1.Radioactivity occurs naturally. The main sources are in space, rocks, soil, water and even the human body itself. This is called background radiation and levels vary from place to place, though the average dose is fairly constant. The radiation which is of most concern is artificial radiation which results from human activities. Sources of this include the medical use of radioactive materials, fallout and contamination from nuclear industry, and the storage and dumping of radioactive waste.
1、輻射在自然界中普遍存在。主要的輻射源存在于空間、巖石、土壤、水、甚至是人體之中。這叫做背景輻射。輻射強(qiáng)度會(huì)因地點(diǎn)而異，但平均輻射量實(shí)則大致相同。最令人擔(dān)憂的是人類活動(dòng)造成的人工輻射。輻射源包括醫(yī)用放射性材料、核工業(yè)的放射性沉降物和污染物，以及輻射廢棄物的積存和傾倒。
2.While artificial radiation accounts for a small proportion of the total, its effects can be disproportionate. Some of the radioactive materials discharged by human activities are not found in nature, such as plutonium, while others which are found naturally may be discharged in different physical and chemical forms, allowing them to spread more readily into the food-chain.
2、雖然人工輻射只占輻射總量的一小部分，其后果卻很嚴(yán)重。人類活動(dòng)所排放的一些放射性物質(zhì)本在自然界中無處可尋，比如說钚。然而另外一些本來天然存在的物質(zhì)卻以各種不同的物理或化學(xué)形式被釋放出來，致使它們能更輕易地進(jìn)入食物鏈。
3.For all these reasons, simple comparisons of background and artificial radioactivity may not reflect the relative hazards. Equally important, it has never been shown that there is such a thing as a safe dose of radiation and so the fact that we are progressively raising global levels should be of as much concern to us as the possibility of another major nuclear test, nuclear reactor or shipment of plutonium means an additional and unnecessary health risk.
3、基于這些原因，也許僅僅拿背景輻射和人工輻射作簡單比較并不能夠反映相關(guān)的危險(xiǎn)性。同樣重要的是，從來也沒有過輻射存在安全攝入量這種說法。因此，就像處理另一場(chǎng)大型核試驗(yàn)、核反應(yīng)堆的制造、钚材料的運(yùn)送等環(huán)節(jié)會(huì)對(duì)健康形成潛在威脅一樣，不斷増加輻射總量也應(yīng)該引起我們足夠的重視。
4.In general, the effects of radiation can be divided into those which affect the individuals exposed and those which affect their descendants. Somatic effects are those which appear in the irradiated or exposed individual. These include cancer and leukaemia. Hereditary or genetic effects are those which arise in subsequent generations.
4、總的來說，輻射的危害可以分為對(duì)輻射接收者本人的影響以及對(duì)其子孫后代的影響。身體傷害尤見于輻射接受者本身，包括癌癥和白血病這類病癥。遺傳影響則發(fā)生在其后代身上。
5.Many of the elements which our bodies need are produced by the nuclear industry as radioactive isotopes or variants. Some of these are released into the environment, for example iodine and carbon, two common elements used by our bodies. Our bodies do not know the difference between an element which is needed and which is not. So radioactive elements can be absorbed into living tissues, bones or the blood, where they continue to give off radiation. Radioactive strontium behaves like calcium—an essential ingredient in our bones—in our bodies. Strontium deposits in the bones send radioactivity into the bone marrow, where the blood cells are formed, causing leukemia.
5、我們身體所需要的許多元素是由核工業(yè)以放射性同位素或者是變體的形式排放出來的。其中有一些被釋放到環(huán)境中，比如說碘和碳，這是我們身體所需的兩種常見元素。我們的身體并不知道需要哪種元素，不需要哪種元素。所以放射性元素能夠被我們的活細(xì)胞組織、骨骼和血液吸收，而進(jìn)入人體后其輻射并未停止。放射性元素鍶在我們體內(nèi)和人體骨骼必需元素鈣表現(xiàn)類似。鍶在骨骼中沉積并且將放射能傳遞至產(chǎn)生血液細(xì)胞的骨髓之中，從而引發(fā)白血病。
6.There are three principal effects which radiation can have on cells: firstly cells may be killed; secondly the way cells multiply may be affected, resulting in the cells of the ovaries or testes, leading to the development of a child with an inherited abnormality.
6、輻射可以對(duì)細(xì)胞產(chǎn)生三大主要影響：第一，細(xì)胞可能會(huì)被殺死;第二，細(xì)胞的繁殖可能會(huì)受影響，進(jìn)而影響到卵巢或睪丸中的細(xì)胞，引起先天性胎兒畸形。
7.In most cases, cell death only becomes significant when large numbers of cells are killed, and the effects of cell death therefore only become apparent at comparatively high dose levels. If a damaged cell is able to survive a radiation dose, the effects of the cell damage may never become apparent. A few malfunctioning cells will not significantly affect an organ where the large majority are still behaving normally.
7、在多數(shù)情況下，只有當(dāng)大量細(xì)胞被殺死時(shí)，細(xì)胞死亡才會(huì)引起嚴(yán)重后果。因此細(xì)胞死亡這一問題只有在輻射量相對(duì)較大的情況下才得以凸顯。如果一個(gè)受損細(xì)胞在接觸一定量的輻射后存活下來，那么細(xì)胞受損的危害就不易被察覺。當(dāng)大多數(shù)細(xì)胞在器官內(nèi)正常運(yùn)作時(shí)，個(gè)別構(gòu)造細(xì)胞受損并不會(huì)對(duì)整個(gè)器官產(chǎn)生重大影響。
8.However, if the affected cell is a germ cell within the ovaries or testes, the situation is different. Ionizing radiation can damage DNA, the molecule which acts as the cell's "instruction book". If that germ cell later forms a child, all of the child's cell will carry the same defect. The localized chemical alteration of DNA in a single cell may be expressed as an inherited abnormality in one or many future generations.
8、然而，如果受損細(xì)胞是卵巢或者睪丸中的生殖細(xì)胞，情況就不容樂觀了。電離輻射可以破壞在細(xì)胞中充當(dāng)著“指令書”作用的DNA。如果受損的生殖細(xì)胞之后發(fā)育形成了胎兒，那么這個(gè)孩子體內(nèi)所有的細(xì)胞都會(huì)帶有同樣的缺陷。單個(gè)細(xì)胞中DNA的局部化學(xué)成分的改變將會(huì)在未來一代或者幾代人身上以畸形的方式表現(xiàn)出來。
9.In the same way that a somatic cell in a body tissue is changed in such a way that it or its descendants escape the control processes which normally control cell replication, the group of cells formed may continue to have a selective advantage in growth over surrounding tissues. It may ultimately increase sufficiently in size to form a detectable cancer and in some cases cause death by spreading locally or to other parts of the body.
9、在身體組織中的體細(xì)胞通過逃脫控制細(xì)胞復(fù)制方式的復(fù)制程序來使體細(xì)胞自身或者后代發(fā)生改變，而新形成的細(xì)胞群體在增殖過程中以同樣的方式來獲得一種優(yōu)于其周圍組織的選擇性優(yōu)勢(shì)。最終它們可能在數(shù)量上急劇增加，從而形成一種可檢測(cè)性的癌癥。在某些情況下，這些細(xì)胞的局部擴(kuò)散或者擴(kuò)散到身體的其他部位還會(huì)導(dǎo)致死亡。
10.While there is now broad agreement about the effects of high-level radiation, they are complicated by the length of time it takes for effects to show up and the fact that the populations being studied (bomb survivors, people exposed to nuclear industry) are small and exact doses are hard to calculate.
10、雖然關(guān)于髙能輻射的危害性如今已達(dá)成廣泛共識(shí)，但由于輻射傷害往往要很長時(shí)間才得以顯現(xiàn)，而且可供研究的對(duì)象(爆炸幸存者、接觸核工業(yè)的人群)人數(shù)很少，而且他們體內(nèi)的輻射量很難被精確測(cè)算，這些都使問題變得更加復(fù)雜。
11.All that can be said is that predictions made about the effects of a given dose vary. A growing number of scientists point to evidence that there is a disproportionately high risk from low doses of radiation. Others assume a directly proportionate link between the received doses and the risk of cancer for all levels of doses, while there are some who claim that at low doses there is a disproportionately low level of risk.
11、我們只能說，人們關(guān)于特定輻射量對(duì)人體影響程度的猜測(cè)層出不窮且各不相同。越來越多的科學(xué)家們指證說明，少量輻射會(huì)給身體帶來難以想象的危害。另一些人則認(rèn)為不管輻射是多是少，人體受到的輻射量和癌癥患病風(fēng)險(xiǎn)之間都存在著某種直接的比例關(guān)系。但是也有一些人聲稱輻射少則危害小。
