Alaw that bans certain chemicals from perfumes medicines and cosmetics would be enforced by the

The U.S. Food and Drug Administration, also known as the FDA.

Explanation:
It is the duty of the U.S. Foof and Drug Administration to protect citizens from the circulation of unsafe food items and drugs.

Furthermore, the FDA regulates the manufacture and marketing of tobacco and pharmaceutical drugs to ensure that they are effective and do not have dangerous side effects.

The FDA also protects the food and water supply from contamination and possible acts of terrorism.
The FDA also monitors air quality to detect the presence of toxic emissions and radiation levels.