Fish and seafood are widely available foods that provide important nutrients to consumers. Research conducted over the past few years suggests that there are health benefits associated with fish and seafood consumption, including for the cardiovascular and visual systems. It was also reported that such a diet increases protection in infants against arthritis or cancer. Although regular seafood consumption has been linked to health benefits for the general population, contaminants that may be present in seafood could pose a risk to humans. There are a number of contaminants that may be associated with seafood, including chemicals, metals, toxins and other substances as well as potentially harmful microbes. Most seafood contains detectable levels of contaminants because these are a part of the environment and food chain. This book discusses shellfish in more detail, including the purification process of bivalve shellfish; shellfish toxins; phycotoxins and heavy metals in shellfish; and shellfish sensitivity.