Tobacco Active and Passive Smoking

4. What other biological effects can active smoking cause?

Active smoking causes adverse reproductive outcomes and various health effects other than tumours, including respiratory and cardiovascular diseases.

Nicotine is the major addictive component of tobacco. In the human body, it is transformed into the metabolite cotinine, which is used as a reference to indicate exposure to tobacco smoke since it is found only in smokers and in passive smokers (in blood, urine and saliva).

Air exhaled by smokers contains higher concentrations of the following chemicals: carbon monoxide, benzene and volatile organic compounds. Moreover, some important carcinogens present in tobacco smoke and their metabolites are found in the urine of smokers.

Carcinogens present in tobacco smoke can react with proteins and DNA to form "adducts". Such carcinogen adducts are present in many tissues of smokers at higher levels than in non-smokers, for instance in the respiratory tract, bladder and cervix (neck of the uterus). Some but not all studies have also found adducts in the umbilical cord blood of smoking mothers and in cardiovascular tissues. Adducts can damage cells by producing gene mutations and chromosomal abnormalities.

Smoking can alter the activity of many enzymes involved in normal body metabolism.

In humans, smoking produces gene mutations and chromosomal abnormalities. Urine from smokers is mutagenic. Relative to non-smokers, lung tumours of smokers have unique features specific to exposure to tobacco smoke. Tobacco smoke is genotoxic in humans and in test animals.

In test animals, exposure to tobacco smoke also alters a variety of enzyme activities, results in formation of DNA adducts in several tissues and alters lung function. More...