A mammal mother draws down the fat stores of her body, including the persistent toxic chemicals she has accumulated and stored over a lifetime in her body fat, into her milk. Thus the load of decades’ worth of contaminants is passed on to her baby in a very short time. 

"It is indeed tragic that breast-feeding is the only efficient way to remove these persistent chemicals from the human body" 

"During breast-feeding, human infants are exposed to higher concentrations of these chemicals than at any subsequent time in their lives. In just 6 months of breast feeding, a baby in the US and Europe gets the maximum recommended lifetime dose of dioxin, which rides through the food web like PCBs and DDT. The same breast feeding baby gets 5 times the allowable level of PCBs set by international health standards for a 150-pound adult." 
 

A dilemma: the undeniable benefits of breast-feedings vs. the fact that nursing babies take in 10 to 40 times higher dose of contaminants than the daily exposure of an adult. 

Older women having their first child would transmit highest levels of contaminants because of having been accumulating them for a longer time..