A re-analysis of the supposed role of lead poisoning in Sir John Franklin’s last expedition, 1845–1848

All my adult life it had been axiomatic that the Expedition was brought low by lead poisoning. Indeed my own initial research into the Expedition was an attempt to find an alternative source for lead poisoning other than from tinned food, BASED ON THIS ASSUMPTION which I took as a fact.

Enter Keith Millar. I first met Keith about a year ago although we had corresponded and spoken on the phone for longer. Keith is Professor of Medical Psychology in the Medical School at Glasgow University and Honorary Senior Research Fellow at the Institute of Health and Wellbeing. He is ideally qualified to assess the medical background of the men Franklin Expedition. Like so many of us he has caught the ‘Franklin bug’ and become fascinated by trying to unpick the mystery of what happened to those ships and men. His idea was to look again at what the evidence for lead poisoning actually is, and then to see how it compares with people today who live with a high exposure to lead. Keith realised that this would involve very careful assessment of what might be quite sparse data and invited as co-author his eminent colleague from Glasgow University, Adrian Bowman, who is Professor and Head of Statistics in the School of Mathematics and Statistics at Glasgow University. The results of this work has been published in ‘Polar Record’ and the link to the paper is here.

So what does the paper say?

It surprised me when Keith dug into the evidence to find that there is a lot less than I had thought. I knew the three men buried at King William Island had been found to have lead in their hair, bone and soft tissue. But it turns out that the bones recovered from King William Island, and analysed for lead, represent many fewer individuals than I had realised – perhaps as few as seven men. Ten men still represent a reasonable sample of those who died on the Expedition, but it is a smaller sample than I had realised.

Another point was a bit of an eye-opener to me. I’ve always know that lead poisons you when it is in your bloodstream and soft tissue, and not in your bones. I’d understood from Beattie and Geiger’s ‘Frozen in Time’ that the soft tissue and hair samples taken from the Beechey Island bodies proved that lead poisoning there had been ‘catastrophic’ for the men. But Keith’s careful assessment of their actual raw data shows that the evidence for this is less clear, and a lot less certain, than I had previously understood.

Although less extensive and compelling than I had realised, there IS evidence for both a short term (from hair and soft tissue) and a long term (in bone) exposure to lead. But how much of this lead uptake took place on the Expedition and how much was in the men before they left England? The problem with answering this question is that Keith could find no practical control population to compare the Franklin bones with, so we really can’t be sure. So if the Franklin men were ‘zombified’ with lead (an allegation I have seen) then who is to say that my great-great grandparents, and the rest of the population living in England then, weren’t ‘zombified’ as well? We know Victorian society was intimately exposed to lead – in pipes, wallpaper, toys, make-up, etc. The problem is that until someone can come up with control samples, we simply don’t know whether Franklin’s men had any more lead in them that the rest of the population.

So what can the evidence we DO have tell us? What Keith does is ‘maps’ the evidence for lead in the men’s bones which IS secure against similar hard evidence from people alive today who we know have been heavily exposed to lead. This is where Adrian Bowman comes in with his painstaking analysis of this data.

Keith used data for the amount of lead in the men’s tibias (shinbones) because this can be compared with statistics for tibia-lead in present day populations. But the tibias of the three men who were buried on Beechey Island were not sampled, and we only actually have four tibia samples from King William Island. As I said before, when we get down to serious analysis we find we have much less evidence that we thought. Any results must be fairly tentative because they are based on a small sample. If just one more tibia of a Franklin sailor was to be found and analysed, it would increase the size of the sample by 25%!

Adrian was able to ‘map’ the distribution of these four men’s samples against five comparable studies of present day people which Keith was able to locate. Keith as a clinician is ideally placed to interpret this. He reads this evidence as suggesting that there was probably quite a wide variation both in the men’s exposure to lead and in the effect it had on them. Some of the men may have been affected to the point of being declared sick, yet others almost certainly experienced absolutely no ill effects at all.

That may sound like a fairly limited conclusion but I actually think it is extremely important. This paper shows that to conclude that the men of the Erebus and Terror were ‘zombified’ by lead poisoning is completely untenable – the evidence does not exist. Similarly the suggestion that their officers’ decision making abilities must have been impaired by lead poisoning – something I have seen quite often stated as a fact – is equally untenable. It MIGHT have happened, but there is no clear proof. Because we have no ‘control’ data, and we now know that the ships were equipped and provisioned no differently from other ships of the time, we have no evidence that lead was any more of a problem on this voyage than on others. No one says that the crew of the Investigator were ‘zombified’ by lead, or that Robert McClure’s decision making was impaired by lead. Yet McClure and his men could well have operated with exactly the same lead in them that Franklin’s men had.

And the experience of the Investigator is also salutary in another respect. Their ship was beset with just as much finality as the Erebus and Terror, and it was only with the most remarkable luck that the men were rescued. Luck, in other words, played a more important role in their fate than lead. It seems likely that ice and weather conditions at the time of the Franklin Expedition were especially challenging. This is something which is discussed in a very interesting 1985 paper “Arctic Climate during the Franklin era” by Alt, Koerner, Fisher and Bourgeois which Keith drew my attention to recently. The Franklin Expedition had no ability to forecast weather or ice conditions and such factors were completely outside their control. Perhaps if they had had the luck of McClure some of them might just have made it though the North West Passage? Maybe emerging in their boats as Sir John Ross had done in 1833, and as some of Franklin’s officers suspected they would, too, before they even sailed from Greenhithe! Again, this is a matter of luck rather than lead.

The basic problem, and the basic mystery, of Franklin’s Expedition is that no one lived to tell the tale, and none of their written records have survived to be read. So we simply don’t know what happened. The whole ‘lead’ saga is a valiant effort to extract as much knowledge as we can from very little evidence. Probably in the past we have all been guilty (me as much as anyone) of trying to squeeze more information from the limited evidence that we have than is justified. So until we can read more of what the men wrote (more about that in a future post), or until Parks Canada can locate a ship, we will probably have to resist the temptation to over-interpret such limited data.