TORONTO — With the lead-contaminated water crisis unfolding in Flint, Mich., and concerns about lead pipes in older Toronto homes, people are asking a lot of questions about the health risks of lead exposure.
Let’s explore this further.
Lead is a metal that has been known to cause toxicity in humans for over a hundred years now. It can leech into our water supply through old lead pipes, or more commonly, from lead solder used to join copper plumbing.
In many cities, including Toronto, thousands of houses built before the mid-1950s still have lead pipes connecting to municipal water mains.
Although there are several acute medical complications that can occur from lead poisoning, the much bigger concern in places like Flint is long-term exposure to low levels of lead in the water supply.
And the most population most vulnerable to this is children under six, because the barrier between their blood stream and their brain tissue (the “blood-brain barrier”) is not fully developed, which allows lead to get into the brain and the nervous system.
In kids, lead inhaled into the respiratory system is absorbed completely, and up to 70 per cent of the lead that’s ingested by mouth is also absorbed. Once it’s in the blood, it’s rapidly absorbed into the bone structure, where it acts as an ongoing reservoir of lead for as long as 25 years.
And what’s terrifying about this kind of lead toxicity is that with mildly elevated levels, most kids will have no obvious symptoms, but brain development will be affected.
Long-term studies show that these kids can have impaired learning and memory, decreased hearing and verbal ability, a lower IQ, and a higher chance of having Attention Deficit Hyperactivity Disorder (ADHD) and/or of simply being hyperactive. And these effects are not reversible.
Do we need to worry about lead toxicity in Canada?
Our biggest source of lead exposure used to be leaded gasoline, but lead was virtually eliminated from gasoline in 1990. Lead in interior paint was banned in 1960, but older homes are still a possible source.
That being said, in 2010 lead blood levels in Canadians were down 70 per cent compared to the late 1970s because of these measures (unfortunately, we don’t have Canadian data on blood levels in kids under six, which is the most vulnerable group).
Although lead levels in toys are now regulated here, older toys and toys from other parts of the world are still a risk. People should also be careful with herbal medicines, some of which contain lead, and avoid storing food or drink in open cans or in pottery that might have a lead glaze.
It’s also important to make sure that kids get enough calcium and iron in their diet, which slows down the absorption of lead, and enough vitamin C, which speeds up the removal of lead from the body.
And if you do live in old house, and you don’t know if your water connection is made of lead, contact the city for a free lead testing kit and check your water’s lead levels.