2. Exposure phase

2.1 Fate of substances in the environment

Many phenomena tend to transform substances in the environment:

• hydrolysis;

• biodegradation ;

• photolysis;

• decomposition ;

• oxidation.

Direct or indirect photodegradation by sunlight is the main process by which substances disappear into the atmosphere. Photolysis essentially involves radical reactions that lead to the transformation or disappearance of the substance in the atmosphere.

In the aquatic environment, the main degradation processes for chemical substances are hydrolysis and biodegradation. Hydrolysis...