120 recently „Hong Kong Flu‟ was estimated to have resulted in about 1 million
deaths in the late 1960‟s.
New strains of the influenza virus continue to emerge in animals with the potential that any particular new strain could cause a future pandemic. These
new strains of the influenza virus occur when they are transmitted to humans from another animal species such as pigs, chickens or ducks.
A recent example of a new variant strain of influenza virus is H5N1 „Bird Flu‟ which was found in 2004 in birds in Vietnam. By 2007 numerous cases had
been found across Asia and much of Europe. There have been human fatalities among people who have had close contact with infected birds. There
has been no, or limited, transmission of the disease from person to person. H5N1 bird flu is not categorized as a pandemic as the virus cannot yet spread
easily or sustainably among the human population. However, if the virus combines with a human influenza virus strain a new sub-type may evolve that
could be highly contagious in humans. Another concern related to pandemics is that many micro-organisms are
becoming resistant to many of the antibiotics currently in use. These antibiotic resistant micro-organisms sometimes terme
d „superbugs‟ may contribute to the re-emergence of many diseases which are currently well controlled e.g.
tuberculosis. A range of common bacteria are also becoming more resistant to antibiotics
leading to a rise in the number of healthcare acquired infections. A well known example of this is methicillin-resistant Staphylococcus aureas or
MRSA.
12.7 Genetic modification
Genetic Modification is a technology developed in the past 30 years for altering the characteristics of living organisms, such as plants or animals. It
involves the addition of new genetic material into an organism‟s genome. Genetically modified organisms GMO have widespread applications. They
are used in biological and medical research, production of pharmaceutical
121 drugs and agriculture. So far the largest application of genetic modification
has been in the production of food crops which are more resistant to disease, or to insect attack, or with increased crop yields.
The benefits of genetic modification are potentially enormous. Potential benefits in the future include new treatments for diseases, crops that are more
resistant to pests and diseases, food of greater nutritional value and the production of pharmaceuticals from plants.
However, there are a number of concerns with regard to this technology. Some people have concerns in principle about the alteration of biological
systems that have evolved naturally. In addition, many people are concerned that we are not yet able to understand all the potential ramifications of genetic
manipulation. A particular concern has been the possibility of genetically modified plants
cross pollinating or „outcropping‟ with other „natural‟ crop varieties to produce another variety whose properties have not been assessed. The safety of
genetically modified organisms in the food chain has also been questioned. As a result of these concerns, strict controls have been implemented in the
use and production of genetically modified organisms.
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13 NOISE
13.1 Background
It has become common practice to define noise, as unwanted sound and it has been known for many years as a cause of hearing loss in industry. So
what exactly is sound and how do we hear it? Sound is the sensation that is perceived by the human or animal brain as a result of longitudinal vibrations of
molecules of the air impinging on the ear. Sounds are actually pressure waves caused by a vibrating body, which
radiate from the source. The human ear can sense and perceive small and rapid pressure waves as sound noise and convey information on their size
amplitude and frequency to the brain.
13.2 The Ear
