Pneumoconiosis, noise-induced hearing loss and poisonings caused by chemicals are major occupational health problems in the early stages of a country’s economic growth. Coal is still a cheap energy source and is relatively easy to get. Noise caused by machines is common in any workplaces. Many chemicals especially heavy metals and organic solvents are being improperly used, and many people do not realize the value of a clean work environment.

These occupational diseases are preventable if proper actions are taken in advance, and when they are detected at an early stage. To this end, many screening test methods have been applied. Simple chest X-ray has been used for detecting abnormalities of the chest caused by dusts that can develop pneumoconiosis. Pure-tone audiogram has been used for measuring the hearing threshold levels that reveals hearing changes caused by noise. Biological monitoring, which analyzes chemicals or metabolites in the blood and urine, is used for measuring the intake amount of or the health effects by chemicals being exposed. However, there have been many concerns about the reliability of those test results when they are applied to actual practice. For example, reading a simple chest-ray seems to be simple but it is not easy work for physicians unless they have a proper knowledge and a rich experience.  

This session will review the possible problems and solutions of several screening methods, which are applied from the early stage of occupational health, with the Korean experience.

Quality assurance for analyzing chemicals

There are two fields of analyzing chemicals in occupational health: one is environmental sample and the other is biological sample.

Environmental samples are taken from air by a sampling pump with absorbent or filter. The samples are sent to a laboratory for analysis. Chemicals are extracted from the samplers and analyzed, usually by atomic absorption spectrophotometer or gas or liquid chromatography. Biological samples are taken from blood, urine or hair. The samples are treated with preparation process and the analysis is performed using the same equipment for analyzing air samples.

There may be many errors if the process of analyzing samples is not properly managed. The range of difference in results between laboratories or within laboratories can be wide that it can lead to misinterpretation about absorption dose or poisoning. Both internal and external quality assurance program are necessary to avoid possible mistakes during analysis. External quality assurance programs are performed in many countries using reference samples. Laboratories can join these programs to assure their quality of analyzing samples. However, not all laboratories in a country can participate in the abroad program. Thus, it is very important to set up a national quality assurance program to improve the quality of reports for chemical exposure[1]. To achieve this purpose, a technique of developing the reference samples is also required; otherwise commercially available ones should be imported. Korea has operated the quality assurance program for environmental and biological samples of chemicals and asbestos samples since 1992[2][3]. This experience will be presented.

Radiograph

Chest X-ray is a simple and inexpensive tool to detect abnormalities of the lung. The International Labour Organization (ILO) developed the standard film for detecting pneumoconiosis. Most physicians use the ILO film for screening and confirming pneumoconiosis. However, it is difficult to differentiate small differences according to the classification. Intrapersonal difference as well as interpersonal difference in interpreting the films exist[4][5]. Misdiagnosis of pneumoconiosis let workers be exposed to dusts longer or leads to social dispute during the process of compensation. 

Many physicians including radiologists who read films of workers exposed to dust are generally not experienced. Training physicians including radiologists is necessary to get the reliable interpretation of chest X-ray. ILO has provided special training courses including film reading practice and examinations in many countries. Since 1997, Korea has developed its own quality assurance program of interpreting chest x-ray for diagnosing pneumoconiosis. Radiologists whose work involves diagnosing pneumoconiosis must pass the examination for the interpretation pneumoconiosis, regardless their status of professional quality when they start to work in OH field.

The quality assurance program is also important to take radiograph to get a quality film. The quality of radiograph process and its facility are also managed by the program.

Audiometry

Audiogram by pure tone audiometry is a simple method to detect hearing loss caused by noise. Air and bone conduction tests are usually performed in several frequencies. It is important to test audiogram at a special area or facility where the background noise level is acceptable. However, it is often taken at workplace, especially in the screening test. Workers should be kept away from noise for at least 14 hours in order to make them unaffected by temporary hearing loss by noise. Many countries do not have a special program to educate a technician for taking audiogram. Audiogram is often performed by nurses and other OH professionals, who are not familiar with audiology. The audiometric test is sometimes regarded as a simple test, which can be performed without special training. Many unreliable data can be obtained when the tests are performed at work or in other places where background noise is not properly controlled.

Those who perform the audiometric test but have not received any education on audiology should be trained for the process of taking audiometry and should be tested whether they can perform it properly. Basic knowledge about audiology is also necessary. Audiometers are also checked regularly for its balance. Korea has started the quality assurance program for audiometry since 1998. All OH professionals who involve audiometry must take the training course of audiometry and pass the examination for audiology. 

Conclusion

Quality assurance programs for analyzing biological sample, taking and reading chest radiograph, performing audiometry are essential to improve the quality of screening and diagnosing classical occupational diseases. When occupational diseases start to occur, the quality of laboratory for screening should be evaluated and the program for improving the quality of diagnosis should be implemented.