We all come into contact with things in our day-to-day environments that have the potential to affect our health. Second-hand smoke, vehicle exhaust, and pesticide residues on fruits and vegetables are examples. We tend to take for granted that our bodies will protect us against such contaminants. However, children are not little adults; their growing bodies and exploratory behaviours make them very different. It is these very differences that make children more vulnerable to the contaminants around them.

The uterus: a child's first environment

During pregnancy the fetus is at risk of exposure to environmental contaminants that can affect its development and long-term health. The placenta (the structure that attaches the fetus to the inside of the uterus) acts somewhat like traffic cop during pregnancy, letting nutrients and oxygen reach the fetus, and preventing toxins and other substances from getting through. However, the placenta is not foolproof; drugs like alcohol, heavy metals like lead and mercury, and pollutants such as PCBs can all pass through the placenta and can potentially harm the developing fetus.

Timing also plays an important role in whether or not a toxin will harm the developing fetus. At certain periods of development - known as "windows of vulnerability" - the fetus is especially susceptible to small amounts of substances in the environment that at other times would not have as significant an effect. For example, exposure to air pollutants like carbon monoxide and ozone during the second month of pregnancy, when the fetal heart is forming, has been linked to the development of heart defects. Other substances, like alcohol, can damage the brain and nervous system of a fetus at any time during pregnancy.

Children's bodies make them vulnerable

Like the fetus, as infants' and children's bodies and organ systems grow and develop, they pass through many more critical stages. During these stages, their developing organs and tissues are particularly vulnerable to harm from exposure to toxins, and less able to process and remove them if they are exposed. For instance, children who are exposed to lead before the age of three are at greater risk for impaired intellectual development, stunted growth, and behaviour and hearing problems.

Infants and children drink more, eat more and breathe more rapidly than adults. They also have a larger body surface area in relation to their weight than adults, which increases their chance of absorbing chemicals through their skin. All of these factors increase children's exposure to environmental contaminants in the water, soil, food and air around them.

Children's behaviours make them vulnerable

Whether in the home, child care setting, park or school, children's short stature and crawling behaviour expose them more readily to pollutants, which tend to settle lower to the ground on surfaces such as carpets. Children also engage in exploratory behaviours, such as hand-to-mouth activities. This increases their likelihood of ingesting chemicals, such as lead dust, or pesticides in soils or on lawns. Household chemicals, such as cleaning products, can be especially hazardous for children and may be mistaken for interesting playthings.

Why do children need healthy spaces?

Children are dependent on adults and the choices that adults make affect them. For example, when an adult chooses to smoke around a child, this involuntarily exposes the child to a wide range of toxins in the smoke. Damage caused by exposure to environmental contaminants during childhood may not surface until much later in life. It is up to adults to take precautions that protect children from contaminants.

Children spend a lot of their "growing up" time in their homes and in child care settings. They have a right to live, play, learn and grow in healthy spaces free from environmental contaminants, hazards and toxins. As caregivers and parents, it is our responsibility to provide children with healthy and safe environments that ensure children's optimal health and well-being.

Healthy Spaces © was developed by the Canadian Institute of Child Health (www.cich.ca) in partnership with the Canadian Child Care Federation (www.cccf-fcsge.ca), funded by Human Resources Development Canada. Healthy Spaces (www.cfc-efc.ca/healthyspaces) is housed on Child & Family Canada (www.cfc-efc.ca).