lems related to trihalomethanes were reported. For instance, the Rhine River wa
s polluted by industrial discharge, and if you added chlorine to the water of t
he Rhine River in Europe, you would get chloroform. The water of Mississippi Ri
ver in the United States is supplied as the piped water to many households, and
contains a high level of chloroform. It was doubted that maybe this is a cause
of the high prevalence of cancer. It was then found that this was caused by di
sinfecting with chlorine.
In order to guard ourselves from bacteria, and to prevent gastro-enteritis and
related dis-eases, we have got this very strong weapon of disinfecting with chl
orine, and with this chlorine we could clean the water. This has led to the imp
rovement of the state of health for the people. On the other hand, however, we
found that chlorine does indeed lead to carcinogenic substances, so is the chlo
rine to be blamed for? That is not the case. Chlo-rine reacts with something, a
nd then you get trihalomethanes. Water pollutants such as domestic discharge, h
ousehold discharge, and night soil react with chlorine to produce trihalomethan
es. So a portion of our river water reacts with chlorine and produces triha-lom
ethanes. So it was found out.
For instance, this is the Bay of Tokyo, and there are rivers flowing into this
bay (see Ta-ble 10). We know that there is a lot of discharge of nitrogen and p
hosphorus into the bay of Tokyo through these rivers. Where do they come from?
Industry is the cause of about 60 percent of the discharge, and households abou
t 20 percent. The majority is therefore industrial discharge. Still there is a
fairly large proportion ascribed to domestic or house-hold discharge. As far as
the industrial discharge is concerned, of course you can come up with stricter
standards for discharge by the govemment. However, to control household discha
rge and effluent, you have to raise the awareness of the people, you have to ed
ucate the public. People should be taught to reduce their discharge of domestic
effluent.
We have reconfirmed of how important it is to teach the public. It used to be t
hat in the developing nations, mothers were told to boil the water to be given
to their children in order to prevent infectious diseases, and the mothers were
taught about public health and hygiene. And now again, in everyday life we hav
e to teach the people to control their waste to reduce their domestic effluent.
It is, of course, important to teach, even in the developed nations.
