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Bioaccumulation. Bioaccumulation refers to those processes by means 
of which organisms take up chemicals from the physico-chemical environment 
and incorporate them into some or all of their tissues. It is a very nor- 
mal set of processes without which life would not be possible. 
The environmental concern with bioaccumulation is related to the uptake of 
toxicants and their effects upon the consuming organism or upon the organ- 
ism that consumes it. Unfortunately the early concern with bioaccumulation 
was based largely upon one compound, namely DDT, which is somewhat unique 
in its ecological characteristics. Simply because an organism takes up a 
toxic compound and assimilates it does not mean that it will suffer debili- 
tation. For example, in the bodies of vertebrate animals DDT is stored in 
adipose or fat tissue depots. Here it has little or no effect on the or- 
ganism. The amount of DDT stored in an organism's tissues then will depend 
upon the amount of fat it possesses and this, as we well know, is related 
to season. If and when it is released from the fat depots some of it is 
detoxified by liver and, in some cases, kidney cells. A third factor that 
protects organisms from the effects of toxicants is the development of im- 
munity. Thus, it is rarely the case that an organism will accumulate a 
given toxicant until it becomes lethal. Rather the organisms will estab- 
lish a dynamic equilibrium wherein the toxicant is assimilated and elimi- 
nated at the same rate as its uptake (Mitchell, 1966; Stanford Research 
Institute, 1963). 
In this event one must consider the effect that such an organism will have 
when it is prey for a predator, including man. Here again this is a com- 
plicated issue. But in general one can say that man has a remarkable abil- 
ity to detoxify his foods. In addition, there is ample evidence to show 
that most of the chlorinated hydrocarbons, when fed regularly at a given 
concentration in the diet, will reach an equilibrium in the fat. Man has 
suffered from the uptake of chemicals such as organochlorines primarily 
when he has been exposed to massive doses over substantial periods of time- 
conditions that were once common in certain kinds of chemical manufacturing 
plants. It is very unlikely that dredged material would cause toxic 
conditions in an organism that when eaten by man would cause untoward 
