Environmental carcinogen: Tobacco

It contains 4,700 chemical compositions, of which 43 are known carcinogens. Out of these carcinogen, tobacco-specific nitrosamines (such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN)), polycyclic aromatic hydrocarbons (such as benzo[a]pyrene) and aromatic amines (such as 4-aminobiphenyl) are the ones that play an important role in causing of cancer. Nicotine and carcinogens are two factors, whose combination leads to 30% of cancer-related deaths in developed countries. Heavy smoking habit parallels the rise in cancer. 1.1billions smokers are estimated world wide. Smoking is now an equal opportunity killer among peoples living in both developing and developed countries. Smoking is responsible for fully 30% of all cancer related deaths. Nicotine is not carcinogenic, but it is addictive and toxic. It is the addiction of nicotine that makes people use tobacco products, which contains various kinds of carcinogens.
Impacts of smoking on health are reflective of rate of lung cancer.
Exposure route and impacts
Exposure can result from:
a) Active smoking- tobacco smoke in environment is derived from either main stream smoke (exhale smoke).

b) Passive smoking – smoke arising from burning end of cigarette and exposure to this smoke is side stream smoke. Non-smokers are exposed in work places, public transport and indoor spaces.

Older people with weak immune system and people that are addicted to tobacco products are more exposed to carcinogenic affects of tobacco.

Impacts of smoking manifest in the form of several diseases. The diseases that are directly linked to inhalation of carcinogens in cigarette smoke are:

a) Cancer of lung, mouth, larynx, esophagus, uterine cervix, breast, stomach. Smoking increases the risk of breast cancer in women who used tobacco at an early age.

b) Respiratory disease – emphysema, chronic bronchitis, asthma, bacterial pneumonia, tubercular pneumonia.
c) Cardiovascular diseases- coronary artery disease, hypertension, aortic aneurysm, stroke.

d) Pregnant women’s and infant health are also affected by smoking. An adverse impact of maternal smoking causes pregnancy complications and birth defects. Intra uterine growth retardation, spontaneous abortion, fetal and neonatal death, and abruption of placenta, premature rupture of membrane, preeclampsia, congenital malformation, low-birth weight, and recurrent respiratory infection in children. Passive smoking causes asthma, bronchitis, ear infections and pneumonia, in infants and children. Eye irritation is common when exposed to passive smoking. It aggravates allergies. Increased risk for lung cancer and coronary artery disease develops in people who live in close contact with the smokers.

Risk Reduction:

Risk declines only with complete cessation of smoking. Important factor for cessation of smoking is the desire of an individual to quit. Smokers that quit live longer than those who continue smoking. However, quitters too are at a higher risk for certain type of cancer than people who never use tobacco.

In order to substantially reduce smoking rates, governments can adopt a comprehensive approach to tobacco control, which should include a range of measures such as: (a) a total ban on tobacco advertising and promotion (b) restrictions on smoking in public places and in the workplace (c) sustained increases in tobacco taxation (d) bold health warnings on tobacco products (e) smoking cessation and health education campaigns (f) Protecting nonsmokers through restriction laws in work places, public transport and indoor public spaces. Public awareness campaigns should be made priority. It increases awareness and helps decline many adverse health impacts of tobacco use.

CHOLERA- What, How, and Where?

Cholera is an intestinal infection caused by a bacteria Vibrio cholerae, which is gram negative comma shaped rod. The Seventh Cholera pandemic began in 1961, started in Indonesia, spreading rapidly elsewhere in eastern Asia, and from there to India and Bangladesh, the USSR, Iran and Iraq. In 1990s it reached Peru and has spread throughout South and Central America. Vibrio cholerae, biotype El Tor, that is responsible for pandemic is more resistant than the classical vibrio. In 1982 the classical vibrio began to reestablish itself in Bangladesh where, in 1992, a new pandemic began, with a new serotype 0139 (Bengal Vibrio cholerae 0139). Many major cholera pandemics have affected countries across the world. An outbreak of Cholera is often linked to contaminated drinking water. Cholera habitats are in the valley of the Ganges and other great rivers of the Far East where the humidity and the increasing population contribute to the disease.

Cholera can spread quickly in areas where there is poor sanitation and where water supplies are tainted. Food contamination by flies or hand, and shellfish also transmit the infection. The bacterium is part of the flora of slightly salty water and when this water somehow mixes into the drinking supply then an outbreak of cholera can start. The bacteria survive for up to 2 weeks in fresh water and 8 weeks in salt water. The development of an infection from the time the pathogen enters the body until signs or symptoms first appear is from a few hours to 5 days.

The main route of transmission is Fecal- oral. It rarely spreads by person-to-person contact. The bacteria are passed in stools or vomit of the patient with cholera which remains in their feces for up to a fortnight and contribute to the illness. The bacteria multiply in the lumen of the small bowel and are non- invasive. They adhere to the mucosal surface and secrete exotoxin, which stimulates the adenylyl cyclase- adenosine monophosphate pathway of the mucosa which results in an outpouring of small bowel fluid. Upto 15 liters of watery diarrhea may be passed each day.

It causes severe diarrhea without pain followed by vomiting suddenly. Once the fecal content of the gut have been evacuated the typical “rice water” material is passed which consists of clear fluid with flecks of mucus. This enormous loss of fluid from the body leads to severe dehydration and muscle cramps. This intense dehydration is the cause of death particularly among children and elderly, as they are vulnerable to the dangerous dehydration. Some symptomatic cases are hard to distinguish from other illnesses that cause diarrhea. Only one in 10 cases shows the severe symptoms such as dehydration.

Diagnosis is made by stool microscopy and culture so that an outbreak can be brought rapidly under control. Stool culture or rectal swab isolates the bacteria and can be viewed under microscope, the bacteria has a characteristic movement. Clinical diagnosis is usually easy during an epidemic.

Treatment of this condition requires strict barrier nursing, replacing the fluid and salt losses. Normally, rehydration salts are the only treatment given, although severely dehydrated patients may need intravenous fluids. Antibiotics like tetracycline is given, which reduces the fluid loss.

A well-organized response to cholera can reduce death from cholera epidemics. However, the clean water and rehydration salts required are often in short supply in areas where they are needed most. There are two types of oral cholera vaccine but is used only for travelers and is not used at a community hit by cholera. Control of an epidemic is difficult in a community unless clean water supplies can be restored.

Alleviating these severe effects requires only simple measures. Drinking boiled or treated water, cooking practices needs to be made safe where possible and practicable, all food needs to be cooked well and eaten while hot, avoid shell fish, peeling all raw fruits and vegetables. Hand washing after going to the toilet is a vital measure to prevent the spread of the disease.

The establishment of proper sanitation system for proper and hygienic disposal of human waste is a must. Control of water sources contamination, and of population movement and public education are most important in an epidemic.