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Take care when using metal containers such as canteens and kettles! – Poisoning from liquidation of metal containers due to acidic drinks

During the hot summer, many people carry beverage flasks and make sports drinks at home.
However, incorrect usage can result in metal containers causing poisoning from the metal dissolving into drinks.
Please take a moment to review the proper way to use such containers here.


1 What drinks are acidic?


Acidic drinks mainly include carbonated drinks, lacto-fermented drinks, fruit juices, and sports drinks.
Drinks can contain acidic substances such as carbonic acid, lactic acid, vitamin C, and citric acid (contained in large quantities in fruits like citrus fruits). Drinks which contain large amounts of these substances are highly acidic.


2 How can metal containers cause food poisoning?


Most people have containers and cooking implements made from various metals such as aluminum, copper, and iron.
When these containers and implements come in contact with acidic foods and drinks, the metal can begin to dissolve.
Under normal, short term use, only a tiny amount of the metal dissolves away. In addition, a variety of measures are taken to prevent excessive dissolving of the metal, including coating the interior of containers and implements to prevent the metal and food or drink from coming into direct contact.

However, when such containers and implements are used incorrectly, such as when they become scratched or are used to store acidic liquids for long periods of time, an excessive amount of their metal can dissolve into food and drink, leading to unexpected food poisoning. Copper, in particular, can cause poisoning when consumed in large amounts.

3 Actual food poisoning examples

4 What measures should be taken?

Past cases of this kind of food poisoning have been caused by the use of copper implements to cook highly acidic foods and the storage of food and drink in copper containers for long periods of time. This resulted in the copper dissolving into the food or drink, leading to food poisoning when it was consumed.
Even containers made of metals other than copper can result in minute amounts of their metals becoming dissolved in food when they become scratched or when used with highly acidic food.
Aluminum and iron are not likely to cause poisoning through dissolving into food, but containers made of these materials can become corroded.
Be sure to observe the following points when using metal containers and implements.

Carefully check to make sure the interior is not rusted or damaged.

Rust and scratches result in material not designed for the purpose coming into contact with food and drink and this can lead to metal dissolving.
In particular, metal vessels can become damaged when dropped or bumped, even if they do not look like they are.
Check carefully before use.

Do not store highly acidic food and drink in metal containers

When placed in metal containers, highly acidic food and drink such as carbonated drinks, lacto-fermented drinks, and fruit juice can result in metal dissolving into food.
Carefully read the instructions for containers and drinks and avoid storing food and drink in metal containers for long periods of time.
If you do store food or drink in a metal container for a long period of time, carefully check to see if its flavor or color is different from normal.

Periodically purchase new containers

Older containers can be damaged inside due to wear and tear.
In order to prevent unexpected food poisoning, purchase new containers periodically.


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Bureau of Social Welfare and Public Health, Tokyo Metropolitan Government
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