1. How do toxic substances enter the body?

1.1 Inhalation

This is the most important route in most occupational exposure situations.

The gases cross the pulmonary barrier and enter the bloodstream directly.

For particles, different size fractions are defined, depending on the depth they are likely to reach in the respiratory tree. These size fractions – are referred to as conventional fractions – and are the subject of an international consensus reflected in the standards ISO 7708:1995 and EN481:1993.

1.2 Size fractions