The phrase "poisonous chemicals" is a mistake. The correct term should be "toxic chemicals." Poison refers to something that can cause harm or death when ingested, inhaled, or absorbed through the skin. Toxins are substances that can damage living organisms and their environment. Therefore, if you meant to say "poisonous," it would not be accurate as most chemicals are not inherently poisonous unless they come into contact with a biological system such as an animal's body or the environment.