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Food Safety Focus (2nd Issue, September 2006) – Incident in Focus

Endosulfan Detected in Eels Exported to Japan from Mainland China

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

Summary of Incident

On 23 August 2006, the media reported that the Ministry of Health, Labour and Welfare of Japan had found that live eels imported from Guangdong Province and Shanghai, China contained the pesticide endosulfan at levels exceeding their requirement. In response to the Centre for Food Safety's (CFS) enquiry, the Guangdong Inspection and Quarantine Bureau (GDCIQ) confirmed that the concerned farms did not export eels to Hong Kong. Following the report, samples of live eels and eel products were collected by the CFS. They showed satisfactory results of endosulfan. There was no cause for alarm.

Illustration: Eel

What is Endosulfan?

Endosulfan is a pesticide used in many countries worldwide. The pesticide is registered and permitted to be used in Hong Kong. It is mainly used to control insects in fruits and vegetables and the regulatory standards in the form of maximum residue limits are set for its use in certain food commodities by the Codex Alimentarius Commission (Codex)1 (Table 1). Endosulfan is normally not used in fish farming as some fish species are very sensitive to the effect of endosulfan and no international standard has been set for endosulfan residue in fish.

Table 1: Codex maximum residue limits for endosulfan in selected food commodities

Maximum Residue Limits (ppm)
Meat (from mammals other than marine mammals)
0.1 (applies to fat)
Oranges, Sweet, Sour

Source: Codex

What about Organochlorine (OC) Pesticides?

Endosulfan is a type of organochlorine pesticide. OC pesticides contain chlorine in their chemical structure and tend to be persistent in the environment. Because of this property, low levels of some of these chemicals in foods might be present as a result of environmental contamination. Some, but not all, OC pesticides, such as DDT, chlordane and hexachlorobenzene, are of particular concern due to their persistence and ubiquitous nature in the environment and their tendency to bioaccumulate in animals. They are classified as persistent organic pollutants (POPs).

Health Effect

Symptoms of 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 accepted methodology, the highest level of endosulfan detected in eels in Japan and the consumption pattern of local secondary school students (as collection of adult consumption data is underway) showed that consumption of the eel concerned would contribute less than 1% of the safety reference value (in terms of acceptable daily intake2 (ADI) for chronic toxicity) set for endosulfan by international authority. (You may read more about hazard and risk in food safety in the “Food Safety Platform” column.) The percent contribution to acute reference dose3 (ARfD) is similar when acute toxic effects are concerned.

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

Acute Toxicity (% ARfD)
    Consumption of 70g of grilled eel a day
Chronic Toxicity (% ADI)
Secondary school students
    Average consumption level
    High consumption level

Follow-up Actions

As a result of the incident, the CFS immediately contacted the GDCIQ in Mainland China. The Mainland authority confirmed that the concerned fish farms were not supplying live eels to Hong Kong. To further assess the situation, the CFS collected samples of eels and eel products for examination of endosulfan. Among the six eel samples tested, no endosulfan was detected in four of them and only small amounts (about 0.02 ppm) of endosulfan were detected in the remainder. There is no cause for alarm.

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

Number of Meat Samples
Number of Vegetable Samples
Number of Unsatisfactory Results
OC pesticides, including endosulfan

Advice to the Public

Importers of live eels from Mainland China should only source eels from farms registered for export to Hong Kong and each consignment should be accompanied with a health certificate. Retailers and consumers are advised to purchase aquatic products from reliable and reputable suppliers. Consumers are advised to maintain a balanced diet in order to avoid excessive intake of chemicals from a small range of food items.

Further Information

For readers who are interested to understand more about the incident, please visit the following related web pages for further information:

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

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 appreciable health 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 less without appreciable health risk to the consumer on the basis of all known facts at the time of the evaluation


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