Abstract

Introduction: Variation in the anthropometric measurements of the different occupational groups can be correlated with the variation in ergonomic design for the betterment of the individual involved in works, which eventually affects the productivity of the work. To correlate the occupation, gender and race of the Nepalese individuals with the anthropometric measurements was the aim of this study.

Materials and Methods: This is a comparative cross-sectional study conducted among the workers associated with elementary occupation in the Sunsari district of eastern region of Nepal. Subjects (N=600) were chosen from the three major subgroups of elementary occupation (cleaners and helpers, industrial workers and agricultural workers or farmers) having age between 25 to 50 year.

Results: Mean standing height of farmers (157.22±4.34 for male and 147.01±4.31 for female) was less than that of industrial workers (163.65±5.43 for male and 149.44±6.40 for females) for male and more than industrial workers for female. Weight was more in farmers (63.66±5.67 for male and 56.68±5.44 for female) than that of industrial workers (59.72±9.29 for males and 52.19±8.53 for female). Wrist breadth was also more in farmers (5.93±0.40 for male and 5.33±0.26 for female) than that of industrial workers (5.92±0.36 for male and 5.30±0.23 for female).

Summary and Conclusion: Physical anthropometry cleaners and helpers and industrial workers were more similar in size as compared with the farmers and this could be useful for designing the equipment according to occupations to improve working conditions and to minimize work related trauma and illness.

Keywords: Elementary occupation; Physical anthropometry; Standing height; Ergonomic

Abbreviations

CTDs: Cumulative Trauma Disorders; BMI: Body Mass Index; ISCO: International Standard Classification of Occupations; VDCs: Village Developmental Committee; IERB: Institutional Ethical Review Board; ANOVA: Analysis of Variance; BPKIHS: BP Koirala Institute of Health Sciences; MSDs: Musculoskeletal Disorders; CTS: Carpel Tunnel Syndrome; WRULD: Work-Related Neck and Upper Limb Disorders

Introduction

The word ‘anthropometry’ means measurement of the human body. It is derived from the Greek words ‘anthropos’ (man) and ‘metron’ (measure). Anthropometric data are used in ergonomics (a science that deals with designing and arranging things so that people can use them easily and safely [1]) to specify the physical dimensions of work spaces, allowable space equipments, furniture and clothing to ensure that physical mismatches between the dimensions of equipment and products and the corresponding user dimensions are avoided [2,3]. This matching is used for occupational injury prevention when the tools and equipment, machinery and spaces are appropriate to the body measures. Otherwise, work efficiency decreases and inappropriate work difficult utility conditions arises. This in turn leads to a physical and mental stress [4]. The work difficult utility conditions are serious such as health impairment and diminished quality of life which finally affects their independence [5]. Musculoskeletal injuries caused by occupation are common. Cumulative Trauma Disorders (CTDs) and Repetitive motion injury are terms used to refer certain musculoskeletal injuries caused by defective coordination between machines and workers [3,6]. Almost 50% of workers in the industrial world are thought to suffer from back problem, originated from improper sitting positions [3]. World today is undergoing tremendous socio-economic and political change, resulting in increasing migration of people. Migration occurs both between the countries and internally within country. National population cannot therefore regard as homogenous. Industrial, service and other workplace now have mixed population, not only in gender but also in ethnic groupings. Population heterogeneity is of great importance to anthropometric consideration in the design of workplaces and consumer products. For example, body proportions of people with different ethnic origins are found to be different. Black Africans have proportionally longer limb length than the European white population. People belonging to Chinese, Japanese, Indonesians and Vietnamese population have proportionally shorter limb than Europeans. Therefore workplace and facilities cannot be used easily and efficiently by all the members of the population due to these variations [7]. Nepal, also known as ‘agriculture dominant country’ had population of 26.49 million with a growth rate of 1.35% per year. Agriculture contributes 36%, service 52%, industry 9.6% to GDP [8]. Agriculture provides an employment opportunity to 73.9 percent of the total population but with very low productivity due to several factors including low adoption of improved technology [9]. Sunsari is one of the six district located in eastern region of Nepal which is divided into three region- Himalayan, hill and Tarai (plane) region from north to south. Total population is 795096 (50.39% male). This district is occupied by multiethnic variety of People with more than 90 types of caste (Jat). By occupation 61.75% of economically active (above 10 yr) population (51.39% of total population) is involved in agricultural, industrial and health sectors which was the reason behind choosing the subjects from those sectors. According to a survey, proportion of male and female in economically active population is nearly equal (50.28% male) [10].

Anthropometry permits us to develop standard and specific requirements against which a product, machine, tolls or piece of equipments can be evaluated to ensure their suitability for the user population [7]. Designs that are incompatible with normal anthropometric measurements of a workforce could result in undesired events. For example the misfit of a heavy equipment cabin to a worker could produce operator blind spots that expose workers on foot to strike by injuries. Inadequate length or configuration of seatbelts could lead to non use of seatbelts, which will affect postcrash survivability. Inadequate fit of personal protective equipment cannot provide workers with sufficient protection from health and injury exposures. The workplace should be designed according to the body size of the user. Engineering anthropometry applies these data to tools, equipment, workplaces, chairs and other consumer products, including clothing design [3].

For using anthropometry in ergonomics, Selection of the user population (gender, age, occupation, ethnicity, and cultural aspect of population) and determination of body dimensions are needed. Beside these, determining the design criteria is utmost important. For the vertical reach, workplace design should be set by shortest individual and if criteria is for passing every individual without bending his/her body the it should be set by tallest individual of that particular population. This approach is called as ‘designing for extreme’ [11]. It is some time desirable to set a range of values as design limit. In this case design should incorporate an adjustment in required dimensions. For example office chairs can be designed to provide adjusted seat height [7]. Existing data on the size and shape of workers is sparse. Because of the lack of anthropometric data for the general worker population, safety researchers have generally had to rely on data drawn from studies of military personnel, most of which was collected during the 1950s through the 1970s. However, substantial anthropometric variability exists among the various U.S. workforce populations, and they are quite different from the average military population. Industrial workers, such as the agriculture, truck driver, and firefighter workforces, are even anthropometrically very different from the average civilian population [12].

The skilled movements needed to use occupational tools are critical to carrying out many daily activities. When performing skilled movements, a person learns how to use muscles, joints, and limbs in a series of coordinated steps that lead to the desired goal. First the person learns how to reach for those tools, to hold the tools, and then to move the tools to get a job done [13].

Work-Related Neck and Upper Limb Disorders (WRULD) are the most common form of occupational disease, accounting for more than 45% of all occupational diseases. These disorders emerge mainly from work performing and the conditions in which work is carried out. Any region of the neck, shoulders, arms, forearms, wrists and hand can be affected. Many of the musculoskeletal conditions are non-specific indicating that a specific diagnosis or pathology cannot be determined by physical examination but pain and/or discomfort, numbness, tingling in the affected areas are reported. Other symptoms which can be exacerbated by cold or use of vibrating tools include swelling in the joints, decreased mobility or grip strength, changes in skin colour of the hands or fingers. These complaints can lead to physical impairment and even disability. The most common occupational MSDs are tenosynovitis of the hand or wrist, and epicondylitis of the elbow. MSDs including CTS accounted for 59% of all recognized diseases in 2005. The incidence rate for musculoskeletal disorders is higher for men than women, but MSDs make up a much higher proportion of all occupational diseases for women: MSDs including CTS represent 85% of all occupational diseases among women [14].

The causes of Work-Related Neck and Upper Limb Disorders (WRULD) are usually multifactorial. The acknowledged risk factors related to various types of MSDs include biomechanical, organisational, psychosocial and individual factors [15]. Important biomechanical factors are listed below.

Hand force exertion – Sustained or excessive force results in heavy mechanical loads on the neck, shoulders and upper limbs: handling objects, using tools, fast movements or excessive force generated by the muscles of the body. Different manipulating actions on a tool are examples of activities that require exerting force or muscle effort (e.g. digital griping is more demanding than palm griping). Not only is the intensity of effort harmful but also its duration.

Repetitive movements- Work involving repetitive movements is very tiring because the worker cannot fully recover in the short periods of time between movements. If the work activity continues in spite of the fatigue, injuries can occur. The cycle duration is significant if less than 30 seconds or if the repetitive movements account for 50% of work time (e.g. repetitive tasks: making folds during packaging, screwing drywall, and tying rebar).

Working posture- This represents unnatural positions, deviated from “neutral positions”, in which joints are held or moved away from the body’s natural position. The closer the joint is to its end of range of motion, the greater the stress placed on the soft tissues of that joint, such as muscles, nerves, and tendons. When muscles are contracted, the body is subjected to a greater mechanical effort. Joint positions of the upper limb, when working outside comfort angle; increase the possibility of WRULD, regardless of effort intensity or degree of repetition.

Contact pressure- any external pressure that is applied to soft tissues (e.g. holding tools where handles press into parts of the hand or arm; sharp edges of tools, machines or furniture that press into the fleshy tissues) can cause distortion and injury.

Few studies were done to compare anthropometric measurements on the basis of races, gender, climate and duration of retirement after work among Nepalese people. According to those study physical anthropometric parameters like weight, standing height, and BMI (Body Mass Index) were found to vary between different groups of population [16-19]. Few studies were available comparing the anthropometric data of Nepalese people with other countries which showed that most of parameters are lesser than that of other countries [6,20,21]. Variation in the anthropometric measurements of the different occupational groups could be correlated with the variation in the measurements of the work places and occupational tools they used for the betterment of the individual involved in works, which eventually affects the productivity of the work. To correlate the occupation and gender of the individual with the anthropometric measurements is key factor to achieve this distant goal. And this was the stimulus for this study. To match the dimensions of occupational tools with the body dimension it is necessary to have the anthropometric data of the workers associated with various occupations to be considered for designing the tools and equipments. This necessitates the separate data bank for Nepalese people for designing tools and also for forensic anthropometry. But in our country there was no study found regarding comparison of the body dimensions of different groups of workers so far, so this study was expected to aid information in anthropometric data bank of Nepal and will open the door for further research in this subject.

Materials and Methods

Sampling population

This was a comparative cross-sectional study conducted among the workers associated with elementary occupation in the Sunsari district of Nepal. Subjects were chosen from the three major subgroups of elementary occupation (cleaners and helpers, industrial workers and agricultural workers) as defined by ISCO (International Standard Classification of Occupations) which is a tool for organizing jobs into a clearly defined set of groups according to the tasks and duties undertaken in the job [22]. Total sample size was 600, 200 (100 male and 100 females) from each subgroup having age between 25 to 50 years (to obtain the maximum dimension due to completion of growth). All the subjects were Nepalese in birth and ancestry. The subjects were also migrated from various other districts of Nepal. Purposive sampling technique was chosen for selecting the VDCs, Industries, Institutes, Clinics, Hotels and restaurants. After that, simple random sampling was chosen to take a total sample unit of 600 among those areas. Individuals having chronic systematic illness, injuries like fractures and having major surgeries in past one year were not included in research.

Ethical clearance

Research protocol was approved by the IERB (Institutional Ethical Review Board) of the BPKIHS (BP Koirala Institute of Health Sciences) and a consent form was signed by the each sample subject before making the observation.

Data collection

A brief semi-structured questionnaire on demographic profile was circulated among participants of the study which included questions about nutritional habit, personal habits of the individual and most worrying occupational hazard related with the occupation. The questionnaire was pretested among 20 subjects before using for research. Nine body dimensions (important for designing the tools and workplace) were measured along with Body Mass Index (BMI) (Table 1). Upper arm length, Hand breadth, Sitting elbow height and Wrist breadth were measured on right side of the individual. Weight was measured in kilogram (Kg) and all other measurements except for BMI were measured in centimeter (cm). BMI was calculated as {weight in kg/ square of height in meter} and international reference was taken to describe BMI (18.5 to 24.9 as normal, 25 to 29.5 as overweight, above 30 as obese and below 18.5 as thinness) [23].