Home / Insight / Mesothelioma and De Minimis exposure. When too little is argued too late.

Mesothelioma and De Minimis exposure. When too little is argued too late.


Ness v Carillion 2023 EWHC 1219

In this case the deceased worked for the defendant for a short period in tax years 1966/67 and 1967/68. The claimant alleged exposure to asbestos for around 14 days when cutting millboard and asbestos cement. The deceased had also been exposed to asbestos fibre by other employers who were not pursued.

Breach of Duty

The defendant argued that the deceased’s exposure did not give rise to a foreseeable risk of harm. This split into two questions. Did the millboard described by the deceased contain asbestos? If not, was the exposure from asbestos cement enough to create a foreseeable risk? The defendant produced expert evidence saying that exposure from cement would not have been regarded at the time as being dangerous.

The first question was resolved in the defendant’s favour. The evidence was too uncertain for the court to find that the millboard used contained asbestos. The second question was decided for the claimant. Although the exposure from asbestos cement was very low, there was enough information generally available to alert employers to the risks. The court emphasised the size of the employer, a major construction company. They would be expected to keep closely up to date with advice about asbestos and conclude that even low-level exposure was dangerous.

This is a questionable conclusion. It accepts the argument advanced by the claimant in Bussey – namely that in the period after 1965 employers should have known of the risks of even low-level exposures and taken steps to mitigate them. Very few employers actually took such steps over that period. This means either that employers suddenly became unusually callous or that the defendant’s expert was right, and not all asbestos exposure would be regarded as risky.

There are plenty of pointers to support the second conclusion. The Factories Inspectorate had not changed its advice about asbestos by 1967 and did not do so for another 3 years. There were no warning labels on asbestos products for another 9 years. Manufacturers of asbestos products continued to advertise in the national press without health warnings. The peak of asbestos importation into the UK occurred around 1970, some years after the deceased’s employment.

The obvious reality is that information available to employers about asbestos risk was sparse, confused and contradictory.

Advancing this argument for defendants is an intensive exercise. It requires a proper examination of every bit of information and advice available to employers – with all its confusion and nuance. Sooner or later that exercise will have to be carried out.


The defendant also argued at trial that the claimant had failed to produce evidence to show that exposure from the cement made a material contribution to the risk of mesothelioma. The claimant complained that this argument had only been raised at the last minute – a complaint the court rejected.

The claimant’s medical report said that there was “no threshold dose below which there is no risk [of mesothelioma]”. The expert did not give evidence. The defendant did not instruct a medical expert. The judge found for the claimant. It is difficult to see how the outcome could have been any different if the defendant could not contradict the claimant’s clear expert evidence.

In the right cases there is nothing wrong with a de minimis causation defence. The court in Bannister 2020 EWHC 1256 accepted its logic. It remains a technically complex point. It must be supported by expert evidence as was done in Bannister.


Although the defence in this case failed it is still viable to argue both breach of duty and causation defences in post-1965 cases. It cannot be done lightly and must be supported by full documentary enquiries and expert evidence. Light exposure claims will become more prevalent in modern mesothelioma cases. Insurers must prepare to meet them.

David Pugh

David Pugh


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