Molecules in the news...

A couple previous molecules of the day were in the news today: polylactide and lead chromate.

I previously covered the use of polylactide in plastic bottles. I also covered a big downside - it's not the sturdiest stuff. Today, Popular Science has a story about its use in plastic bags, which isn't that bad an idea strength-wise, but it is a bit of a bad idea in the sense that we need to wake up to the fact that we are running up against a wall in our ability to ability to produce enough corn to produce oil, staggering though our ability to produce it is.

Also, lead chromate, which apparently makes its way into artificial turf as a pigment. As was pointed out in the comments, it's not very soluble at all, but bacteria have a knack for concentrating whatever's around. Apparently, it's starting to show up in the soil under some of this artificial turf. Apparently anywhere from 10 to 500mg/kg is normal for urban soil, so I imagine it's in the 100s of mg/kg elevation. Can there possibly be that much pigment in there? Milligram(s) per square centimeter? I'm not following. Comments especially welcome here...

That's the thing about pigments that are exposed to light - it's tricky to make a UV-fast dye! Metals tend to hold up a little better. White (a very hard effect with organic dyes) is usually achieved via titanium dioxide. We used to use another lead pigment to make white, but we found out kids who eat titanium paint chips grow up healthier than those who eat lead paint chips!