Hi Raimundo,Polio predates DDT by many thousands of years. There is evidence that it was present in ancient Egypt, while such famous persons as the Scottish poet Sir Walter Scott had also suffered from that disease (Which in those times was known as “Infantile Paralysis”).However, epidemics of polio only started to appear from the 1880s and onwards. Note, though, that this still predated the introduction of the insecticide, DDT, by some sixty-odd years.(DDT first saw widespread use during the second half of World War Two, when it was used to prevent such insect- bourne diseases as typhus and malaria).Prior to that, epidemics of polio regularly occurred in countries which had achieved a low level of infant mortality - such as the Scandinavian lands, Canada, Australia, New Zealand and the N.E. parts of the USA.It was very much a “Disease of Civilisation” - for example, during the early part of WWII, allied troops in Egypt came down with it by the dozen, yet it was unknown amongst the local population).(And that was before the widespread use of DDT as an insecticide).It was noted that once a population’s infant mortality rate had been reduced below a certain level, then it became much susceptible to “Infantile Paralysis”, and epidemics of polio began to occur every ten years.The use of DDT was not banned until the year 1972. However, the last polio epidemics in the developed world occurred ten years before that - coinciding with the mass immunisation campaigns, which used the orally - administered Sabin vaccine.
If the eradication of polio was the result of the withdrawing of DDT as a pesticide, we would not have expected an eradication of polio until well into the late 1970s (given the time it would have taken DDT to have worked its way out of the ecosystem).I’m sorry, but those who blame heavy metals, DDT and similar for outbreaks of polio are more than a little off-beam!