Causation Asbestos in UK Law

This approach does not seem to me, however, to address the fundamental point that, while the pleural plaques can be said to amount to an injury or a disease, neither the injury nor the disease was in itself harmful. This is not a case where a claim of low value requires the support of other elements to make it actionable. The need for this is due to what the pleural plaques indicate about the extent of the exposure to asbestos.

In most cases, indeed possibly in all cases, it is caused by the inhalation of asbestos fibres. The rule in its current form can be stated as follows: when a victim contracts mesothelioma each person who has, in breach of duty, been responsible for exposing the victim to a significant quantity of asbestos dust and thus creating a "material increase in risk" of the victim contracting the disease will be held to be jointly and severally liable for causing the disease.

The expert evidence, given by both medical and epidemiological experts, but based in the case of each, I suspect, on epidemiological data, was that asbestos and cigarette smoke not merely combined cumulatively to cause lung cancer, but that they had a synergistic effect in doing so. This evidence was enough, as I see it, to satisfy the Bonnington test of causation, as the victim had been exposed both to significant quantities of asbestos fibres and to significant cigarette smoke.

In my view, these considerations justify a conclusion that, for the purposes of the insurances, liability for mesothelioma following upon exposure to asbestos created during an insurance period involves a sufficient "weak" or "broad" causal link for the disease to be regarded as "caused" within the insurance period. The risk is no more than an element or condition necessary to establish liability for the mesothelioma.

It is accepted that the risk of developing a mesothelioma increases in proportion to the quantity of asbestos dust and fibres inhaled: the greater the quantity of dust and fibre inhaled, the greater the risk. But the condition may be caused by a single fibre, or a few fibres, or many fibres: medical opinion holds none of these possibilities to be more probable than any other, and the condition once caused is not aggravated by further exposure.

To determine that question, it seems to me the judge had to make findings about (1) the actual level of exposure to asbestos fibres to which Mr Williams was exposed; (2) what knowledge the University ought to have had in 1974 about the risks posed by that degree of exposure to asbestos fibres; (3) whether, with that knowledge, it was (or should have been) reasonably foreseeable to the University that, with that level of exposure, Mr Williams was likely to be exposed to asbestos related injury; (4) the reasonable steps that the University ought to have taken in the light of the exposure to asbestos fibres to which Mr Williams was exposed in fact; and (5) whether the University negligently failed to take the necessary reasonable steps.

It follows that, unless he was exposed to asbestos dust in the general atmosphere, the mesothelioma must have been caused by the dust to which he was exposed at the second respondent's factory. If he was not exposed to asbestos dust in the general atmosphere, causation will have been established in the conventional way.