Sabin v BRB (Residuary) Ltd

In a claim alleging that asbestos exposure caused fatal pulmonary fibrosis, causation is determined on the balance of probabilities by evaluating all relevant evidence. This includes the extent of exposure, estimated asbestos dose, recognised risk thresholds, clinical and morphological features, and asbestos body and fibre analysis.

Morphological features and a rapid clinical course typical of usual interstitial pneumonia do not necessarily exclude asbestosis. In borderline cases, quantitative lung-digestion analysis and electron-microscopy evidence may be more sensitive and reliable than counting asbestos bodies in a small number of routinely stained tissue sections. Laboratory reference ranges must be approached with regard to their size, representativeness, diagnostic criteria and the effects of fibre clearance over time.

The claimant, suing as widow and executrix of the estate of Leslie Sabin, claimed damages from BRB (Residuary) Ltd, the successor to the British Railways Board. The defendant admitted the deceased’s employment, asbestos exposure and breach of statutory and common-law duties. Damages were agreed at £100,000, leaving causation as the sole issue.

The deceased had diffuse interstitial pulmonary fibrosis. The claimant alleged that it was asbestos-induced asbestosis. The defendant alleged that it was usual interstitial pneumonia of unknown cause. The central question was whether asbestos exposure had caused the fibrosis on the balance of probabilities.

1. Approach to causation. The claimant had to establish, on the balance of probabilities, that the deceased’s fibrosis resulted from asbestos exposure. The court considered the exposure history, estimated asbestos dose, accepted threshold of risk, radiological evidence, clinical course, morphological features, and post-mortem asbestos body and fibre findings together.
2. Exposure and threshold. The deceased had been exposed for approximately four years, with estimated exposure of 42 and 47.2 fibre/ml years. The accepted threshold of 25 fibre/ml years remained the recognised general threshold for the risk of clinically evident asbestosis. His exposure was significantly above it, although only a minority of persons exposed at that level develop asbestosis.
3. Clinical and morphological evidence. The rapid disease course, honeycombing, fibroblastic foci and inflammatory features favoured UIP. They did not, however, exclude asbestosis. The authoritative medical literature recognised cases in which asbestosis presents with UIP-like morphology and progression. In such cases, asbestos body and fibre evidence may distinguish the conditions.
4. Asbestos bodies. The finding of fewer than two asbestos bodies per square centimetre on routinely stained sections did not necessarily exclude asbestosis. Lung digestion was the more sensitive and accurate technique for quantifying asbestos bodies, particularly where fibres were unevenly distributed, difficult to detect, or poorly coated. Professor Roggli’s findings strongly suggested that the deceased’s tissue-section count was an underestimate.
5. Fibre analysis and reference ranges. The Llandough Hospital reference range was too small and insufficiently representative to provide a reliable fifth-percentile or minimum value. The Duke University range was preferable in several respects, although it required caution because of its diagnostic composition and lack of independent peer review. The deceased’s fibre count was well within the Duke Grade 4 reference range.
6. Clearance. The substantial period between the deceased’s last exposure and death meant that natural clearance, particularly of crocidolite, was relevant when interpreting his fibre count. Although published reference ranges made no allowance for clearance, the evidence supported the conclusion that his earlier count would have been materially higher.
7. Conclusion and order. Taking the evidence as a whole, the court was entirely satisfied that the fibrosis resulted from asbestos exposure, notwithstanding the UIP-like features. Judgment was entered for the claimant in the agreed sum of £100,000.