sanitary epidemiological serveice 如何翻译?

Should any of this material be introduced into a sanitary sewer system,请问这是一个什么语法现象.
全句如下：
Should any of this material be introduced into a sanitary sewer system,flush
with copious amounts of water.

Sanitary,Health,Hygiene三个词均有卫生的意思,如何区别?
最好可以有具体的举例应用来说明~一个句子也好~

clean,sanitary ,healthy和hygienic有什么区别
You should use cotton wool to clean the wound.It's much more-----.
你应该用 棉花羊毛（?） 来清理伤口.这比较卫生（?）.选sanitay和hygienic中哪一个啊?

阅读理解many people dump (倾倒) most of their garbage in sanitary landfills
many people dump (倾倒) most of their garbage in sanitary landfills (垃圾填埋池). now the landfills are overflowing(泛滥) with garbage. people are noticing that certain items in the garbage aren’t breaking down and mixing with the soil. things made of glass, plastics and tin change little over years and they are piling up (堆积).
we need to do something about it. but how? recycling is the answer to the problem. people in many countries are trying to use these items again to make new things. it is important because it conserves (保护，保持，保存) natural resources and saves energy. for example, recycling paper saves trees. recycling also saves space in landfills. let’s work together to make our world beautiful.
1). garbage overflows because ________.a. the landfills are too smallb. there are many items of itc. people dump most of it into landfil***. people don’t know where to dump it 满分：3 分
2). which item can mix with soil?a. paperb. glassc. tind. plastics 满分：3 分
3). people can _______ to solve the garbage problem.a. save energyb. save treesc. dump garbaged. recycle 满分：3 分
4). things made of glass, plastics and tin _________.a. change a lot over the yearsb. mix easily with soilc. are too hard to break downd. do harm to people’s health 满分：3 分
5). recycling is to _______.a. save treesb. preserve resourcesc. use space to dump garbaged. use old items to make new ones

More and more people begin to__ __ __ the sanitary is to health.
越来越多的人开始意识到食品卫生对人的健康有多么重要

for sanitary reasons clean or spoiled glasses .关于酒杯的
for sanitary reasons clean or spoiled glasses should never be touched inside or on rim with fingers是什么意思?关于酒杯的