The Maya used so much red paint that they accidentally poisoned their lakes and waterways with mercury, a new study finds.
The problem was cinnabar, a vivid-red mercury-sulfide mineral that can be used as the pigment vermilion in red paint. The run-off from the paint can enter waterways, where anaerobic bacteria then transform cinnabar into highly toxic methylmercury in the sediments of lakes. Over time, the methylmercury accumulates to higher levels in the food chain.