There are various substances in our environment today that not only affect adults, but also affect children. Children are affected by environmental hazards as early as in the fetal stage of human development, through the mother's exposure to these hazards. The different routes of exposure include air, water, food and soil. These hazardous substances include lead, air pollution in schools and homes, pesticides, PCBs, solvents, asbestos, radon, mercury, arsenic, sulfur dioxide and ozone and neurotoxins. Exposure to these substances can have a significant impact on the health of the children.

Some of the consequences of exposure include learning disabilities, respiratory diseases such as asthma, cancers and damages to the nervous system. Children are different from adults in terms of their physiology and environment. Through their "hand-to-mouth" behavior and spending more time closer to the ground, they are readily exposed to toxic substances in the environment. Children consume more fruits and vegetables in proportion to their body weight than adults and also breathe in more air in proportion to their weight due to undeveloped respiratory system. This causes them to be exposed to a variety of toxicants and pesticide residues in the foods and in the air. Children are still at a developmental stage where their undeveloped metabolic systems are not able to detoxify or excrete toxins ingested or inhaled.