TF写作真题第012套（gm002）

GM_002

Dental amalgam has been for decades and remains today the most commonly used material in dental repairs such as tooth fillings. However, it is a mercury alloy, meaning that it is a mixture of mercury and other metals. It is well documented that direct exposure to mercury has a toxic effect, but there are many experts who believe that mercury may be dangerous even in alloy form. For this and other reasons, mercury should be prohibited from use in dental repairs.

Health Concerns

First, mercury has long been known to have adverse effects on human health. Some experts consider it possible that the small amounts of mercury in the amalgam used to repair a tooth can, over long periods of time, enter a person’s central nervous system, potentially causing neurological, psychological, and immunological problems.

Pollution Problems

Second, waterways in the United States and the wildlife in them are being harmed by mercury contamination. The escape of amalgam waste from dentists’ offices is responsible for a large percentage of the mercury contamination in waterways in the United States. Amalgam waste is washed down the dentists’ office drains and into sewer systems that empty into lakes, rivers, and other bodies of water. Ultimately, the mercury in this amalgam ends up at the bottom of lakes and rivers; there, bacteria transform it into methylmercury, a form of mercury that is especially harmful to wildlife.

Alternatives Available

Third, dental repairs can be made without exposing people and animals to the dangers of mercury. Alternative materials such as gold, porcelain, and resin are widely available. Many dentists are now recommending that those or other materials be used instead of amalgam.

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