How does each of the harmful substances affect the body?

Harmful substances can have various detrimental effects on the body depending on their nature. For instance, tobacco smoke contains carcinogens that can lead to respiratory diseases and lung cancer, while alcohol can cause liver damage, addiction, and neurological impairments. Illicit drugs, such as opioids, can lead to dependency, overdose, and significant mental health issues. Additionally, pollutants and heavy metals can disrupt bodily functions, leading to chronic health problems and impairing the immune system.