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Arsenic is an element that exists in different forms in the earth and nature

2020-05-26 来源: 51Due教员组 类别: 写作技巧

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下面为大家整理一篇优秀的essay代写范文-Arsenic is an element that exists in different forms in the earth and nature。本文讲述砷是以不同形式存在于地球和大自然中的元素。它的大多数化合物都是可溶的,因此很容易进入食物链。砷作为一种有毒元素,确实会对人类的生长和健康产生负面影响。尽管砷对某些疾病具有潜在的治疗功效,但是慢性砷中毒可能会导致皮肤,血管和神经系统以及癌症恶化。世卫组织已将水中的砷列入致癌物质清单。

随着土壤和水中砷的大量存在,砷可以在农产品中以大米的形式积累,由于婴儿饮食限制,砷可能后来被制成婴儿食品并引发一系列婴儿问题,婴儿接触砷的风险可能高于成年人,他们的饮食习惯更加多样化。人体主要通过食物获取砷,尤其是海鲜,其吸收的砷占小麦,蔬菜,肉类和牛奶的70%以上。其他获取砷的方法包括呼吸和皮肤吸收,但是通过这两种方法摄入的砷很少。

Arsenic is an element that exists in the cover of the earth and the nature in different forms. Most of its compounds are soluble and thus easily enter the food chain. As a toxic element, arsenic does has a negative impact on human growth and health. Despite arsenic’s potential therapeutic efficacy to certain diseases, chronic arsenic poison might cause deterioration to skin, vascular and nervous system, along with cancers. WHO had put arsenic in water into the list of cancer driving substance.

With the wild existence of arsenic in soil and water, arsenic can accumulate in agriculture products as rice, which might latter made into infant food and raise a series of  baby problems since infants eat a more limited diet, their exposure to arsenic may be higher than  adult who are eating a more varied diet. Human body mainly obtain arsenic by food, especially seafood, which accounts for more than 70% arsenic absorbed, following wheat, vegetable, meats and milk. Other ways of getting arsenic include breath and skin absorption, but the intake arsenic by these two ways is slight.

Since a diversity of food contains arsenic to a certain amount, and the unfavorable effect it brings to our body, it’s believed that the regulation of arsenic of our food should be set accordingly. The US EPA has set a maximum permissible level in drinking water of 10 ppb. However, no regulation for inorganic arsenic in food has been carried out in US.  WHO recommended 15mg/kg arsenic on weekly basis after evaluating the toxicity of arsenic.  

From my perspective, an exact value for total arsenic intake from food is useful in research and making major plans. But in terms of guidance to daily diet, it is unrealistic and has little meaning. First of all, the data from given article was from a single research team in certain region, which means it did not have good validity statistically. Content of metals in food varied because of plenty factors as climate, geography, ways of cooking, pollutions, etc. So it’s hard to calculate how much arsenic one consumes in a day or a week accurately. Besides, people who expose to arsenic-rich diet because of customs or environment probably have higher tolerance of this toxic metal. So it seems a value of total arsenic should differ according to cultures and regions.

A study decades ago indicated that the average daily intake for arsenic (as As2O3) has decreased from about 130 mug/day in 1968 to about 20 mug/day in 1974 (Jelinek CF, 1977). Though it’s still too high for safe sake, we can see the amount of arsenic intake changes through time, probably due to change of life style. Therefore, rather than setting a value for toxic metals in food, it’s wiser to advocate the idea of healthy diet to the public. Besides, there are other trace elements exist in food that have potential threat to human health. If each of these toxic element have regulation and a right value, it would be so silly for people to calculate all of them before eating or drinking.( Castro-González MI1, 2008) The idea of healthy diet, environment protection and strict censorship for food quality might be more helpful than single regulation with exact safe value.

 

bibliography and further reading

Jelinek CF, Corneliussen PE. Levels of arsenic in the United States food supply. Environ Health Perspect. 1977 Aug;19:83-7.  

Castro-González MI, Méndez-Armenta M. Heavy metals: Implications associated to fish consumption. Environ Toxicol Pharmacol. 2008 Nov;26(3):263-71. doi: 10.1016.

 

 

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