Types of tin based substances found in food

Stannous Chloride (SnCl₂)

Also known as E-number, E512, this is used in food as an antioxidant and for colour retention.

Tin metal

When food is stored in tin cans, dissolution of tin metal into the food may occur. Dissolution may be accelerated in foods that have a high acid content.

Food Contaminants

A contaminant can mean any substance that is not intentionally added to food which is present in such food, as a result of the production. Of primary concern is the ingestion of contaminants through the consumption of food. Fish can contribute significantly to the dietary exposure to some contaminants such as methylmercury, persistent organochlorine compounds, brominated flame retardants and organotin compounds.  These organotin compounds can include TBT (tributlytin), DBT (di-butlytin), TPT and DOT (di-n-octyltin).

Tin oxide

Tin (IV) oxide is used as both as an opacifier and as a constituent of coloured pigments in high quality tableware e.g. bone china and porcelain products. It can also be used in beer and milk bottles to provide a scratch resistant coating.

Restriction Limits

Europe:

Limits for the acceptable amount of tin to be found in food is covered by EC regulation 1881/2006 and covers what is found in the table below. The Council of Europe has raised the Specific Release Limit (SRL) from 50mg/kg to 100mg/kg; however this is not applicable to products covered by EC 1881/2006. This 100mg/kg applies to pewter, tinned cookware and bronze cutlery etc.

Nature of tin found in food	Limit/restriction	Exceptions
Stannous Chloride  (E512)	25 mg/Kg	White asparagus
Tin metal (through can dissolution)	200mg/Kg (Food)
	100mg/Kg (Beverage)
	50mg/Kg (Baby Food)
Tin oxide
Food Contaminants TBT DBT DOT	0.25 µg/kg

US:

The amount of stannous chloride found in foodstuffs is not to exceed between 15-20mg/kg, calculated as tin for all food categories.

There does not seem to be a specific limit for the amount of tin found in food from tin cans but measured levels seem to be low at around 25mg/kg. Though if they are adhering to the ‘Codex General Standard for Contaminants and Toxins in Food and Feed’ then the 250 mg/kg will be the specific release limit for food. Canned beverages have a SRL of 150 mg/kg.

 Australia/New Zealand:

All canned foods must contain no more than 250 mg/kg tin, it is not specified whether that refers to food or beverage items.

China:

The following tin dissolution levels are permitted in China:

Canned fruits and vegetables: ≤250mg/kg

Canned meat: ≤250mg/kg

Fruit and vegetable juice: ≤200mg/L

No current information or limits known about SnCl₂ in canned foods. However there is a limit of 0.3g/kg of the amount of disodium stannous citrate limits in canned food.