Almost each heavy metal is serious toxicants as carcinogens. Heavy metals are kept under environmental pollutant category due to their toxic effects in plants, human and food. These are heavy metals persistence, accumulate and not metabolized in other intermediate compounds and do not easily breakdown in environment. Heavy metals are naturally occurring elements, and are present in varying concentrations in all ecosystems. Some of the heavy metals i.e. Arsenic (As), Cadmium (Cd), Lead (Pb), Mercury (Hg) are accumulative poison. Arsenic (As), cadmium (Cd), chromium (Cr), and nickel (Ni) are category 1 heavy metals according to the International agency for Research on Cancer. There is the large of number of heavy metals. Total metals have caused major human health problems in various parts of the world. The term “heavy metal” is connected in many people’s minds to metals that are toxic. There is a relationship between the chronic diseases and geologic environment. Geochemical environment is indeed a significant factor in the serious health problems. These metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the WHO. This reviews paper definite heavy metals and their toxicity and effects on human health.