Today’s suicides a legacy of 1970s gas-sniffing?
LEAD POISONING LINK TO GENETIC CHANGES PROBED
It was 1973, and federal epidemiologist Dr. John Davies was concerned by what he saw among northwestern Ontario’s aboriginal population.
Gas sniffing seemed widespread, he wrote a colleague at the Sioux Lookout hospital, and tests showed young sniffers had as much as 17 times the level of lead in their blood as could inflict brain damage.
Four decades later, the fallout from that abuse may still be taking a lethal — and surprising — toll, actually helping fuel Canada’s epidemic of First Nations suicide, suggest researchers who unearthed the letter recently.
They theorize in a just-published paper in the journal Psychiatry Research that gas-sniffing and other sources of lead poisoning in the 1970s and 1980s triggered genetic changes in the users, which in turn may have been passed on to their children, a process called epigenetics.
And those gene changes could still be causing neurological problems that make young people more prone to depression and suicide, say the scientists at St. Michael’s Hospital and the University of Toronto.
The hypothesis might partially explain an unusual fact: suicide rates in indigenous communities were minimal before the mid-1980s and now are among the highest in the world.
“Suicide is not a traditional aspect of indigenous culture in Canada,” the article notes. “This commentary raises the possibility that the effects of tetraethyl lead poisoning during the 1970s and 1980s contributed to the rise in suicides, and continues to contribute to the growing problem through epigenetic modifcations.”
No one suggests the inter-generational legacy of toxic lead — if proven true by more study — would turn out to be the sole cause of the spate of suicides.
But it would add an intriguing risk factor to those more commonly cited, including feelings of hopelessness in impoverished communities, personal and family histories of mental illness or addiction, childhood abuse and the knockon impact of the residential-school era.
“I think it is a contributing factor, but I don’t think it’s the primary one,” said Trehani Fonseka, the article’s co-author and a leader of the First Nations depression and suicide-prevention program at St. Michael’s. “It’s not just going to be one thing, there are going to be a lot of interactions between environmental risk factors and the biological ones, too.”
We’re always struggling to find some simple explanation for complex, multi-factorial things
A spokesman for Nishnawbe Aski Nation, which represents about 50 First Nations in Northern Ontario, declined to comment until the group can review the paper further.
One outside expert said the theory is plausible, though largely speculative and lacking in hard evidence.
But it would be wrong to put too much credence in it when there are many other issues at play as well, said Dr. Laurence Kirmayer, a McGill University psychiatry professor and head of a national network for aboriginal mental-health research.
“We’re always struggling to find some simple explanation for complex, multi-factorial things,” he said. “It’s a mistake to interpret this (suicide epidemic) as some kind of inevitable consequence.”
Still, Kirmayer acknowledged the upsurge in suicides over the past 30 years is a hot topic of discussion among scientists.
The problem has certainly captured headlines recently, with 11 suicide attempts in one day last spring at Ontario’s Attawapiskat reserve, six deaths among girls aged 10 to 14 in northern Saskatchewan last fall and six suicides in a remote Quebec community in 2015.
A 2010 coroner’s inquiry into 16 child suicides at Ontario’s Pikangikum First Nation said young indigenous people kill themselves five to six times as often as nonnative youth.
Yet prior to the mid-1980s, such deaths were relatively rare. The 20 First Nations in northwestern Ontario — including Attawapiskat and Pikangikum — recorded an average of only one or two a year back then, notes the new paper, citing coroner’s office figures.
Fonseka and colleagues, including U of T suicide expert Dr. Sidney Kennedy, pointed to animal research that suggests lead poisoning can affect genes that regulate the release of serotonin — itself linked to depression and suicidal thoughts.
And some studies suggest those gene changes can then be inherited by subsequent generations, they say.
Lead was not banned from gas in Canada until 1993. As well as gas sniffing — an inexpensive high common to marginalized populations around the world — indigenous people in the 1970s could have also been exposed to the toxic metal from pipes, paint and boat fuel, the paper notes.
The 1973 letter from Health Canada scientist Davies — discovered in the University of Toronto archives — cited tests showing lead volumes in gas sniffers of up to 85 micrograms per 100 millilitres of blood. Neurological damage is known to start at levels as low as five micrograms.
Fonseka said more study is planned to test the hypothesis. If confirmed, the presence of genetic changes linked to lead poisoning could serve as an “early warning” sign for groups at risk of suicide and help direct preventive programs to them.