Lead was one of the first metals to be mined, and it has been used widely since then – including in paint, pipes, and gasoline. However, there is a global push to lower levels of lead exposure because we know that high levels of lead impact human health. Notably, this includes decreased IQ in children.
In Canada, lead has been removed from gasoline and paint, and levels have been reduced in our drinking water, cutting our exposure to less than half of what it was 20-25 years ago.
To help define safe limits, Fiona McNeill, professor of medical physics and applied radiation sciences at McMaster University, is measuring long-term metal exposure and its impact on human health.
“At the moment, we assess people’s exposure through measurements of blood in urine, but they only tell us about a person’s recent exposure and we know that most health effects are consequence of long-term exposure,” explains McNeill. “Using radiation-based techniques – mostly x-ray techniques – I assess people’s exposure painlessly and simply.”
This technology is portable, allowing McNeill to study at-risk populations all over the world.
The case for fluoride is more complex. While lead reduction is a clear goal, we choose to add fluoride to our drinking water as a public health benefit, mainly for its protective effect on teeth. However, at high exposures, there is increased risk of bone fracture. Finding the right amount to achieve dental health and avoid fracture risks is important. McNeill is now working on defining safe levels by measuring fluoride non-invasively.
