专业英语-week 14

中毒极限量是指健康被显著影响的初始量。该极 限也取决于化学物质、暴露的类型以及个体自身 的因素。
• The detection limit is the minimum amount of a substance that can be determined by a laboratory test procedure. This limit depends on the state of the art in analytical laboratories.
二三十年前，对于许多物质来说，其检测极限和 中毒极限都差不多，但现在，检测极限已经远远 低于中毒极限。
• Figure 1 depicts schematically the relation between the fatality limit, toxicity limit, and changing detection limits for mercury.
图1示意性地描述了致死极限值与中毒极限值的 联系，以及汞的检测极限的变化。
Figure 1. Schematic diagram illustrating the relation between the fatality and toxicity limits and the changing detection limits with time for mercury.
如图1所示，中毒极限区域中的毒性曲线显示出 渐进的变化而不是突变，这表明这个极限是任意 的，可以适用于所有物质。
• The general public and even many scientists have been slow to recognize the significance of the dramatic changes in detection limits brought about by improved analytical methods.
只要检测极限低于中毒极限，那么检测极限与死 亡极限和中毒极限间的不同就无关紧要。
• Two or three decades ago, detection limits and toxicity limits for many materials were in the same range. But now detection limits have dropped far below toxicity limits.
检测极限是指物质可被实验室检测程序检测到的 最小量。这个极限值取决于分析实验室的技术发 展水平。
• The detection limit is completely independent of the other two and is continually being lowered as knowledge of chemistry improves and more sensitive instrumentation is developed.
• The toxicity limit is the limit where well-being is first noticeably affected. This limit also depends on the chemical, the type of exposure, and individual human factors.
几十年前，当对食物中的有毒物质进行检测时， 如果没检测到此类物质，那么人们认为这些食物 是安全的。而如今，所有的食物中都显示出含有 一大批超过可检测量的有毒物质。
• Nevertheless, food now is probably generally safer and of better quality than ever before, what has happened? To clarify this seeming contradiction, two terms relating to toxicity and one concerning the limit of analytical measurement should be described.
Analytical Chemistry and Problems in Society
• Analytical chemistry, because it permeates almost every aspect of society, has profound implications for human welfare. An example is the analysis of materials for chemicals of possible toxicity to man.
• Every mouthful of food that we or our ancestors have ever eaten is radioactive at far above present detection limits, and all foods contain numerous toxic substances well above these limits. In short, it is no exaggeration to say that detectable amounts of almost everything are present in almost anything. 我们以及我们的先人吃的每一口食物的放射性都 远远超过了现在的检测极限，所有食物中都含有 许多远高于检测限的有毒物质。简而言之，我们 可以毫不夸张地说任何物质中都含有可检测量的 几乎所有物质。
• As indicated in Figure l, the toxicity curve in the region of the toxicity limit shows a gradual rather than a sharp change, indicating the limit to be somewhat arbitrary. This applies to all substances.
公众甚至许多科学家对于由于分析方法的改进带 来的检测极限的明显改变的意义的认识是非常缓 慢的。
• Instead of being reassured by more precise information on levels of potentially hazardous substances, they have often responded negatively to reports that toxic substances have been detected in our food and general environment, without realizing the difference between what is detectable and what is harmful. 他们没有对于具有潜在危险物质的含量的更为精 确的信息感到安心，而是消极地回应说在我们的 食物和环境中检测到了有毒的物质，却忽略了什 么是可检测的与什么是有害的之间的差别。
然而，现今的食物一般情况下应该比早前的更为 安全，质量更好，那么，究竟发生了什么事情呢？ 为了澄清这种矛盾，此处介绍两个与毒性有关的 概念以及一个关于分析测量的界限(的概念)。
• The fatality limit is the level of chemical exposure that when maintained for any length of time results in death. This limit depends on the nature of the chemical, the type of exposure, and on individual human factors such as size, age, general health, and smoking habits. 致死极限量是指暴露在某种化学物质中一段时间 后会导致死亡的物质浓度水平。此极限量取决于 化学物质的本质，暴露的类型，以及被研究的人 类个体的特征如体型、年龄、健康程度以及是否 有抽烟的习惯等等。
分析化学，由于其渗透进社会的几乎每一个领域， 因而对人类幸福具有深刻的意义。如对物质中可 能对人类有毒的化学物质的分析。
• When foods were tested in past decades for toxic materials, they were presumed safe if such materials were not detected. Today, all foods can be shown to contain detectable amounts of a host of toxic materials.
ቤተ መጻሕፍቲ ባይዱ
检测极限与另外两个极限值完全无关，且随着化 学知识的改进以及更精密的仪器的开发，检测极 限值不断地降低。
• The difference between detection limit and fatality or toxicity limit is not significant as long as the detection limit is below the toxicity limit.