This chain has made me curious; has there been any study of the negative health consequences of people's behavior with shoes within their living space? I'm not

This chain has made me curious; has there been any study of the negative health consequences of people's behavior with shoes within their living space? I'm not aware of any health concerns (major or minor) over such a thing. For example, if such things were a worry then I'd be more concerned over my dog's bare paws while outside and his nonchalant attitude of not wiping them as he comes inside.