This is an attempt to deflect off vaccinations as the cause.
Good chance that they spray more for this in urban areas where pop density is higher anyway, so density may account for higher rates of cases because more people live in these areas ie it could be a conclusion based on a bogus stat.
There are some reports indicating that autism did not rise until the early 80’s yet vaccines have been around since the early 70’s. Some people are linking autism to the surge in “fat free” diets in the 80’s.