Low level asbestos exposure – what constitutes “a material increase in risk” – Part 2

The Court of Appeal (Lord Justice Coulson, Lady Justice Davies, Lord Justice Zacaroli) has handed down judgment in the appeal against the judgment of HHJ Simon on 13 December 2023, with all three Appeal Court Judges agreeing that the appeal should be dismissed. 

Weightmans LLP (Steve Phillips) acted for the successful Respondent.

Factual background

The deceased was employed at the defendant’s garage as a clerk in the accounts office between 1982/1983 and 1989/1990.

It was alleged that she was exposed to asbestos due to the activities of a mechanic servicing brakes and clutches in a workshop opposite the accounts office, with an airline being used on average one day a week to blow out dust that contained a small proportion of asbestos fibres. Dust was blown across the yard between the workshop and office and around the office where the deceased worked.

The defendant admitted breach of duty and called no factual witnesses, but causation remained in dispute and expert evidence was heard from a number of experts in the disciplines of respiratory medicine, occupational hygiene, epidemiology, and toxicology.

The first instance decision

HHJ Simon found in favour of the defendant and dismissed the claim. 

He preferred the evidence of the defendant’s expert, Mr Stear, to that of the claimant’s expert, Mr Chambers, finding that the mechanic’s cumulative exposure across the relevant period was in the order of 1 fibre/ml year or less and the deceased’s exposure was in the region of 0.001 to 0.002 fibre/ml years.

HHJ Simon also preferred the evidence of the defendant’s expert, Professor Jones, to that of the claimant’s expert, Professor Norrie finding that the deceased’s environmental exposure was 0.046 fibre/ml years, that her background risk (best estimate) was 0.022 per 100,000 and that her increased risk arising from occupational exposure was in the order of 0.1% or less, which was not material.

Grounds of appeal

Permission to appeal was given by LJ Davies on five grounds.

Grounds one to four concern the judge’s interpretation of the expert evidence and his approach to assessing material increase in risk. These grounds did not raise any issue regarding the judge’s assessment of the deceased’s cumulative exposure, but ground five that the judge erred in refusing to draw an adverse inference because the defendant failed to keep proper air monitoring records in breach of regulation 15 of the Control of Asbestos at Work Regulations 1987, was recognised by the Court of Appeal as an indirect attack on the judge’s assessment of cumulative exposure.

The Court of Appeal’s decision    

The Court of Appeal first dealt with ground five and rejected the argument that the judge should have drawn an adverse inference from the defendant’s failure to keep air monitoring records for a number of reasons:

•          This argument did not form part of the claimant’s pleaded case or opening, so was not addressed in detail in the evidence at trial and there was no evidence as to whether the “action level” had been exceeded relevant to how long the records should have been kept.
•          If the action level was not exceeded, records would only have been kept for five years and would have been destroyed more than two decades before the trial.
•          The 1987 regulations came into force on 1 March 1988 towards the end of the deceased’s employment and the evidence showed that during this period, asbestos lined brakes were increasingly replaced by disc brakes so records would only have been retained for a limited period and would not necessarily have provided guidance as to what her level of exposure may have been.      
•         The nature of the adverse inference to be drawn was not entirely clear during trial or on appeal, but it appeared to be the Appellants case that the absence of records meant that the judge should have preferred the evidence of Mr Chambers to the evidence of Mr Stear. The court recognised that this required the judge to make findings of fact he did not accept on the evidence he heard which went far beyond the principles established in Keefe and other modern authorities on adverse inference.

The Court of Appeal moved on to grounds one to four considering the differing methods for assessing material increase in risk as advocated by the parties

Method 1: advocated by the Appellant which the court referred to the “exposure/risk approach” a straightforward comparison of the deceased’s occupational exposure with her environmental exposure as adopted by the Supreme Court in Sienkiewicz.

Method 2: advanced by the Respondent and accepted by the trial judge which the court referred to as the “direct risk assessment approach”, calculating the deceased’s risk of contracting mesothelioma from her occupational exposure utilising the risk model in the Hodgson and Darnton (2000) study (H&D) compared with her background risk from other factors calculated using the Peto & Rake (2009) report (P&R).

 Method 3: advanced by the Respondent on appeal but not at trial which the court referred to as the “absolute risk approach” which required an assessment of the deceased’s risk of developing mesothelioma using H&D and then inviting a medical expert to say whether that risk was medically significant or not – the approach accepted by the court in Bannister. 

Court of Appeal's scope of decision

The Court of Appeal expressly stated that it is not deciding whether the direct risk assessment approach advanced by the Respondent and adopted by the trial judge is the valid and appropriate method to be followed in future. The court is simply deciding whether the judge’s findings were open to him based on the evidence, critically the expert evidence, adduced by the parties at trial.

Assessment of expert evidence

The court rejected ground one that the trial judge had misunderstood Professor Norrie’s evidence, noting that there was a measure of agreement with Professor Jones that the H&D model could be used with appropriate caution to assess risks arising from low levels of exposure, notwithstanding that this involved extrapolation from the much higher dose cohorts on which the study was based. 

Acceptance of Background Risk Assessment

The court found that the judge was entitled to accept Professor Jones assessment of the deceased’s background risk of developing mesothelioma when assessing the material increasing risk, notwithstanding a concession made when he gave oral evidence and that the P & R report he used when making this assessment was relevant to the deceased.

Rejection of the third ground of appeal

The court rejected the third ground of appeal that the “direct risk assessment approach” could not be adopted in place of the “exposure/risk approach” because it involved an improper use of statistics and/or it was contrary to the principle that the creator of the risk should bear the consequences of any evidential uncertainties relying on Fairchild and McGhee.

Use of statistics and causation principles

The court was satisfied that the direct risk assessment approach did not involve an improper use of statistics, particularly as the application of the special rule of causation in Fairchild necessarily involved the use of epidemiology to some degree. Furthermore, the judge’s assessment of material increase in risk was not simply a matter of statistics, and included a consideration of expert occupational hygiene, medical and epidemiological evidence.

No absolute duty on the tortfeasor

The court further found that there was nothing in the approval of McGhee in Fairchild or in the Fairchild and Sienkiewicz decisions to suggest that the tortfeasor must bear the consequence of each element of evidential uncertainty when applying the special rule of causation.

Critique of the absolute risk approach

Turning to the absolute risk approach, the court did not accept that it assisted in proving the special rule of causation as it did not involve adequate consideration of the extent of any increase in risk with the danger that a large increase in risk may still be regarded as insignificant in absolute terms. The court was also not comfortable with the apparent delegation of this issue to a medical expert when it should be for the court to determine. 

Discussion

Insurers may be disappointed that the Court of Appeal has not endorsed method two which it calls the “direct risk assessment” approach more enthusiastically.

What insurers can take from this decision is that the Court of Appeal declined to embrace the criticisms of the “direct risk assessment” approach made by the Appellant and did not reject the use of the H&D and P&R studies to introduce a more nuanced approach to the assessment of material increase in risk, introducing factors such as age, gender, fibre toxicity, and the incidence of idiopathic disease, ignored by the “exposure/risk approach” adopted in Sienkiewicz. Furthermore, the Court of Appeal has not approved the “exposure/risk approach” as the only method to assess material increase in risk.

Insurers may also be disappointed that the Court of Appeal has rejected the “absolute risk” Bannister approach, although its comments on this approach are obiter. Medical experts are commonly asked to assist the court on causation issues in disease claims and personal injury claims generally, so it is difficult to see why this should be considered an unacceptable delegation. This decision is unlikely to mean the end of the Bannister approach.

The decision confirms that low level exposure claims can be defended with the right expert evidence within certain parameters. Insurers should note that the occupational exposure in this case at up to 0.002 fibre/ml was higher than in Bannister at 0.0004 fibre/ml years, but lower than Sienkiewicz 0.013 fibre/ml years.

It is understood that the Appellant will apply for permission to appeal to the Supreme Court.