I don't know why you would think that an upward trend in IQ scores necessarily contradicts a claim that we are adding neurotoxins to our environment. We've bee

I don't know why you would think that an upward trend in IQ scores necessarily contradicts a claim that we are adding neurotoxins to our environment. We've been doing that for many decades; it's entirely possible that we're doing less of it now, and yet the amount we're still adding is still having significant effects. As for why a downward trend in IQ wasn't noted in the first half of the 20th century, when we were ramping up our production of neurotoxins, that can easily be put down to improvements in nutrition. It's not inconsistent to note that, even though things are getting better, they're still not as good as they could be.