B)the wind losing its force.

C)the water becoming cooler.

D)violent storms.

4.El Niňa is a phenomenon that A) reserves the effect of El Niňo.

B) produces similar weather conditions. C) forms part of the same pattern.

D) occurs every four or five years.

5.The effect of El Niňo

A)can be reliably forecast.

B)are sometimes beneficial.

C)are never accurately reported.

D)do not reach the northern hemisphere.

(Fowler W.S. New Fowler proficiency. Listening and speaking, 2003)

15.Discuss the following facts and figures.

1.As a result of human activity 156 mln. tons of sulphur dioxide and 60 mln. tons of nitric oxide are released into atmosphere every year. In the cities where there are many industrial enterprises the air is contaminated even greater. For example, in Tokyo every month 34 tons of soot falls per each square kilometer of the territory, in NewYork it amounts 17 tons.

2.As a result of industry and transport development oxygen is used for burning in greater amount. For example, an automobile spends a man’s daily rate (суточная норма) of oxygen per 1,5 thousand kilometers. (A man spends 500 liters of air daily on average). A modern jet liner uses 35 tons of oxygen per 1 transatlantic flight.

3.One of the terrible catastrophes in the history of mankind was the accident in Chernobyl in April 1986.There happened destruction, melting, evaporation and emission of nuclear fuel into the atmosphere. In all nearly 50 tons of nuclear material were released into the atmosphere. The mass of radioactive bomb fallen on Hiroshima was 4,5 tons. In Chernobyl the radioactive substances rose at the height up to 11 kilometers, the territory of Ukraine, Belorus, and central regions of Russia were contaminated.

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16.Discuss the following problems. Find some additional information to prove your point of view.

1.Can the ozone layer be preserved in the current conditions? If so, in what way?

2.Why does not the contamination of atmosphere disturb the processes taking place in it?

17.Choose any questions. Discuss it in pairs.

1.What will climate change lead to?

2.What is the difference between the greenhouse effect, global warming and climate change?

3.How do we know the greenhouse effect is a reality?

4.What do the experts conclude about climate change?

5.Global warming and climate change? Is there still a debate?

6.How can we predict climate change when we can't even predict the weather?

7.Will all the impacts of the greenhouse effect be negative?

8.What must be done to reduce human contributions to the greenhouse effect?

9.Can the world survive without fossil fuels? What are the alternatives?

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UNIT 5

THE IMPACT OF CHEMICAL ELEMENTS ON HUMAN

ORGANISM

Serious health problems and diseases may arise from toxic elements in water, air, soil, and even the rocks on which we build our homes. Almost every part of the human body is affected by one pollutant or another. The same is wildlife.

Lead-in

1.Once the famous physician and alchemist Paracelsus said: “Everything is poisonous, yet nothing is poisonous”. What did he mean? Give your examples.

2.How can harmful substances get into organism? Enumerate all possible pathways.

3.The impact of what substances on human organism do you know? Can you describe it?

1. Read the words and learn their pronunciation.

[i:] convenience, excretion, breathing, intravenous

[oυ] process, scope

[u:] rout, include, remove, evolution [ai] biology, kinetics, xenobiotics [dʒ] geology, agent, ingestion

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Regardless of their effect or origin, the behaviour of xenobiotics in the body can be described by general terms and models reflecting the mechanisms by which exposure occurs and the body handles the chemicals. From the standpoint of evolutionary biology, it is supposed that these mechanisms developed in response to selection pressures indicating either of two biological needs: to detoxify and excrete harmful substances ingested in foods and to metabolize endogenous chemical compounds (such as steroid hormones).

Four terms describe the disposition of xenobiotics: absorption, distribution, metabolism, and excretion. Modelled together, the terms indicate the entry, local and overall accumulation, transformation, and removal from the body of the xenobiotic. Because tissue level depend on transport of the xenobiotic to the target organ and the degree to which the xenobiotic partitions or is sequestered into the tissue, the kinetics of the xenobiotics determines the presentation of the xenobiotic to the target organ at the receptor level, where the toxic effect occurs (see Fig.).

Xenobiotics may enter the body through any of several “portals” or routs of entry. By far the most common opportunities for exposure are skin contact and breathing in the agent. Ingestion, resulting from eating or placing objects (e.g. cigarettes) in the mouth in a situation where the object or the hands may have been contaminated, or in suicide attempts, is not a common problem in environmental medicine, but appears from time to time. Other routs of exposure, such as intravenous infusion or implantation of soluble agents, are artificial and seldom seen outside of medical care and experimental studies.

Once the xenobiotic is absorbed and enters the organism, it is transported to capillary level in tissues of the body where it becomes available for uptake by the target organ. After one pass through the circulation the xenobiotic is uniformly mixed in arterial blood regardless of its entry. When a bolus is absorbed, the peripheral tissues are therefore presented with an increasing concentration in the blood which peaks and then declines as the xenobiotic is distributed to tissues throughout the body and removed by metabolism, excretion, or storage.

Many xenobiotics are substrates for intracellular enzyme systems which transform it from the original compound to a series of stable metabolites, often through intermediate unstable compounds. These transformations may have the effect of either “detoxifying”, by rendering the agent toxicologically

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inactive, or of “activation”, by converting the native agent into a metabolite that is more active in producing the same or another toxic effect.

The xenobiotic or its metabolite would accumulate and remain within the body, if there were no mechanisms for excretion. Elimination is the term used for removal of xenobiotic from the bloodstream, whether by excretion, metabolism, or sequestration (storage).

(From Essentials of Medical Geology. Elsevier Inc., 2005)

4. Read the following word-formations, translate into Russian.

Toxicology – toxicity – detoxify – toxic – toxicologically

To act – active – inactive – activity – activation

To produce – product – production

To absorb – absorption – absorptive

To transport – transportation – transportive

To metabolize – metabolite – metabolism

5. Give Russian equivalents to the following words and set-expressions.

To play an essential role

To result from

To expand the scope

To provide the framework

Regardless of smth.

In response to

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