Can formaldehyde in dishwashing liquid cause cancer? Is it as serious as the rumors online?

Author: Sun Yafei, PhD in Chemistry, Tsinghua University

Reviewer: Ruan Guangfeng, Deputy Director of the Science and Technology Information Exchange Center for Food and Health

gossip

If there are elderly people at home, you may often hear reminders that you should never use detergent when washing dishes, otherwise the consequences can be serious, ranging from infertility to cancer.

If you check online, you will find that this statement is quite common, and many media have also made official reports that investigations have found that some dishwashing liquids contain excessive formaldehyde.

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analyze

Why does formaldehyde appear in detergent?

This is mainly related to the formula of the detergent.

Contrary to what many people think, dishwashing liquids usually do not kill bacteria, especially in the early years, because people use dishwashing liquids to remove grease from dishes, and to achieve this, they only need to contain surfactants.

Surfactants are a type of substance that can combine with both oil and water. With them, oil and water can achieve "peaceful harmony". There are many types of surfactants, including the most basic sodium dodecylbenzene sulfonate and the advanced sodium fatty acid methyl ester sulfonate. With thousands of options, it is not difficult to find a variety with low toxicity and low cost.

In addition to surfactants, you usually just need to add some fragrance to adjust the smell, and a dishwashing liquid is ready.

However, the biggest risk of dishwashing liquid made in this way is that it is easy to breed bacteria. Until now, when market supervision conducts random inspections on the category of dishwashing liquid, excessive colony counts are still the most common problem.

Formaldehyde is used in this context, because as we all know, the aqueous solution of formaldehyde is called formalin, which is a particularly useful preservative. In the era when laws and regulations were not sound, using formaldehyde to preserve and sterilize detergents became a basic operation for many low-end detergents.

There are standards for the formaldehyde content of detergents

However, the toxicity of formaldehyde cannot be ignored. Therefore, the problem of excessive formaldehyde was soon noticed, and relevant regulations were gradually introduced and improved.

The national standard GB 19430.1 is a specification for detergents and is enforceable. The 1994 version of this standard is called "Hygienic Standard for Detergents Used in Food Tools and Equipment", which does not involve formaldehyde (and methanol related to formaldehyde). In 2015, the standard that had remained unchanged for more than 20 years was significantly adjusted, and the title was changed to "Detergents", which specifically added standards for methanol and formaldehyde.

According to the classification in the standard, detergents are divided into Class A and Class B. Class A can be used to directly wash food, while Class B is used to wash dishes. The "dishwashing liquid" we talk about in daily life actually belongs to Class B detergent. In Class A detergents, the content of methanol and formaldehyde must not exceed 0.05%, while Class B requires no more than 0.1%.

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In the updated standard GB 19430.1-2022, the detection limits of methanol and formaldehyde follow the numbers of the previous version.

Therefore, as long as it is a genuine dishwashing liquid, the possibility of formaldehyde exceeding the standard in the product is very low, and there is no need to worry too much.

How can we ensure the antibacterial properties of dishwashing liquid without using formaldehyde?

In fact, there are already many types of new antibacterial agents. According to the requirements of GB 19430.1-2022, preservatives in detergents must comply with the scope of GB 22115-2008 "Specifications for Raw Materials for Toothpaste". In other words, as long as the preservatives can be used in toothpaste, they can be used in detergents, including the well-known triclocarban, potassium sorbate, sodium benzoate, etc. The preservatives here are mainly to have a bactericidal and antibacterial effect.

It is worth noting that after years of development, some new surfactants have also achieved antiseptic effects, especially quaternary ammonium surfactants, such as benzalkonium chloride and benzalkonium bromide, which are also included in the list of preservatives allowed for toothpaste. Therefore, for today's detergent products, it is technically very easy to achieve the antiseptic function without using formaldehyde.

in conclusion

According to the national standards for detergents, the formaldehyde content of Class B detergents such as dishwashing liquid is required to be no more than 0.1%. Therefore, as long as it is genuine dishwashing liquid, the possibility of formaldehyde exceeding the standard in the product is very low, and there is no need to worry too much.

Planning｜Fu Sijia

Editor-in-charge｜Liu Yantong (internship)

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