Environmental toxicology examines the fate and effects of contaminants in the environment. Exposures to heavy metals can affect human health both directly or indirectly by disrupting ecological systems that exist in rivers, lake, oceans, streams, wetlands, estuaries and other ecosystems. It is known that cadmium input to the aquatic environment through discharge of industrial waste, surface run off and deposition of cadmium also strongly absorbed onto sediments and soils. On the other hand, non-ferrous metal mines and human activities such as using phosphate fertilisers, burning coal, iron alloys, steel and cement and disposing household waste, represent a major source of cadmium release to the aquatic ecosystems. Cadmium can easily entered into the body by food chain, drinking water, smoking a cigarette or even breathing the air. Acute and chronic exposure to cadmium in both human and animals results in health diseases. Cadmium was classified as a potential human carcinogen under the EPA (1996) cancer guidelines. The aim of this study was to review the effect of cadmium on human health and ecosystem. In this study, the effects of cadmium on vacating, digestion, and digestive system was reported. It was observed that cadmium has caused kidney disease, severely irritated the stomach, vomiting and diarrhea, sometimes even sudden deaths.