home   full contents   local contents   disclaimer

Occuptaional Asthma

Contents

  1. Home Page
    1. Research
      1. Occupational Asthma
        1. Introduction
        2. Types of Workplace Asthma
        3. Prevalence
        4. Prognosis
        5. Prevention
        6. Which Chemicals are Hazardous
        7. Further Reading

Introduction

Asthma is a disease of the airways. Symptoms include wheeze, cough and chest tightness. The patient experiences difficulty in breathing. Often the symptoms subside, only to reappear at a later date. Occasionally symptoms deteriorate to the extent that the disease becomes life-threatening. People can and do die from asthma.

Asthma is now recognised as one of the most important health issues in the United Kingdom. It affects between 5% and 10% of the population and it is believed to be on the increase.

Types Of Workplace Asthma

Asthma in the workplace can be of two main types.

Work-aggravated asthma
Pre-existing asthma made worse by exposure to substances in the workplace.
Occupational asthma
Asthma caused by exposure to substances in the workplace.

The second type of asthma is of particular concern because one a worker has developed asthma due to exposure to a chemical, subsequent exposures (even of lower concentrations of that chemical) will provoke an asthma attack.In essence the worker has become sensitized (in an allergic or allergic-like manner) to the chemical.

Prevalence

Within the United Kingdom approximately 1000 cases of occupational asthma are diagnosed each year by specialist doctors. This is believed to be the tip of the iceberg - many more cases are likely to be missed.

Surveys in USA and Japan suggest between 5% and 15% of asthma is work-related. It is probable that at least 5% of asthma in the UK is also work related.

For a more detailed review of occupational asthma see this review by my supervisor. To see the abstract of an oral presentation presented at The British Occupational Hygiene Conference during the spring of 1996 click here.

Prognosis

Workers who develop occupational asthma may improve if removed from exposure however in some cases symptoms may persist for years after exposure ceases. Some form of long term drug therapy may be required. The avoidance of re-exposure to the relevant chemical should promote a favourable outcome.

Prevention

It is in the interest of both employer and employee to provide and comply with measures to prevent occupational disease and injury. Prevention of occupational asthma involves two steps:
  1. Identification of hazardous chemicals.
  2. Elimination, substitution, reduction and/or containment of the hazardous chemicals.
The first step is not easy for either employer or employee - until very recently the only way of knowing whether a chemical causes occupational asthma is if it has been reported to. This would require extensive searching of medical literature (in a number of languages).

The second step, whilst not trivial, is within the power of employer and employee. Care must be taken not to replace one hazardous chemical with another of equal or greater hazard.

Which Chemicals are Hazardous?

Whilst it is not possible to produce a 100% accurate list of chemicals that pose and occupational asthma hazard risk it is possible to indicate some of those asthma causing compounds that have been identified as a problem. You can also find a general overview of the types of chemicals with regards occupational asthma.

Useful References:

  1. Ross, D.J., Sallie, B.A. and McDonald, J.C. (1995) Occupational Medicine 45, 175-178.
  2. Chan-Yeung, M. and Malo, J.L. (1995) New England Journal Of Medicine 333/2, 107-112