If you must give him milk then yes, organic. You really want to stay away from the growth hormones in the foods these days. You'd be wise to do some research on milk before introducing it to your son. We buy organic milk from Costco, my son drinks it on occasion, maybe a a couple of glasses a week and my husband too. My daughter and I don't drink it at all. If it were up to me, I wouldn't buy it though. We get our calcium/vit d from other sources. The following was taken from www.milksucks.com (yes it is pretty one sided - but has some good information none the less);
Dairy products are a health hazard. They contain no fiber or complex carbohydrates and are laden with saturated fat and cholesterol. They are contaminated with cow's blood and pus and are frequently contaminated with pesticides, hormones, and antibiotics. Dairy products are linked to allergies, constipation, obesity, heart disease, cancer, and other diseases.
The late Dr. Benjamin Spock, America's leading authority on child care, spoke out against feeding cow's milk to children, saying it can cause anemia, allergies, and insulin-dependent diabetes and in the long term, will set kids up for obesity and heart disease, America's number one cause of death.
And dairy products may actually cause osteoporosis, not prevent it, since their high-protein content leaches calcium from the body. Population studies, backed up by a groundbreaking Harvard study of more than 75,000 nurses, suggest that drinking milk can actually cause osteoporosis.
Bottom line, skip it if you can. If not, then yes, buy organic.
Best wishes,
M.