Are Nanomaterials Really Stealthy Health Hazards? (Part 1)
Release time:
2023-06-08
About seven or eight years ago, I attended a lecture on nanomaterials given by a renowned scholar in the field. After presenting his latest research findings, the scholar shared a story: He had a colleague who studied carbon nanotubes. This colleague didn’t smoke and loved to exercise, yet out of nowhere he developed lung cancer and passed away shortly thereafter.
About seven or eight years ago, I attended a lecture on nanomaterials given by a renowned scholar in the field. After presenting his latest research findings, the scholar shared a story: He had a colleague who studied carbon nanotubes—this colleague didn’t smoke and loved to exercise, yet inexplicably developed lung cancer and passed away shortly thereafter.
Of course, this is actually a typical online rumor with no clear origin or conclusion. However, if we look into the news further, on November 14, 2019, the International Chemical Secretariat (ChemSec) updated its SIN (Substances of Very High Concern that Need to Be Replaced Promptly) list. One name appears on this list—carbon nanotubes (CNTs). 。
So, do nanomaterials—this cutting-edge technology with limitless application potential—pose any health risks to the human body? ？
Carbon Nanotubes: Angel or Devil?
Carbon nanotubes (CNTs) are coaxial cylindrical structures composed of carbon atoms, ranging in number from several to dozens of layers. This is a “star” nanomaterial that, thanks to its outstanding mechanical, electrical, and other properties, is widely used in fields such as ultra-strong fibers, electronic devices, and batteries.
SIN is an abbreviation of the English phrase “Substitute It Now,” which literally translates to “Hurry up and replace it!” As the name suggests, this list enumerates hazardous chemicals commonly used in the manufacture of various products. ChemSec recommends that any substance listed here is harmful to both humans and the environment and should be avoided whenever possible.
Carbon nanotubes are the nanomaterials ever listed on the SIN inventory. 。
Screenshot of the page related to “carbon nanotubes” in the SIN List | www.sinlist.chemsec.org
In January 2020, Anna Lennquist from the toxicology team at ChemSec, along with other researchers, published an article in the journal Nature Nanotechnology explaining the reasons for incorporating carbon nanotubes into SIN.
The SIN list has three selection criteria: carcinogenicity and reproductive toxicity. (Carcinogenic, Reproductive toxicity, Persistent).
In terms of carcinogenicity, As early as 2014, the International Agency for Research on Cancer (IARC) classified a carbon nanotube called “MWCNT-7” as “possibly carcinogenic to humans.” Their research found that these carbon nanotubes can cause pulmonary inflammation in mice, meeting the criteria for carcinogenicity. In 2019, studies by Chinese scholars also demonstrated that the accumulation of carbon nanotubes in the lungs can accelerate tumor metastasis.
Carbon nanotubes also meet the criteria for reproductive toxicity. Studies have shown that intravenous injection of carbon nanotubes into pregnant mice can cause embryonic lethality and teratogenic effects. Female mice exposed to carbon nanotubes in their environment also exhibit a higher incidence of early miscarriages and fetal malformations.
Carbon nanotubes have a half-life of over 60 days in water and can remain stable in soil for more than 180 days.
With three perfect hits, these studies have given ChemSec sufficient confidence to include CNTs on the SIN list. As the project leader at ChemSec put it: “These studies are more than enough—they prove that these materials (CNTs) cannot be used.”
However, one stone stirred up a thousand ripples, and many scholars in related fields could no longer sit still.
First, Professor Bengt Fadeel of Sweden’s Karolinska Institute argues that we can’t tar all carbon nanotubes with the same brush. There are many different types of carbon nanotubes. Their biological properties can be influenced by factors such as varying lengths, numbers of layers, diameters, and surface chemical states. As he puts it: “Not all CNTs are created equal.”
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Are nanomaterials really silent killers that pose a threat to health?
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