The growing epidemic of obesity in America has different States formulating new healthy policies. More than 60 per cent of American adults and 13 per cent of children and adolescents are obese. Lax policies on fast food, which is usually, junk, high on fat content and almost zero in nutritive value aids the rise in the obesity epidemic sweeping across America. Almost 43 per cent of elementary schools, 74 per cent of middle schools and all high schools have vending machines offering carbonated soft drinks. Fast food like McDonald's is available in more than 20 per cent of schools at all levels. Schools get payoff from the coke companies and the fast food joints in terms of sports uniforms and scoreboards, which helps schools cut down on their education budgets. California in the meantime has banned the sale of soda and junk food in elementary schools and has limited their sale in middle school. In Tennessee and Wisconsin, it was the parents protests that made school districts refuse to sign contracts with soft-drink vendors.

Worried nutritionists say that it is time that the country redesigns its nutrition policies to improve dietary health. The rate of Type II diabetes in New York City is today 8 per cent, double than what it was in 1994. The increase has been attributed to people who eat much but exercise little. Growing evidence now suggests that fat people are actually victims of the type of food sold in fast-food outlets. These outlets sell hazardous products without providing any sort of health warnings that could be expected on these goods. Informing consumers properly is one of the key issues today in determining better health policies. Biologists are now putting forth the theory that the high sugar content in these fast foods may be triggering a physiological reaction which may be muting the hormonal signals which tell the brain when to stop eating. Leptin, which is continuously secreted by fat cells and whose level in the bloodstream indicates the status of the body's fat reserves, may become resistant in people who eat more of junk food. "The fatter a person becomes the more resistant they will be to the effects of leptin and the harder it is to reverse those effects", says physiologist Luciano Rossetti of the Albert Einstein College of Medicine in New York City, USA. Neurobiologist Sarah Leibowitz of the Rockefeller University in New York City is of the opinion that early exposures to fatty food can very well reconfigure children's bodies so that they always choose fatty foods. Foods high in sugar content can set up a cycle of instant satiation followed by a plunge in blood sugar, which leads to a natural desire for another snack. Fast food could well turn out to be as addictive as perhaps nicotine and cocaine.

Chlorinated water
C Villanueva et al in the study titled: "Meta-analysis of studies on individual consumption of chlorinated drinking water and bladder cancer" show that long term consumption of chlorinated drinking water is associated with risk of bladder cancer, particularly in men. It was observed that for a vast majority of population of industrialised countries exposed to chlorinated byproducts for long periods, the risks would be higher. In India, the situation is different because of the interplay of economics and public health. Chlorine is used to treat water and in the absence of any disinfection, there would be a high risk of biological diseases. On a risk scale, diseases and fatality due to biological contamination of water is far higher than that of bladder cancer. Chlorine provides what is called as 'residual' disinfection to protect against the biological contamination. This property is not provided by any available substitute like ozone or ultraviolet (UV). Till today, even in the US and Europe, 99 per cent of municipal water is chlorinated. Unless there are other viable alternatives in terms of affordability and easy applicability, chlorine will continue to be used widely.

E-mail: kogenvinas@imim.es

Mercury babies
A two-year long study carried out on 1,057 infants by Professor Fok Fai Tai of the department of pediatrics, The Chinese Unit of Hong Kong, has found that a quarter of infants in Hong Kong have excessive mercury in their blood. Excess of mercury is known to cause mental retardation. Pregnant mothers, who consume too much fish, readily pass on the methylmercury into the foetal circulation system. This methylmercury then gets deposited in the foetal brain, and may lead to stillbirth, cerebral palsy, mental retardation, speech delay, poor control of chewing, salivation and swallowing.

In as many as 24.7 per cent of the infants, cord blood mercury concentrations were found to be of over 61 nanomol/litre, which is the upper allowable limit. Three per cent had blood mercury concentrations of over 100 nanomol/litre. Says Professor Fok Tai Fai, "Eating too much fish by the mother during pregnancy is the major factor in elevating the blood mercury level of the foetus." It just takes four days for methylmercury to be readily absorbed into the blood after ingestion and to get distributed to all tissues of the body.

In adults, mercury poisoning causes personality changes, nervousness, irritability, fatigue, insomnia, headache, loss of memory, hearing and vision and even renal failure.

E-mail: taifaifok@cuhk.ed.hk

Age and cancer
The US government finally accept that children are more vulnerable to the effects of certain carcinogens than adults. The US Environment Protection Agency's (EPA) draft for new guidelines for cancer risk assessment considers children aged two and younger to have 10 times the cancer risk of adults when exposed to mutagenic carcinogens. These carcinogens such as arsenic, benzene, formaldehyde, mutagen X, brominated organics and polycyclic aromatic hydrocarbons are known to cause cancer through direct damage to the DNA. Children between the ages of 2-15 years have three times the risk of adults.