视频文本

Nitrate containing compounds in the soil are generally soluble and readily migrate with ground water.
含有硝酸盐的物质可以在土壤中分解并且污染地下水，
Increased nitrate levels can present health risks to children.
硝酸盐含量过高会影响儿童的身体健康
Contaminated food stuffs, prepared baby foods,
儿童饮食中一些食材受到污染
and sausage preserved with nitrates and nitrites have caused exposure in children.
以及含有亚硝酸盐和硝酸盐的香肠都对儿童的身体有害，
Although vegetables are seldom a source of acute toxicity,
尽管蔬菜通常并不会造成中毒，
they account for more than 70% of the nitrates in a typical human diet.
但人类饮食中70%的硝酸盐来自于蔬菜
Cauliflower, spinach, collard greens, broccoli,
花菜，菠菜，羽衣甘蓝嫩叶，花椰菜，
and root vegetables have naturally greater
以及根菜中的硝酸盐成分
nitrate content than other plant foods do.
都要高于其他食物
The remainder of the nitrate in a typical diet comes from drinking water, about 21%,
剩下的硝酸盐主要来自饮用水，大概占21%，
and about 6% from meat and meat products in which
还有6%来自于肉类和肉制品，因为为了保存
sodium nitrate is used as a preservative and color enhancing agent.
在它们的制作过程中用了硝酸钠
For infants who are bottle fed,
对于奶粉喂养的婴幼儿来说
however, the major source of nitrate exposure in drinking water is used to mix powdered milk formula.
硝酸盐的主要来源是饮用水和配方奶粉
It appears that organic production of food results in
有机食品中的硝酸盐含量
lower nitrate levels most likely because nitrates are
更低，这其中的原因或许是因为
not allowed in organic food production.
在有机食品生产过程中禁止使用硝酸盐
A study conducted by Baker et al in 2002 summarized the
2002年由贝克和其他人进行的研究
results of 18 studies comparing nitrate levels of organic and conventional foods
总结了18项对比有机食物和传统食物中硝酸盐含量的研究，
and found 127 cases where nitrate levels were higher in conventional foods
发现其中127例中传统食品的硝酸盐含量高
43 cases where nitrate levels were higher in organic foods,
43例中，有机食品的硝酸盐含量高
and 6 cases where no difference was noted.
另外6例中，两者的硝酸盐含量相当
The Baker study demonstrates that organically
贝克的研究表明，有机食物中的硝酸盐
produced foods have lower detectable nitrate levels
含量较低，由于有机食品生产过程中
which is not surprising given that nitrates aren't used in conventional farming.
禁用硝酸盐，这一点不足为奇
Now let's look at the issue of nitrate in drinking water,
下面我们来看看饮用水中的硝酸盐含量
and what this means to you.
这对你来说意味着什么
The major sources of nitrates in drinking water are runoff from fertilizer use,
饮用水中硝酸盐的主要来源是化肥的残留，
leaching from septic tanks or sewage, and erosion of natural deposits.
主要来自于化粪池和污水管道，还有自然沉积
In 1974, Congress passed the Safe Drinking Water Act.
1974年，国会通过了饮用水安全法案
This law requires the EPA to determine the level of
法律规定，环保局应当决定饮用水中
contaminates in drinking water at which no adverse health affects are likely to occur.
污染物的含量上限，以保证不会对人体造成伤害，
The EPA has set an enforceable regulation for nitrate called a
环保局发布了强制性的监管条例，规定污染物的最高含量
maximum contaminant level or MCL at
这个最高含量标准也叫MCL
10 milligrams per liter, or 10 parts per million.
它的值为每升10毫克
MCL's are set by considering cost, benefits,
MCL的制定过程考虑到了公共供水系统
and the ability of public water systems to detect and
利用合适的处理技术对污染物
remove contaminants using suitable treatment technologies.
进行检测和去除过程中的成本，能力和利润，

视频及简介

视频简介：

本课程的目标是，向公众提供最新的有关营养方面的信息和话题，内容涵盖饮食因素对于癌症的影响作用，健康的饮食习惯，学校能提供的营养有哪些，咖啡因与癌症的联系，水果蔬菜与癌症预防等。通过本课程的学习，人们可以学习到健康的生活饮食习惯，在每天的饮食中防癌症于未然