What substances do cigarettes contain that are harmful to the developing child?

Well it has been estimated that a single cigarette contains approximately 8000 different chemicals, from which most still remain unknown. While nicotine on it's own is not "harmful" it's the main cause of addiction- along with conditioning. Now among the other chemicals it has been estimated that at least 80 of them are carcinogens, and since we are talking about a child, every single cigarette contributes in the child's abnormal development and could potentially cause a variety of chronic, non-chronic, and permanent diseases and disabilities.

Quitting is the most uplifting thing you can do for your body, mind and soul, along with those living around you.

When it comes to children I think every detail and ingredient is dangerous.