Heavy metals

Metallic elements with high atomic weights, e.g. mercury, chromium, cadmium, arsenic, and lead.

They can damage living things at low concentrations and tend to accumulate in the food chain.

Source: US EPA Drinking Water Glossary 

Bioaccumulation - Biomagnification - Elemental Arsenic - Elemental mercury - Methylmercury

Deutsch: Schwermetalle
Español: Metal Pesado
Français: Métal lourd
Nederlands: Zware metalen

PCBs

Dioxins

Genetically Modified Crops

Mercury

Water Resources