Users' demands regarding dental safety glasses. Combining a quantitative approach and grounded theory for the data analysis.

Eye infections are common among dentists and many are concerned, but few are using proper eye protection. To understand users' demands behind the low use of safety glasses, all dental teams in Sweden were asked which factors they found most important when choosing dental safety glasses, and rate the importance of 31 statements regarding ergonomic aspects of dental safety glasses in a questionnaire. Data were analysed using the Grounded Theory and a quantitative approach. Results showed that dentists ranked the visual aspects as most important and chair assistants the protective aspects. The highly visual demanding work performed by dentists requires safety glasses that are not yet available on the market, which might explain the low use.

Role of ergonomics in the transfer of technology to industrially developing countries.

Technological development has contributed to economic growth and social progress as well as a reduction of many sources of occupational accidents, injuries and stresses. However, advanced technology has also brought new sources of work stress and injuries. Industrially developing countries (IDC) have tended to try to achieve economic growth and development by importing technology designed for IDC. However, because of several complex technical, cultural and socio-economic factors, this policy has not been always successful. Inappropriate technology transfer has led to many work environment and productivity problems. Consideration of ergonomics in the choice and utilization of the transferred technology can help to create a good fit between technology, technology users and the operating environment. Application of ergonomics is, however, not widely spread in most IDC. Ergonomics input will create the appropriate working environment in which people are safe and motivated to participate and can better utilize company resources for increasing system productivity, reliability and availability.

Working conditions in small private enterprises in Poland.

The study deals with working conditions in small private enterprises in Poland. Data come from 50 small enterprises from the Warsaw area. Information about the evaluation of working conditions and the existence of programmes for their improvement was gathered with the help of questionnaires addressed to employees and employers. The results constitute a "photograph" of the Polish reality at the beginning of its transition from planned to market economy. The study revealed a lack of programmes for the improvement of working conditions in a significant number of the enterprises studied as well as little interest in occupational safety on the part of employers (owners). The study also revealed that all decisions--including those about the improvement of working conditions--were made by employers. Hence, the need for the widest possible dissemination of knowledge on occupational safety and the protection of human in the working environment with particular stress put on employers. Employers who are knowledgeable in this field and who are aware of its importance can significantly influence the improvement of working conditions in small enterprises.

Prevalence of musculoskeletal disorders at workplaces in the People's Republic of China.

This paper presents 2 musculoskeletal disorders questionnaire surveys in 10 different Chinese occupational groups. Data collected from 1,603 workers using a modified Nordic musculoskeletal disorders symptom questionnaire showed that the 12-month prevalence of musculoskeletal disorders, particularly in the low back and shoulder-neck regions, was high at many Chinese workplaces. Significant differences existed between occupational groups. Assembly workers usually had higher neck-shoulder complaints compared to workers in most other occupations. However, the nature of assembly seemed also to influence the prevalence rate. Workers at a cassette recorder and a TV set assembly plant appeared to have more neck complaints compared with a group of thermos flask assemblers.

Evaluating the potential occupational hazard of handling dental polymer products using the HET-CAM technique.

The irritation potencies of 8 dental polymer products, used as dental restorative materials, adhesives, or temporary constructions, were tested using the HET-CAM (hen's egg test-chorioallantoic membrane) technique. Liquid and powder components, and extracts of cured and freshly mixed non-cured materials of 5 glass ionomers, 1 bonding, 1 composite, and 1 cold-cured acrylate were examined. Results showed that the liquid component of all products had a strong irritation capacity but powder suspensions and extracts from cured and freshly mixed non-cured materials had no effect on the CAM. Thus, dental personnel who handle liquid and powder manually are exposed to components with a high irritation potential, in contrast to patients who are exposed to the cured and mixed non-cured materials with low irritation potential. This illustrates the importance of safe handling procedures and practices for dental personnel who handle non-cured polymers manually.

Atopic dermatitis, conjunctivitis, and hand dermatitis among Swedish dental personnel, including use of personal protective devices.

A previous study on dental personnel in northern Sweden show that dentists had a significantly higher prevalence of self-reported and physician-diagnosed atopic dermatitis and conjunctivitis, compared to chair assistants and referents (Lönnroth & Shahnavaz 1998). Further, significantly more male dentists reported experience of hand dermatitis compared to male referents. To compare the prevalence among dental personnel working in other geographical areas of Sweden, and survey the use of personal protective equipment, a questionnaire study was conducted during 1997, which included all dentists and his/her chair assistants, working in general private and public dental care in Sweden. A total of 7384 dental personnel were included in the study, 4293 dentists (54.7% male and 45.3% female), and 3090 chair assistants. Logistic regression was used for analysing data. Results show that significantly more dentists reported symptoms of atopic dermatitis, conjunctivitis, and hand dermatitis, and had been diagnosed by a physician, compared to chair assistants. However, they did not report more sick-leave due to symptoms, compared to chair assistants. More female used protective devices, than male, and more chair assistants than dentists. Significantly more dental personnel in public dental care used protective devices, than in private dental care. Use of gloves, and face mask, decreased with increasing age but, use of eye protection, mainly in form of prescription spectacles, increased. The prevalence of hand dermatitis decreased significantly with increasing age but, more for female (p < 0.0001), than for male (p = 0.01).

Hand dermatitis and symptoms from the fingers among Swedish dental personnel.

Hand dermatitis among dental personnel has been an issue in recent years. Dental personnel manually handle polymer materials which are known to irritate skin, and also cause allergy. In addition, dental personnel wash their hands frequently, and use latex gloves, and are therefore at risk to develop hand dermatitis. To survey the occurrence of hand dermatitis among dental personnel, questionnaires were sent to all dental teams (dentist + chair assistant) working in the two northern Swedish counties. Referents were; researchers, teachers, and secretaries from a university and high schools, from the same geographical area. The response rate was 76% for dental teams, and 66% for referents. The results show that male dentists reported a significantly higher prevalence of hand dermatitis than male reference. In contrast to chair assistants and referents, dentists (both male and female) reported a higher extent of hand dermatitis on the left than on the right hand. There was an association between hand dermatitis among dental personnel and; age, eczema in childhood, and hay fever but, not with; sex, asthma, frequent washing of the hands, and glove use. Whitening of the fingers increased with increasing age among dental personnel. Pricking was also associated with frequent glove use. Pricking of the fingers was associated with sex, and 3.5 times more common among female dental personnel than male dentists. Numbness of the fingers, and finger pain was reported by more dentists than chair assistants and referents.

Adverse health reactions in skin, eyes, and respiratory tract among dental personnel in Sweden.

Dental personnel manually handle products that contain monomers. Several studies have documented adverse health effects after exposure to such products. Gloves made of vinyl or latex are easily penetrated by monomers. Ordinary glasses, or visors, do not protect against vapour from polymer products. Dental face masks filter out about 40% of respirable particles. To survey the prevalence of asthma, atopic dermatitis, conjunctivitis, hay fever/rhinitis, and hand eczema among dental personnel, a questionnaire was distributed to all dental teams in Northern Sweden. Referents were researchers, teachers, and secretaries from the same geographical area. The response rate was 76% for dental teams, and 66% for referents. The results show a significantly higher prevalence of conjunctivitis, and atopic dermatitis among dentists, both male and female. Hypersensitivity to dental materials was reported by significantly more dental personnel than by referents.

Use of polymer materials in dental clinics, case study.

Dentistry uses a variety of different polymer materials. Dental polymer materials are based on methacrylate, its polymer, and polyelectrolytes. The setting of restorative materials and adhesives is initiated chemically by mixing two components or by light. In both cases, polymerisation is incomplete and monomers, not reacted, release. Studies have documented that monomers may cause a wide range of adverse health effects such as irritation to skin, eyes or mucous membranes, allergic dermatitis, asthma, parenthesise in the fingers, and disturbances from central nervous system such as; headache, pain in the extremities, nausea, loss of appetite, fatigue, sleep disturbances, irritability, loss of memory and changes in blood parameters. Dental personnel are occupationally exposed when handling the non reacted monomers. The use of gloves do not give enough protection as monomers, released from the material, easily penetrate all gloves used in dentistry. Face masks do not prevent inhalation of monomers. Ordinary glasses do not protect the eyes against vapor from monomers. The result from this study demonstrate the need for the development of ergonomic procedures and practices for safe handling of such materials in dental clinics.

Dental clinics--a burden to environment?

To estimate environmental burden of mercury from dental clinics, a survey was conducted in 1993 at dental clinics in northern part of Sweden. Factors regarding amalgam separators, maintenance and disposal of collected sludge, age of clinics, cleaning of waste pipes, and sorting and handling of amalgam contaminated products were investigated. The result showed that many were not familiar with maintenance of the amalgam separator. A majority, 68%, were working in clinics older than 10 years, but only 9% reported that waste pipes had been cleaned or changed. Classification of amalgam contaminated products as high-risk and low-risk waste differed a lot, as well as handling of waste products. The result shows that there is need for more information and attention to all individuals working in Dental Care on how to reduce environmental burden of mercury from dental clinics.

Evaluation of an ergonomics intervention programme in VDT workplaces.

This paper focuses on an intervention programme based on the concept of participatory ergonomics. The study was designed within the framework of a multidisciplinary project concerned with identifying the work conditions and problems necessary to improve the working life of VDT operators with routine data-entry and data-dialogue tasks. The intervention programme was evaluated in two follow-up studies. The evaluation criteria covered the proposals for improvement emerging from (1) the intervention programme's final joint decisions (of experts and employees) on measures needed, and (2) workers' views of the effectiveness of the programme itself. As the implementation period was marked by increasing turbulence caused by recession in many branches of the Swedish economy, attention was paid to the impact of the restructuring and rationalization effected by company management in the workplaces under study. To obtain a better understanding of the outcome of the intervention programme, the follow-up was extended systematically to explore the disturbing organizational factors operating during the implementation period. The results of the evaluation offer increased knowledge of organizational barriers to the implementation of ergonomics measures decided upon within the framework of intervention research.

Amalgam in dentistry. A survey of methods used at dental clinics in Norrbotten to decrease exposure to mercury vapour.

A survey was conducted on the possible factors influencing exposure to mercury vapour during the handling of amalgam and amalgam contaminated products at dental clinics in Norrbotten, the northern part of Sweden, as well as the current methods being used to minimise, if not prevent such exposures. Increased room temperature, a serious problem when working with amalgam, was the most common complaint from the dental personnel reflecting the observation that ventilation in most clinics was far from being satisfactory. However, methods of treating amalgam-contaminated waste products as well as the classification of products as high- or low-risk wastes also differed a lot. The results further showed that although majority of the dental personnel showed concern on the possible hazards of mercury vapour exposure and were interested in having the level of mercury vapour measured in their clinics, very few had access to any protective equipment against it. And among the few who had some forms of protective wear, most found the equipment disturbing and disruptive of work performance.

A model of ergonomics intervention in industry: case study in Japan.

This paper presents the results of an ergonomics survey in four different Japanese work places. The survey consisted of two parts. In the first part, the physical and psycho-social problems of the female workers were investigated. Questionnaire techniques were used to assess musculoskeletal disorders in various parts of the body and of psycho-social stress at work as well as in the daily life situation. Furthermore, work posture analysis, task analysis, simple clinical tests and flexibility tests were conducted. In the second part, the ergonomics intervention practices in different types of Japanese work places were examined. Three different questionnaires were developed and used to collect information from representatives of employees, management and responsible governmental agents of the Department of Industrial Safety and Health, Ministry of Labor, with regard to ergonomic interventions at work places. Management, employees, and government representatives expressed desire for cooperation and participation for arrangement of the ergonomics intervention program. A model for appropriate ergonomics intervention in industry is developed with regard to physical and psycho-social problems at work. Factors influencing worker participation and the establishment of a dynamic system of ergonomics intervention at work places are discussed. Practical ways for improving the working conditions of female workers are: (i) cooperation between managers, workers, and government officers is regarded as vital for the ergonomics intervention program, (ii) worker participation, (iii) appropriate training course with regard to ergonomics education, and (iv) managerial support.

Ergonomics method for prevention of the musculoskeletal discomforts among female industrial workers: physical characteristics and work factors.

In industrial work, working postures play an important role, separately and combined with other strain factors. The combined effects may be worse than those of single factors. The purpose of this investigation was to compare the body size, work postures and musculoskeletal discomforts between a group of female workers in a pharmaceutical plant and another group in a textile plant. Two hundred workers have participated in the following studies; (i) measuring anthropometric data in the standing and sitting positions, (ii) using the Ovako Working Posture Analysis System (OWAS), and (iii) using the detail Standardized Nordic Questionnaire for analyzing the musculoskeletal troubles in different parts of the body. The investigation has identified five main factors associated with the musculoskeletal discomforts: (i) lack of worker selection and lack of appropriate training to prevent occupational hazards or work-related diseases, (ii) poor ergonomic design of the work place and task including work organization, (iii) poor working postures, (iv) lack of task variation, and (v) insufficient rest breaks. These could be improved by introducing ergonomic interventions for both adjusting the individual work places and the task performed. It is necessary to consider preventive measures for musculoskeletal disorders, especially for female workers in industrially developing countries. Ergonomic aspects of the preventive measures should include: (a) consideration of appropriate worker selection for various works with sufficient training and instruction, (b) ergonomic redesign of work places, and (c) ergonomic considerations in work organization.

Musculoskeletal disorders of female workers and ergonomics problems in five different industries of a developing country.

An ergonomics survey was carried out using interviews based on Standardized Nordic Questionnaires for evaluating musculoskeletal disorders of 1,000 female workers in five different industries in Thailand, viz. garment, fertilizer, pharmaceutical, textile, and cigarette. A checklist used in an ILO study for examining ergonomics problems was used for identifying ergonomics problems. The results show that about 50% of the female workers experienced a high prevalence of musculoskeletal symptoms in their lower backs, particularly the textile workers. The musculoskeletal symptoms of each body region were significant in each industry during the last year and the preceding 7 days (p < 0.05). Other ergonomics problems in the survey industries included heavy manual handling, prolonged sitting and standing, awkward work postures, poor machine design and operation, high repetitive and monotonous movements, poor work organization, and unsatisfactory working environments. Based on the results of this survey, it became obvious that ergonomics problems related to occupational health and safety of female workers seem to fall into three categories: (i) poor working practices and workplace programmes without sufficient knowledge of ergonomics principles, (ii) lack of adjustment to local population of imported machinery and equipment and their use, and (iii) lack of appropriate work organization. The findings demonstrate the need and the importance for ergonomics intervention in industrially developing country using low-cost improvements and appropriate training methods. It also indicates that research in ergonomics applications is needed, considering the specific characteristics of the industrially developing country.

Musculoskeletal discomfort and feeling of fatigue among female professional workers: the need for ergonomics consideration.

Subjective feeling of general fatigue and physiological strain were studied in one hundred female professional employees of industrial worker and full-time nurses. Using an interview questionnaire the feeling of fatigue were studied. The subjects were asked to indicate on the body diagram all the areas of musculoskeletal pain from which they perceived discomfort. Furthermore physical strength test consisting of grip test, back and leg strength test were carried out before and after work on all subjects. The results indicated that the two groups of employees showed different symptoms of "pain" and/or "fatigue," with regard to the different parts of body. It was also noted that the physical strength after work was lower for both groups as compared to before work and even lower for the industrial workers than the nurses. The feeling of fatigue between the two investigated groups was not significantly different, but for the musculoskeletal pain was highly significantly different. The worker group used also more pain-killing drugs for releasing the muscle pain. It was evident that ergonomics intervention for female professional workers was of great importance and urgency, particularly for making the workplace more human. Improvement of the working conditions, better organization of work, and ergonomics interventions are suggested as necessary measures for reduction of pain and feeling of discomfort.

Adaptation to discomfort in personal protective devices: an example with safety helmets.

Discomfort in the use of personal protective devices (PPD) has been one of the chief causes of their non-use. A field trial using industrial helmets was carried out to ascertain whether by training and repeated wearing subjects could experience a significant adaptation to discomfort. Ten subjects took part in the trial in a tropical environment by wearing helmets repeatedly (6 h a day) for one month. Subjective evaluations of discomfort were made at the end of the 1st, 3rd, 5th, 14th and 30th day. It was revealed that complaints of discomfort, viz. hotness, heaviness, bad fit, etc., decreased markedly throughout the 30 day period. Though positive responses of adaptation to discomfort seem to reach an optimum towards 30 days, it is difficult to draw any conclusions on the optimum period of adaptation for each discomfort factor. In relation to inherent discomforts that are extremely difficult to overcome without compromising the protection efficiency of a PPD, the principle of adaptation seems to be a very important facet which has to be developed for an effective PPD programme.

A head-model reconstruction based upon photogrammetric data from Sri Lankan adult males relevant to the design of headgear.

Due to the large variability in heads and faces in one population, the standard anthropometric dimensions of the head, measured from anatomical landmarks alone, may not suffice for the design of fitting headgear, e.g., helmets. To provide adequate data of the shapes and contours of the head to the designer, appropriate head models sculptured using comprehensive head dimensions, must be developed. This paper describes (a) a procedure of collecting comprehensive anthropometric data of the head using a photogrammetric method and (b) a simple sculpturing technique to reconstruct a head model of the user population.

The promises and problems of ergonomics application in the People's Republic of China.

Ergonomics or human factors, as an applied science concerning the design of interfaces between man, machine and the working environment, has shown its great capacities and potentials for improving working conditions and efficiency during its applications in most industrially developed countries (IC). As a means of improving the economy, industrialisation has been initiated in many industrially developing countries (DC). Knowledge and technology available in ICs have been transferred to DCs in order to increase the process of industrialisation. Ergonomics as a western discipline has also been transferred to many DCs during the technology transfer process. As an example of the transfer and development of ergonomics in industrially developing countries, this paper examines the development of ergonomics and its various areas of application in the People's Republic of China. After reviewing the current ergonomics situation and its applications in China from various points of view - i e, from organisation, research, education and industrial application - promises and problems associated with the development of this new area of science are discussed.