dr. walinga, i want to take a look at what mcdonald's says about this policy. while mcdonald's will only source chicken menu will continue to responsibly use ionofores, a type of antibiotic not used for humans that helps keep chickens health. let's talk about two things, important to human medicine and responsibly used ionophores. they are still sticking with ones the they give to chickens. >> yes, i think it's an important distinction. the human drugs are the ones we ought to be focused on mostly. these are things like penicillin and tetra sigh psychcycline. when you put that in their feed pretty much continuously over the life of the bird what you end up doing is creating and helping to spread bacteria in those birds that are resistant to those ant bottlics and then those -- antibiotics and those resistant bugs can spread to the meat we eat or in the farm environment and then reach people. so by taking those out of the chicken supply chain mcdonald's is doing a good thing. those human antibiotics account for about 60% of all the antibiotics used in agricultur