Question

Polychlorinated biphenyls (PCBs) are toxic compounds, which have a very long biological half-life: when absorbed into the body, they are stored in fatty tissues and eliminated only very slowly. Look up the chemical structure of PCBs. What chemical property of PCBs mainly accounts for their tendency to accumulate in fat?

Answer 1

After observing the chemical structure of Polychlorinated biphenyls (PCBs), their chemical properties which mainly accounts for their tendency to accumulate in fat are:

• Polychlorinated biphenyls (PCBs) are highly hydrophobic as they lack any functional groups which are capable of forming hydrogen bonds or other favorable interactions with water.
• So they very effectively partitioninto the body's depot fat tissues but are excreted very slowly for example in the form of urine.
• Polychlorinated biphenyls are poorly metabolized.This kind of behavior shown by PCBs is called "bioaccumulate".
• This type of tendency to accumulate in fat tissues is an significant contributor to the toxicity of Polychlorinated biphenyls and some other environmentally-significant compounds like insecticide DDT, TCDD and additive, tetraethyl lead.