- Apportionment (occupational disease)
- Chronic obstructive lung disease
- Smoking
- Apportionment (non-economic loss) (co-existing conditions)
In 2008, the Board granted the worker entitlement for chronic obstructive pulmonary disease, based on workplace exposure from 1964 to 1978 and from 1981 to 1987. The worker appealed a decision of the Appeals Resolution Officer apportioning a 15% NEL award between occupational dust exposure and smoking.
An indivisible injury with multi-factorial causes cannot be apportioned. The question is whether there is sufficient evidentiary basis to determine what component of the worker's respiratory symptoms was due to his compensable dust exposure and whether the respiratory impairment constituted a divisible or indivisible injury.Decision No. 484/06 considered a report from a Tribunal medical assessor, which indicated that each exposure causes a different component of damage and, therefore, has a distinct physiological effect on respiratory function. This is implied from the assessor's description of the effects as additive and his opinion that the effects of an exposure end when the trigger is removed and that the condition does not progress after the end of the exposure. Such a description is more consistent with the description of an injuring process, such as hearing loss, than of a disease.However, newer medical opinion indicates that COPD is a relentlessly progressive disease and does not reverse when occupational exposure is discontinued.Based on the new medical evidence, the Panel concluded that COPD cannot be apportioned between concurrent dust exposure and smoking, because the condition constitutes a disease process rather than a time-limited physiological injury. Once commenced, the condition is progressive and, thus, more similar to cancer than to hearing loss. Once cancer commences, it follows its own progression. The various carcinogenic factors that may have caused the cancer to commence do not cause distinct increments of damage that can be estimated. With COPD, the threshold at which it develops may be different in different persons but once the lungs develop the abnormal inflammatory process, the disease may be expected to progress. If the effects of dust and smoking occur simultaneously, leading to the commencement of the progressive and inflammatory process, then it cannot be said what increment of impairment might have resulted but for one of the exposures.The Panel noted the question of timing factors. The occupational dust exposure stopped in 1987. He continued to smoke until 2000 and to experience non-occupational dust exposure. The first evidence of medical attention for respiratory symptoms was in 2000. The question, then, is whether the exposure prior to 1988 was a causative factor in the later disease. There was no clear evidence as to whether occupational exposure will cause COPD to commence 20 years later. However, it was not necessary to consider the timing factors in this case, as the Board granted the worker entitlement for COPD based on his exposure prior to 1988.The Panel concluded that the COPD could not be apportioned between the occupational exposure and the worker's smoking history. The worker was entitled to the 15% NEL award without apportionment. The appeal was allowed.