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Radioactive compounds

The radioactive compounds found in highest concentration in cigarette smoke are polonium-210 and potassium-40. Other radioactive compounds present include radium-226, radium-228 and thorium-228. Radioactive compounds are well established as carcinogens.(12)

From: James Middleton []
Sent: Thursday, January 03, 2008 14:49
Subject: – constituents of tobacco smoke are already classified as Toxic Air Contaminants by HK EPD

Hong Kong  EPD Report classifies many of the compounds present in tobacco smoke as TOXIC AIR POLLUTANTS

“Toxic Air Pollutants Monitoring Operation
The Air Science Group has installed in July 1997 additional monitoring facilities at the Tsuen Wan and Central/Western stations to measure regularly the levels of Toxic Air Pollutants (TAPs) in Hong Kong.

The TAPs being monitored can be broadly classified as volatile organic compounds (e.g.

benzene, perchloroethylene and


dioxins and furans (e.g.2,3,7,8-TCDF and 2,3,7,8-TCDD), carbonyl compounds (e.g.


polycyclic aromatic hydrocarbons (e.g. benzo(a)pyrene), and

hexavalent chromium.

Five distinct methods were used to analyse the collected samples for target TAPs (please refer to Table B4 for details).
All these methods have stringent QA/QC criteria to ensure the data quality. Sampling media used include stainless steel canisters, Sep-Pak cartridges, polyurethane foams and bicarbonate impregnated filters. TAP samples are analysed by the Government Laboratory.”

Table B4 Sampling and Analysis Methods Used in Measuring Toxic Air Pollutants (on Page B6)

5.1 Constituents of tobacco smoke

Unless otherwise noted, information in this section comes from reference 1.

Tobacco smoke is estimated to contain over four thousand compounds, many of which are pharmacologically active, toxic, mutagenic and carcinogenic. There are 43 known carcinogens in tobacco smoke.(2)

The following major components of tobacco smoke have been identified as most likely to cause disease:


‘Tar’ describes the particulate matter inhaled when the smoker draws on a lighted cigarette. Each particle is composed of a large variety of organic and inorganic chemicals consisting primarily of nitrogen, oxygen, hydrogen, carbon dioxide, carbon monoxide, and a wide range of volatile and semivolatile organic chemicals.(3) In its condensate form, tar is the sticky brown substance which can stain smokers’ fingers and teeth yellow brown. It also stains the lung tissue.

Among the carcinogens or tumour initiators present in cigarette smoke are two major classes of tumour initiators, polycyclic aromatic hydrocarbons (see above EPD TAC) and tobacco-specificnitrosamines. Benzo[a]pyrene, (see above EPD TAC) well established as a carcinogen, is a prominent polycyclic aromatic hydrocarbon found in tar.


Nicotine appears to be the most important acute-acting pharmacological agent in tobacco smoke, and is the drug in tobacco which causes addiction among smokers.(4) Its immediate physiological effects include increased heart rate and blood pressure, constriction of cutaneous blood vessels, and muscular, hormonal and metabolic effects.(4) With prolonged exposure, it may contribute, in combination with carbon monoxide, to increased platelet stickiness and aggregation and damage to the lining of the blood vessels, suggesting a potential role in causing coronary disease. It is also implicated in the causation of reproductive and gastrointestinal disorders.(4) Although nicotine does not appear to possess direct carcinogenic activity itself, it enables the formation of tobacco-specific nitrosamines, which are potent carcinogens.(4)

Nicotine is among the most toxic of all poisons and acts with great speed. The average lethal dose for an adult human is estimated to be between 30 to 60 milligrams (mg). Once relatively common due to its use in insecticides in the 1920s and 1930s, nicotine poisoning is less usual these days.(5) Dosages of nicotine obtained through tobacco smoking are far too low to cause acute poisoning, although there is a serious risk for children who ingest cigarettes (see also Chapter 3, Section 6). Before building up a tolerance to nicotine, the smoker may experience mild effects of nicotine toxicity.

Except where it occurs in tobacco products, nicotine is scheduled as a poison and its availability is controlled by the State Poisons Acts. Products containing nicotine for therapeutic (drug) use are categorised as Schedule 3 and 4 poisons. Included in these Schedules are nicotine chewing gum and transdermal nicotine patches, aids in breaking nicotine addiction. The gum is available in two dosages, in 2 mg and 4 mg of nicotine per gum piece. The 2 mg gum is available without prescription from pharmacists, and classified as a Schedule 3 product. The 4 mg gum, nicotine patches and other products containing nicotine and intended as aids in tobacco withdrawal, are categorised as Schedule 4 products and available on prescription from a medical practitioner. Advertising of Schedule 3 and 4 products is restricted to professional or trade journals, or in publications intended for circulation in the medical, dental, veterinary or pharmaceutical professions or the wholesale drug industry.

All other forms of nicotine (tobacco products excepted) come under Schedules 6 or 7, which apply to highly toxic agricultural, domestic and industrial poisons.(6,7)

It is ironic that except in the case of tobacco products, which are expressly manufactured for self-administration by humans at great loss of life, products containing nicotine are highly regulated.See Chapter 11 for further discussion about nicotine.

Carbon monoxide

Carbon monoxide (CO) is an odourless, tasteless gas, giving no warning of its presence in most circumstances.(8) In large amounts it is rapidly fatal.

CO is formed when a cigarette is lit. It has a number of toxic effects on the body, the most important of which is its impairment of oxygen transportation in the blood. As CO has a chemical affinity for haemoglobin over 200 times greater than that of oxygen, it binds preferentially with the haemoglobin, thereby reducing the amount of oxygenated blood circulated to body organs and tissues.(8)

CO is strongly linked with the development of coronary heart disease. It is thought that this might occur through interference with myocardial oxygenation, increasing platelet stickiness, or promotion of atherosclerosis. Although CO is not in itself a carcinogen, it may contribute to cancers and other diseases of the respiratory tract because of its inhibiting effect on the respiratory tract’s mucus clearance mechanism. Instead of being cleared away, toxic substances contained in cigarette smoke remain in the airways, causing inflammation and damage, impairing lung function, and increasing the likelihood of lung disease.(9) CO may also have a short term effect on vision(10,11) (see also Chapter 3, Section 6).

The factors that influence the CO yield of a given brand of cigarettes depend on the manufacturing process (for example porosity of the paper and filter ventilation) and therefore may vary independently of tar yield. The absorption of CO is more dependent on depth of inhalation than is the absorption of nicotine, and, if a change to lower tar products results in a compensatory increase in depth of inhalation (see Section 5.3 below), smoker exposure to CO may remain unchanged or actually increase compared to dosages from the higher tar brands.

Nitrogen oxides

Cigarette smoke contains oxides of nitrogen in relatively high levels. This gas is known to cause lung damage in experimental animals similar to that noted in smokers, and may be responsible for initiating lung damage leading to emphysema.

Hydrogen cyanide and other ciliatoxic agents

Hydrogen cyanide has a direct, deleterious effect on the cilia, part of the natural lung clearance mechanism in humans. Interference with this cleaning system can result in an accumulation of toxic agents in the lungs, thereby increasing the likelihood of developing disease.(3) Other toxic agents in cigarette smoke which directly affect the cilia include acrolein, ammonia, nitrogen dioxide and formaldehyde. (see above EPD TAC) (9)


Thirty metals have been detected in tobacco smoke, including nickel, arsenic, cadmium,(12)chromium and lead (see above EPD TAC) .(2) Arsenic and arsenic compounds and chromium and some chromium compounds are causally associated with cancer in humans, while nickel and cadmium and their compounds are probably carcinogenic to humans. Arsenic levels in tobacco have been elevated in the past due to the use of arsenical pesticides. Cadmium levels may be related to the presence of cadmium in phosphate fertilisers.(12)

Radioactive compounds

The radioactive compounds found in highest concentration in cigarette smoke are polonium-210 and potassium-40. Other radioactive compounds present include radium-226, radium-228 and thorium-228. Radioactive compounds are well established as carcinogens.(12)

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