A spokesman for The Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department said today (November 11) that the CFS has stepped up surveillance on hairy crabs subsequent to finding levels of dioxins and dioxin-like polychlorinated biphenyls (PCBs) of two hairy crab samples exceeding the action level adopted by the CFS. The latest test results on six samples were all satisfactory. The CFS will continue to follow up on the incident and conduct the sampling of hairy crabs for testing to ensure food safety.
The CFS spokesman said, "The test results and assessment showed that the total levels of dioxins and dioxin-like PCBs of the six samples had not exceeded the action level adopted by the CFS (i.e. 6.5 picograms toxic equivalent per gram (6.5 parts per trillion) of the food sample (wet weight)). All the samples passed the test."
In response to the levels of dioxins and dioxin-like PCBs of two hairy crab samples being found exceeding the action level adopted by the CFS earlier, the CFS had suspended the import into and sale within Hong Kong of hairy crabs raised at the two aquaculture farms concerned since November 1 to ensure food safety.
Dioxins and dioxin-like PCBs are a group of chemical compounds which are persistent environmental pollutants and highly toxic. They can cause reproductive and developmental problems, damage the immune system, interfere with hormones and can cause cancer. The International Agency for Research on Cancer has classified dioxins and dioxin-like PCBs as human carcinogens. Dioxins are ubiquitous in the environment, which arise either naturally (e.g. from volcanic eruptions and forest fires), or as by-products of industrial activities. Dioxins and dioxin-like PCBs are fat-soluble and not easily broken down. Hence, they tend to accumulate in fatty tissues and along the food chain.
The spokesman said, "Sources of human exposure to dioxins and dioxin-like PCBs include food intake, drinking water, air inhalation and skin contact. Dietary intake is by far the most important exposure. Fatty foods such as meat, poultry, seafood, milk and their products are the major dietary sources of dioxins and dioxin-like PCBs.
"For aquatic animals, body parts which naturally have a higher content of fat may also contain a higher amount of dioxins and dioxin-like PCBs. For example, fish livers and brown meat (including the gonads, livers and digestive glands) of crabs are known to usually contain higher amount of dioxins and dioxin-like PCBs."
In general, some foods may contain dioxins and dioxin-like PCBs. However, the concentrations will not cause acute adverse effects. As regards chronic health effects, the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives have established a Provisional Tolerable Monthly Intake (PTMI) of 70 pg/kg of body weight per month for dioxins and dioxin-like PCBs. Occasional short-term exposure above the PTMI would have no health consequences provided that the average intake over a long period is not exceeded.
The analysis of dioxins and dioxin-like PCBs involves a very complicated process with a high degree of precision. The process includes extraction, multiple clean-up steps, instrumental analysis and substantial data analysis. Thus, it normally takes about two to four weeks for the analysis of dioxins and dioxin-like PCBs.
The spokesman said that in order to reduce the risk of the dietary exposure to dioxins and dioxin-like PCBs, members of the public are advised to trim fat from meat and consume low fat dairy products. They are also advised to have a balanced and varied diet which includes a wide variety of fruit and vegetables, so as to avoid excessive exposure to dioxins and dioxin-like PCBs from a small range of food items. According to World Health Organization, the above mentioned advice is a long-term strategy to reduce body burdens and is probably most relevant for girls and young women to reduce exposure of the developing fetus and when breastfeeding infants later on in life.
For details, please refer to "The frequently asked questions on hairy crabs with dioxins and dioxin-like PCBs exceeding CFS' action levels" (www.cfs.gov.hk/english/programme/programme_rafs/files/QA_on_dioxin_in_hairy_crabs_e.pdf). The CFS will publish updated or additional dietary guidelines for consumers from time to time.
The CFS will continue to conduct routine food surveillance based on a risk-based principle, taking into account past surveillance results, local and overseas food incidents and relevant risk analyses, etc, to ensure food safety and safeguard public health.
Reprinted from HKSAR Government:
http://www.info.gov.hk/gia/general/201611/11/P2016111100811.htm