The ancient Romans knew all about lead, a byproduct of silver mining. They knew the chemistry needed to get metallic lead, a soft and easily melted metal that could be worked into sheets and pipes. Their name for lead was plumbum, from which the word plumber and the chemical symbol Pb are derived. Lead pipe usage increased as civilization developed over the next two millennia, and well into the 20th century—look up Joseph Bramah, an Englishman who invented the hydraulic press to make lead pipe in 1797. As late as 1946, lead pipe was important enough for a patent to be granted (US 2,409,540) for adding approximately 1% of silver to make it stronger.
The Romans also knew that lead wasn't good for you, and scholars have speculated that so many Romans suffered from lead poisoning that they couldn't offer enough resistance to stop the barbarian invasions (the Goth sieges of Rome in 408 and 537 AD, for example). I've got a simpler explanation, untested by scholarship but interesting nevertheless.
Lead was used in cooking vessels to concentrate grape juice, as sheets to line water channels and as pipe to bring water into homes. Not everyone could afford such luxuries, so only the rich and powerful could have the running water that is taken for granted these days (even in California). While the rich and powerful men who lived in such homes were out in the city exercising their power, their children back home were drinking water that had passed through, and maybe even languished for a while, in extruded lead pipes.
It is known that lead promotes intellectual disabilities, so we can expect that these children were mentally deficient compared with their parents. But in a society where children inherit their parents' power, that meant that each generation of leaders was more mentally underdeveloped than the previous one. Eventually, Rome had a subnormal ruling class, incapable of implementing the high-powered military strategy that got them their empire in the first place, and certainly incapable of defending it. Ergo, the fall of the empire.
For a quite thorough study of the other views (the scholarly ones), I direct you here.
In the meantime, we can look at our extruders as historically significant, as we speak the modern version of Gothic (English) instead of Latin!
Allan Griff is a veteran extrusion engineer. He started out in tech service for a major resin supplier, and has been working on his own now for many years as a consultant, expert witness in law cases, and especially as an educator via webinars and seminars, both public and in-house. Griff wrote the first practical extrusion book in the 1960s, as well as the Plastics Extrusion Operating Manual, which has been updated almost every year and is available in Spanish and French as well as English. You can find out more on his website, www.griffex.com, or via email at [email protected].