FAQs - Canadian House Dust Study
Q. Why did the Government study household dust?
House dust may contain lead and other harmful chemicals. The study provides valuable information about Canadians' typical exposure to these chemicals in house dust and may help guide actions to manage chemicals in the indoor environment.
Q. How was the study conducted?
The study was conducted in four phases between 2007 and 2010. Dust samples were collected from 1,025 randomly-selected detached homes from the following 13 cities across Canada: Richmond, Vancouver, Calgary, Regina, Burlington, Hamilton, Cambridge, Barrie, Thunder Bay, Sudbury, Gatineau, Montreal and Halifax.
A vacuum dust sample was taken from all living areas of each home (including living rooms, dining rooms, bedrooms, hallways and finished basements) and analyzed for lead. The dust samples are now being analyzed for other metals (zinc, cadmium, antimony and nickel), as well as sulphides, carbonates and organic carbon compounds. In addition, *wipe samples were collected from bare floors of individual rooms.
All participants were provided with their individual test results and guidance on identifying and minimizing exposures to lead in their homes.
Bacteria samples were collected in Phase 1 only, in collaboration with Public Health Agency of Canada. The information that was collected was used for the development of improved cleaning guidelines.
* Note: Wipe sampling is wiping a section of flooring using a piece of pre-moistened non-woven polyvinyl alcohol fibre square, and then folding the square or "wipe" inward to preserve the dust that was picked up.
Q. What were the results? Did certain rooms in the home that have higher lead concentrations than others?
The results showed that all 1025 homes sampled had measureable concentrations of lead in their house dust, ranging from 8 to 3916 parts per million (ppm) with a median value (50th percentile) of 63 ppm. 90% of urban Canadian homes have dust lead levels between 8 and 250 ppm, and 10% have dust lead levels above 250 ppm.
One third (33%) of urban Canadian homes with dust lead levels below 250 ppm were built before 1960. This indicates that that many homeowners are effectively renovating older homes to remove lead paint and other sources of exposure. It should also be noted that 10% of homes with higher lead levels (>250 ppm) were built after 1980, indicating that lead is not only found in older homes.
These results are based on a vacuum sample that combines all living areas of the house. In addition, wipe samples were collected from bare floors of individual rooms, and these showed that concentrations of lead vary widely from room to room in the same house.
Previous studies have shown that concentrations of lead in house dust are highly variable, even among homes within a single neighborhood.
Where elevated levels were found, they predominantly consisted of older homes in central core areas of cities (which is explained largely by the lead content found in older paint).
Health Canada has not yet set reference levels for lead in house dust. The measurements from this study provide an important starting point for future research and risk management activities related to lead exposure in indoor environments.
Q. Why are lead levels in homes so variable?
There are a number of factors that can influence the levels of lead in indoor dust, including the individual characteristics of a home and the activities of its residents. For example, lead levels can be influenced by renovation activities, hobbies, and by consumer product choices - all of which are highly variable from home to home. Also, outdoor sources of lead (i.e. soil) can contribute to lead in house dust but, again, the amounts are highly variable.
Q. Did some cities have homes with higher lead levels than others?
The Canada House Dust Study is a national study that looks at typical exposures of Canadians to lead in house dust. The data is not broken down by city, or by province because the sampling was designed to be representative of Canada as a whole.
Q. Why is lead being found in all homes?
Lead is a naturally occurring mineral in the Earth's crust and has been widely used in many industrial applications for centuries. As a result, low levels of lead are found everywhere in the natural and human environments.
Lead exposure in Canada has decreased substantially since the early 1970s, mainly because leaded gasoline and lead-based paints were phased out and the use of lead solder in food cans was almost completely eliminated. In fact, blood lead levels in Canadians have declined by more than 70% since 1978-79.
Canada has some of the most stringent lead limits for consumer products in the world, and the Government of Canada continues to work to reduce the risks to Canadians from all sources of lead exposure.
Q. How can Canadians reduce their exposure to lead in house dust?
Effective house cleaning (e.g. using damp mopping) to remove dust and particles can reduce exposure to lead and other chemicals in house dust. Regular vacuuming of carpets and taking shoes off at the door is another way to prevent lead and other substances from getting into dust inside the home.
For more information on how to reduce exposure to lead in the home, please consult the following:
- The Effects on Lead and Human Health - Minimize your Risk
- Hazards in Your Environment
Q. What are some of the possible sources of lead in indoor dust?
Dust and soil can be significant lead exposure sources, especially for young children. Lead in soil can get tracked indoors from outdoor soil that is high in lead due to industrial sources or erosion of lead-bearing rocks, or penetrate indoors as airborne particles. Lead dust can also come from within the home, for example older homes that still contain lead-based paints or lead solder.
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