食物 安全焦點

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Incident in FocusEndosulfan Detected in EelsExported to Japan from MainlandChina

Food Safety PlatformHazard and Risk in Food Safety(Part II)

Food Incident Highlight Danger of Eating Raw orUndercooked Freshwater Animals

What Constitutes anIncident/Food Safety Case?

Summary of RiskCommunication Work

Editor-in-chief

Dr. Y Y HOConsultant (Community Medicine)(Risk Assessment and Communication)

Executive EditorDr. Samuel YEUNGPrincipal Medical Officer(Risk Assessment and Communication)

Editing Member

Dr. Tina MOKPrincipal Medical Officer (Risk Management)

Dr. Y H CHONGHead (Risk Communication Section)

Dr. Shirley CHUKSenior Veterinary Officer(Veterinary Public Health)

Dr. Scott CRERARFood Safety Officer (Risk Management)

Mr. W C LEESenior Superintendent(Food Surveillance & Certification)

Dr. K S LEUNGSenior Chemist (Food Chemistry)

Dr. Anna WONGHead (Risk Assessment Section)

Reported by Mr. Arthur YAU, Scientific Officer, Risk Communication Section, Centre for Food Safety

Summary of IncidentOn 23 August 2006, the media reported that

the Ministry of Health, Labour and Welfare ofJapan had found that live eels imported fromGuangdong Province and Shanghai, Chinacontained the pesticide endosulfan at levelsexceeding their requirement. In response to theCentre for Food Safety's (CFS) enquiry, theGuangdong Inspection and Quarantine Bureau(GDCIQ) confirmed that the concerned farms did notexport eels to Hong Kong. Following the report,samples of live eels and eel products were collectedby the CFS. They showed satisfactory results ofendosulfan. There was no cause for alarm.

What is Endosulfan?Endosulfan is a pesticide used in many

coun t r ie s wor ldwide . The pes t i c ide i sregistered and permitted to be used in HongKong. It is mainly used to control insects inf ru i t s and vege tab les and the regu la to r ystandards in the form of maximum residue limitsare set for its use in certain food commoditiesby the Codex A l imen ta r iu s Commiss ion(Codex)1 (Table 1). Endosulfan is normally notused in fish farming as some fish species arevery sensitive to the effect of endosulfan and noin te rna t iona l s tandard has been se t fo rendosulfan residue in fish. Table 1: Codex maximum residue limits for endosulfan inselected food commodities

Commodity Maximum Residue Limits (ppm)

Carrot 0.2

Cucumber 0.5

Lettuce, 1

Spinach 2

Meat (from mammals other 0.1than marine mammals) (applies to fat)

Oranges, Sweet, Sour 0.5

Grapes 1

Pineapple 2

Source: Codex

What about Organochlorine (OC)Pesticides?

Endosulfan is a type of organochlorinepesticide. OC pesticides contain chlorine in

Endosulfan Detected in Eels Exported to Japan from

Mainland China

Incident in Focus

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1Codex is an international body under the World Health Organization (WHO) and Food andAgriculture Organization (FAO) of the United Nations for setting food safety standards. Thewebsite contains documents with detailed description of what Codex is.

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their chemical structure and tend to be persistent in theenvironment. Because of this property, low levels ofsome of these chemicals in foods might be present as aresult of environmental contamination. Some, but notal l , OC pest ic ides, such as DDT, chlordane andhexachlorobenzene, are of particular concern due tothe i r pe r s i s t ence and ub iqu i tous na tu re in theenvironment and their tendency to bioaccumulate inanimals. They are classified as persistent organicpollutants (POPs).

Health EffectSymptoms o f acute poisoning caused by

endosulfan include hyperactivity and muscle spasm,while chronic toxicity may cause kidney damage.However, endosulfan is not known to be carcinogenic.

Risk assessment using internationally acceptedmethodology, the highest level of endosulfan detectedin eels in Japan and the consumption pattern of localsecondary school students (as col lect ion of adultconsumpt ion da ta i s under way) showed tha tconsumption of the eel concerned would contribute lessthan 1% of the safety reference value (in terms ofacceptable daily intake2 (ADI) for chronic toxicity) setfor endosulfan by international authority. (You mayread more about hazard and risk in food safety in the“Food Safety Platform” column.) The percent contri-bution to acute reference dose3 (ARfD) is similar whenacute toxic effects are concerned.

Table 2: Estimation of percentage contribution of endosulfan to ADIand ARfD from eels at the level detected in Japan

Acute Toxicity (% ARfD)

Consumption of 70g of grilled eel a day 0.6%

Chronic Toxicity (% ADI)

Secondary school students

Average consumption level 0.1%

High consumption level 0.5%

Follow-up ActionsAs a result of the incident, the CFS immediately

con tac ted the GDCIQ in Main land China. TheMainland authority confirmed that the concerned fishfarms were not supplying live eels to Hong Kong. Tofurther assess the situation, the CFS collected samplesof eels and eel products for examination of endosulfan.Among the six eel samples tested, no endosulfan wasdetected in four of them and only small amounts (about0 .02 ppm) o f endosu l fan were de tec ted in theremainder. There is no cause for alarm.

Table 3: Number of meat and vegetable samples analyzed for OCpesticides in Hong Kong, 2005.

Pesticides Number of Number of Number of Meat Vegetable Unsatisfactory

Samples Samples ResultsOC pesticides,

including 30 47 0endosulfan

Advice to the PublicImporters of live eels from Mainland China should only

source eels from farms registered for export to Hong Kongand each consignment should be accompanied with ahealth certificate. Retailers and consumers are advised topurchase aquatic products from reliable and reputablesuppliers. Consumers are advised to maintain a balanceddiet in order to avoid excessive intake of chemicals from asmall range of food items.

Further InformationFor readers who are interested to understand more

about the incident, please visit the following relatedweb pages for further information:

Risk in Brief on "Pesticide Residues in Food"; and FAQ for pesticide residues in food.

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2 The ADI of a chemical is the estimate of the amount of a substance in food or drinking-water,expressed on a body-weight basis, that can be ingested daily over a lifetime without appreciablehealth risk to the consumer on the basis of all the known facts at the time of the evaluation.

3 The ARfD of a chemical is an estimate of the amount of a substance in food and/or drinking water,normally expressed on a body weight basis, that can be ingested in a period of 24 hours or lesswithout appreciable health risk to the consumer on the basis of all known facts at the time of theevaluation

Hazard and Risk in Food Safety (Part II)

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Food SafetyPlatform

Reported by Dr. Anna TANG, Research Officer, Risk Assessment Section, Centre for Food Safety

IntroductionAs mentioned in Part I, hazards and risks are part

of everyday life. For food, we are constantly exposedto various materials, natural or synthetic, that arepotentially hazardous to us which may be presentun in ten t iona l l y due to con tamina t ion o r addedintentionally for reasons like improving texture andtaste. With advances in modern technology, we areable to detect these materials at a lower and lowerlevel. While achieving zero tolerance for all foodhazards is not realistic, our exposure to these hazardswill determine if our health is at risk.

The Effect of DoseToo much of a good thing may be bad. A little of a

bad thing may not be as bad as we may think. Dose,i.e. amount of substance we are exposed to and theduration of exposure determines whether something isa poison. Taking oxygen as an example, it is a goodthing because we all need it for survival. However,oxygen concentration above 60 % may cause irritationto lungs and affect respiration. High oxygen concen-tration over a prolonged period can lead to oxygenpoisoning, causing convulsions and unconsciousness.Similarly, vitamins, which are essential to our life, canbe considered as poisons when they are taken inexcess because harmful effects to our bodies mayoccur.

Safety Reference ValuesIn food safety control, safety reference values are

established as guidelines for a safe level of intake.They represent the amounts of a substance that can beingested by a person over a period of time withoutappreciable health risk. When considering acute orimmediate effects, an “acute reference dose” is used asa reference for the safe ingestion of a substance over ashort period of time (e.g. 1 day). When consideringchron ic o r long te rm e f fec t s , va lues such as“acceptable daily intake” (ADI) for food additives and“tolerable daily/weekly/monthly intake” for foodcontaminants over a lifetime period are usually takenas reference. Since these chronic reference values aredetermined based on lifetime intake, an occasionalexposure above these values would not cause harm tohealth provided that the level is not high enough tocause immediate effects and its intake is not over in thelong term.

Safety reference values generally used are thoseestablished by the Joint FAO/WHO Expert Committeeon Food Additives (JECFA) and the Joint FAO/WHOMeeting on Pesticide Residues (JMPR). These organi-zations establish safety reference values for foodaddi t i ves and con taminan t s fo l lowing sa fe tyassessments that take into account results of animalstudies and human data. An ample margin of safety isgiven to protect public health. Substances evaluatedby the JECFA and the JMPR undergo a periodic reviewprocedure to ensure that new scient i f ic data areconsidered whenever available.

Mercury as an ExampleMercury is a heavy metal that may cause adverse

health effects particularly to the nervous system ofdeveloping foetuses and children and the kidney.Dietary food items are the major source of mercury.

The risk associated with ingestion of mercury infood by Hong Kong secondary school students can be

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Figure 1. Assessment on the Health Effects of Mercury in Food

Level of Mercury ina Food

Amount of that FoodConsumed

Exposure PTWI

Figure 2. Dietary Exposure to Mercuryamong Secondary School StudentsRepresented as a Percentage of PTWIBased on Results of Risk Assessment on“Dietary Exposure to Mercury inSecondary School Students” conductedby the Food and Environmental HygieneDepartment

%PT

WI

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estimated by comparing the intake of mercury (i.e. theexposure ) in th i s g roup o f popu la t ion wi th theappropriate safety reference value (in this caseprovisional tolerable weekly intake (PTWI) established byJECFA) (Figure 1). In general, the risk of an adversehea l th e f fec t due to inges t ion o f a subs tance i sconsidered as acceptable when the dietary intake islower than the safety reference value.

Accord ing to the foodconsumption pat tern of HongKong secondary school studentsand the levels of mercury in foodde te rmined by labora to r yanalysis, the estimated dietaryintakes of mercury for averageconsumers and high consumersamong secondar y schoo lstudents were all below the PTWI(Figure 2). The risk of adverseheal th e f fec t s due to d ie tar yintake of mercury is thereforelow for th is group wi th in thepopulation.

Danger of Eating Raw or Undercooked FreshwaterAnimals

Adverse health effects due to consumption of raw or undercookedfreshwater animals are reported from time to time. Since June of this year,

over a hundred people have been infected with parasites in Beijing aftereating raw snails. Investigation found that the snails were infested with aparasite known as Angiostrongylus cantonensis. In Guangzhou, casesof Clonorchis sinesis parasitic infection were also reported due to theconsumption of raw freshwater fish.

Angiostrongylus cantonensis may invade the central nervoussystem and lead to meningitis. Clonorchis sinesis, which stays andirritates the bile duct, is a risk factor for cancer of bile duct.

To avoid being infected with parasites and other pathogenicmicroorganisms, consumers should not eat raw freshwater

animals such as fish, shrimp, snail, crab and frog and shouldcook these food items thoroughly before consumption. Consumers

should also note that wine, vinegar, wasabi, mustard and spices cannotdestroy the parasites. In Hong Kong, it is against the law to sell Chinese

dishes Yu Sang (i.e. freshwater fish intended for raw consumption).

What Constitutes an Incident/FoodSafety Case?

The table “Summary of RiskCommunication Work” aims to reflect the workof the CFS in a number of important areas.One of the areas, namely “Incidents/FoodSafety Cases” refers to the number of incidentsor events with potential food safety implications,and were actively evaluated and handled bythe CFS in the past month. They include reportson food safety issues by food authorities andmedia agencies outside Hong Kong but mayhave local implications, as well as local foodsafety issues with wide media coverage andsignificant public concern. The CFS monitorsthe reports from a wide range of sources,assesses their local significance and takesfollow up actions to address any food safety riskand concern that may be identified.

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