National standard fights, who we believe？

20National City, March 15, '22The General Administration of Site Supervision and Administration and the National Standardization Administration issued GB5749-2022 "Sanitary Standards for Drinking Water", which will be implemented on April 1, 2023。

In our in-depth study of this standard, we found an interesting phenomenon: in the standard for the concentration of selenium (Se) in water, the standard is the same as the 2006 version of the GB5749 standard, which is used as a "toxicological indicator", the limit value is set to 0.01mg/L。This shows that the two versions of the standard maintain continuity in the indicators and limits of selenium。

However, when we look up another national standard GB8537-2018 "National Standard for Food Safety for Drinking Natural Mineral Water", we find that selenium is considered a "beneficial element" in it, and its concentration is required to be > 0.01mg/L。

We can't help but ask when the concentration of selenium in water is greater than 0.At 01mg/L, drinking this water is harmful or beneficial to human health？

Someone told me: The standard of drinking water GB5749 is based on a standard body weight of 60Kg, and the daily drinking water amount of 2L per person is calculated to ensure the life safety of consumers for 70 years。

Mineral water is beverage water, and its standard GB8538 is based on a person with a standard body weight of 60Kg, and each person drinks 0.5L water calculation can also guarantee the life safety of consumers for 70 years。It should be compared like this。

Ok, let's take a look at this logic:

一、硒

GB5749-2022, page 5, Table 3 Extended indicators and limits of drinking water quality, II. Toxicological indicators, Item 54, Selenium (mg/L), limit value is 0.01。

GB8538-2018, page 2, Table 3 Limit index, Selenium (mg/L), limit index is 0.05。

Let's do the math again:

Press GB5749, 60Kg person, 0.01mg/L x 2L/ day x 365 days/year x 70 years = 511mg

Press GB8538, 60Kg person, 0.05mg/L×0.5L/ day x 365 days/year x 70 years = 638.75mg

Well, according to this logic, the two standards are still fighting, 5749 said that a 60Kg person's lifetime (at the age of 70, the same below) intake of 511mg selenium is safe, while GB8538 said that a 60Kg person's lifetime intake of 638.75mg of selenium is safe!

Obviously, of the two standards, the index of selenium, GB5749, is stricter。

二、氟

If in the two standards, the gap in the lifetime safe intake of selenium in water is not too large, then the gap in the lifetime safe intake of fluorine in water is more significant。

GB5749-2022, page 2, Table 1 Drinking water quality standard indicators and limits, 2. Toxicological indicators, Item 10, fluoride (mg/L), limit is 1.0。

GB8538-2018, page 2, Table 3 Limit index, fluoride (in F-) (mg/L), limit index is 1.5。

Let's do the math again:

According to GB5749, 60Kg people, 1mg/L×2L/ day ×365 days/year ×70 years = 51100mg

Press GB8538, 60Kg person, 1.5mg/L×0.5L/ day x 365 days/year x 70 years = 19162.5mg

In the two standards, the lifetime safe intake of fluorine in water is very different, the former is the latter.67倍。This is a big fight!

Obviously, according to this logic, of the two standards, the index of fluorine, GB8538, is much stricter!

三、铬

Here's another example of these two standards fighting:

In GB5749-2022, page 2, Table 1 Drinking water quality routine indicators and limits, 2. Toxicological indicators, Item 6, chromium (hexavalent) (mg/L), limit is 0.05。

In GB8538-2018, page 2, Table 3 Limit index, total chromium (mg/L), limit index is 0.05。

Let's do the math again:

Press GB5749, 60Kg person, 0.05mg/L×2L/ day ×365 days/year ×70 years = 2555mg (hexavalent chromium)

Press GB8538, 60Kg person, 0.05mg/L×0.5L/ day x 365 days/year x 70 years = 638.75mg (total chromium)

Even though from the limit point of view, both of them are 0.05, but the former is marked as hexavalent chromium, while the latter is clearly marked as total chromium。The chemical values of chromium are -4, -2, -1, 0, +2, +3, +4, +5, +6, and the common +2, +3, +6, that is to say, +6 chromium is only a part of the total chromium。

Then, the problem comes: according to 5749,60 Kg of people, as long as the lifetime intake of hexavalent chromium within 2555mg, are safe。

According to GB8538, 60Kg of people, the lifetime intake of total chromium in 638.Within 75mg is considered safe;Total chromium is 638.75mg, hexavalent chromium is only a part of the total chromium, its limit is of course lower。

This fight is even worse!

Obviously, according to this logic, among the two standards, the index of chromium, GB8538 is much stricter!

How much water does each person drink per day？

In addition, the reference amount of water per person per day based on the GB5749 standard is 2L, which is also questionable。

In drinking water, which enters the human body from the mouth, in addition to drinking water (including drinking water, tea, coffee, honey, milk powder, etc.), there is cooking water (including cooking rice, porridge, noodles, stir-frying, soup, decocting Chinese medicine, etc.), toxic impurities in cooking water will also be harmful to human health。

According to Xiaobian daily consumption, the former and the latter are about 2L each, that is, a total of 4L of water is required per person per day rather than 2L。