In nature, there are various "toxic substances", such as bacterial mycotoxins, heavy metals, organic pollutants, etc. For health, we naturally hope that they do not exist in food. However, they inevitably exist in the food we eat, water we drink and air we breathe, so we can only hope that their content is "as low as possible".
Aflatoxin is one example. It is widely found in grains, such as rice, whose content is not more than ten ppb Can be marketed. Why selected 10 ppb Because the social cost paid for its realization is acceptable, and the health risks it brings are also acceptable - this is the true meaning of "as low as possible". Lower standards, such as five ppb , which means about 10% Thirty percent of the rice cannot be eaten because of the "aflatoxin excess" - that is the ration of more than 100 million people, at least at present, our society cannot afford it. So, 5ppb The content of is "impossibly low".
So, this 10ppb What is the risk of cancer?
In the food risk assessment, the "maximum possibility" is estimated. In other words, suppose a person eats a lot of rice every day (for example five hundred G), and all the rice eaten is "critical excess" (i.e. aflatoxin ten ppb ）, then the aflatoxin taken every day is five Micrograms. Suppose his weight is sixty According to the relationship between aflatoxin and the risk dose of liver cancer, his probability of getting liver cancer will increase by 1/120000 every year. If according to the national thirteen Counting at 100 million people, the number of liver cancer increased by eating rice alone will exceed one Ten thousand people!
Is it scary? No accident?
This algorithm is certainly unreliable. One in 120000 is the "maximum risk", which is obtained when each parameter is taken as the limit value, indicating that the actual situation will not be worse than it. For example, it is difficult for one person to eat every day five hundred Grams of rice, even less likely to eat all the rice is aflatoxin ten ppb "Critical Qualified Product" of. Multiplying this risk by the total number of people in the country to get the number of people who get liver cancer because of eating rice every day in the country is a big overestimation of the actual situation. because ten ppb It is just "the maximum content that may be encountered". In fact, most rice will not be so high.
After seeing this example, you should know how the cheats play with the Aspergillus flavus data of Pu'er tea to scare people, right?
If I still don't understand, I'll break it down again:
According to public reports, there are many data showing that there is no aflatoxin in the standardized production and storage of Pu'er tea. But in the data cited most, it is "the market's seventy Samples of Pu'er in wet warehouse ". These samples are basically cheap (or even inferior) Pu'er tea, which does not represent the overall situation of "Pu'er tea". Even for this batch of tests, most of the results did not exceed five ppb , only 11% Of has exceeded 5ppb 。 In order to estimate the "maximum risk", we took ten ppb This "almost unattainable content", and assume that a person must drink every day ten It is also assumed that all aflatoxins in such Pu'er tea are soaked in the tea water - under this extreme assumption, the aflatoxins that this person consumes every day are zero point one Micrograms. If you want to take this "maximum possible value" as an example, it is equivalent to the daily problem of rice five Microgram, which means that the aflatoxin taken during meals is from Pu'er tea fifty Multiple; If we need to consider that most of the rice we eat will not have such a high content, we must also consider that most of the actual Pu'er tea does not contain aflatoxin, and even these "wet warehouse Pu'er" tested are mostly 5ppb following.
That is to say, this zero point one The figure of microgram, as the "maximum possible value" considered in the risk assessment, is similar to that of rice five Microgram.
And the trick of a liar to frighten people is to use zero point one This "extreme number"“ ten Annual increase among 10000 people zero point one four The probability of "patients with liver cancer" is multiplied by the total population of the country to get the "annual increase in the country one thousand and eight hundred "Patients with liver cancer" to scare the public. (In fact, the dose relationship between aflatoxin and liver cancer risk varies from source to source. For the general population, "daily intake one Nak / About one case of liver cancer will be increased among thousands of people with aflatoxin of kilogram weight. Only for patients with hepatitis B will it be "one case increased among millions of people". And the swindler got“ ten Increase among 10000 people zero point one four Only for patients with hepatitis B can it be obtained. However, even according to his calculation, "drinking Pu'er increases every year one thousand and eight hundred The corresponding "liver cancer patients" is "eating rice increases every year nine Ten thousand patients with liver cancer ".
Do you believe this conclusion?
In fact, the definition of "food safety" is not "zero risk", but "control the risk to an acceptable level". This is common sense for food safety professionals, but it is different from the psychological expectations of the public. Because the public generally has this unrealistic perception, it also gives the opportunity for cheats to play with numbers to scare everyone.
Even if calculated by a liar“ ten Annual increase among 10000 people zero point one four What is the risk of "one patient" in the risk management of food safety?
Look at the next copy WHO Files for:
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This is WHO A document establishing standards for bromate in drinking water. The red line part says that if you drink water with bromate content of the recommended standard for life, the upper limit of the possibility of getting cancer is one in 10000. By one person seventy The increased probability of cancer every year is ten Ten thousandth zero point one four 。 in other words, WHO The risk is acceptable. In fact, bromate in drinking water is produced during disinfection - if this risk is considered unacceptable, then this disinfection method can not be used.
In the professional food safety science popularization, we discussed "how big the risk is" and "whether it is worth worrying". Only when cheats scare people to attract the public's attention, they always use the judgment of "whether there is" and "whether there is". The classic rumors of "tap water causes cancer" and "overnight dishes cause cancer" spread in the circle of friends and WeChat groups, and laymen or liars use this idea to scare people.
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