of the oxygen dissolved in the stream that fish and other desirable forms of 

 life can no longer survive. Such disposal of sewage may endanger the health 

 of cities located downstream. 



To avoid these disadvantages sewage is managed by several different meth- 

 ods. These include sand filters and chemical treatment for precipitating sus- 

 pended matter. Other satisfactory systems depend upon the action of aerobic 

 or anaerobic organisms. 



As population becomes more concentrated, it is found to be more satis- 

 factory from the point of view of health to have central municipal agencies 

 remove and dispose of ashes, rubbish and garbage. And in the long run com- 

 munity agencies are the most economical. 



Food Protection A large part of our food comes to us in sealed packages. 

 We do not know where or of what the food is made. Expanding commerce 

 brings us food products from foreign lands. As individuals, we cannot tell 

 from the appearances or the taste whether the preparations contain harmful 

 preservatives or coloring matter or adulterants, or whether, they lack any of 

 the essentials. It has become necessary to protect buyers of food and other 

 products through public regulations and official agencies. 



As we learn more about the relation of food to health and efficiency, and 

 as we become more and more separated from the sources of supply, the public 

 must protect the buyer still further. We must be assured (1) that what is 

 offered is suitable for our purposes and (2) that it is harmless. 



Because food travels greater distances from its source, and is kept for 

 longer periods, nearly all the states regulate the sale of prepared meats, fruits, 

 vegetables, fish, that may become spoiled or contaminated. Shipping spoiled 

 food from one state to another is prohibited by federal laws. In many cities 

 special ordinances authorize officials to seize and destroy any unsuitable food 

 that they may find, and to penalize dealers or manufacturers who offer such 

 food for sale. 



It has been practically impossible to obtain milk in large quantities without 

 excessive numbers of bacteria. The practice of pasteurization has therefore 

 come into general use. This consists of keeping the milk at a temperature of 

 145° F for twenty minutes. 



Food in Wartime In Great Britain during the first three years of the 

 Second World War, the general health of the population appeared to improve. 

 And this in spite of the great strains brought on by the bombings and other 

 conditions, and in spite of the rationing of food. The improvement is in part 

 explained by the fact that a considerable fraction of the food used was raised 

 on the island instead of being imported. This made certain that only needed 

 food was produced, while imports were carefully planned. And the rationing 

 ensured everybody a suitable diet within the limits of what was available. 



In every factory employing two hundred and fifty or more workers, com- 



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