the ... of waste materials by factories and households causes ... to rivers and lakes.the Rhine river in Europe and the great Lakes in North America are good examples of a river and lakes that are polluted.their ... can not be drunk.the same thing is happening to the sea In one instance,certain factories in Japan dumped industrial ... into the seaMany people suffered from lead or mercury ... after eating fish caught in such polluted waters.Pollution in certain areas of the sea is now reaching dangerous levels.Many ships discharge their waste materials and unwanted ... oil into the sea.These wastes contain lead and mercury which are poisonous.Sometimes,accidents to oil tankers can cause oil to be discharged into the sea and on to the ...
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