| The two comment threads are the same discussion so I'm merging my responses. > I bet you can't find a study demonstrating natural selection in the split-leaf philodendron, either, but that isn't a good reason to go around saying "some questions remain unanswered" It absolutely is! The criterion for whether a question has been answered is whether that question has actually been asked, studied, and answered. In cases where there is no specific evidence, you attempt to make assumptions that extend existing evidence into spaces that it does not explicitly cover. But these aren't answers; they are educated guesses. Some guesses are better than others, and really the fundemental act of science is feeling out these hypotheses and deciding which ones are sturdy and which are shaky. So for example consider the claim 'PTFE doesn't affect human health when ingested, because there is strong evidence that is safe in implants and is chemically inert in acids.' This claim relies on two assumptions in the absence of quality direct supporting evidence: (1) Safety in one biological context directly transfers to other biological contexts and (2) Chemically inert compounds cannot affect human health. There is mounting evidence against ~both~ of these assumptions, and so claims based on them should be treated with caution, and probably as warranting further study. This is no witch-hunt, this is simply using critical thinking and available evidence to gauge the validity of assumptions, and updating the validity of claims based on changes in the validity of underlying assumptions. This process ~is~ the scientific method. > Nanometer-sized pores matter enormously, (...) but not in ways that make other forms of amorphous silica more toxic than silica gel. Try replacing your morning cheerios with silica gel and let me know the results. The pores in silica gel are specifically interesting because they allow silica to readily form hydrates. The human body has a lot of water in it. There are absolutely health effects that depend on the physical shape of silica in addition to its chemistry compared to say, consuming an equal mass of fully dense quartz particles. You'd probably have to eat a lot of silica gel to really feel the effects, but there are other more accessible and serious health concerns that are driven by nanometer or smaller physical effects. The reaction between diet coke and mentos is primarily physical, driven by nanometer-scale surface roughness on the candy. Proteins sometimes fold in abnormal shapes, and in the right circumstances, the presence of a chemically identical but differently-shaped protein can induce other proteins to change shape as well, leading to prion diseases such as Mad Cow and CJD, both of which can be acquired via ingestion of the trigger protein shapes. The claim that nanometer-sized structural changes in a compound can have no effect on human health when ingested is demonstrably false. Obviously, this calls directly into question the dependent claim that chemically inert compounds can have no possible impact on human health when ingested. |
Quartz is not amorphous silica, and unlike amorphous silica, it's carcinogenic if you inhale it.
You don't get nanometer-sized structural changes in teflon by scraping it off your skillet with a spatula. You're being ridiculous.
I'm interested to hear what response you get from biologists when you propose to them that natural selection might be inoperative in the split-leaf philodendron. I imagine they'll wish they had a PTFE cord handy.