Long-term drinking water boiled in an electric kettle, the body will be poisoned and hurt the brain? 3 suggestions to listen to

Question: It has been reported that the manganese in the high-manganese steel electric kettle will be dissolved into water during the high-temperature heating process, and then ingested by the human body, resulting in nervous system damage. Is this danger real?

First of all, the results: from the inspection methods in the report and the interpretation of the data, the conclusion that [electric kettles will make people stupid] [only 304 steel kettles can be used] is not reliable.

by Yun Wuxin (Ph.D. in Food Engineering)

Why? In view of the fact that the topic of "manganese exceeding the standard" has been hot for several rounds, let's simply talk about this manganese thoroughly -

What is manganese?

One of the essential trace elements of the human body

For the human body, the situation of manganese is very similar to that of iron. Iron deficiency can be problematic, but too much iron can also cause iron poisoning.

The situation is similar for manganese. First of all, manganese is an essential trace element for the human body. It is a component of connective tissue, bones, clotting factors, sex hormones, etc., and is also indispensable for fat and carbohydrate metabolism, calcium absorption, and blood sugar regulation. Normal brain and nerve function are also inseparable from its participation; Manganese deficiency can affect neurodevelopment.

▲A well-known vitamin tablet ingredient list. Image source: Husk

What happens if there is an excess of manganese?

Like many mineral nutrients, too much manganese can harm the human body. Manganese excess will inhibit iron absorption, and long-term excess will affect the function of the nervous system - scaring the public "manganese overdose causes Parkinson's disease" and "makes people stupid" is not out of nothing.

But it's still the old saying: "Talking about toxicity without the dose is all hooliganism." ”

How much manganese does the human body need per day? How much manganese can the human body withstand? Scientific data is not very uniform, and the interpretation of countries around the world is different, and the recommended standards are also different.

For adults, "adequate amounts (eating so much a day is enough to meet needs, not that more is harmful)" is 2-3 milligrams per day in the United States, 3.5 milligrams in China, and higher in Canada. And "the maximum intake (not exceeding is considered safe, exceeding the risk is increased)", the standard set by China and the United States is about 10 mg per day.

There is manganese in water, air, soil, and food, and the main manganese intake route for ordinary people is food. The manganese intake of residents in different countries is different, generally in the form of a few milligrams. The manganese intake of Chinese residents is roughly 6.8 mg per day: most people will not be "deficient in manganese", and there is still a considerable distance from the "safe intake limit".

So is there more or less manganese in the tableware?

Because manganese is an essential nutrient for the human body, excessive intake is harmful, so whether it is harmful should be discussed according to the amount. If manganese stays in the steel well and the amount of precipitation is insignificant, there is naturally no need to worry. If precipitation in the dishes cannot be ignored, then there will be three cases:

First, if a person ingests insufficient manganese from other ways, then such tableware even plays the role of "manganese supplementation";

Second, if a person ingests enough manganese from other sources, but there is still a relatively large distance from the excess, and the manganese precipitated in these tableware is still significantly lower than the "safe limit", then these manganese do not matter;

Third, if a person's manganese intake has approached or exceeded the safe limit, then the manganese precipitated in the tableware is worse.

Therefore, whether the "manganese exceeds the standard" tableware is safe, its manganese content is not the only determining factor. The key factors are the amount of "precipitation" and the amount of "intake by other routes". Without these two indicators, everything is on paper.

Is the manganese content of electric kettles harmful to health?

Here's the big thing you care about! Why did this article begin by saying that it was a farce? Because the detection method in this report is very problematic.

by Ju (former metrological testing engineer)

First of all, let's look at the cause of the incident - "2016 Electric Kettle Product Risk Monitoring Quality Analysis Report", the media also saw this before interviewing and investigating.

The report did not actually involve "memory loss", but did two related tests:

Stainless steel composition analysis: This uses spectroscopy to analyze the manganese content of the electric kettle itself, which is a relatively mature and reliable detection method, and there is basically no problem.

Manganese precipitation: After all, no matter how high the manganese content of the material itself is, you also have to enter the water to affect the human body, so it is independent of the above test. Looking further, it is found that the "manganese content is less than 0.1 mg/L" mentioned in China's GB5749-2006 Sanitary Standard for Drinking Water is used in the "judgment basis" of manganese precipitation. This is the indicator of health risks in 22 batches of 45 batches of products.

What is the problem with this result?

Originally, I thought that this report was justified and a firm conclusion, but the occupational disease still attacked many years ago - what is the detection method of this manganese precipitation? So curious...

"Manganese precipitation amount refers to SN/T 2829-2011 "Food contact materials, metal materials, determination of heavy metal content in food simulants, inductively coupled plasma emission spectrometry" standard specified method test" - according to this sentence in the report, I really went to the SN/T 2829-2011 standard and found two surprising facts:

1. Food simulant: The standard is not water, but "4% acetic acid food simulant". Alas? We usually boil water, and as a result you go to boil acetic acid? The pH value of the simulated liquid is about 2.5, which is completely different from the daily boiling water...

2. The detection scope of heavy metals covered by the standard: "This standard applies to the determination of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), antimony (Sb) and zinc (Zn) content in 4% acetic acid food contact materials (enamel products, stainless steel products and aluminum products). "—only manganese is missing... Using unapplicable standards to exceed the standard is a serious violation...

Image credit: https://commons.wikimedia.org/wiki/File:Zelmer_Electric_kettle_in_Poland.jpg#file under CC-BY-SA-4.0

So, if I'm not mistaken, this thing looks like another farce: the wrong detection method leads to the wrong conclusion (the simple and direct method is to boil the pure water directly after washing the kettle and test the manganese content in the water), and the wrong conclusion is forcibly linked to the composition ratio of the manufacturing material.

Of course, to finally answer this question, it may take the authority to test again in the right way to see how it turns out. However, from what has been disclosed so far, it is likely that this is just a farce.

Does an electric kettle still work?

1. From the perspective of electricity safety, if conditions permit, it is better to buy electrical appliances with more stable quality and higher material requirements.

2. But it does not mean that everyone should immediately throw away all the electric kettles at home, and then people are worried that they will "become stupid" if they eat too much manganese... Until the authorities revert to the correct method, all this will remain unsolved.

3. Be especially careful not to drink water for fear of excessive manganese intake! Not to mention that we mainly consume manganese through three meals a day, reducing water intake is definitely due to the practice of choking on food, which is harmful to the body! Especially the elderly and children!

In view of the nutritional and toxic characteristics of manganese, there are generally no international standards for manganese precipitation in tableware. We also expect that the public's sensitivity to food safety issues can promote the dissemination of relevant knowledge, and then promote the establishment of standards, risk assessment, and play a more accurate and efficient supervisory role.