Exposure to environmental risks differs between adults and children. The environment in which fetal and childhood development occurs is critically important, and factors such as infectious diseases and exposure to toxins play a key role in children's health.
Generally speaking, the presence of an environmental hazard (e.g. a pathogen, pollutant or physical hazard) does not necessarily mean that it will do harm. Many factors influence the risk of health effects from exposure to hazards, including the degree of susceptibility or vulnerability. Children are more likely to suffer from adverse reactions and long-term health effects than adults, since they are subject to greater exposure and are more vulnerable to environmental hazards, especially chemicals.
- Children need more food, water and air per kilogram of body weight compared to adults. In the first months of life, for example, babies drink seven times more water than an adult, and in their first five years they eat three to four times more than an adult, compared to their body weight.
- A child’s immune system and other key physical defence mechanisms are not fully developed, leading to greater risk from exposure to contaminants in the outdoor and indoor air, water and soil.
- According to recent research, exposure to certain chemicals of concern begins at a very early stage of development (including exposure in utero).
- Children breathe more rapidly than adults, taking in four to six times more air for their body weight. They also have a larger lung surface area in relation to their body weight, which increases exposure to air pollutants.
- The way in which they breathe, combined with the incomplete development of their respiratory tract, makes them more vulnerable to infections that may be triggered by an inflammatory response to air pollutants.
- Children have thinner skin than adults, which makes them more susceptible to the absorption of substances. They also have a proportionately larger body surface area than adults, which increases the area of exposure to skin contact and the absorption of toxic substances through the skin.
- Children’s cells grow in number more rapidly than adults’, causing increased vulnerability to the effects of radiation.
- Children’s limited diet in the first year of life may lead to increased exposure to food-specific contaminants (e.g. mercury in fish).
- Children have immature blood-brain barriers, thus the brain tissue is more vulnerable to the intrusion of toxic pollutants from the blood stream.
- Children’s immature immune systems may increase their susceptibility to infections and allergic reactions.
Last but not least, very young children are unaware of risks. They are unable to protect themselves from hazards and their typical behaviour (crawling, playing on the ground, putting their hands and objects in their mouths) facilitates the ingestion, skin contact and absorption of pollutants in dust and dirt.