Module 4: Occupational Asthma - Lecture

1. EPIDEMIOLOGY:

The proportion of adult cases of asthma attributable to occupational exposure is estimated to be 10%.

Recent studies from Finland indicate:

• work-related factors responsible for 29% of male asthma cases and 17 % of female adult cases;
• incidence rate of occupational asthma = 17.4 cases/100,000 employees.

Incidence depends on:

• industry and job type;
• circumstances surrounding exposure (concentration, duration and route);
• nature of the hazardous agent (molecular weight, biochemical and immunological properties);
• other: legislation and reporting, diagnostic criteria; level of awareness of the disease.

Most common causes of asthma in the workplace worldwide are:

• flour, grain and feed dust;
• animal dander/urinary proteins;
• isocyanates.

In South Africa:

• In 1998, 180 cases of occupational asthma were reported (3% of total number of diseases) under COIDA;
• 44 of platinum salt sensitivity were reported (1% of total number of diseases) under ODMWA;

Occupational asthma (associated with latency or irritants) is the second most common occupational lung disease (8% of 4 049 cases) after pneumoconioses (SORDSA).

Under SORDSA a higher than average number of OA reported from:

• motor industry (e.g. isocyanates), health care (e.g. latex), food processing (e.g. flour, grain) and platinum refining (e.g. platinum salts) (SAMJ 2001,91:509-13);
• incidence rate: Western Cape > KZN > Gauteng.

2. LEGISLATION:

• Occupational asthma is compensable under the Compensation for Occupational Injuries and Diseases Act (COIDA) 1993.
• Occupational Health and Safety Act (OHSA) 1993, makes it obligatory for medical practitioners to report all cases of suspected occupational disease to the Chief Inspector in the Department of Labour.
• In mining industry, platinum salt sensitivity (including asthma) is compensable under the Occupational Diseases in Mines and Works Act (ODMWA).