Death after asbestos exposure: Correlation is not causation (again)

HM Area Coroner for Cumbria v Leech [2023] EWHC 3476 (Admin) here

In the wake of the Wandsworth decision (here) in which the High Court emphasised how correlation is not causation when dealing with a death from mesothelioma, those who read the above judgment from a s.13 application will be forgiven for scratching their heads wondering when,  if ever, a death from lung disease where there was a clear work history of asbestos exposure alongside asbestos fibres being found in the lungs at autopsy, might be safely considered to be a death from ‘industrial disease’.

The Coroner had conducted an inquest into the death of a 89 year old man who, during his 45 years employed by British Rail from the age of 15, undoubtedly had a history of exposure to asbestos in his work as both a cleaner and a fireman.

Before Mr Leech died, a consultant respiratory physician had indicated that CT scanning showed that he had asbestosis.[1]  After his death, at autopsy, it was identified that Mr Leech’s lungs showed fibrosis and a superimposed infection (bronchopneumonia). The pathologist examined samples of Mr Leech’s lung tissue and she identified more than 20 asbestos bodies in a single 20-micron thick pearl-stained section, which was also in keeping with asbestosis. In her conclusion, the pathologist gave the cause of death as 1a) Bronchopneumonia due to 1b) Asbestosis.

Unsurprisingly given that evidence, at the inquest the coroner found that Mr Leech  died as a result of exposure to asbestos during the course of his employment” and returned a conclusion ofindustrial disease.

New expert evidence after the inquest

Sometime later however, in the context of a civil claim, a Professor and Consultant Histopathologist (with a special interest in thoracic pathology) reviewed the lung tissue samples. He concluded that Mr Leech’s case did not meet the accepted criteria for a pathological diagnosis of asbestosis, [2] as this would require an appropriate pattern of pulmonary fibrosis, alongside a finding of alveolar septal fibrosis and an average rate of asbestos bodies of at least two per square centimetre of lung.

On seeing the Professor’s report the original pathologist revised her view and now attributed the death to 1a) Bronchopneumonia due to 1b) Idiopathic Pulmonary Fibrosis, stating that “the lung fibrosis cannot be directly attributed to asbestos exposure”.   Against that background the Divisional Court acceded to the coroner’s application to quash the inquest and ordered that a fresh investigation was to be held by the same coroner under s.13(2)(a) Coroners Act 1988.[3]

The issue that had tripped up the first pathologist here is that for asbestosis to be diagnosed pathologically, it requires not merely evidence of excess asbestos in the lungs but also pulmonary fibrosis of a particular pattern.   Here that pattern was absent.

Although the pulmonary fibrosis of asbestosis is similar to that seen in idiopathic pulmonary fibrosis, (which is the principal differential diagnosis). There are important differences between the two diseases. First, in idiopathic pulmonary fibrosis inflammation is seen, whilst with asbestosis the fibrosis is accompanied by very little inflammation.  Second, in idiopathic pulmonary fibrosis there are characteristic fibroblastic foci that are infrequently seen in asbestosis. Third, asbestosis is almost always accompanied by mild fibrosis of the visceral pleura, a feature that is rare in idiopathic pulmonary fibrosis. [4]

It took advice from Dr Google for your inexpert blogger to try and understand that differential diagnosis (so a health warning even the above summary may not be correct!)

The important headline message to all coroners and lawyers (and perhaps non-specialist pathologists too)  is that medicine can be very complicated, so step very carefully before coming to conclusions, and even if asbestos fibres are found in the fibrotic lungs of a deceased who dies from a respiratory disease, do remember CORRELATION IS NOT CAUSATION!




[1] Asbestosis is diffuse pulmonary fibrosis caused by the inhalation of excessive amounts of asbestos fibers.

[2] See: Asbestos Committee of the College of American Pathologists and the Pulmonary Pathology Society (and see Roggli et al. below).

[3]  The inquest has now been re-heard as an inquest in writing under s9C CJA with the revised determination that:  Mr Robert Leech died on 4 March 2019 at Workington Community Hospital. Post-mortem examination showed diffuse interstitial pulmonary fibrosis. Whilst asbestos fibres were present in some lung tissue samples, there is insufficient evidence that the lung fibrosis was caused by exposure to asbestos.  The fresh conclusion was “Natural Causes”.

[4] Roggli et al [2010] Pathology of asbestosis – An update of the diagnostic criteria: Report of the asbestosis committee of the college of American pathologists and pulmonary pathology society. Archives of Pathology and Laboratory Medicine [2010] Vol 134 part 3 here