Lead Exposure & Poisoning

Recent concerns related to LEAD have prompted many questions. The following is intended to provide some insight into why lead exposure and poisoning can be a problem.

What is Lead? – Lead (Pb) is a naturally occurring substance extracted from ores dug from under-ground mines. It is a soft, corrosion-resistant, grey metal that is a common environmental contaminant in air, food, paint, and water. Romans used lead to in making potable water piping. In fact, the word "plumbing" is derived from the Latin word for lead, plumbum. Besides plumbing, lead has been used in the making of ceramics, cosmetics, lead batteries, leaded paint, and leaded gasoline. The US based Agency for Toxic Substances and Disease Registry (ATSDR) estimates that more than one million workers in one hundred occupations are exposed to lead, such as in the lead-battery recycling and lead-smelting industries. Equally important, almost all persons are exposed to lead in residential settings from sources such as paint chips, food, water, cigarettes, and clothing that have been worn in lead-contaminated work environments. Lead has many industrial uses and has been used in water systems since the late 1880s. While lead can leach into drinking water from lead service lines and plumbing, the bulk of human exposure is from other sources.

The level of exposure to lead by the general public to lead has significantly decreased over in the past decades due to restrictions in the use of lead as an additive in gasoline, paint and solder. For the most part, in Canada:

• Lead in paint was reduced or eliminated in the mid 1970s.
• Lead in solder, used for tin cans and drinking water pipes, was reduced or eliminated in the mid to late 1980s
• Lead additives in gasoline were eliminated for most applications in the early 1990s

Why is Lead a Problem? – Canada Mortgage & Housing (CMHC) states that lead is what is known as a neurotoxicant 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 haemoglobin (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.

Lead, a heavy metal, can accumulate in the body when consumed orally and interfere with chemical reactions in the body. It can result in decreased performance in school, permanent learning disabilities, kidney problems, liver damage, nerve problems, high blood pressure, immune system failure, convulsion, comma, brain damage and in severe cases death. In pregnant women, lead poisoning can lead to premature birth and babies with low birth weight, mental retardation, nerve damage, and impaired blood formation, and to infant mortality. Serious learning and behaviour disabilities are seven times more likely to occur in children exposed to low-levels of lead over an extended time (New England Journal of Medicine -- 01/11/90). Lead poisoning in children can seriously damage a child’s brain and central nervous system. It can also cause attention span deficits, impaired hearing, reading and learning disabilities, and even, reduced IQ scores.

Although adults may suffer various ailments due to excessive lead in their blood, the groups most at risk from exposure to lead are fetuses, infants, and children under seven. Since the fetus is at risk from high blood-lead levels in the mother, pregnant women and women of childbearing age must also be aware of the hazards of high blood-lead levels. Children are especially at high risk because they routinely ingest non-food items contaminated with lead.

For more information get Health Canada’s “Lead Information Package - Some Commonly Asked Questions About Lead & Human Health” at www.hc-sc.gc.ca.

Sources of Lead -- Humans are being exposed to lead from numerous sources including, paint pigments, automobile and industrial emissions, surface and ground water, and some forms of solder. Common household examples of where lead can be found may include, water, dinnerware, pottery & ceramics (most commonly form Mexico and Italy), toys, soil, dust, food cans, antiques, and furniture. Recently, inexpensive imported mini-blinds and toys have been found to be lead contaminated. In young children, lead exposure can also come from eating dirt and dust from the environment.

Lead dust is a special concern because the smaller lead particles can be more easily transported and absorbed by the body. For example, lead-based paint dust can come from the normal abrasion of painted surfaces such as the opening and closing of windows. For young children this can be hazardous because they play on the floor and engage in a great deal of hand-mouth activity.

In soil, lead dust can accumulate and contaminate it. For years, lead-based exterior paints were designed to “chalk”, or lose some their surface when they are washed off by rain, to remain looking newer. For younger children who play in this soil or track it into the house it can increase lead levels in the home.

Who should read this CMHC booklet?

Do you live in a home built between 1960 and 1980 that you plan to renovate, that is currently being renovated, or that has recently been renovated?

Do you live in a home built before 1960 that has chipped, cracked or peeling paint accessible to pre-school aged children?

Was the plumbing in your home installed before 1960?

Do you live near a large painted metal structure, (such as a bridge), or near an industry (such as a lead-battery recycling factory) where lead has been used?

Are you concerned about the effects of household lead?

Approximately one out of four Canadian dwellings was built prior to 1960. It is best to assume that a dwelling constructed before 1960 contains leaded paint. If you answered “yes” or “I don’t know” to any of the above questions, your family may be at risk of lead exposure. While not all older homes pose lead hazards, some do, and there are precautionary measures that you need to be aware of as a homeowner or tenant.

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