The government has pledged to reduce the amount of chemicals used in food production.
Each year, factories release millions of tonnes of toxic chemicals into the atmosphere.
There are a lot of chemicals and sewage in the river Dollmitz and the lakes, too. (First Certificate in English; B2; German)
a chemical reaction
The chemical industry produces such things as petrochemicals, drugs, paint and rubber.
In the latter many chemical reactions may be reproduced to show the students the final compounds generated. (First Certificate in English; B2; Italian)