Toxins can be found in seafood

Due to the lack of testing and monitoring, seafood with harmful substances can easily enter the market while remaining undetected.

Here are some examples In Hong Kong:

1. Heavy metals

Tests found inorganic arsenic in canned sardines (2020),
which can cause diseases such as diabetes, respiratory and cardiovascular impairments, Blackfoot disease, skin lesions, and skin cancer.

Tests found Methyl-mercury in tuna sashimi (2019) and canned tuna (2020),
which can impair cognitive thinking, memory, attention, language, and fine motor and visual-spatial skills.

Tests found Cadmium in canned sardines and tuna (2020),
which can damage the kidney, kill tissues in the reproductive system, and causes a loss of bone density.

Regulations

Cap. 132V Food Adulteration (Metallic Contamination) Regulation 2018
proscribes the sale of food with specified metals in excessive concentrations

Fine of HK$50,000
and 6 months of imprisonment.

2. Malachite Green

Usually found in farmed fish.
Tests found malachite green in Orange-spotted grouper (2020), Brown-marbled grouper (2020), snakehead (2021), fried dace (2015).
Researchers also found malachite green in Chinese perch and Grass carps (2019). Toxic to the liver, the thyroid and can damage genes.

Regulations

Cap. 132AF Harmful Substances in Food Regulations
proscribes the sale of food with harmful substances in excessive concentrations, including malachite green

Fine of HK$50,000
and 6 months of imprisonment.

3. Polychlorinated biphenyls (PCBs)

Tests found PCBs in canned sardines (2020). Probable carcinogens and can suppress the immune system.

Regulations

Section 54 of Cap. 132 Public Health and Municipal Services Ordinance
All food for sale in Hong Kong must be fit for human consumption.

4. Paralytic Shellfish Poisoning toxins (PSP)

Tests found PSP toxins in fresh scallops (2007) and poisoning from contaminated sea snails occurred (2021).
Severe Paralytic Shellfish Poisoning can cause headaches, dizziness, or even difficulty in swallowing and speech, paralysis, or death.

Regulations

Section 54 of Cap. 132 Public Health and Municipal Services Ordinance
All food for sale in Hong Kong must be fit for human consumption.

5. Ciguatera

Ciguatera Fish Poisoning were reported in multiple reef fish species, especially groupers, snappers, and moray eels. Can cause vomiting, diarrhoea, nausea, and abdominal pain. In severe cases, low blood pressure, slow heart rate, and respiratory difficulties are possible.

Regulations

Centre for Food Safety encourages businesses to comply with the Code of Practice when importing and selling live reef fishes.

For the maximum levels of metallic contents

consult the following table:

MetalFoodMax Level (mg/kg)
AntimonyFish; Oysters; Crabs; Prawns and shrimps1
ArsenicAquatic animals, other than fish0.5
Fish; Fish oil0.1
Seaweed1
CadmiumFish0.1
Crustaceans; Bivalve molluscs;
Cephalopods; Gastropods
2
ChromiumFish; Oysters; Crabs; Prawns and shrimps1
LeadAquatic animals aside the other categories1
Fish0.3
Crustaceans0.5
Bivalve molluscs1.5
Mercury (methyl-mercury)Fish0.5
Mercury (total mercury)Aquatic animals, other than fish0.5