• lung function
• laboratory animal worker

In their recent paper Portengen and colleagues¹ have made an important contribution to our understanding of laboratory animal allergy. However, they have omitted to draw attention to an observation of clinical importance to occupational physicians.

They have suggested that the lack of decline in lung function in “experienced” workers may be due to the healthy worker effect. Their suggestion is not supported by their own data: the decline in lung function over two years among newly exposed workers with symptoms of LAA was not significant and surprisingly there was a significant increase in function among the symptomatic experienced workers. This being the case there seems little reason to conclude that the loss of symptomatic workers (due to a healthy worker effect) would adequately explain the absence of a decline in function. An equally valid conclusion is that the effect observed in newly exposed workers is small and may not be sustained in the long term.

Physicians are wise not to preclude sensitised workers and those with symptoms of LAA from work with animals solely on the basis of concern that this may have a deleterious effect on health.^2–4 Portengen et al have provided new evidence that supports this.

I agree that the results and conclusions should be interpreted with caution and that further work is needed. However, this is a reassuring study, with important implications for current animal workers and their health providers.