.

This orientation requires the operator to draw products into the body, but the operator's position requires the trunk to be twisted and shoulders abducted. It is not possible to keep the wrists straight. The customer will typically stand to the left and slightly behind the cashier requiring the cashier to twist to converse and receive payment. This design is illustrated by Figure 2.

 

 

Figure 2. Side Facing Checkstand.

 

Illustration based upon: Grant et al (1993)

 

2.2.2 Front Facing Checkout

This checkout arrangement has the cashier facing the customer, and the scanner placed between the two people, mounted horizontally. Products flow parallel to the operator - usually arriving to the operators right hand. Displays and key pad are typically in front of the cashier - commonly raised above the bench. Alternatively, in this set-up, they may be to the operators right. This design promotes a two handed operation. One hand may select and orientate the product, whilst the other may then scan and place the item on the take-away belt. Loading on the wrists is lower than single handed scanning operations.

The disadvantage of this design is that it requires a relatively large amount of floor space. Figure 3 shows a typical configuration of the elements in this design.

 

 

Figure 3. Front Facing Checkstand.

 

Illustration based upon: Grant et al (1993)

 

A variation of this design incorporates a 'workplate', an area of counter immediately in front of the operator between the end of the input belt and the scanner, which allows the operator to orientate and manipulate items, without necessarily lifting them, before attempting to pass them over the scanner. Such a space makes the motion across the scanner more fluid, since the scan area is less cramped.

2.2.3 Right Hand Take-Away Checkout

The cashier stands facing the flow of goods, with the vertical scanner immediately in front of the input belt. The customer stands to the left of the cashier. After scanning the goods they are placed on a take away belt which starts parallel to the cashiers right hand. The operation is somewhat similar to selecting from 1st to 4th gear in a car. Rodrigues (1989), describes a similar configuration as the Over The End Counter checkout (see 2.2.5 below). It is illustrated by Figure 4.

 

 

Figure 4. Right Hand Take-away Checkstand.

 

Illustration based upon: Grant et al (1993)

 

2.2.4 Over The Counter Checkout

This variation is very similar to the front facing checkstand (2.1.2) but does not have a goods input belt. It is the task of the cashier to unload goods directly from the shopping trolley, before scanning them (usually with a horizontally mounted vertical scanner) and placing then on to the take away belt. For this reason this configuration is sometimes also referred to as 'checker- unload'. The keyboard and cash drawer may either be located in front or to one side of the operator. Grant et. al. (1993) reported that ergonomists assessed this design as poor, because the operator needed to lift, rather than slide groceries from a belt, and often needed to reach excessively i.e. to retrieve goods from the back, and base, of the trolley.

Using this system operators often had to reposition the trolley so that they could remove goods from it. Herrin (1991) found that such moving of loaded trolleys placed excessive loading on the upper body muscles. Figure 5 illustrates where the trolley would be positioned, and how the operator would have to reach to retrieve goods.

 

 

Figure 5. Over The Counter Checkstand.

 

Illustration based upon: Grant et al (1993)

A subsequent study of this type of checkout (Grant et. al. 1994) noted that this type of checkout was becoming increasingly popular in the US since it was seen as an additional customer service - i.e. the customer was not required to unload their own trolley - and that it was a service that customers had come to expect. This study compared the operation of the checker-unload system with the front facing customer unload design and tested the hypothesis that the former was "associated with a higher frequency of awkward postures and forceful movements during grocery checking tasks" (Grant et. al. 1994 pp.311). It proved this hypothesis and recommended that designs be altered to incorporate a feed belt, and job rotation be practised.

 

2.2.5 Over The End Checkout

Here the cashier stands 'over the end' of the vertical scanner which lies immediately after the input belt. The flow of the items is head on into the body of the cashier. the key-pad and cash drawer are at 90° to the operator - typically on the right.

Although the operator does not need to rotate the body to receive goods, such rotations are often necessary to place goods on take-away belts (where provided). The 'square-on' positioning of the cashier leads to a tendency to bend forward to pick-up items from the belt as they approach. Rodrigues (1987) suggests that such reaching forward can extend to 60cm and, if it occurs routinely, places excessive strain on the upper body muscle groups. Some variations of this design place a bagging platform between the operator and the scanner. As bags become full the operator strives to reach over the bags, and reach levels are further extended. Figure 6 illustrates one variation of this type of checkout.

 

 

Figure 6. Over The End Checkstand.

 

Illustration based upon: Grant et al (1993)

 

2.2.6 Side Facing Checkout (With no take away belt)

This is a simple variation of the side facing checkout described above (2.1.1), this time with no take away conveyor. In this design the operator bags the majority of the groceries on a bagging platform, to the cashier’s left, before lifting the bags onto a collection area. Figure 7 shows this type of checkout.

 

 

Figure 7. Side Facing Checkstand with no take-away conveyor belt.

 

Illustration based upon: Grant et al (1993)

2.2.7 The Positioning of the Scales

Johansson et. al. (1993) investigated the ergonomic merits of locating the scales at two different points, firstly to the left of the cashier - a traditional location, and secondly, below the conveyor belt. The findings of their small scale pilot study of two operators suggested that the second location was favourable. Mounting the scales below the conveyor belt was said to decrease the handled weights, improve the working position of the left arm and improve wrist action.

 

 

2.2.8 The Ideal Design

Can there be a definitive checkout design? This question is, perhaps, still to be answered - however, most authors have expressed an opinion.

Rodrigues (1989), argues that the "more ergonomically sound" (pp.958) design would be the front facing configuration described above (2.1.2). This design is thought to prevent some of the awkward hand and wrist combinations forced by the others, and almost eliminates the need for bending or reaching and associated shoulder abduction.

Grant et. al. (1993) suggests that the goods input conveyor should deliver goods directly to the scanner (whilst Rodrigues argues the merits of a 'workplate'). The scanner itself should be positioned between 31 and 34 inches above the floor. Several experts preferred the scanners to be mounted to scan horizontally so that goods could be slid along a work plate and did not need to be carefully lifted over the delicate scanner window.

Barron & Habes (1992) suggested that both the scanner and the scale should be mounted directly in front of the cashier, to eliminate the need to twist the trunk. The keyboard should be above the scanner and be fully adjustable - so that it could be moved left or right, and be tilted as preferred.

A study by Strasser et. al. (1991) investigated the effects on various muscle groups during the lifting and moving of products across a simulated scanning area. With the checkout operator seated and with the workplace either face-on or side-on to the work station. The study concluded that the movement of products from left to right was preferable.

Carrasco et.al. (1995) looked in detail at the ancillary task of bagging produce for customers. This area had typically been ignored but was proven to be yet another example of poor ergonomic design of the checkstand. Design alterations were proposed and tested proving that changes could be made and potential problems could easily be eliminated.

 

 

2.3 Early Investigator’s Concerns

Since the ‘retail revolution’ is perceived to have occurred within the last two decades some might assume that before this period there were no recognised problems linked to checkout (or cash register) operators, and that retailers had not been unduly slow to act. This presumption is, however, flawed.

There is a significant body of research which was published between 1960 and 1980, which shows that many current concerns had been formerly identified. These concerns, which are mainly connected with worker welfare issues, are investigated below.

 

2.3.1 Seating.

Carlsöö (1967), investigated the seating needs of checkout workers and found that cashiers worked best when seated - but that the amounts of lifting and reaching involved meant that a standing position often had to be adopted. Main (1975), observed that cashiers were spending 50% of their time standing because they found a range of their work activities uncomfortable whilst seated.

 

2.3.2 Muscular Stress.

Nishiyama et. al. (1973) reported that 71% of Japanese checkout workers reported muscular conditions associated with the neck shoulder and arm. Busch (1978), discussed the different weights which cashiers were commonly moving and observed that postural constraints resulted in muscular fatigue. Corlett & Bishop (1976), found that cashiers work routine forced them to overload muscles and tendons and to load joints in an uneven manner which commonly resulted in fatigue, pain or injury.

 

2.3.3 Environmental Stressors

Poorly positioned and maintained lighting commonly caused glare problems and high levels of ambient noise and the mundane, repetitive, nature of the task made concentration difficult. Various authors - including Umeda (1974), Ahola (1975), Nakeseko (1975 a&b) and Ohara et al. (1976), concluded that the fundamental problems experienced by cashiers stemmed from overwork in conjunction with poor lighting and badly designed equipment. Poor thermal comfort (generally too cold) and inadequate protection from draughts was also identified by Salord (1978).

 

2.3.4 Work Organization

Frequently checkout operators had poor work programmes, with insufficient job rotation. They may have spent extended periods on a busy express checkout and had infrequent breaks - especially among part-time staff who may work for up to four hours without a respite (Ivergard (1972) and Ohara et. al. (1976)). Such authors have suggested that the improved operational efficiency of the staff would more than offset the loss of productivity envisaged by offering breaks. Onishi et.al. (1974) advocated that checkout work spells should not exceed 60 minutes, and Hari (1976) expressed that limits on checkout work hours were necessary to combat occupational ill-health.

 

2.4 Health Effects & Possible Injuries

In recent years the levels of research into health and safety issues related to supermarket checkouts have intensified and begun to focus on medical issues. All researchers identified have shown that there is a high level of dissatisfaction amongst employees with this work operation. Such levels of dissatisfaction are known to be linked to higher levels of symptom reporting. However, do such reported symptoms stem from medically diagnosable conditions? The findings of Wallersteiner (1981) are typical, indicating that there remain a number of design shortfalls which do have adverse health effects on workers.

This section will now concentrate on these health effects (and in some cases injuries), which researchers claim are linked to checkout work.

 

2.4.1 Carpal Tunnel Syndrome & Hand / Wrist Pain

Carpal Tunnel Syndrome is "the compression of the median nerve at the wrist as it travels with the flexor tendons through the carpal tunnel" (Dyck 1982, as in: Margolis & Kraus 1987a pp953). In recent years numerous researchers have investigated this injury. Of note are the studies of Margolis & Kraus (1987 a&b.), whose research which is based upon self reported symptoms rather than clinical evidence, showed that the prevalence of this condition increased with the age of the worker with the highest reported rates of 76% being for women in the age group 35-49 years. They suggested that rates of carpal tunnel syndrome were higher amongst checkout operators who used laser scanning equipment than those who used older forms of price data entry. The numbers of years worked as a checkout operator and the number of hours worked per week were also suggested to have a positive correlation to the occurrence of the condition. Commentators such as Coe (1988), criticised this work because of its limited scale.

Barnhart & Rosenstock (1987) reported similar findings. They investigated a cluster of 7 cases among grocery workers, finding workers often handled more than 500 items and could fill more than 80 bags per hour. They could find no other identifiable risk factors which would trigger the condition other than their occupation. Morgenstern et. al. (1991) believed that the development of laser scanning checkouts had increased the risk of checkout operators suffering carpal tunnel syndrome.

2.4.2 Neck and Shoulder Disorders.

Several authors including: Nakeseko (1975b), Ohara et al. (1976) and Sällström & Schmidt (1984) have commented that the levels of neck and shoulder (cerviobrachial) disorders amongst cashier workers were higher than amongst control groups. Maeda (1977), Waris (1980), Bjelle et. al. (1981) and Hagberg (1984) have explored the complicated etiology of such conditions.

In a small scale survey of 23 checkout workers, Orgel et. al. (1992) found that 96% suffered some neck and shoulder discomfort, and in 41% of these, symptoms were severe.

Lannersten & Harms-Ringdahi (1990) studied electromyographic activity of muscle groups. Expressing their results as time-averaged myoelectrical potential (TAMP) they found that levels of muscle activity in the neck and shoulders were higher than safe levels recommended by previous research. However, they note that the clinical relevance of such data is unclear.

In a study of Swiss checkout operators, Hinnen et. al. (1992) noted that reporting of left shoulder symptoms were noticeably elevated in checkout workers compared to keyboard operators, however, such symptoms could not be confirmed by medical examinations.

Acknowledging the findings of Sällström & Schmidt (1984), who suggested that 76% of checkout workers (compared to 40% of office workers) suffered from neck and shoulder disorders, they considered that this was probably due to the high levels of static activity routinely performed by checkout workers.

They found that muscle activity was significantly higher among workers using scanners than older cash register systems and was higher when standing rather than sitting. They conclude:

"that cashier work - the repetitive handling of merchandise - no matter what cash register system is used, causes excessive static neck and shoulder muscle load"

Lannersten & Harms-Ringdahi (1990 pp.63)

2.4.3 Lower Back Pain.

Using the results from his research, which had more than 500 respondents, Ryan (1989) discovered that the lower back was the area with the highest rate of symptoms. Such complaints were the most common musculoskeletal symptom which had 'prevented usual work at least once in the past year' Ryan also found a positive association between the reported prevalence of lower back pain and the amount of time spent standing (standing typically accounting for 89.8% of the surveyed checkout operators posture).

 

 

Table 4. Prevalence of regular back pain symptoms by department and body area. (rate per 10,000 person hours)

Department

Body Area
  Upper Back Lower Back
Checkout 8.3 17.4
Grocery 3.8 8.7
Store & Nightfill 5.7 7.1
Speciality 3.6 10.0
Management & Office 1.3 5.2

Source: Ryan (1989, pp.365)

 

Ryan's work was by no means the first in this area. Kimura et. al. (1979) writes of a three year study of 5,000 Japanese supermarket workers which identified high levels of back pain and, although not able to directly link the condition to supermarket checkout work alone, suggested the necessity for check-ups by orthopaedic doctors and further research into the condition.

 

2.4.4 Lower Leg, Ankle and Foot Pain.

Ryan (1989) also noted a significant amount of reported lower leg and ankle / foot pain expressed by checkout operators. Rates of reported symptoms were in excess of double those for grocery, delicatessen, fruit and vegetable, nightfill or storeroom staff, who had otherwise similar occupations.

 

 

Table 5. Prevalence of regular lower body pain symptoms by department and body area. (rate per 10,000 person hours)

Department Body Area
  Lower Limb Ankle & Foot
Checkout 10.3 11.6
Grocery 3.8 2.3
Store & Nightfill 0 1.4
Speciality 2.9 2.9
Management & Office 4.5 3.2

Source: Ryan (1989, pp.365)

 

 

Buckle et. al. (1986) proved a dose-response relationship between reports of foot pain in department store and checkout workers and time spent standing during the working day.

 

2.4.5 Cumulative Trauma Disorders (CTDs)

So far we have looked at effects attributed to specific parts of the body. However, a growing body of research shows that there may be a more systemic effect. Grant et.al. (1993) suggested that "Increasing evidence suggests that musculoskeletal disorders are common in the US. retail food industry. Cashiers who use electronic scanners appear to be at especially high risk for upper extremity cumulative trauma disorders (CTDs)."(pp.929)

Ryan (1989) investigated the prevalence of musculoskeletal disorders in detail. In an extensive study of 7 supermarkets of varying size 1/3 of the 705 respondents reported regular symptoms in some part of the body.

One of the latest studies on this subject, Marras et al (1995) suggested that the activities required to scan items do have the potential for causing CTDs - but that alterations to the design of the work station can substantially reduce movements necessary and can significantly reduce the risk of such injuries.

 

2.5 Recent Research

The volume of research investigating all aspects of supermarket checkouts has shown a marked increase in the last ten years. A brief perusal of the bibliography at the end of this study should prove this.

Whilst much of this research has focused upon the health effects and ergonomic interventions - which have been reviewed in the preceding sections, some had again focused on more physical aspects of the job - such as work organization. Of particular note is the work of Hinnen et. al. (1992).

Hinnen's findings compare favourably with those of Ohara (1976) which were discussed previously. Hinnen argued that work practices were as much a cause of ill health as the designs of the checkouts themselves. Supporting this hypothesis Hinnen contends that part time workers suffer similar symptoms to those of permanent employees because they are employed to cover periods of the highest work load. Again the merits of job rotation were proposed.

Authors have also turned their attentions again to psychosocial issues. It has been contended that reporting rates for musculoskeletal symptoms are not always simply related to physical tasks. Spurgeon et. al. (1996) suggested that exposed and non exposed populations could have similar patters of symptom prevalence. Ekberg et al (1994) demonstrated that psychosocial influences - beliefs and attitudes, are as important as physical work related factors in the reporting of neck and shoulder symptoms. Burton et. al. (1997), studying a group of nurses, contended that certain individuals could be more positive about pain, work and activity and as such would report symptoms less frequently than a group undertaking lighter tasks which were deemed to have depressive tendencies. Burton concluded that in this case low back pain was not directly linked to workload.

Researchers agree that symptom reporting is clearly a complex topic - and a relatively new area of study. It is linked to factors such as job satisfaction, relationships with work colleagues, and perceived value within an organisation. Nevertheless, it must be remembered that simply because certain groups are more or less inclined to comment, does not mean that they do not all face the same risks.

There is also evidence to suggest that workers are becoming increasingly concerned about the possible dangers of the electromagnetic fields (EMF) in which they work. Fields will be created by the scales, scanner, computer equipment, and is some cases EMF security equipment. Research in this area is expected in the near future.

Perhaps the most thorough research, commissioned in the United Kingdom, in recent years, has been undertaken by the Health & Safety Executive (HSE). The remained of this chapter now focuses upon this work, and its origins.

 

2.6 Health & Safety Executive Research

In response to concerns expressed mainly by Environmental Health Officers, an ad hoc working group was established by the Health and Safety Executive (HSE). To ensure co-ordination between various interest groups, a one-day workshop was set up by the Executive. This took place on the 4th July 1988 and was organised by the Robens Institute at the University of Surrey.

From the Workshop, HSE received several initiatives to consider. The Executive indicated that it was intent on further thorough investigation to clarify the extent of the health problems associated with checkout operation and proposed that it would subsequently produce guidance on what are desirable working practices at checkouts (Dickinson 1989).

 

Following the 1988 workshop the Health and Safety Executive commenced a detailed study of the problems with musculoskeletal disorders amongst supermarket cashiers. The researchers, who included advisors from the Spinal Research unit of the University of Huddersfield, believed that a report was necessary because of "the limited extent of contemporary information and advice in respect of musculoskeletal disorders amongst checkout workers" (HSE 1998 pp3)

This report is the largest to date ever undertaken into supermarket cashier health and safety issues in the UK. More than 50 British supermarkets were involved and almost 2,000 cashiers participated.

The study was broken down into a number of elements:

  • Epidemiological Survey

  • Ergonomics Field Study

  • Biomechanics Study

2.6.1 HSE’s Epidemiological Survey

HSE used a Musculoskeletal Disorders Questionnaire, in order to attempt to quantify the discomfort and disability amongst checkout workers. The eight page questionnaire sought information of worker demographics and data relating to discomfort to nine areas of the body. A diagram was supplied clarifying the regions which the descriptions related to. A copy of the diagram is reproduced below to show the regions under study.

 

 

Figure 8. Nine Regions of the Body - the subject of the HSE

Musculoskeletal Disorders Questionnaire.

 

Answers were sought relating to both a seven day period and twelve month period. Work history was also requested. A twelve point General Health Questionnaire was also administered to determine ‘general well being’. The survey also attempted to gain an insight into workers general level of job satisfaction using a third questionnaire exploring satisfaction (and dissatisfaction) with their checkout, chair, work environment, work organisation and work activities.

The survey sample consisted of 1830 checkout operators from 47 sites. They were the employees of nine retailers and between them they operated 10 types of checkout.

 

The survey found that for 92% of the sample (1830 workers) supermarket work was their only paid job. On average they worked 20.6 hours and spent in excess of three quarters of this time on checkouts. 74% of the sample had additional rest periods in addition to statutory meal breaks, of those 53% had more than one break. Only 20% of the sample worked under a job rotation system.

The majority of workers did not identify that they experienced any difficulty using scanner, scales and till. Most of the sample said that they did adjust their seating where adjustment was possible, however, many identified difficulty adjusting their seat backrest (52.2%), their seat height (78.2%), the position of their seat (78%), and a smaller proportion identified problems with adjusting their foot rest (26.1%).

There was a high incidence of musculoskeletal symptom reporting. 81% stated they had experienced problems in at least one of the nine body areas within the last 12 months. 60% identified problems in more than one body area and a significant group, accounting for some 15% suggested that they had had problems in five or more areas.

 

18% of the sample had consulted a medical practitioner in connection with shoulder pain and 27.2% had done the same in connection with lower back pain. 21% of the sample (379 cashiers) had been absent from work at some stage in the proceeding twelve months due to a musculoskeletal injury.

Comparing details of reported symptoms from this study with a larger referent data set it was demonstrated that levels of musculoskeletal reporting was high across a number of occupations. The level of lower back complaints was seen as higher than the comparison population, but that elbow and wrist complaints were much lower.

The following table (table 6) identifies the annual prevalence of reported symptoms. Figures in bold italics depict areas where the data is statistically significantly different between the populations.

 

 

Table 6. Reported musculoskeletal symptoms by cashiers

 

HSE Cashiers

(Sample 1,545)

HSE Referent Data

(Sample 4,707)

 

% Reporting

Rank

% Reporting

Rank

Neck

34.6%

2

43.5%

2

Shoulders

37.3%

3

41.0%

3

Elbows

10.3%

9

11.8%

9

Wrists

23.6%

5

38.7%

4

Upper Back

25.6%

4

24.8%

5

Lower Back

56.7%

1

48.0%

1

Hips

17.3%

7

16.2%

8

Knees

17.8%

6

20.0%

6

Ankles

13.6%

8

16.6%

7

 

Figure 9. Reported Musculoskeletal Symptoms Amongst Female Workers

Data from the satisfaction survey suggested that seating was an important issue. with a significant number identifying dissatisfaction with the ability to adjust the backrest, the ability to lean back and use the support of the back rest, the condition of the chair, and the ability to move the seat, amongst others.

Checkout type also affected workers over all job satisfaction level, although not to the same extent as seating. Conveyor systems were preferred to chute systems and to trolley load/unload systems. The limited amount of space was a common subject of complaint as was the positioning of items such as carrier bags etc.

Dissatisfaction levels for the categories of ‘Environment’ (noise, lighting, temperature etc.), ‘Work organisation’ (weekly hours, overtime, training pay etc.), and ‘Job activity’ (customer interaction, breaks, use of equipment, etc.) were all high but did not differ significantly from other occupational groups forming the referent data.

 

2.6.2 HSE’s Ergonomics Field Study

 

Based on site visits, physical descriptions of checkouts were compiled identifying type and standards of seating provided, heights of workstations, configurations of equipment etc. Video task analysis of 256 workers from 31 stores was used to identify the range of movements used by the checkout worker and to identify if the design of the workstation caused awkward postures.

This evidence also allowed workload to be quantified - it identified the number of items handled and range of tasks undertaken.

A smaller sample of workers were studied to collect data for computer modelling of typical movements and body posture.

 

Seating in 20% of stores was found to be of a non height adjustable form. Only 20% of those designed to be adjusted could easily be altered. Many seats did not have back rests which could be varied to change the height and angle of the support. Where supports should have been capable of being repositioned, many of the mechanisms were defective. Footrests were provided in 60% of the stores. Seated provision generally failed to meet ergonomic requirements.

Workstation height was found to be on the whole acceptable for the types of seating used, however, reach envelope modelling suggested that key components were often poorly located and lay outside the normal reach envelope.

 

Stills photography and video tape evidence of posture, showed numerous examples of awkward posture routinely being adopted during the checkout process. Problems were particularly linked to stacking baskets, picking up carrier bags from their storage areas, and assisting customers load their bags.

 

2.6.3 HSE’s Biomechanics Study

Using a checkout constructed in a laboratory, two groups of eight checkout workers scanned 18 standard grocery items with the checkout configured in eight different ways.

Using a motion analysis system, upper body movements were recorded. Wrist movement/angle was also measured, as was electromyographic activity in the seven main upper body muscle groups.

1 The hypothesis that sitting was preferable to standing was tested. Standing was found to reduce biomechanical loading on the upper body. It also reduced upper arm elevation and enables the worker to better position themselves for lifting tasks.

It was found that placing the scanner in an offset position required increased muscle activity for raising and supporting the left arm. This was considered ergonomically undesirable. There was no significant difference between vertical and horizontal scanner configurations in terms of its impact on upper body musculoskeletal loadings.

It was found that cashiers worked faster with familiar checkout configurations and that they had a tendency to lift, rather than slide goods - possibly linked to the need to lift goods across older delicate horizontal scanner windows.

 

2.6.4 Outcome Of HSE’s Research

HSE intend to publish the outcome of their investigation as a technical report. It is anticipated that this document will be entitled "Musculoskeletal Disorders in Supermarket Cashiers" and will be available from mid 1998.

It is also anticipated that a summary / worker information leaflet will also be produced along with a Local Authority Circular offering advice on inspection procedures for enforcement officers and assessment advice for employers.

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