146 Ecology and Applied Environmental Science
ever, i.e. plants may be genetically modified in order to make them resistant to the use of powerful pesticides that are toxic to ordinary varieties.
The prospects for genetically modified organisms are great, and potentially
they can reduce environmental degradation from agricultural production;
however, they may entail significant environmental hazards and thus they
have given rise to strong reservations internationally. They cannot be used
safely unless studies capable of providing adequate guarantees are first performed. Their hazards emanate mainly from the following:
• The possibility that various genetically modified organisms with competitive advantages may escape into natural ecosystems
• The possibility that the health of people consuming genetically
altered foods may be damaged. To date, however, no such damage
has been identified.
The optimal aim of using various methods to protect agricultural production must be to lower to acceptable levels the damage caused by hostile
organisms, by minimising ecological disturbances and hazards to human
health. In any case, the economic and ecological cost of a drastic treatment
that would lead to the complete disappearance of hostile organisms is disproportionately high.
7.4 toxic Pollution FroM MEtalS
and inorganic SubStancES
7.4.1 lead
Lead (Pb) enters the human body in a ratio of 2/3 via the peptic system
and 1/3 via the respiratory system. Smoking increases its absorption. It
accumulates in the organism, mainly in the bones. It impacts the production and functioning of a variety of enzymes, affecting many functions
of metabolism. The effects of chronic lead toxicity are far-reaching and
are manifested mainly in hypertension, blood composition abnormalities,
hyperactivity and brain damage; in children in particular, reduced mental
ability has been noted. The effects of lead vary from one person to another.
The levels usually measured in human tissues are of the same order of magnitude as the levels that may begin to cause damage, and that is why any
further lead burden must be avoided. The US EPA has set a very low limit
for drinking water.
It has been proposed that excessive exposure to lead may have been
one of the causes of the decline of the Roman Empire. The Romans used
ever, i.e. plants may be genetically modified in order to make them resistant to the use of powerful pesticides that are toxic to ordinary varieties.
The prospects for genetically modified organisms are great, and potentially
they can reduce environmental degradation from agricultural production;
however, they may entail significant environmental hazards and thus they
have given rise to strong reservations internationally. They cannot be used
safely unless studies capable of providing adequate guarantees are first performed. Their hazards emanate mainly from the following:
• The possibility that various genetically modified organisms with competitive advantages may escape into natural ecosystems
• The possibility that the health of people consuming genetically
altered foods may be damaged. To date, however, no such damage
has been identified.
The optimal aim of using various methods to protect agricultural production must be to lower to acceptable levels the damage caused by hostile
organisms, by minimising ecological disturbances and hazards to human
health. In any case, the economic and ecological cost of a drastic treatment
that would lead to the complete disappearance of hostile organisms is disproportionately high.
7.4 toxic Pollution FroM MEtalS
and inorganic SubStancES
7.4.1 lead
Lead (Pb) enters the human body in a ratio of 2/3 via the peptic system
and 1/3 via the respiratory system. Smoking increases its absorption. It
accumulates in the organism, mainly in the bones. It impacts the production and functioning of a variety of enzymes, affecting many functions
of metabolism. The effects of chronic lead toxicity are far-reaching and
are manifested mainly in hypertension, blood composition abnormalities,
hyperactivity and brain damage; in children in particular, reduced mental
ability has been noted. The effects of lead vary from one person to another.
The levels usually measured in human tissues are of the same order of magnitude as the levels that may begin to cause damage, and that is why any
further lead burden must be avoided. The US EPA has set a very low limit
for drinking water.
It has been proposed that excessive exposure to lead may have been
one of the causes of the decline of the Roman Empire. The Romans used