The shoe manufacturing industry in Viet Nam has been expanding, with employee numbers increasing apace. Medical reports suggest that a high proportion of these workers suffer from headaches, neurasthenia, and musculo-skeletal disorders.

This study was conducted in a shoe factory in Hanoi, with the aim of determining the main adverse factors in working conditions among 240 female workers and their effects on worker health.

• The study investigated working conditions, measuring microclimate (temperature, humidity, air velocity) and concentrations of solvents such as toluene and ethyl acetate.
• Standard questionnaires were used to interview workers about musculo-skeletal disorders.
• Tests were applied to measure neuro-behavioural changes in the workers.

The study was carried out in the autumn. Temperatures and concentrations of solvents might be higher in the summer.

• The temperature ranged between 32 and 34^oC, 2-4^oC higher than the threshold limited value (TLV).
• The humidity ranged around 70 per cent. The air velocity was about 0.5-1.5 m/s, which conforms with the national standard.
• The concentration of toluene was about 190 mg/m³, equal to 1.9 of the maximum acceptable concentration (MAC). The concentration of ethyl acetate averaged about 16 mg/m³ (below the MAC). Some partially used solvent containers were left uncovered, which might have contributed to workplace air pollution.

Working hours depended on product demand. Generally, in the first half of the year employees worked 8 hours per day. In the second half, they usually worked 10 hours per day or more.

Workers worked on a production line. Work benches were inappropriately high, given Vietnamese anthropometry. There were no foot supports, so workers usually had to put their feet on baskets of work items.

Production line work may be classified according to five types, depending on the character of the tasks performed:

1. Highly repetitive work, with stress on the arms. Among this group, operations involved 40-50 arm movements per minute, and workers had to hold a form of 500-700 grams with one hand while stretching to reach work items.
2. Awkward postures. During the execution of tasks, these workers often had to stretch their arms to reach work items above their heads.
3. Work with machines ( for tightening the heels, waists, and toes of shoes). Employees worked in a standing position, often having to bend and twist their backs and wrists. There was one machine located on each side of the production line, and workers also had to constantly twist to the side. These jobs also required the exertion of considerable force using the arms.
4. Highly repetitive work requiring little exertion of force.
5. Continuously sitting while checking and packing products, no stretching or work with heavy items.

Musculo-skeletal disorders

Among the five groups, a high (85.4 per cent) average percentage of workers complained of musculo-skeletal disorders. The highest rate was in the first group, followed by the second group.

Shoulder, lower back, neck, and wrist pains were most common, varying in relative proportion among the five groups. Because workers had to reach high for work items in the first and second groups, these had the greatest number of people complaining of shoulder pain (59-60 per cent, or twice as many as in the other groups). The greatest number of wrist pain cases appeared in the first and third groups, while lower back pain was most prevalent in the fifth group, where people had to sit for long periods.

Neuro-behavioural changes have been mentioned in many reports.

Our study showed that exposure to organic solvents significantly affected central nervous system function. Changes between the beginning and end of the work shift were manifested in increasing slow reaction times and a reduced ability to concentrate. When both exposed and control groups were tested and compared, the exposed group performed significantly worse (in terms of both raw and standardized, or Z scores) than did the control group on most neuro-behavioural tests.

Furthermore, the exposed group suffered more negative moods, displaying more tension, anxiety, depression, anger, fatigue, and confusion that did the control group.

Improved workstation design

• foot support for sitting workers
• chairs or stools for standing workers so they can rest occasionally
• organize workstations and position work items in a way that avoids unnecessary stretching
• alternate worker positions on the production line, where possible, to avoid having workers exert effort all on one side or the other

Control of hazardous substances

• move or cover partially full containers of chemicals

Improved exhaust systems and ventilation

Exercise during short breaks or after work

Periodic medical examinations

This study should be followed up. Among other things, health impact evaluations should be conducted after implementation of the above recommendations.

Updated by PAP/SUT/TRS. Approved by BKL. Last updated on 21 November 2000

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