What is Lead?
Lead is the most common of the heavy elements, and is found in natural deposits such as ores that also contain other elements. Lead was used in pipes during Roman times and has been used extensively since then. As a result, lead has become widely distributed throughout the environment.

Lead is now used in items such as car batteries, copper and lead alloys, pipes, ammunition, pigments, glass and ceramic production, insecticides and fertilizers. The most well known uses of lead were in household plumbing materials or in water service, as a gasoline anti-knock additive, and in household paints.

Everyone is exposed to trace amounts of lead through air, soil, household dust, food, drinking water and various consumer products. The amount of lead in the environment increased during the industrial revolution, and again significantly with the introduction of leaded gasoline. However, since the early 1970's, lead exposure in Canada has decreased substantially, mainly because leaded gasoline was phased-out and the use of lead solder in food cans was virtually eliminated.

How does Lead enter our water?
Lead enters drinking water primarily by corrosion of lead plumbing or fixtures. All water is corrosive to metal plumbing materials to some degree, especially soft, acidic waters. Lead is rarely found in source water, but lead mining and smelting operations may contaminate the source water. Most lead entering surface water eventually becomes associated with bottom sediments. In two national surveys done in 1976 and 1977, lead concentrations in untreated water were generally less than 1 microgram per litre in 71 Canadian municipalities.

How does Lead affect human health?
Even small amounts of lead can be harmful, especially to infants, young children and pregnant women. Short-term exposure to high levels of lead can cause vomiting, diarrhoea, convulsions, coma or even death. But severe cases like this are rare in Canada.

Symptoms of long-term exposure to lower lead levels may be less noticeable but are still serious. Anaemia is common and damage to the nervous system may cause impaired mental function. Other symptoms are appetite loss, abdominal pain, constipation, fatigue, sleeplessness, irritability and headache. Continued excessive exposure, as in an industrial setting, can affect the kidneys.

Lead exposure is most serious for young children because they absorb lead more easily than adults. Even low level exposure may harm the intellectual development, behaviour, size and hearing of infants. During pregnancy, especially in the last trimester, lead can cross the placenta and affect the unborn child. Female workers exposed to high levels of lead have more miscarriages and stillbirths.

How does Lead affect the aquatic environment?
Lead is toxic to freshwater fish and invertebrates. Used in pure form as lead shot and in fishing tackle such as sinkers and lures, lead can often harm waterfowl and other wildlife that eat the shot or sinkers, are poisoned and die. Regulations on lead shot and fishing sinkers are helping to reduce the amount of lead affecting wildlife.

What are the Lead guidelines?
The Federal-Provincial-Territorial Committee on Drinking Water has established a guideline for lead of 0.010 micrograms per litre of drinking water. This guideline was established to be protective of children, who are most likely to be adversely affected by lead.

• Drinking Water Guidelines

The Canadian Water Quality Guideline for the Protection of Aquatic Life for lead is set at 1-7 micrograms per litre of water, but this has not been changed since it was set in 1987. To protect bottom-dwelling aquatic life, there is an interim Canadian Sediment Quality Guideline for the Protection of Aquatic Life of 35 milligrams per kilogram of sediment.

• Canadian Water Quality Guidelines for the Protection of Aquatic Life:
  • for water
  • for sediment

What can individuals do to help?
To help avoid lead from contaminating our water supply:

• Recycle lead-containing batteries.
• Be aware of the product contents and use ones that are less toxic. Many products commonly used around the home contain lead such as paints, ceramics, glass, plumbing pipes and solder.
• Properly dispose of old paints, fertilizers, and other products at hazardous waste collection centres. Do not pour them down the drain or in the sewer. Pouring chemicals in these areas may disrupt the septic system or contaminate water supplies.
• Use non-lead containing ammunition and fishing sinkers.
• In older homes, reduce lead by:
  • Always using cold, fresh water for drinking, cooking, making baby formula and preparing beverages.
  • Flushing the plumbing system by letting water run for about a minute or until it gets cold if it has been standing in the pipes for any extended period of time. Changing water-use patterns so that water that has been standing in pipes is used for showering or laundry.