What is lead?
Lead is a heavy, soft, bluish-grey metal that occurs naturally in the earth’s crust in small amounts. Much higher concentrations are found in lead ores. It can be found everywhere in our environment, not only because it occurs naturally, but also because it is used extensively in modern industry (mining, manufacturing and burning of fossil fuels).
In some situations painted surfaces are in poor condition. Often, paint chips are visibly flaking. These areas need immediate attention – but exercise caution. Repairing lead painted surfaces can create more lead dust. You may want to consider hiring an experienced contractor for jobs such as:
Tearing down plaster walls
Sanding large painted surfaces (such as, the side of a house or a complete room)
Window or door replacement
Carpet replacement – carpets can be reservoirs of lead dust
Tearing up old flooring
Tearing down ceilings
Removing old drop-ceilings – dust can accumulate above ceiling panels
Stripping leaded paint using chemical strippers, heat guns, or other methods
Quantity of lead in lead paint
Until the 1960s, lead was used as a pigment in many paints, especially white and pastel shades. Some paints contained as much as 50 percent lead by weight. Other pigments replaced lead in the 1960s, but small amounts were still used in some paints as a sealant or to speed up drying.
In 1976, federal government regulations limited the amount of lead in interior paint to 0.5% by weight. Exterior paints can contain more than 0.5% lead by weight, but paint cans have to be labeled with a warning that the paint contains lead and is not to be used on surfaces children can chew.
By 1991, Canadian paint manufacturers had voluntarily stopped using lead altogether. Paint in your home that is more than a few decades old may contain lead. Lead levels vary depending on when the paint was manufactured.
If your house was built between 1960 and 1980, the interior or exterior paint may contain small amounts of lead. If it was built before 1960, and surfaces are covered with several layers of paint, your house undoubtedly contains high levels of lead.
The determination of lead in lead paint as having greater than 1 µm per square centimeter of surface or 0.5% by weight. Lead inspections are performed by XRF, paint chip analysis, or a combination of both. The occupational exposure limit for airborne lead is 0.05% mg/m3.
Source: Health Canada and HUD, Housing and Urban Development, USA Guidelines
Why is lead so dangerous?
Lead-based paint doesn’t pose a danger if it’s in good condition, and is not disturbed. However, if the paint is peeling or flaking, then a potentially harmful situation exists.
Even friction from opening and closing doors or windows with painted frames can produce paint dust. This dust can get onto children’s hands and toys, and from there, into their mouths. Paint chips can easily be swallowed by young children. Ledges and trim that are accessible to teething toddlers should also be cause for concern.
Renovating an older house can expose occupants to lead. Sanding, scraping, or heating lead-based paint can produce large amounts of lead-containing dust or fumes.
Even remodeling without sanding or scraping can damage old paint or release old lead-laden dust. Weathered paint on the outside of the house can contaminate gardens and sandboxes. Contaminated soil and sand can then be tracked inside, adding to the lead level indoors of lead.
Lead is what is known as a neuro-toxicant or a brain poison. Even in very small amounts, lead can harm the developing brain and nervous system of fetuses and young children, which can lead to behavioural and learning difficulties. Lead can also interfere with the way that hemoglobin (the oxygen carrying part of blood) is produced. Lead can disturb processes essential to vitamin D and calcium metabolism. Chronic, or long-term lead exposure, can lead to high blood pressure and peripheral vascular disease. It is generally agreed that there is no safe level of lead exposure, although risk of suffering adverse health effects from lead exposure will decline as exposure declines.
What do I do if my home contains lead paint
Sometimes the best option, when dealing with lead-based paint in good condition, is to leave it alone. Homeowners untrained in lead precautionary measures can create a big problem when removing lead.
Removing sources of lead-based paint takes specialized knowledge. As an interim measure, homeowners and tenants may be able to keep lead dust levels under control by regular damp mopping of floors; damp dusting horizontal surfaces such as windowsills and stairs; and regular vacuuming of carpets. Exterior windowsills that are chipping and flaking can be covered with metal cladding.
Reference: Canada Mortgage and Housing Corporation and Health Canada (Lead in your Home #61941)
For more information, refer to Lead-Containing Paints and Coatings: Preventing Exposure in the Construction Industry
Acceptable Methods for Testing Lead
Lead in Paint Sample: SW8467000B Flame AA, NIOSH 7082, 7105, 7300, 7300
Lead in Surface Coatings: Portable X-Ray Fluorescence Analyzer
Surface Dust Sampling: NIOSH 9100
Airborne Lead: NIOSH 7303