Will consumption of dioxin-contaminated hairy crabs result in immediate health hazards?

       The European Union has established maximum limits for dioxins in food as 3.5 pg/g (wet weight) and that for the total level of dioxins and dioxin-like PCBs as 6.5 pg/g (wet weight). In the two collected samples of hairy crabs in Hong Kong, dioxins and dioxin-like PCBs were detected at levels of 11.7 pg/g and 40.3 pg/g toxic equivalents (TEQ) respectively. Concerned authorities have taken necessary measures since the levels of pollutants have exceeded the established limits.

       However, it does not mean that consumption of these hairy crabs would result in immediate health hazards. The respective food safety risks are determined by the quantity of pollutants in them. Despite the fact that dioxins were detected in hairy crabs in this inspection, it is unlikely to present a risk of acute poisoning at usual dietary consumption levels. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has established a provisional tolerable monthly intake (PTMI) for pollutants (like dioxins), which is 70 pg/kg of body weight/month TEQ. This safety reference value implies that occasional intake of pollutants (dioxins) exceeding the prescribed level has no adverse health impacts. It will lead to health risks only if the intake exceeds the prescribed level monthly and throughout a lifetime.

       Eating problematic hairy crabs on a long-term basis may pose considerable health risks. But after all, it is seasonal food that is only available during these few months yearly. For the vast majority of people, it is not possible to eat such a huge quantity of hairy crabs every month throughout a lifetime. Therefore, we should not worry too much about it.

(Note: Picogram is a very tiny unit of mass. One picogram is equivalent to a trillionth of a gram (i.e. 0.000000000001g).

How to reduce intake of dioxins?

       Food intake is the main source of exposure to dioxins which accumulate in fatty tissues of food. For consumers who wish to reduce health risks induced by dietary intake of dioxins, they should consume less animal fats and oils. Moreover, it is essential to maintain a balanced diet and avoid excessive intake of dioxins due to picky consumption of certain high-fat food.