Conventional vs. organic milk

In a small study of milk collected from stores across the United States, Rollins researchers found traces of current-use pesticides and antibiotics in conventionally produced milk but not in milk produced using organic methods. They also found, that growth hormone levels were higher in the conventional vs. organic milk samples. While most samples were within FDA and EPA limits considered safe for these substances, several samples of conventionally produced milk exceeded FDA limits for a few of the antibiotics tested.

Dr. Dana Boyd Barr, professor of environmental health, is senior author of the paper that was published in Public Health Nutrition. Barr is director of a laboratory that studies human exposure to a wide range of chemicals.

“Sufficient exposure to pesticides may lower birth weight, contribute to delayed motor and neurological development, and increase cancer risk,” the authors say.

They also note the long-time hypothesis that levels of antibiotics in dairy and meat products could lead to antibiotic resistance and hypersensitivity.

Researchers collected samples from a total of 69 half-gallon milk cartons: 34 organic and 35 conventionally produced. They tested multiple brands of milk collected from across the U.S. The majority of samples were of milk with 2 percent milkfat, the type most commonly consumed by U.S. children.

“To our knowledge, this is the first study in several years to compare levels of pesticides, antibiotics, and growth hormones in milk according to production method (conventional vs organic),” the authors say.