Bente Schibye

Collection of domestic waste. Review of occupational health problems and their possible causes.

During the last decade, a growing interest in recycling of domestic waste has emerged, and action plans to increase the recycling of domestic waste have been agreed by many governments. A common feature of these plans is the implementation of new systems and equipment for the collection of domestic waste which has been separated at source. However, only limited information exists on possible occupational health problems related to such new systems. Occupational accidents are very frequent among waste collectors. Based on current knowledge, it appears that the risk factors should be considered as an integrated entity, i.e. technical factors (poor accessibility to the waste, design of equipment) may act in concert with high working rate, visual fatigue due to poor illumination and perhaps muscle fatigue due to high work load. Musculoskeletal problems are also common among waste collectors. A good deal of knowledge has accumulated on mechanical load on the spine and energetic load on the cardio-pulmonary system in relation to the handling of waste bags, bins, domestic containers and large containers. However, epidemiologic studies with exposure classification based on field measurement are needed, both to further identify high risk work conditions and to provide a detailed basis for the establishment of occupational exposure limits for mechanical and energetic load particularly in relation to pulling, pushing and tilting of containers. In 1975, an excess risk for chronic bronchitis was reported for waste collectors in Geneva (Rufèner-Press et al., 1975) and data from the Danish Registry of Occupational Accidents and Diseases also indicate an excess risk for pulmonary problems among waste collectors compared with the total work force. Surprisingly few measurements of potentially hazardous airborne exposures have been performed, and the causality of work-related pulmonary problems among waste collectors is unknown. Recent studies have indicated that implementation of some new waste collection systems may result in an increased risk of occupational health problems. High incidence rates of gastrointestinal problems, irritation of the eye and skin, and perhaps symptoms of organic dust toxic syndrome (influenza-like symptoms, cough, muscle pains, fever, fatigue, headache) have been reported among workers collecting the biodegradable fraction of domestic waste. The few data available on exposure to bio-aerosols and volatile compounds have indicated that these waste collectors may be simultaneously exposed to multiple agents such as dust containing bacteria, endotoxin, mould spores, glucans, volatile organic compounds, and diesel exhaust. Several studies have reported similar health problems as well as high incidence rates of pulmonary disease among workers at plants recycling domestic waste.(ABSTRACT TRUNCATED AT 400 WORDS)

Sorting and recycling of domestic waste. Review of occupational health problems and their possible causes

In order to reduce the strain on the environment from the deposition of waste in landfills and combustion at incineration plants, several governments throughout the industrialized world have planned greatly increased recycling of domestic waste by the turn of the millennium. To implement the plans, new waste recycling facilities are to be built and the number of workers involved in waste sorting and recycling will increase steadily during the next decade. Several studies have reinforced the hypothesis that exposure to airborne microorganisms and the toxic products thereof are important factors causing a multitude of health problems among workers at waste sorting and recycling plants. Workers at transfer stations, landfills and incineration plants may experience an increased risk of pulmonary disorders and gastrointestinal problems. High concentrations of total airborne dust, bacteria, faecal coliform bacteria and fungal spores have been reported. The concentrations are considered to be sufficiently high to cause adverse health effects. In addition, a high incidence of lower back injuries, probably due to heavy lifting during work, has been reported among workers at landfills and incineration plants. Workers involved in manual sorting of unseparated domestic waste, as well as workers at compost plants experience more or less frequent symptoms of organic dust toxic syndrome (ODTS) (cough, chest-tightness, dyspnoea, influenza-like symptoms such as chills, fever, muscle ache, joint pain, fatigue and headache), gastrointestinal problems such as nausea and diarrhoea, irritation of the skin, eye and mucous membranes of the nose and upper airways, etc. In addition cases of severe occupational pulmonary diseases (asthma, alveolitis, bronchitis) have been reported. Manual sorting of unseparated domestic waste may be associated with exposures to large quantities of airborne bacteria and endotoxin. Several work functions in compost plants can result in very high exposure to airborne fungal spores and thermophilic actinomycetes. At plants sorting separated domestic waste, e.g. the combustible fraction of waste composed of paper, cardboard and plastics, the workers may have an increased risk of gastrointestinal symptoms and irritation of the eyes and skin. At such plants the bioaerosol exposure levels are in general low, but at some work tasks, e.g. manual sorting and work near the balers, exposure levels may occasionally be high enough to be potentially harmful. Workers handling the source-sorted paper or cardboard fraction do not appear to have an elevated risk of occupational health problems related to bioaerosol exposure, and the bioaerosol exposure is generally low.(ABSTRACT TRUNCATED AT 400 WORDS)

A dynamic 3D biomechanical evaluation of the load on the low back during different patient-handling tasks.

The objective of this study was to investigate the low-back loading during common patient-handling tasks. Ten female health care workers without formal training in patient handling performed nine patient-handling tasks including turning, lifting and repositioning a male stroke patient. The low-back loading was quantified by net moment, compression, and shear forces at the L4/L5 joint, measured muscle activity (EMG) in erector spinae muscles and rate of perceived exertion (RPE; Borg scale). The experiments were videotaped with a 50Hz video system using five cameras, and the ground and bedside reaction forces of the health care worker were recorded by means of force platforms and force transducers on the bed. The biomechanical load was calculated using a dynamic 3D seven-segment model of the lower part of the body, and the forces at the L4/L5 joint were estimated by a 14 muscles cross-sectional model of the low back (optimisation procedure). Compression force and torque showed high task dependency whereas the EMG data and the RPE values were more dependent on the subject. The peak compression during two tasks involving lifting the patient (4132/4433N) was significantly higher than all other tasks. Four tasks involving repositioning the patient in the bed (3179/3091/2932/3094N) did not differ, but showed higher peak compression than two tasks turning the patient in the bed (1618/2197N). Thus, in this study the patient-handling tasks could be classified into three groups-characterised by lifting, repositioning or turning-with different levels of peak net torque and compression at the L4/L5 joint.

Biomechanical analysis of the effect of changing patient-handling technique

The objective of the study was to assess the changes in the mechanical load on the low-back when shifting from a self-chosen to a recommended patient-handling technique. Nine female health care workers without formal education in patient-handling carried out 8 different tasks involving moving, turning and lifting situations. By means of a dynamic 3D biomechanical model of the lower part of the body, peak torque, compression and shear forces at the L4/L5 joint were compared using the two different patient-handling techniques. In 5 of the 8 tasks, a significant reduction was observed in spinal loading. Application of the recommended technique decreased the compression value significantly for all tasks with a mean value above 3000 N. For the two tasks with the highest compression values when using the self-chosen technique (4223, 4446 N), the loading was reduced with 36% and 25%, respectively. If the principles behind the recommended technique are implemented and maintained, a decrease in the risk of low-back disorders during patient-handling should thus be expected.

Reliability of isometric muscle strength tests for the trunk, hands and shoulders

The objective of this study was to determine the reliability of isometric muscle strength tests for the trunk, hand and shoulders. At the same time the inadequacy of correlation coefficients as useful manifestation of reliability was highlighted. Nineteen healthy subjects performed a test and retest with exactly 1 week interval. The measurements consisted of recordings of maximal voluntary contractions (MVC) during isometric back flexion, back extension, shoulder elevation, shoulder abduction and handgrip. No habituation to the equipment was made before the initial test since this is often for practical reasons not possible in occupational settings. All Pearson and Intraclass correlation coefficients showed r-values above 0.9. However, a significant increase from test to retest was present in the muscle strength measures for back flexion, back extension and handgrip. In conclusion all tests showed reasonable reliability on group level judged by 95% confidence intervals, however on the individual level the variation was wide according to the calculated limits of agreement. If this variation is not taken into consideration the tests can be of limited use on individual level. Finally, this study clearly showed the inadequacy of correlation coefficients as a single number estimate of reliability.Relevance to industryIn this study we have looked at isometric strength tests, which are applicable at the workplace for measuring shoulder, hand and trunk strength. In the description of the relationship between work demands and workers capacity these measures are important.

Shoulder muscle load and muscle fatigue among industrial sewing-machine operators

SummaryPhysiological responses to physical work were assessed for 29 female industrial sewing-machine operators during an 8-h working day under ordinary working conditions. During sewing-machine work, the average (left and right) static load in the trapezius muscle was 9% of the maximal electromyogram (EMG) amplitude (% EMGmax), while the average mean load was 15% EMGmax, and the average peak load was 23% EMGmax. The static load level was unrelated to the muscle strength of the sewing-machine operators, which for the group as a whole was within the normal range. The load levels remained unchanged during the working day, while changes in the EMG mean power frequency and zero crossing frequency rate occurred, both indicating the development of muscle fatigue in left and right trapezius muscle during the working day. In line with this, the rating of perceived exertion in the shoulder and neck region increased during. the working day. Dividing the group of sewing-machine operators into two groups, those with the highest frequency and those with the lowest frequency of shoulder/neck troubles showed that the former group had significantly lower muscle strength, despite the fact that no differences in the surface EMG during sewing were found between the two groups. It was concluded that industrial sewing-machine work involves a pattern of shoulder muscle activity which induces fatiguing processes in the shoulder and neck regions. Furthermore, since the static shoulder muscle load was independent of muscle strength, factors other than working posture may be of significance for the static shoulder muscle load.

Mechanical load on the low back and shoulders during pushing and pulling of two-wheeled waste containers compared with lifting and carrying of bags and bins

OBJECTIVE Compare the mechanical load on the low back and shoulders during pushing and pulling a two-wheeled container with the load during lifting and carrying the same amount of waste. BACKGROUND Only little is known about risk factors and mechanical loads during push/pull operations. DESIGN A complete 2(3) factor push/pull experiment. A two-wheeled container with 25 or 50 kg was pushed in front of and pulled behind the body by seven waste collectors. Further, the same subjects lifted and carried a paper bag and a dustbin both loaded with 7 and 25 kg. METHOD All operations were video recorded and the push/pull force was measured by means of a three-dimensional force transducer. Peak Motus and Watbak software were used for digitising and calculation of torque at L4/L5 and the shoulder joints and compression and shear forces at L4/L5. RESULTS During pushing and pulling the compression at L4/L5 is from 605 to 1445 N. The extension torque at L4/L5 produced by the push/pull force is counteracted by the forward leaning of the upper body. The shear force is below 202 N in all situations. The torque at the shoulders is between 1 and 38 Nm. CONCLUSION In the present experiments the torques at the low back and the shoulders are low during pushing and pulling. No relation exists between the size of the external force and the torque at the low back and the shoulder. RELEVANCE Pushing and pulling are common in many workplaces and have often replaced lifting and carrying situations. This has emphasised the need for more knowledge of the internal mechanical load on the body during these activities.

Aerobic power and muscle strength among young and elderly workers with and without physically demanding work tasks

The aim of the study was to investigate the effect of waste collection on the physical capacity of the workers. A total of 19 young and 28 elderly male waste collectors and two age-matched control groups participated. The aerobic power was estimated. The maximal isometric muscle strength was measured for back extension and flexion, shoulder elevation and abduction, and handgrip. The aerobic power was lower among the elderly workers compared with the young workers of both groups. No differences were found between waste collectors and control groups. A general tendency to larger muscle strength was found for both young and elderly waste collectors compared with the control groups. Waste collectors generally have a higher physical capacity than the control groups which is an indication of an early selection of the young waste collectors. With respect to the elderly waste collectors, the job seems to have a training effect especially for the shoulder muscles. No training effect is found for the aerobic power, and a discrepancy between work demand and individual aerobic capacity may occur among elderly workers resulting in a negative health effect unless the work task is evaluated according to age dependent criteria.

Increase in spinal stability obtained at levels of intra-abdominal pressure and back muscle activity realistic to work situations

In this study, sudden load was applied to the trunk and situations with alternating low levels of intra-abdominal pressure (IAP) realistic to work situations were compared. The aim was to see if IAP and the small increases in co-contraction of back muscles that follow are capable of increasing the stiffness of the lumbar spine. Nine subjects participated in ten sudden load situations during which they were asked to hold a box and conduct a percentage of maximal IAP. The hip was fixed and the load was applied horizontally on the trunk. EMG, IAP, and movement of the trunk were measured. It was found that IAP of a size likely to appear in work situations, and the concomitant increase in muscle co-activation increased the spine stiffness. This increase in stiffness decreased the movement caused by the sudden load. These results show that both abdominal- and back muscles may have an important role in stabilising the spine, and in decreasing movements caused by sudden loads likely to appear in numerous work

Measures of low back function: A review of reproducibility studies

OBJECTIVE The objective of the present study was to make a systematic literature review with preset quality criteria concerning reproducibility of the tests of the low back regarding strength, endurance and range of motion. DESIGN Literature in Medline and local databases was reviewed for articles concerning the reproducibility of strength, endurance, and range of motion measurements. BACKGROUND Measures of low back function are widely used, and are important for both clinical and research purposes in relation to low back problems. A review of the reproducibility of these tests has not previously been made. METHODS After extensive discussion among all the authors, general evaluation parameters were defined for the quality assessment. Every study was graded from 0 to 2 for each parameter. Parameters evaluated were: number of subjects, subject description, method description, test/retest interval, description of results, and statistics. RESULTS The literature search revealed a total of 79 studies. Most studies suffered from methodological weaknesses and only eleven studies received ten or more quality points (maximum 14). The results from the highest graded studies are highlighted. CONCLUSIONS It may be concluded that there is a considerable lack of information about the reproducibility of functional measures for the low back, and therefore a recommendation for consensus is difficult. However, most tests performed in the sagittal plane are reliable for use on groups. RELEVANCE Measures of low back function are thought to be of great importance for clinicians, and low back researchers in general. A review of reproducibility will be helpful both as a survey of tests, and to provide information on the usefulness in relation to the level of reproducibility.