Lead poisoning may have made life difficult for the doomed men of John Franklins 1845 expedition, which got lost in the Arctic while in search of the Northwest Passage linking the Atlantic and Pacific Oceans. But it probably didnt contribute much to their inevitable fates. Thats the conclusion of a new study of lead concentrations in the hair of one of the men who died while the expedition was stranded on King William Island between late 1846 and early 1848.
129 Doomed Men
Captain Sir John Franklins expedition wasnt the first to sail north in search of a passage linking the Atlantic and Pacific Oceans, and it wasnt the last. But its disappearance left behind a compelling mystery, one kept in the public consciousness for years by the tireless efforts of Franklins widow. For years in the late 19th century, the search for the lost sailing ships HMS Terror and HMS Erebus nearly rivaled the search for the Northwest Passage itself.
Thanks to a note found in 1869 on King William Island, we know that all was well on the wooden ships in May of 1847, aside from being stuck in the ice. But by April of 1848, 24 men had died, including Franklin and the expeditions assistant surgeon, naturalist Harry Goodsir. The remaining 105 had abandoned their trapped ships and set off across the ice to try to reach Back River on the Canadian mainland. Neither ship would be seen again for over 150 years. A century and a half later, historians are still debating exactly what went wrong.
A number of fingers have pointed at the ships food and water supplies, which they suggest may have been poisoning the explorers all along. The pipes from both ships water tanks were made of lead, and nearly all of the crews food came in tin cans held together with lead-soldered seams. Many of the medicines Dr. Goodsir and his colleagues would have dispensed to sick or injured explorers also contained lead, not to mention arsenic and a few other things the FDA would balk at today.
And a 1991 study found high lead concentrations in the bones of three men who died on Beechey Island in early 1846, during the expeditions first winter in the Arctic. All this evidence makes a morbidly fascinating story: two ships full of intrepid Arctic explorers perished because their food and water all carried high doses of lead, and they unwittingly succumbed to muddled thinking, irritability, digestive ailments, pain, and kidney damage.
But a closer look suggests thats not the case.
Splitting hairs
Anthropologist Lori DOrtenzio of McMaster University and her colleagues turned to Dr. Goodsir. His remains were tentatively identified based on facial reconstruction in a previous study, and they were used to help understand whether lead poisoning might have played a role in the expeditions tragic end. The researchers examined lead concentrations in Goodsirs hair. Because hair retains some of the lead taken into the body, and because it grows at a rate of just over a centimeter a month, the few preserved sections of Goodsirs hair captured a record of his lead exposure in his final months.
The bones of the Beechey Island men, on the other hand, provided a longer-term record. The human body remodels and replaces bone tissue very slowly, over about 10-50 years, so the lead stored in the Beechey Island mens bones probably entered their bodies at least a decade before they set foot on the ill-fated ships and sailed north. The crews lead exposure would have been high enough to alarm modern occupational health regulators, but it almost certainly didnt come from their time on the expedition.
“The lead burdens likely originated from contamination in the atmosphere, water, food sources, tableware, drinking vessels, and medicine ubiquitous in 19th-century Britain,” DOrtenzio and her colleagues wrote.
When DOrtenzio and her colleagues sampled Goodsirs hair, they didnt just look at how much lead was in it. They examined the ratio of different isotopes of lead. This helped confirm that Goodsir and his shipmates buried at Beechey Island had been exposed to the same general lead sources.
But Goodsir died about a year after the Beechey Island men, which means the lead stored in his hair would have been absorbed on the expedition. Hair and bone each store lead in different proportions than blood, but those proportions are pretty consistent. That allowed DOrtenzio and her colleagues to calculate how much lead would probably have been in the bloodstream of all four dead men. It turned out that Goodsirs body was no more contaminated than the remains of his shipmates.
In fact, lead concentrations were actually slightly lower in the section of Goodsirs hair closest to the root: 77.3 parts per million, down from 84.2 near the tip. That meant his lead exposure had actually decreased slightly in the final weeks of his life–which DOrtenzio and her colleagues say may actually be a clue about how he died.
“The fatal end was inevitable”
The crews of HMS Erebus and HMS Terror were clearly ingesting a staggering amount of lead—but apparently no more than their families back home. That makes it highly unlikely that lead poisoning is what finished off Franklins crews.
Individual responses to lead exposure vary so much that modern doctors would be hard-pressed to predict a patients symptoms solely based on the level of lead in their blood. But DOrtenzio and her colleagues say the concentrations in Goodsirs hair and the bones of the Beechey Island men probably wouldnt have been enough to incapacitate the crews.
In their final months, Franklins crews may have felt pain in their joints and abdomens, or they may have struggled with nausea or constipation. They may have had headaches or had to push through fatigue, irritability, or sluggish thinking. But those discomforts may not have stood out much against the cold, hunger, and fear of being stranded in the uncharted Arctic. “Lead burdens may have exacerbated the physical decline of the men in the final months of the expedition, but by then, the fatal end was inevitable,” DOrtenzio and her colleagues wrote.
Death of a naturalist
In Goodsirs case, the culprit may have been an infected tooth, which was evidently serious enough to leave its mark on the bone of his upper left jaw.
Goodsirs grave lies on the far side of the island from the trapped ships, on the path of the crews final, desperate march toward the mainland. But “his grave was carefully dug, whereas it is clear that those who died on the final march were not buried but simply abandoned where they fell,” write DOrtenzio and her colleagues. Goodsir may have died on a sledging excursion, probably intended as a combination of hunting and ecological research.
Being away from the ship for a few weeks and living on freshly killed meat rather than canned food might explain the decrease in Goodsirs lead exposure. But it clearly wasnt enough to save him.
Journal of Archaeological Science: Reports, 2018. DOI: 10.1016/j.jasrep.2018.08.021 (About DOIs).
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Ars Technica
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