At some of those sites a number of M55 rockets, loaded with nerve agent, have been leaking a vapor. There's no conclusive evidence of the cause, but one theory is that the stabilizer in the fuel is deteriorating, which could increase the risk of accidental ignition. The Defense Department lists 200 other sites where chemical weapons or materials may have been disposed of in ways now considered unsafe. World War I. Russia has a declared chemical weapons arsenal of 40,000 metric tons of agent. Our own stockpile is 30,000 tons.
Chemical weapons are a security and environmental nightmare.
My third example operates on a much smaller scale than nuclear or chemical weapons, yet has produced for many countries a monstrous environmental hazard. Antipersonnel landmines used to be laid in fields and mapped. Now they're often scattered at random, perhaps out of an airplane, with no record to guide anyone who might want to return and dig them up. They used to be fairly bulky and made mostly of metal. Now they often approximate a hockey puck made mostly of undetectable plastic.