I recently saw a post online which called into question the safety of the Moderna vaccine through an interesting argument. One of the ingredients in the Moderna COVID-19 vaccine is the ionizable amino lipid SM-102. [Source]

Information about this chemical can be found on this website. As expected, the description of this chemical is the following:

SM-102 is an ionizable amino lipid that has been used in combination with other lipids in the formation of lipid nanoparticles.1 Administration of luciferase mRNA in SM-102-containing lipid nanoparticles induces hepatic luciferase expression in mice. Formulations containing SM-102 have been used in the development of lipid nanoparticles for delivery of mRNA-based vaccines.

However, as a standalone chemical it seems to have many safety warnings and hazards. This information is available on the accompanying safety data sheet for SM-102. Here are some of the listed hazards:

WARNING This product is not for human or veterinary use.

H310 Fatal in contact with skin.

H351 Suspected of causing cancer

H372 Causes damage to the central nervous system, the kidneys, the liver and the respiratory system through prolonged or repeated exposure.

Now, my presumption is that these hazards are supposed to be overly cautionary, and also only apply to the direct handling of the raw chemical. But many people do not see it this way, and thus are reasonably skeptical about the safety of the Moderna vaccine. So, I have a couple questions:


  1. Are all these hazards relevant to the chemical's pharmacological use as part of an mRNA vaccine? Why?
  2. How are these hazards determined in the first place?
  3. Are there examples of other chemicals with similar hazards/warnings, which are ingredients in common medical drugs?
  4. Opposite to the previous question, are there chemicals with little to no hazards/warnings, which nevertheless form key components to actually dangerous drugs?

1 Answer 1


The MSDS linked to is for a product sold as a solution of 10% SM-102 in 90% chloroform. It's listed as "SM-102" because that's the interesting/useful thing that the company is selling. It's common for chemicals to be sold packaged with solvents to make a solution. Sometimes that solvent is just water, but if the product is not water-soluble in sufficient concentrations then other solvents may be necessary. Alcohol solutions are quite common, but for more hydrophobic chemicals it may be necessary to use more "exotic" solvents.

Because chloroform is quite a dangerous chemical for people to be exposed to and because this product is mostly chloroform, the MSDS is also primarily based on chloroform, not SM-102.

You can see this in some of the language in the MSDS itself, for example:

Hazard-determining components of labeling: Chloroform

(this notes that the hazards listed below it are attributable to the presence of chloroform in the packaging)


· Chemical characterization: Mixtures · Description: Mixture of the substances listed below with nonhazardous additions

· Dangerous components: CAS: 67-66-3 RTECS: FS9100000 Chloroform 90.0%

· Other ingredients 2089251-47-6 SM-102 10.0%

You'd have the same hazards listed on the MSDS of 10% water and 90% chloroform. Presenting this as an argument about vaccine safety seems misleading at best.

From this fact sheet:

Each (0.5 mL dose) dose of the Moderna COVID-19 Vaccine contains the following ingredients: a total lipid content of 1.93 mg (SM-102, polyethylene glycol [PEG] 2000 dimyristoyl glycerol [DMG], cholesterol, and 1,2-distearoyl-sn-glycero-3-phosphocholine [DSPC]), 0.31 mg tromethamine, 1.18 mg tromethamine hydrochloride, 0.043 mg acetic acid, 0.20 mg sodium acetate trihydrate, and 43.5 mg sucrose.

(the section in parenthesis is added by me from the previous section)

Chloroform is not listed as an ingredient in the Moderna vaccine, and determinations about the safety of the vaccine should not be based on MSDS for a product that is 90% chloroform.

  • 20
    @ArturodonJuan The data sheet is for safety of a jar in the lab which contains solvent + some compound of interest, and solvents are quite important to safety. You can't ignore them, especially since solvents themselves are often flammable poisons, it's just important to recognize that this is what MSDS are for: labeling jars in the lab, not for talking about the safety of some individual ingredient. I agree that the info about the solvent is buried a bit, other times you might have an MSDS that explicitly lists the solvent at the top. But if you search "chloroform" it's all over the sheet.
    – Bryan Krause
    Commented May 17, 2021 at 20:18
  • 16
    Yeah, that tends to be true of all sorts of anti-vax arguments, whether due to inexperience/lack of knowledge and a dose of confirmation bias, or outright intentionally lying about data. They often seize on some minor glint of truth to support an argument that has no actual ground to stand on.
    – Bryan Krause
    Commented May 17, 2021 at 20:58
  • 16
    @LorenPechtel It's just the label given to the jar that's sold, and it makes sense to name it after the "active ingredient" rather than the solvent. When you buy a jar of pickles, you just refer to them as pickles, when more accurately you might say they are pickles in brine.
    – Bryan Krause
    Commented May 18, 2021 at 4:59
  • 8
    People need to understand that (M)SDSs are to assess occupational hazards (and to lesser extent, environmental) and are to be used in this context only. For pharmaceutical products, the relevant information are contained in monographs.
    – xngtng
    Commented May 18, 2021 at 22:49
  • 7
    Or reading the safety sheet for acetic acid after a balsamic salad... SDSs contains many pro-forma information. I remember the fire safety section for distilled water literally said "In case of fire, use water spray to extinguish." (Of course, the information is still useful e.g. in case of special containers that have particular fire safety concerns)
    – xngtng
    Commented May 18, 2021 at 23:27

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