I never heard of Kenneth Mellanby, but I know that Dr. Gordon Edwards (Emeritus U.C. Berkeley) testified to Congress and advocated against the ban and for its continued use and drank the chemical during many subsequent lectures. However, ignorance is always embraced by the arrogant.
Appreciate the testimony. All I know is that, given its widespread and somewhat indiscriminate use, it can't be that harmful to humans.
And the harm from disease-carrying insects is well-know and well documented. It seems like a simple risk/benefits calculation to me.