According to the World Health Organization, large predatory fish (e.g. shark, swordfish, tuna, pike, etc.) are likely to contain higher levels of mercury (and hence higher levels of methylmercury) as a result of eating a lot of smaller fish that have acquired mercury through ingestion of plankton.

In addition, based on the past results of the routine food surveillance programme of the Centre for Food Safety (CFS), certain samples of the following fish types were found to have lower compliance rates in terms of metallic contaminant(s), i.e. < 95% of samples with metallic contaminant levels equal to or below the maximum levels (MLs) set out in the Amendment Regulation:

• Tuna
• Cod
• (Fillet of) Green wrasse / Blackspot tuskfish
• Sword fish
• Splendid alfonsino

Nevertheless, fish contain many essential nutrients for growth and development such as omega-3 fatty acids and high quality proteins.  The public is therefore advised to maintain a balanced and diverse diet and to consume a variety of fish as part of a healthy diet.  To get the most benefits from eating fish, women of child-bearing age and young children are advised to consume a variety of fish in moderation and avoid overindulgence in only a few species.  Pregnant women, women planning pregnancy and young children should avoid consumption of the large predatory fish.

Based on the past results of the routine food surveillance programme of CFS, certain samples of the following fish types were found generally in compliance with the MLs, i.e. > 95% of samples with metallic contaminant levels equal to or below the MLs set out in the Amendment Regulation:

• Bighead carp
• Catfish

• Freshwater grouper / Mandarin fish

• Grass carp
• Largemouth black bass
• Mud carp
• Bombay-duck
• Brownspotted grouper / Duskytail grouper / Areolate grouper
• Flounder
• Golden threadfin bream
• Goldlined seabream
• Greater amberjack
• Green grouper / Orange-spotted grouper
• Halibut
• Horsehead / Tilefish
• Mackerel / Saba
• Red seabream (except Splendid alfonsino)   
• Red snapper
• Scad
• Yellow croaker
• Yellowtail
• Grey mullet
• Salmon
• Sole / Tonguefish
• Yellowfin seabream
• Leopard coral grouper
• Tiger grouper / Brown-marbled grouper

Would the Government provide a list of conversion factors that has been used for interpreting MLs of metal in food that has gone through a process of drying, dehydrating or concentration?

According to regulation 3(2)(b) of the Amendment Regulation, “the ML of a specified metal in a specified food that has gone through a process of drying, dehydration or concentration is to be proportionally adjusted according to the change in the concentration of the metal in the food caused by the process.”  For the interpretation of the MLs of metal in the food, the conversion factor that accounted for the changes in metal in the food caused by the process can be derived from:

1. laboratory test results of the water content of a food sample before and after drying, dehydration or concentration; and / or
2. generally accepted data (e.g. food composition database) regarding the water content of the processed food and its unprocessed counterparts.

It is important to note that the water content of a food sample before and after drying or dehydration may vary with a number of factors including species, seasons, geographical locations, processing requirements, etc.  Therefore, direct laboratory analysis of the water content of the food sample before and after processing will provide a better estimate of the conversion factor.  If generally accepted data is used to estimate the conversion factor, the trade should ensure that the data sources are accurate and reputable.  Examples of food composition databases from adjacent regions are listed in Annex II of the Guidelines on Food Adulteration (Metallic Contamination) (Amendment) Regulation 2018.

Examples of conversion factors for selected food in dried form are illustrated below:

1. China Food Composition (Book 1, 2nd Edition) (available in Chinese). 
2. ASEAN Food Composition Table.
3. Taiwan Food Nutrients & Composition Database (New Edition) (available in Chinese).
4. Standard Tables of Food Composition in Japan, Seventh Revised Edition.
5. Korean Standard Food Composition Table, The 9th Revision.

In general, CFS' follow-up actions regarding problem foods include, among other things, tracing the source of the concerned consignment from which unsatisfactory samples are found, informing the relevant authorities of the exporting places to take follow-up actions, requesting the importers / distributors to stop selling and surrender the problem foods for disposal where necessary.  If there is sufficient evidence, prosecution would also be instituted.  Also, CFS would consider informing the public via various channels.  The actions to be taken would be considered on a case-by-case basis. 

The MLs of metal in rice laid down in Part 2 of the Schedule have been established for rice in a dried form.  If the “rice vermicelli / rice noodle” is in a dried form and 100% made from rice, the relevant MLs of metal in rice could be applied to “rice vermicelli / rice noodle”. 

What are the MLs of metal in lotus seed, algae, herbs and cinnamon stick?  How about the MLs for novel food ingredients such as peach resin (桃膠)?

One of the key features of the Amendment Regulation is to adopt the Codex MLs unless otherwise specified.  The food descriptions and nomenclatures in the Amendment Regulation also make reference to the Codex food classification and product definitions as appropriate.

According to Codex food classification (CAC/MISC 4-1993, as well as the revised classification on vegetables and cereal grains adopted in 2017), lotus seed, algae, herbs and cinnamon stick are not considered as vegetables or cereal grains.  In other words, the relevant MLs of metal listed in Part 2 of the Schedule do not apply to lotus seed, algae^#, herbs and cinnamon stick.  Peach resin, the natural resin secreted from the peach tree, has also not been listed under the Codex food classification. 

For food / food groups without relevant MLs under the Amendment Regulation, CFS will conduct risk assessment to determine whether the food contains the metal concerned in an amount that is dangerous or prejudicial to health, thereby contravening regulation 3AA of the Amendment Regulation.  Moreover, section 54 of the Public Health and Municipal Services Ordinance (Cap. 132) (“the Ordinance”) stipulates that all food for sale in Hong Kong, locally produced or imported, should be fit for human consumption. 

^# As stipulated in Part 2 of the Schedule to the Amendment Regulation, the ML of inorganic arsenic in seaweed in fresh state is 1 mg/kg.  There is no other ML in the Schedule applicable to seaweed.

What is the definition of “secondary milk products” under the Amendment Regulation?

According to Part 1 of the Schedule to the Amendment Regulation, “secondary milk products” means skimmed milk, partly skimmed milk, evaporated milk and milk powder.

Codex MLs are generally set for primary food commodities.  According to the Codex food classification, condensed milk, cheese and yoghurt are not secondary milk products and they belong to “manufactured milk products”.  The MLs of metal specified for condensed milk, cheese or yoghurts are not available under the Amendment Regulation whereas the MLs of lead and mercury in milk and secondary milk products, as well as the ML of lead in infant formula and follow-up formula are specified.  The trade are advised to take note of the interpretation for milk, secondary milk products, follow-up formula and infant formula as listed in Part 1 of the Schedule; and to ensure that the ingredients (e.g. milk) used for the manufacture of milk products, have complied with the relevant MLs laid down in the Amendment Regulation.

In connection to this case, CFS will conduct risk assessment to determine whether the food concerned, i.e. condensed milk, cheese or yoghurt, contains the metal concerned in an amount that is dangerous or prejudicial to health, thereby contravening regulation 3AA of the Amendment Regulation.  Moreover, section 54 of the Ordinance stipulates that all food for sale in Hong Kong, locally produced or imported, should be fit for human consumption.

Would the ML of lead for “tea, green, black” be applicable to floral tea or tea made with “Luo han guo”?

According to the Codex food classification, “tea, green, black” refers to several cultivars of Camellia sinensis (L.) O Kuntze.  It does not cover floral tea such as rose tea, chamomile tea, chrysanthemum tea, etc., or beverage solely prepared from “Luo han guo”.

For food / food groups without relevant MLs under the Amendment Regulation, i.e. beverage solely prepared from “Luo han guo”, rose tea, chamomile tea and chrysanthemum tea in this case, CFS will conduct risk assessment to determine whether the food contains the metal concerned in an amount that is dangerous or prejudicial to health, thereby contravening regulation 3AA of the Amendment Regulation.  Moreover, section 54 of the Ordinance stipulates that all food for sale in Hong Kong, locally produced or imported, should be fit for human consumption.

Risk assessment is a science-based method which is well-recognised in the international arena.  CFS performs risk assessment based on the principle that is in-line with those adopted by other international food safety authorities.  The acceptability of the potential risks upon consumption of a food sample containing metallic contaminants is judged on the basis of comparison of relevant health-based guidance values (HBGVs) for the metal concerned with the dietary exposure estimates as appropriate, i.e. based on the reported levels of metallic contaminants in the food concerned and the available food consumption data (please refer to the formula below for illustration).

* To compare with the relevant HBGV for the metal concerned

CFS would make use of the best available food consumption data, e.g. the data collected under the Hong Kong Population-Based Food Consumption Survey 2005-2007, during its risk assessment.  We would also consider factors such as the serving size of a particular item, e.g. weight of the food sample concerned per individual pack; instruction for use or serving size as indicated on the food label, as well as results of back calculations (e.g. the amount of food product concerned could be consumed such that the resulting dietary exposure would reach the relevant HBGV) as and when appropriate.

Regarding the relevant HBGVs for comparison with the dietary exposure estimates to determine the resulting food safety risks, international food safety authorities such as the Joint Food and Agriculture Organization of the United Nations (FAO) / World Health Organization (WHO) Expert Committee on Food Additives (JECFA) have conducted extensive evaluations on the possible adverse health effects of various metallic contaminants and established HBGVs based on the available toxicological data where appropriate.

For food items without relevant MLs under the Amendment Regulation, e.g. chrysanthemum, is the trade required to test all the 14 metallic contaminants listed in the Amendment Regulation, followed by risk assessment of the laboratory results?

The Government recommends the trade to adopt the control-at-source approach for ensuring food safety.  Food traders should understand the origin of the food for sale or for further processing, choose reputable food suppliers who can provide the necessary documentary evidence, conduct relevant laboratory testing according to their needs, and keep the relevant records.  The trade may consider the need of testing all or some of the 14 metallic contaminants based on the available information with respect to the nature and risk of the individual food product.  The trade is also recommended to compare the latest testing results with those collected in the past to see if there is any significant variation in the levels of metallic contaminants which may imply an increased food safety risk.

What is the ratio of methylmercury to mercury levels in fish?

The ratio of methylmercury to mercury levels in fish varies between body size and species. Since methylmercury is the major form of mercury in fish, the level of methylmercury in fish will be equal to (if the ratio is 100%) or less than the total mercury in fish.