Irradiation is useful in preservation of food, control of sprouting of items such as potato and onion and control of food-borne diseases. Irradiation destroys or inactivates organisms that cause spoilage thereby extending shelf life of certain foods. But foods must be kept in airtight bags to prevent reinfestation.

I like fresh food. But the food I consider fresh may not be fresh. It may contain harmful bacteria. Most of the pulses we eat contain the ova of insects. Contaminated food causes food poisoning. Often, the symptoms of food poisoning are mild. In rare instances it may be fatal. The concern over the prevalence of food-borne diseases is mounting. The US Food and Drug Administration recognised that irradiation is the only known method to eliminate deadly bacteria in raw meat.

Precise data on food-borne diseases from different countries are not available. The data from the USA are illustrative of developed countries. In 1994, the Council for Agricultural Science and Technology estimated that the number of cases of food-borne diseases due to salmonella, compylobacter and shigella in the USA may have varied from 6.5 million to 33 million annually and that deaths may be as high as 9000.

Bacteria thrive in meat. Harmful E-coli is beastly; it causes hemorrhagic colitis leading to high fever, vomiting and bloody diarrhoea. The patient is dehydrated. If the patient has weakened or immature immunity system, the disease may progress to kidney damage. Six per cent of such patients die.

On February 22, 2000, US FDA issued final rule which permitted using radiation to refrigerated or frozen uncooked meat the meat products to reduce levels of food-borne pathogens and to extend shelf life.

Food Irradiation is the treatment of food by ionising radiation. The process greatly reduces, but does not eliminate, bacteria. The American Dietetic Association, The American Council on Science and Health, American Medical Association, the American Council on Science and Health, the American Medical Association, the Council for Agricultural Science and Technology, the International Atomic Energy Agency, the Institute of Food Technologists, the Scientific Committee of the European Union, the United Nations Food and Agricultural Organisation and the World Health Organisation have endorsed the process. Approval for the process came after 40 years of scientific research and testing. Food scientists have not studied any other food technology more extensively.

In a position paper on food irradiation, the American Dietetic Association stated thus: "All reliable scientific evidence, based on animal feeding tests and consumption by human volunteers, indicated that these products pose no unique risk to human beings. In fact, people requiring the safest food, hospital patients, receiving bone marrow transplants are routinely given irradiated foods. Furthermore, because spices, being of tropical origin, are often microbe laden, irradiated spices are preferred for routine use in hospital food service for patients. Thus, as with pasteurisation, the evidence suggests that food irradiation can make a quality food supply better."

The International Atomic Energy Agency reports that currently health and safety authorities in over 40 countries have approved irradiation of over 60 different food items ranging from spices to grains to de-boned chicken meat, to beef, to fruits and vegetables. As of August, 1999, over 30 countries irradiate food commercially. Nearly 60 irradiation facilities are operated worldwide; more are getting ready in different countries. But the total amount of food products irradiated is estimated to be about half a million tonnes — a small fraction of the total amount of processed foods.

Irradiation is useful in preservation of food, control of sprouting of items such as potato and onion and control of food-borne diseases. Irradiation destroys or inactivates organisms that cause spoilage thereby extending shelf life of certain foods. But foods must be kept in airtight bags to prevent reinfestation.

The process is energy efficient. It does not leave any residue. The products remain closer to the fresh state in flavour, colour and texture. The chemical change in food due to irradiation is so small that it is difficult to design a test to identify whether a food has been irradiated. During the process, no liquid is added; it does not cause loss of natural juices. Large or small amounts of foods can be irradiated in appropriate containers.

Food irradiation is essentially a cold process. Because of this, nutrient losses are significantly less than those associated with canning, drying and heat pasteurisation. Macronutrients such as carbohydrates, proteins and fats undergo little change during irradiation.

One of the reasons for the unpopularity of food irradiation is the mistaken notion that irradiated food is radioactive. Gamma rays from Cobalt 60, electron of 10 million electron volts if X-rays of 5 million are the only types of radiation approved for use in the process. These radiations will not make food radioactive. No radioactivity is produced or released during the process. It is also impossible for a "meltdown" to occur in a gamma irradiator facility.

The European Committee for Standardisation of the European Commission has published six standards to identify irradiated food. Irradiated food containing fat can be identified by gas chromatic analysis of hydrocarbons. If irradiated food contains cellulose or bone or crystalline sugar, electron spin resonance spectroscopy is used. Spices may contain traces of silicate minerals. Thermoluminescence of the silicate fraction is useful to identify irradiated spices. More sophisticated methods such as photostimulated luminiscence. DNA comet assay are also used in the case of some foods.

The irradiators are designed with several levels of protection. A system of carefully designed interlocks ensures that no person can enter the radiation area when the sources is exposed. The staff employed at the facility are well trained and qualified. They follow diligently prepared operating procedures. AERB inspects the facility periodically and reviews the safety reports from the radiological safety officer. The radiation doses to workers in the facilities are only small fractions of the limit prescribed by AERB.

The Atomic Energy (Control of Irradiation of Foods) Rules 1996 and the Prevention of Food Adulteration (Fifth Amendment) Rules 1994 and other rules and notifications issued from time to time are the applicable rules for commercial irradiation of food in India The Department of Atomic Energy (DAE) and the Atomic Energy Regulatory Board enforce the former rules. (AERB). DAE licenses the irradiator after AERB issues a certificate of approval. Before this, inspectors from AERB ensure that the installation satisfies all the prescribed safety requirements.

The AERB is empowered to withdraw the certificate of approval if it is found necessary. As a matter of fact, in 2001, AERB withdrew the certificate of approval of the Spice Irradiation Facility operated by the Board of Radiation and Isotope Technology when an inspecting team from AERB found certain violations of safety requirements. The approval was granted after all safety provisions were met.

The DAE has licensed four irradiation facilities so far. More facilities are being planned in the near future. AERB has standardised the procedure to issue certificate approvals to any applicant in the shortest possible period. Wrong notions have come in the way of achieving progress in the commercial use of irradiation. The International Consultative Group on Food Irradiation had listed several studies to show that the consumer acceptance of the technology improved when they are informed about the facts about this unique technology.

Space may seem empty, beautiful and boundless but in the immediate neighbourhood of Planet Earth it is quickly resembling an ugly junkyard.

Scientists are dismayed at the debris that is piling up in orbit less than 45 years after Man launched the first satellite, Sputnik.

"There are more than 100,000 objects in orbit, of which only 600-700 are operational satellites," says Walter Flury, the European Space Agency’s coordinator on space debris.

"There are no international laws about the debris problem and you cannot clean it up. It’s that simple."

The trash includes tiny fragments from exploded boosters. Lens covers that have dropped off satellite cameras. Enormous fuel tanks, Soviet-era nuclear-powered satellites, dripping sodium and potassium coolant from their decrepit hulls. Drifting nuts, bolts, screwdrivers and wrenches accidentally dropped by spacewalking astronauts.

The risk of collision with this trash is statistically remote, but it is increasing as more countries join the space powers, and any impact can be catastrophic.

In about 4,000 rocket launches, there has been only one documented case of a serious incident. That happened in 1996 when a French spy satellite, Cerise, was wacked at about 50,000 kilometres per hour by a wheeling fragment left from an exploded Ariane rocket.

Experts say they fret most over the smaller items, some of which can be impossible to track by radar and telescope from Earth.

The website space.com reports NASA had a major scare last November, when a Russian spy satellite, Cosmos 2367, which had been lofted in December, 1999, broke up in more than 300 pieces, 40 per cent of which were thrown into orbits that crossed the path of the ISS. In June, 1983, the windscreen of US shuttle Challenger had to be replaced after it was chipped by a fleck of paint, measuring 0.3mm, that impacted at 4 km per second.

The worst debris clouds are in two main areas, in Low Earth Orbit (LEO), which is at an altitude of between 800 and 1,500 km above the Earth, and in geostationary orbit, about 35,000 km away. AFP

Preventing air disasters

Scientists are developing a novel system for the surveillance of the runway and flight trajectories of jet aircraft, which could allow accidents to be explained more quickly, in turn making them easier to prevent.

Experts investigating air disasters usually find precious few clues as the probe gets under way. Months often pass, sometimes years, before the events leading up to an accident can be reconstructed with any precision.

This is why safety experts are increasingly turning to sensor programmes for the purpose of apron monitoring, which can allow accidents to be explained more quickly, perhaps in turn making them easier to prevent.

"Such a system could set off an alarm, for example, if an aircraft loses a part, or if another plane is blocking its path," explains Gunther Grassemann of Fraunhofer Institute for Information and Data Processing IITB in Karlsruhe.

"We are currently working in cooperation with the Vitracom company on developing a system for the surveillance of the runway and flight trajectories of jet aircraft. Based on our Site View video monitoring system, we can fully document take-off and landing approach in 3D," continues Grassemann, who has been working as an engineer on the project for some years now. PTI

NEW PRODUCTS & DISCOVERIES

Tiny robotic bulldozers

They’ll be too small to clear the way for settlements, but tiny robotic bulldozers may soon be on their way to Mars.

Weighing 8 pounds each, the rovers will dig for water or other treasures. Each is equipped with an arm that can scoop Martian soil into an overhead bucket. They’re not yet scheduled to fly. Popular Science

Shampoos containing female hormones may be causing girls to go through puberty at an ever earlier age, the British weekly magazine New Scientist says.

"Unknown to many parents, a few hair products — especially some marketed to black people — contain small amounts of hormones that could cause premature sexual development in girls, reports AFP.

The article acknowledges that the evidence is "largely circumstantial and the case is still unproven."

Clinical data, it said, is limited so far to a small study involving four girls, one of which was a 14-month-old baby, who developed breasts or pubic hair after using the shampoo, and whose symptoms disappeared when the product was no longer used.

Girls are reaching puberty earlier in every developed country, a phenomenon that has been blamed on such things as improved diet and chemical or hormone pollutants in the environment. However, African-American girls are developing even earlier than their white counterparts.

About half of black girls in the USA reach puberty by the age of eight, compared with only 15 per cent of their white counterparts, according to one study. PTI

Scientists at Roorkee have developed a novel microwave absorbing paint that can help India build "stealth" aircraft, which will be invisible to radar.

A team of electronics and materials science students at the Indian Institute of Technology in Roorkee claimed, in Current Science, that two layers of this paint, coated on the exterior surface of the aircraft, will make it almost invisible to a broad range of radar signals from 12 Giga Hertz (GHz) to 18 GHz.

The paint, developed by M.R Meshram and co-workers absorbs significant amount of the incoming radiation.

Consequently, the strength of the reflected signal is very much reduced.

According to their report, the microwave absorbing paint is based on "manganese-substituted barium hexagonal ferrite". PTI

SCIENCE & TECHNOLOGY CROSSWORD

1. Shape of our milky way.

6. Centres set up by Govt of India under its scheme "Health for all". (abbr.)

9. Seven star constellation seen in sky in winter.

10. A conductor made from aluminium alloy rods and used in power sector to bring down power losses.

11. Large edible fish.

12. Bitter-leaved evergreen shrub.

13. Ante Meridiem i.e. before noon.

14. Fog intensified by smoke.

16. Process of ploughing and cultivating the land.

17. A programme launched by UN to create awareness for a healthy environment.(abbr.)

18. A soft grey metal having high density.

19. Equipment fitted in an aircraft to help the pilot to measure the distance between the flight and runway.

20. Plankton or seaweed.

21. Minimum potential through which an electron has to fall to ionise an atom. (abbr.)

22. Short for pound.

24. Bulbous spring flowering plant.

25. A mixture of gases vital for life.

1. Metal that burns in air with a golden flame.

2. Technique of taking photographs from air for military purposes.(abbr.)

3. Abbr. for Indian Institute of sugarcane research situated in Lucknow.

4. Edible fresh water fish.

5. Disease caused by deficiency of folic acid.

6. Main ore of Zinc.

7. Protein regulating body function.

8. An important part of video camera that senses light and produces electric signal for image.

14. This is checked to know the workability of concrete.

15. Extract metal from ore by melting.

16. Power generated from sea waves is called thus.

19. Another name for downward inclination.

22. Symbol for Lithium.

23. Symbol for Bromine.