At rest, children's breathing rates are faster than those of adults, and children's greater levels of physical activity can increase their breathing rates even further. Children often play at ground level. In contrast, an adult's common breathing zone is four to six feet above the floor. Children will receive greater inhalation and dermal exposure to chemicals present on floors, carpet, grass, or dirt. Also, heavier chemicals such as lead and particulates will settle and accumulate in the air at ground level.
Childhood is characterized by rapid physical and mental growth.
Accordingly, certain organs may not be fully developed and may be more vulnerable to injury. Children absorb, metabolize, and excrete compounds differently than adults. The fetus is particularly sensitive to environmental toxicants. Chemicals can affect the children born to women exposed during pregnancy, while the women remain unaffected. For example, the children of women from Michigan who ate two to three meals of fish contaminated with PCBs per month for six years before pregnancy had lower birth weights, memory deficits at seven months and four years of age, and cognitive deficits persisted at eleven years of age.