"Harmful chemicals" refers to substances that can cause damage or danger to living organisms or the environment. These chemicals have the potential to cause negative health effects or harm ecosystems. Full definition
You don't want to be putting a lot of harmful chemicals in your body because they can sometimes cause a lot more harm than good. (fitnesshealthzone.com)
The use of potentially harmful chemicals in medical marijuana can be hazardous since the product is considered medicine and is sometimes used by patients with compromised immune systems. (theglobeandmail.com)
And sadly, a lot of the time, the products we use to try to clear the air contain harmful chemicals of their own. (mindbodygreen.com)