Harmful effects of pesticides
The Centers for Disease Control and prevention released findings showing measurable amounts of residual organophosphate pesticides in a group of people who were studied. The National Academies of Sciences indicated that one out of four developmental and behavioral problems in children may be linked to genetic and environmental factors, including exposure to lead, mercury and organophosphate pesticides. When you put these two studies together, the conclusions could be cause for concern.
Runoffs from the farms can introduce harmful pesticides, wastes and other pollutants into rivers and streams. Organic farming reduces the level of these contaminants from runoffs.
With increasing demands for food supplies during the last years, we saw the introduction of the use of harsh chemicals and synthetic fertilizers as a way for farmers to boost crop yields. This subsequently has been followed by the more recent adoption of planting genetically modified crops. Even today, toxic and persistent pesticides are still used in agriculture. Organophosphate pesticides account for approximately half of the insecticides used in the United States. An estimated 60 million pounds of organophosphate pesticides are applied to about 60 million acres of U.S. agricultural crops annually, and an additional 17 million pounds are used per year for nonagricultural uses, such as household pest control products and in lawn and garden sprays.
Perhaps the harvest and most damaging of the chemicals introduced as a pesticide was DDT (dichlorodiphenyl – trichloroethane) which caused so much harm to animals and humans, its use was banned in the US in 1973. In fact DDT directly attributed to the near-demise of the bald eagle (as well as other species), which taken off of the endangered species list nearly 25 years after DDT was banned. DDT is still used in some parts of the world.
4.5 Answer the questions to the text.
1) What is environmental chemistry?
2) What causes acid rains?
3) What are the effects of acid rains?
4) What is the main component of acid rain?
5) What harmful ways are used to boost crop yields?
6) What is the effect of residual pesticides on human health?
7) Are toxic and persistent pesticides still used in agriculture? Why?
4.6 Match the words with the definitions:
4.7 Fill in the gaps using the words given below the text:
Air pollutant is any … in air that could, in high enough concentration, harm human beings, animals, vegetation, or material. Pollutants may include almost any natural or … composition of matter capable of being airborne. They may be in the form of solid particles, … droplets, gases, or combinations of these states. Generally, they fall … two main groups: a) those emitted directly from identified sources and b) those produced in the … by interaction between two or more primary pollutants or by reaction with normal atmospheric constituents, with or without photoactivation. Exclusive of pollen, fog, and dust, which are of natural … , about 100 contaminants have been identified. They fall into the following … : solids, sulphur compounds, volatile organic chemicals, nitrogen compounds, oxygen compounds, halogen compounds, radioactive compounds, and odors.
artificial, liquid, origin, substance, into, categories, air
Вернуться в категорию: Растения
© 2013-2019 cozyhomestead.ru - При использовании материала "Удобная усадьба", должна быть "живая" ссылка на cozyhomestead.ru.