LATENCY PERIODS IN MESOTHELIOMA CLAIMS.
Claims with short latency periods.
Reading newspaper reports and websites seems to have led some to believe that the minimum latency period for mesothelioma is considerably below ten years. It is for instance possible to find reports of cases of mesothelioma which have been attributed to the collapse of the World Trade Centre in 2001 of as short as three and four years. These reports seem to have encouraged an increasing number of claimants to maintain that exposure less than ten years before onset of symptoms might, despite previous medical consensus, be causative of mesothelioma. Medical evidence properly so called is unable to provide a definitive answer to the issue of how short a latency period might be before it can be considered to be causative.
For these reasons I think it is helpful to have a closer look at the epidemiological literature in order to see exactly what it says about the latency period for malignant mesothelioma. In this context the most significant of the Bradford-Hill criteria to consider is consistency in the properly conducted studies undertaken. There is a remarkable consistency in the major surveys undertaken by epidemiologists.
It is necessary to beware of literature dealing with non malignant mesothelioma, a much rarer condition which may also be caused by asbestos, and, if it is caused by asbestos exposure, the latency period appears to be very short but the sufferer lives for many years after diagnosis. Not all authors of anecdotal reports have noticed this distinction.
Many commentators have observed that the latency period for children is much shorter than for adults. The reasons for this are unknown but a number of plausible hypotheses have been put forward. I have not found a single commentator who suggests that the minimum latency period for an adult bears any relationship to that for children. Some of the surveys contain instances of exposure as a child and have to be discounted for that reason.
Lanphear and Buncher.
In a paper appearing in the Journal of Occupational Medicine in 1991 Lanphear and Buncher analysed the previous epidemiological studies that had been undertaken. There were 21 such studies available to them of which they examined 18 in detail. They rejected the remaining three papers as they failed to meet the criteria they had set of being published in a peer reviewed journal, having occupational exposure established and the diagnosis confirmed pathologically. The total number of cases they considered was 1105.
Of this number only five had latency periods of under 15 years; two had latency periods of 14 years, two had latency periods of 13 years and the shortest was one case with a latency period of 11 years. It is apparent from their paper that the 11 year latency period was rejected by them as being unrepresentative.
De Lajarte and de Lajatre.
The 11 year latency period was found in a review conducted by de Lajarte and de Lajarte published in 1979. This was a study of 70 deaths amongst ship-yard workers in St Nazaire. The authors commented that, “it is noteworthy that the subject with the shortest latency period , 11 years, had the earliest exposure; his father was a lagger in the shipyards and quite likely brought home asbestos dust on his clothes”. Although Lanphear and Buncher do not specifically mention this factor in their paper they also appear to have rejected this isolated case as being probative of short latency periods as they say the “reported range from initial exposure to death is 13 years to 70 years.”
The destruction of the World Trade Center.
The destruction of the World Trade Center led to the establishment of a fund to provide treatment for those who were within the area of Manhattan covered by dust. There are some 400,000 registered as falling within this category. Within five years five or six of this cohort had been diagnosed as suffering from mesothelioma. However, the number of those covered by the scheme was very large and New York is known to be an area containing many who inhaled asbestos in an industrial or building context. As a result the it was necessary for the administrators of the scheme to review the literature to determine whether these cases were in fact a result of inhaling asbestos during the collapse of the World Trade Center.
Included in the papers they studied was that by Lanphear and Buncher. They also reviewed the 5 major papers published since 1979 and, apart from the single example found in the de Lajatre paper found none with a latency period of under 13 years.
There are three papers which suggest that the minimum latency period may be less than 13 years. One is a survey of mesothelioma deaths in an area of Poland which was so heavily contaminated with asbestos waste from an asbestos cement factory that the amount of asbestos in the air was many times the normal background level. In this paper there are two cases in which exposure was 11 years from commencement of employment in the asbestos factory. However, in both cases substantial quantities of asbestos cement waste had been used in their immediate living areas giving rise to the probability that they had been exposed before they commenced employment at the asbestos works. The second is a degree paper by Frost in which she found a number of cases in which exposure under ten years had been reported. However, she discounted them on the basis that the underlying evidence for such a short latency period was not present. The third is a paper by Neumann and Gunthe. In their paper, the data for which was simply taken from the German asbestos registers, they record a single case of a latency period of 11 years but make no comment on it.
The rule of thumb used by most lawyers for the shortest possible latency period is ten years. However, the epidemiological papers barely support a latency period of under 13 years.
In Burnett v British Telecommunications plc  EWHC 3893 (QB) Mrs Justice May rejected a claim based on a latency period of almost exactly ten years. She concluded that there was no epidemiological evidence to support such a short latency period.
Unless the person suffering from mesothelioma is very young, it is impossible to succeed in a claim against any person responsible for exposure within 11 years of diagnosis and almost impossible in the case of latency periods of under 13 years.
ANDREW HOGARTH QC.
 The mesothelioma center, an American law practice, suggest that these cases are properly attributable to the collapse of the World Trade Centre.
 Bitchatchi E, Kayser K, Perelman M, Richter ED. Diagn Pathol. 2010 Dec do not appear to have noticed the distinction. For the distinction see “Well-differentiated papillary mesothelioma of the peritoneum: a separate entity.”Hoekman K, Tognon G, Risse EK, Bloemsma CA, Vermorken JB. Eur J Cancer. 1996 Feb;32A(2):255-8.
 Journal Occupational Medicine Vol 34 pages 718-21
 Annals of New York Academy of Science 1979 page 323.
 Minimum Latency and Types or Categories of Cancer. Jan 6th 2015.
 The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005). Frost G.
Br J Cancer. 2013 Oct 1;109(7):1965-73
Int Arch Occup Environ Health. 2001 Aug;74(6):383-95.Malignant mesothelioma–German mesothelioma register 1987-1999.Neumann V1, Günthe S, Mülle KM, Fischer M.
 Leave to appeal to the Court of Appeal has been refused.