"We take issue with only one statement in the book, and that is the warning to avoid animal fats. This suggestion is actually inconsistent with a statement on the following page that cows' milk (and, by implication, the butterfat in the milk) contains only one-fifth the concentration of persistent contaminants than that of humans, because cows are shorter-lived animals, vegetarians and are constantly eliminating contaminants as they are milked daily. Of course our animal foods--indeed all our foods--should come from clean sources, but animal fats provide vitamin A and many other protective nutrients. A thoroughly good case is made for avoiding domestic freshwater fish, however, which still test high in levels of DDT, even years after it has been banned."
I also feel that if you search out pasteure feed beef, etc. that there could possibly be less of a problem? It is your choice, but hope this gives you some additional information and insight.