Crab Roe and Dioxins

Recently, the media has reported that the US New York State Department of Health has classified crab roe as unsuitable for human consumption. The US New York State Department of Health advise the public not to eat the soft "green stuff" (mustard, tomalley, liver or hepatopancreas) found in the body section of crabs and lobsters from any waters because cadmium, polychlorinated biphenyls (PCBs) and other contaminants concentrate there. As contaminants are transferred to the cooking liquid, the public should also discard crab or lobster cooking liquid.

Dioxins are a group of polychlorinated aromatic compounds arising either naturally or as by-products of industrial activities, e.g. metal smelting, moulding or burning of chlorine-containing organic chemicals such as plastics. Dioxins are fat-soluble and not easily broken down. They tend to accumulate in fatty tissues and along the food chain.

Sources of human exposure to dioxins include food intake, drinking water, air inhalation and skin contact, of which dietary intake is the most important source. Foods high in fat such as meat, poultry, seafood, milk, egg and their products are the major dietary sources of dioxins.

The Centre for Food Safety (CFS) has analysed different kinds of food samples (including crabs) for dioxins under its Total Diet Study and the report was released in 2011. According to the findings of the study, general population in Hong Kong would be unlikely to experience adverse health effects as a result of dioxins absorbed from our daily diet.

In addition, the CFS has analysed a total of 23 aquatic products (including crabs) for dioxins in the past three years and the results were all satisfactory.

As dioxins are mainly found in fat, the risk of dioxin exposure can be reduced by avoiding foods with a relatively high level of fat. The public is advised to maintain a balanced diet so as to avoid excessive exposure to contaminants from a small range of food items.