After the Chinese New Year, some citizens love to preserve fruits of ornamental citrus plants in salt, turning them into “salted citrus fruits / kumquats”. However, it is recently rumoured that Chinese New Year (CNY) citrus plant would contain excessive pesticide residues at levels exceeding the legal limit by 100 times. Peoples are therefore warned not to use those fruits to prepare kumquats for consumption.
Is it true? First, we must realize that the rumour comes from WhatsApp and is open to doubt. For example, there is no evidence available to show the excessive levels of pesticide residues in CNY citrus plants; source of the rumour is unknown; and the names of problematic pesticides involved are not mentioned.
Pesticide Use in Chinese New Year Citrus Plants
Although there is doubt about the reported pesticide residue level, it is strongly believed that Mainland farmers will apply pesticides to CNY citrus plants.
Major Species of Chinese New Year Citrus Plant Found in Guangdong
Chemicals including pesticides are used to control pests (e.g. spider mites) and treat plant diseases (e.g. bacterial infections), as well as to maintain the beauty of potted citrus plants. For example, it is reported that farmers in Shunde (a key area of CNY citrus plant production in Mainland) will use pesticide “Propargite” to destroy spider mites.
Other Pesticides Possibly Used in CNY Citrus Plants
No Pesticide Residue Limit Set for Fruits of CNY Citrus Plants?
According to Pesticide Residues in Food Regulation (Cap. 132CM), Hong Kong already sets tolerance levels for many pesticide residues possibly present in food. For example, maximum residue limit (MRL) of Propargite in Kumquat is 5 mg/kg. However, the food standard only applies to Kumquat intended for human consumption i.e. food, but not Kumquat for ornamental purpose.
Indeed, overseas countries also unlikely establish MRL / extraneous MRL (EMRL) for ornamental plant fruits.
Any Regulation of CNY Citrus Plant-derived Food?
1) For Sale
If anyone prepares salted fruits from CNY citrus plants and the fruits are sold out as “food”, then the fruits are subject to the food regulation - Cap 132 Public Health and Municipal Services Ordinance i.e. meeting the food safety requirements (e.g. tolerance limits of pesticides and heavy metals) and of course, must be fit for human consumption.
Since the production of ornamental citrus plant seldom takes into account of food safety criteria, and there is lack of data showing the types of pesticides and their levels present in ornamental citrus fruits，we cannot rule out the possibility that those fruits may contain prohibited pesticides (e.g. Methamidophos & Omethoate) which are highly toxic, mutagenic and carcinogenic, and heavy metals (e.g. Cadmium) as well.
In this connection, I think CNY citrus fruit is neither an ideal raw material fit for food production nor good for direct consumption.
If food trade really need to use CNY citrus fruits for food production, then every batch of the fruits must be tested. Only fruits free of harmful substances can be used for subsequent food processing and/or sold out. This is in line with the food safety assurance and risk assessment practices for all raw materials.
2) For Personal Consumption
If salted fruits from CNY citrus plants are prepared for personal consumption only, then the fruits are not regarded as a commercial food subject to the regulation of Cap 132. However, for the sake of your own health, I do recommend not to use / eat those fruits because the CNY citrus plant is not intentionally farmed for food production.
Regarding the acute or chronic toxicity of pesticides after ingestion, it depends on several factors. For example, properties of individual pesticides, amount and duration of consumption，as well as safety reference values (e.g. acceptable daily intake) set for individual pesticides.