In a recent Court of Session decision, Kerr v Midlothian Council and Moray Council [2024] CSOH 112, the court considered the application of a special rule of causation, the Fairchild exception. The Kerr case was an action for damages arising from the development of a rare form of mesothelioma. The Fairchild exception enables a pursuer to rely on "materially increasing risk" of harm, rather than the usual test of "balance of probability" that the injury was caused by the negligence.
Background
The action was brought by the husband and family of Sarah Kerr, who was employed as a chemistry and science teacher by the defenders for various spells between 1983 and 2003. During her employment she handled Bunsen burner heat mats and wire gauzes. It was claimed that through the poor condition of the equipment, Mrs Kerr was exposed to asbestos fibres. Mrs Kerr was diagnosed with peritoneal mesothelioma (a rare form of the disease that affects the lining of the abdomen) in 2020 and sadly died of this condition in June 2022.
Mrs Kerr's family sought damages on the basis that the defenders should have been aware of a significant risk of asbestos related injury. They argued that their breach of duty exposed Mrs Kerr to significant quantities of asbestos dust and thereby created a material increase in her risk of contracting the disease. As to proof that asbestos played a causative role in Mrs Kerr's death, reliance was placed on creation of this risk as opposed to demonstrating that the exposure caused or contributed to the injury.
Evidence
The pursuer relied on affidavit evidence given by Mrs Kerr prior to her death and evidence from one of her former colleagues. Both parties also led evidence from experts including Laura Martin (Consulting Forensic Scientist (Occupational Hygiene)), Dr Alan D Jones (Senior Consultant Physicist) and Dr John Moore-Gillon (Consultant Respiratory Physician).
Ms Martin estimated that Mrs Kerr incurred an overall dose in the range of about 0.001-0.11 of a fibre per millimetre of air over her working years. Recognising that it was a matter for medical evidence, she opined that the exposure was not negligible and was likely to have introduced a materially increased risk of developing mesothelioma. She could not comment with any certainty what type of asbestos was present in the products that Mrs Kerr was handling.
Dr Jones was instructed by Moray Council. He considered it likely that the mats and gauzes in use in many schools at the relevant time contained asbestos. His opinion was that the handling of the equipment was likely to release to a much lower airborne concentration level, which he estimated at 0.001 s/ml. In considering the level of risk that flowed from the overall dose, Dr Jones referred to influential epidemiological study published in 2000 by John Hodgson and Andrew Darnton. It stated that for an exposure to chrysotile of 0.005 f/ml years the risk of this causing mesothelioma was "insignificant".
Dr Moore-Gillon noted that as with pleural mesothelioma, there is a strong association between peritoneal mesothelioma and asbestos exposure. Despite some limitations to the Hodgson and Darnton report, he described it as the best available tool for assessing levels of risk of mesothelioma associated with asbestos exposure. He stated that at very low levels the risk of peritoneal mesothelioma is far lower than that for pleural mesothelioma.
Parties' submissions
The pursuers accepted that no more than indicative levels of the Mrs Kerr's exposure could be given. However, applying the Fairchild v Glenhaven Funeral Services Ltd exception, it was necessary only to establish a material increase in risk, specific measurements are not required.
The pursuers accepted that it was not possible to prove what caused Mrs Kerr's cancer but argued that the defenders' breaches of duty amounted to conduct capable of causing her injury, including the disease that she developed. The pursuers submitted that being unable to prove that the exposure caused the disease was not fatal to the claim. Exposure that materially increased the risk of developing the disease was sufficient.
The first defender's submissions were that the pursuers failed to prove (i) the extent of any exposure, (ii) negligence, and (iii) that any exposure caused Mrs Kerr's illness. The attempt to extend the Fairchild exception was flawed. In Fairchild there was no question over whether asbestos caused the injury. Given all the uncertainties in this case, any attempt to estimate an airborne concentration level was no more than speculation. The second defender urged the court to accept the evidence of Dr Moore-Gillon and Dr Jones. As to risk of contracting the disease, they submitted that cumulative exposure was the most important factor, Ms Martin had over-estimated her range. The epidemiological evidence does not support an association between chrysotile exposure, particularly at low exposures and peritoneal mesothelioma. It had not been established that any likely level of asbestos exposure caused Mrs Kerr's disease.
Decision
Lord Malcolm took the view that the Fairchild exception was not designed for a case where it is neither admitted nor established that asbestos exposure caused injury. The court had no difficulty in concluding that Mrs Kerr handled Bunsen mats and gauzes made of asbestos, particularly during her early years teaching. However, it was much more difficult to assess the amount of respirable fibres, likely chrysotile, to which Mrs Kerr was exposed. All that could be said with any confidence is that in comparison with the levels commonly discussed in claims of this kind, Mrs Kerr's exposure to respirable asbestos and overall dose were of a very low level.
The Fairchild exception depends on proof of a material increase in risk of harm. Lord Malcolm accepted the evidence that if Mrs Kerr's work exposed her to any risk of developing peritoneal mesothelioma, which on the evidence led, was a doubtful proposition, the risk was so small as to merit disregard, in other words it was not material. It followed that liability could not attach.
Observations
Lord Malcolm also made some observations about whether the Fairchild exception is designed for a case like this one:
"[77] To date [the exception] has been applied only where non-asbestos related causes of the injury can be discounted. In such cases liability is established against anyone who is breach of duty has exposed a claimant to asbestos fibres and has thereby materially increased the risk of the development of mesothelioma ("materially" meaning more than minimally), see Sienkiewicz. If that is demonstrated, it is not necessary to prove that exposure caused or contributed to the disease. The injury must result from the kind of risk created by the employer's wrongdoing (or one operating in the same way), see Fairchild at paragraph 170, and Sanderson v Hull, paragraph 53. If the exception cannot be used, factual causation must be established in the normal manner."
It is therefore on the grounds of policy and fairness that the exception can be justified. Where current science is not at the stage that it can identify which exposure to asbestos caused the disease to take hold, an exception can be made. The differentiating factor in this case was that it related to a rare form of mesothelioma, where the causative link to asbestos exposure, especially at low doses, is much weaker. The scientific uncertainty did not arise from being unable to establish which defender was responsible for the asbestos exposure that caused the disease, but rather that asbestos exposure caused the disease full stop. Therefore, where asbestos is one of several possible explanations for the disease, the exception cannot apply.
