Chemical carcinogens Health effects of tobacco

smoke, or partially burnt organic matter, contains carcinogens (cancer-causing agents). potential effects of smoking, such lung cancer, can take 20 years manifest themselves. historically, women began smoking en masse later men, increased death rate caused smoking amongst women did not appear until later. male lung cancer death rate decreased in 1975 — 20 years after initial decline in cigarette consumption in men. fall in consumption in women began in 1975 1991 had not manifested in decrease in lung cancer-related mortalities amongst women.

smoke contains several carcinogenic pyrolytic products bind dna , cause genetic mutations. particularly potent carcinogens polycyclic aromatic hydrocarbons (pah), toxicated mutagenic epoxides. first pah identified carcinogen in tobacco smoke benzopyrene, has been shown toxicate epoxide irreversibly attaches cell s nuclear dna, may either kill cell or cause genetic mutation. if mutation inhibits programmed cell death, cell can survive become cancer cell. similarly, acrolein, abundant in tobacco smoke, irreversibly binds dna, causes mutations , cancer. however, needs no activation become carcinogenic.

there on 19 known carcinogens in cigarette smoke. following of potent carcinogens:

polycyclic aromatic hydrocarbons tar components produced pyrolysis in smoldering organic matter , emitted smoke. several of these pah s toxic in normal form, however, many of can become more toxic liver. due hydrophobic nature of pah s not dissolve in water , hard expel body. in order make pah more soluble in water, liver creates enzyme called cytochrome p450 adds additional oxygen pah, turning mutagenic epoxides, more soluble, more reactive. first pah identified carcinogen in tobacco smoke benzopyrene, been shown toxicate diol epoxide , permanently attach nuclear dna, may either kill cell or cause genetic mutation. dna contains information on how cell function; in practice, contains recipes protein synthesis. if mutation inhibits programmed cell death, cell can survive become cancer cell, cell not function normal cell. carcinogenicity radiomimetic, i.e. similar produced ionizing nuclear radiation. tobacco manufacturers have experimented combustion less vaporizer technology allow cigarettes consumed without formation of carcinogenic benzopyrenes. although such products have become increasingly popular, still represent small fraction of market, , no conclusive evidence has shown prove or disprove positive health claims.
acrolein pyrolysis product abundant in cigarette smoke. gives smoke acrid smell , irritating, tear causing effect , major contributor carcinogenicity. pah metabolites, acrolein electrophilic alkylating agent , permanently binds dna base guanine, conjugate addition followed cyclization hemiaminal. acrolein-guanine adduct induces mutations during dna copying , causes cancers in manner similar pahs. however, acrolein 1000 times more abundant pahs in cigarette smoke , able react is, without metabolic activation. acrolein has been shown mutagen , carcinogen in human cells. carcinogenicity of acrolein has been difficult study animal experimentation, because has such toxicity tends kill animals before develop cancer. generally, compounds able react conjugate addition electrophiles (so-called michael acceptors after michael reaction) toxic , carcinogenic, because can permanently alkylate dna, mustard gas or aflatoxin. acrolein 1 of them present in cigarette smoke; example, crotonaldehyde has been found in cigarette smoke. michael acceptors contribute chronic inflammation present in tobacco disease.
nitrosamines group of carcinogenic compounds found in cigarette smoke not in uncured tobacco leaves. nitrosamines form on flue-cured tobacco leaves during curing process through chemical reaction between nicotine , other compounds contained in uncured leaf , various oxides of nitrogen found in combustion gasses. switching indirect fire curing has been shown reduce nitrosamine levels less 0.1 parts per million.

sidestream tobacco smoke, or exhaled mainstream smoke, particularly harmful. because exhaled smoke exists @ lower temperatures inhaled smoke, chemical compounds undergo changes can cause them become more dangerous. well, smoke undergoes changes ages, causes transformation of compound no more toxic no2. further, volatilization causes smoke particles become smaller, , more embedded deep lung of later breathes air.