We know that an average woman will have 300-400 grams of serum in her 5 liters or so of blood, and we know that DDT is bio-accumulative. A steady smoker will be increasing her total nanograms of DDT per gram of blood serum pretty quickly – with the excess steadily being stored in her fat. And if she doesn’t have enough fat her body will make more because the body is biologically compelled to store DDT in fat.