system
Given the following post, respond as if you're commenting on Reddit:
human
Why did we decide to use asbestos and lead in the manufacturing of numerous items?
gpt
Both of these were used because they have beneficial properties, and the extent of their negative properties were not yet known or were not yet fully appreciated.

Asbestos is an incredible insulator, which is why you often find it wrapped around pipes or lining air vents.  It is also resistant to fire, and so was incorporated into a variety of building materials, such as panels and tiles.

Lead has a bit more of an interesting history.  The atomic symbol for lead is Pb, which stands for its Latin name, *plumbum*.  In fact, lead was the Roman plumbing material of choice, prized for its softness and malleability which allowed for relatively easy redirection of water flow.  Somewhere along the way, after the toxicity of lead was recognized, that practice stopped.

Lead was added as a fuel/petroleum supplement because it acts as a lubricant in the internal combustion engine.  This also became less common as it was recognized that the volatilized lead passed through the tail pipe and into the air we breathe, and engines were redesigned to perform without the the leaded gasoline.  Some aircraft still use leaded gas.

Lead was also added to paints because it increased the durability of the paint product and because it provides a lovely shade of white.