Nickel belongs to the heavy metals and usually occurs bound to other substances. In ambient air arsenic is measured bound to particulate matter.
Metals and selenium are found in the environment in various different compounds. Their geogenic concentrations (background concentrations ) vary. Some metals and selenium are essential for organisms at low concentrations.
The Federal Environment Agency decided to conduct a special GerES on children because they must be considered as a risk group for adverse health effects caused by environmental factors
