Pesticide Residues in Food
1. Which of the Government Department is responsible for the control of food safety, including the control of pesticide residues in food in Hong Kong?
In Hong Kong, the Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department is responsible for the overall safety of food. The Administration has made the Pesticide Residues in Food Regulation (Cap. 132CM) (“the Regulation”). The Legislative Council has completed its scrutiny of the Regulation in June 2012 and the Regulation came into operation on 1 August 2014.
2. What is pesticide?
In broad sense, pesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating pests. Classes of pesticides commonly used in crops growing include insecticides (to control insect infestations), fungicides (to control the spread of fungal diseases) and herbicides (to control the competing effects of weeds). The term includes substances intended for use as a plant growth regulator, defoliant, desiccant, fruit thinning agent, or sprouting inhibitor and substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport.
3. Why would pesticide residues appear in food?
Pesticide residues may be present in food because of the following reasons:
direct use of pesticides on food crops;
animal feeding on pesticide-treated feed; or
Common use of pesticides in modern farming might leave some residues on food crops.
4. Why would food contain excessive pesticide residues?
Excessive pesticide residues in food may arise from the trade not observing good agricultural practice, e.g. the use of excessive pesticide and not allowing sufficient time for pesticide to decompose before harvesting.
5. Should I take less vegetables as they may contain pesticide residues?
The use of pesticide might leave some residues on food crops. However, if pesticide is used in accordance with good agricultural practice, the residual level would be low and consumption of these vegetables will not affect health. Furthermore, vegetables are an essential component of a healthy diet. You are advised to take a balanced diet and eat a variety of fruits and vegetables so as to avoid excessive exposure to pesticide residues from a small range of food items.
6. Would my health be affected if I consume food containing excessive pesticide residues?
The adverse effects of pesticide residues depend on the nature of the pesticide, as well as the amount and duration of exposure. Eating food with excessive pesticide residues may cause acute and/or chronic adverse health effects. Symptoms of acute poisoning include vomiting, diarrhoea, abdominal pain, dizziness and numbness. In severe cases, people may even have difficulties in breathing, blurred vision and convulsion. Prolonged excessive intakes of pesticide residues have been shown to cause damage to the nervous system or other organs such as liver and kidneys, as well as affect foetal development in animals.
7. Have international authorities assessed the safety of pesticides and established safety standards?
The Joint Food and Agriculture Organization (FAO) / World Health Organization (WHO) Meeting on Pesticide Residues (JMPR) is responsible for evaluating the safety of pesticides and estimating safety reference values (i.e. Acceptable Daily Intake (ADI)) for individual pesticide.
8. Would my health be affected if the level of pesticide residue intake in a meal exceeds the ADI?
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. Occasional dietary intake above the ADI does not automatically mean that health is at risk, as ADI is developed based on one’s lifetime exposure.
9. Are there any international standards on pesticide residues in food?
In order to protect the health of the consumer while facilitating international trade, the Codex Alimentarius Commission (Codex) has established Maximum Residue Limits (MRLs) for individual pesticide in selected food commodities. MRL is the maximum concentration of a pesticide residue to be legally permitted in a food commodity. The primary objective of setting MRLs is to encourage the trade to observe Good Agricultural Practice (GAP) to ensure that only the minimum amount of pesticide is applied to food for achieving pest control need, thereby protecting the health of consumer.
Codex MRLs are established on the basis of appropriate residue data obtained mainly from supervised field trials. Supervised trials are scientific studies in which pesticides are applied to crops or animals in the way which is intended to reflect commercial practice according to GAP. GAP is a set of nationally authorised conditions to use the pesticide safely (e.g. in relation to public health and environmental safety concerns) for effective and reliable pest control.
10. Does eating food with pesticide residues exceeding MRLs constitute an immediate health risk?
Eating food with pesticide residue exceeding MRL does not automatically imply a hazard to health provided the dietary exposure to that particular pesticide falls within the safety reference value. A distinction needs to be made here between MRLs and safety reference values, i.e., ADI for chronic toxicity or Acute Reference Dose (ARfD) for acute toxicity. Even though the primary purpose of setting MRLs in food is to protect the health of consumers and the levels are intended to be toxicologically acceptable (i.e., unlikely to cause acute or chronic toxicities in humans), the MRL is not an equivalent of and should not be taken as a safety reference value per se.
11. Media sometime reported that some vegetable samples were found to contain prohibited pesticides. Does it mean that there is a problem in the control of pesticide use?
For some pesticides that have been banned or are no longer in use (e.g. DDT, lindane), trace amount of their residues and metabolites may be present in food as environmental contaminants because of their persistence in nature. As such, if the level of these pesticides detected is not high, it does not necessarily reflect that they are still being used in agriculture. Cap.132CM stipulated "extraneous maximum residue limits" (EMRLs) for some of these persistent pesticides.
12. How does CFS monitor and control the level of pesticide residues in vegetables on sale in Hong Kong ?
CFS operates a Food Surveillance Programme and regularly takes food samples including fruits, vegetables and cereals at import, wholesale and retail levels for testing. Most of the vegetables on sale in Hong Kong come from the Mainland. CFS has a Food Control Office at Man Kam To and examines vegetable consignments imported from the Mainland. Under the current administrative arrangement, only vegetables from farms and processing establishments registered with the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) of the People’s Republic of China will be allowed for export to Hong Kong. When the vegetable vehicles reach Man Kam To Food Control Office, CFS will check the seal, examine the vegetables and verify the export document of each vegetable consignment and, if necessary, take samples of vegetables for testing of pesticide residues. In addition, CFS would also collect vegetable samples at the wholesale and retail levels for testing of pesticide residues.
13. What will CFS do if they find that the vegetable consignment does not tally with its accompanying export document?
If CFS finds any vegetable consignment does not tally with its accompanying export document, the consignment of vegetables will be detained for detailed inspection and relevant Mainland authorities will be notified for follow-up actions. If any vegetable sample is tested to be unsatisfactory, CFS will destroy the vegetable consignment concerned and inform the relevant Mainland authorities of the analysis result. CFS will also record the information of the vegetable processing establishment concerned as well as vegetable vehicle involved for detention and sampling of the subsequent vegetable consignment to Hong Kong. The consignment will only be released upon receipt of satisfactory testing result.
14. Does CFS monitor and control the level of pesticide residues in fruits on sale in Hong Kong ?
CFS operates the same Food Surveillance Programme to take samples of fruits at import, wholesale and retail levels. The samples will be tested for pesticide residues. This ensures that fruits on sale in the markets are safe and fit for human consumption.
15. Why are there differences between the Government and other parties on the testing results of pesticide residues in food?
CFS follows the testing methods of pesticide residues recommended by Codex, e.g. conducting the test on the whole leafy vegetables after the removal of obviously decomposed or withered leaves. If only part of the vegetables such as leaves or outer skin of fruiting vegetables such as tomatoes are tested, the result may be different and cannot be compared with the
16. How can I reduce pesticide residues in vegetables?
You can wash vegetables and produces thoroughly under clean running water. When appropriate, scrub produces with hard surfaces with a clean produce brush to remove dirt and contaminants like pesticides from the surface and crevices.
17. Is washing vegetables under running water or soaking in water a better method to remove pesticide residues in vegetables?
Washing vegetables and produces thoroughly under clean running water is effective in reducing surface contaminants, including pesticide residues. Although soaking can also reduce pesticide residues in some studies, it will also cause loss of nutrients. As of the first quarter of 2017, CFS no longer recommend soaking vegetables in view of the low level of pesticide residues detected and no food poisoning incidents related to pesticide residues were reported in recent years. This position has been endorsed by the Expert Committee on Food Safety .
18. Will soaking or washing vegetables with water result in nutrient leaching?
Nutrients, especially water soluble vitamins, will leach out into water if vegetables are being soaked.
19. How should I handle fruits to reduce the intake of pesticide residues?
You can wash fruits thoroughly under clean running water. When appropriate, scrub produces with hard surfaces (e.g. melons) with a clean produce brush to remove dirt and contaminants like pesticide residues from the surface and crevices.
20. Is the use of detergent specialised for cleaning fruits and vegetables recommended?
Use of soaps, special detergents or produce washes is not recommended for cleaning produces.