The ancestors of the Fourth World did not live the way humans live best. They lived in a way that made them sick. Some of this sickness dwelled in their bodies, and some in their spirit. And because it did not occur to them to live a different way, they made medicines to cure themselves of these sicknesses. And because they did not understand their role in an interwoven community of life, their attempts to make themselves well made others sick.
Most of these medicines flowed through their bodies and into the water. The random mix of different medicine for different maladies did strange things to fish and frogs, changing their bodies, making them slower to reproduce — or incapable of doing so.
Though people stopped making the medicines, the medicines remained. Over time, they collected in drainage areas. They remain there to this day, in these “pools of madness.”
We warn our children away from such pools. Those who drink from them may die, or change, or go mad, or become infertile. The effect is always different, and never good.
People today take a large quantity and a wide variety of different drugs, ranging from antibiotics to antidepressants to birth control pills to simple antihistamines. Traces of what we take ends up in the water supply, minimally filtered through our urine. And scientists have known for years that this random cocktail of drugs has negative effects on wildlife, particularly amphibians and fish.
In the Fifth World, the collapse of civilization long ago brought the age of pharmaceuticals to an end. But traces of them remain, 400 years later, in the water table. And by that point, they will have become concentrated in a few low drainage areas where stagnant water tends to pool.
This allows people of the Fifth World to avoid them more easily — but also makes them stronger and more dangerous to anyone who can’t. Already unwise places to obtain drinking water, these “pools of madness” have unpredictable effects on whomever drinks from them. Songs and legends warn people away from such pools, but curiosity and, occasionally, desperation may lead the odd person to have a drink.