A spokesman for the Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department said today (November 16) that the CFS has stepped up surveillance on hairy crabs and found that the total level of dioxins and dioxin-like polychlorinated biphenyls (PCBs) in one sample taken at the retail level on November 3 exceeded the action level adopted by the CFS and hence failed the test. The CFS is following up on the incident.
The spokesman said, "The CFS has taken six hairy crab samples for testing, of which three were taken at the import level and another three at the retail level. The results showed that among the six samples, the total level of dioxins and dioxins-like PCBs in one sample exceeded the action level adopted by the CFS (i.e. 6.5 picograms (pg) toxic equivalent per gram (6.5 parts per trillion) of the food sample (wet weight)) and failed the test. The remaining five samples passed the test."
The unsatisfactory sample was taken from a retailer, Shing Lung Hong Co. The CFS, when taking the sample, was told by the retailer that the concerned sample originated from a Mainland aquaculture farm. However, initial investigation by the CFS found that the concerned sample, when comparing against one of the two samples taken from the two aquaculture farms in Taihu where the import of hairy crabs to Hong Kong was suspended earlier, the proportions of the individual dioxins level of these two hairy crab samples were highly similar. Furthermore, among the six samples being tested, two of them also originated from the aquaculture farm claimed by the retailer. However, when making comparison, the proportions of the individual dioxins level of the concerned unsatisfactory sample is highly unmatched with that of the two samples which were found to be satisfactory.
The CFS has reasonable doubts that the unsatisfactory sample did not originate from the aquaculture farm claimed by the retailer. The CFS immediately launched an investigation including following up the matter with the retailer and took appropriate action.
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, substantial data analysis and review of the findings when necessary. Thus, it normally takes about two to four weeks for the analysis of dioxins and dioxin-like PCBs.
In response to the levels of dioxins and dioxin-like PCBs of two hairy crab samples taken at the import level 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 in Jiangsu Province since November 1 to ensure food safety.
According to Section 54 of the Public Health and Municipal Services Ordinance (Cap 132), all food available for sale in Hong Kong, locally produced or imported, should be fit for human consumption. An offender is subject to a maximum fine of $50,000 and imprisonment for six months upon conviction.
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 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 the 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 follow up on the incident and take appropriate action to ensure food safety and safeguard public health. Investigation is ongoing.
Reprinted from HKSAR Government: