What Are Zinc Salts?

This is part of our ongoing series helping consumers better understand chemicals, chemistry, and product formulations. We translate the science, bust the myths, and give you an honest assessment, so you can make informed choices for your family!

Ingredient:

Zinc Salts

What they are:

Ready for a mini science lesson? (This won’t be graded.) Zinc alone is a natural element necessary for all forms of life (you’ve probably seen it listed in the ingredients on nutritional supplements). Chemically speaking, salts are composed of an acid and a base – one composed of positively charged ions and the other of an equal amount of negatively charged ions, so they balance out as a neutral compound. Zinc salts are an entire class of compounds where zinc molecules are bound to other elements to create the aforementioned neutral compound. These include: zinc nitrate, zinc chlorate, zinc sulfate, zinc phosphate, zinc molybdate, zinc chromate, zinc ricinoleate, and more.

What they do:

Since there are so many different forms of zinc salts, you can probably guess that there are also many different uses. Some zinc salts act as pesticides and paint pigments, others are used for medicinal purposes like treating gastric reflux and the common cold. Their applications are wide ranging – and so are their toxicity and safety profiles.

Why we’re featuring them today:

We use zinc salts in our Air + Fabric Freshener, specifically, zinc ricinoleate. Zinc ricinoleate is the zinc salt of ricinoleic acid, a major fatty acid found in castor seed oil obtained from the seeds of the Ricinus communis plant. This interesting little ingredient traps and absorbs odor molecules, making them imperceptible to the odor receptors in your nose. Simply put: it naturally eliminates and neutralizes odors. Even so, on our Deodorant label, you’ll find zinc salts listed in our Honestly Free section.

How can that be? Why is it good for one product and not the other?

In this case, we’re talking about two entirely different applications and uses. While there isn’t anything especially risky about zinc ricinoleate (and many natural deodorants actually contain it), we opted not to put it in our deodorant. For some people, it can cause contact dermatitis and many consumers are looking for a mineral and mineral salt-free deodorant. We wanted to provide an effective alternative to suit everyone’s needs.

The ultimate chemistry lesson here? Just because something is on an Honestly Free list doesn't mean that it's inherently bad. As in this case, sometimes something’s perfectly suitable for one type of product, and not so good for another. (Think of lemon juice – it’s safe and natural and works great in a multi-surface cleaner, but you wouldn’t want it in a makeup remover because it would really sting your eyes!)

Clearly there are chemicals we would never, ever use (you can find a short list of those in our Honestly Free Guarantee description), but the list on each product is specific to that individual product. We take into account how the product will be used, the dilution of the different ingredients, and what consumers are looking out for based on personal preferences. It takes a lot of research and a lot of time, but that’s just the Honest way.

And, if you ever have any questions at all about what’s in our products – or what’s not – we’re always happy to do our very best to answer them. Yes, that takes more time too, but we wouldn’t have it any other way. Being transparent about our choices and helping you understand how to make better ones for yourself is part of our mission.

With knowledge, together we can make it better!

References:

• Bohmer, T., Muller, F., & Peggau, J. (2003). New results on odor absorption with zinc ricinoleate. JORNADAS-COMITE ESPANOL DE LA DETERGENCIA,33, 143-154.
• Dooms‐Goossens, A., Dupré, K., Borghijs, A., Swinnen, C., Dooms, M., & Degreef, H. (1987). Zinc ricinoleate: sensitizer in deodorants. Contact dermatitis, 16(5), 292-294.
• Final Report on the Safety Assessment of Ricinus Communis (Castor) Seed Oil, Hydrogenated Castor Oil, Glyceryl Ricinoleate, Glyceryl Ricinoleate SE, Ricinoleic Acid, Potassium Ricinoleate, Sodium Ricinoleate, Zinc Ricinoleate, Cetyl Ricinoleate, Ethyl Ricinoleate, Glycol Ricinoleate, Isopropyl Ricinoleate, Methyl Ricinoleate, and Octyldodecyl Ricinoleate. (2007, 12). International Journal of Toxicology,26, 31-77. doi: 10.1080/10915810701663150
• Kuhn, H.; F. Müller; J. Peggau; R. Zekorn (April 18, 2000). “Mechanism of the odor-adsorption effect of zinc ricinoleate. A molecular dynamics computer simulation”. Journal of Surfactants and Detergents (Springer Berlin/Heidelberg) 3: 335–343. doi:10.1007/s11743-000-0137-9.ISSN1097-3958
• Magerl, A., Heiss, R., & Frosch, P. J. (2001). Allergic contact dermatitis from zinc ricinoleate in a deodorant and glyceryl ricinoleate in a lipstick. Contact dermatitis, 44(2), 119-121.
• Taghipour, K., Tatnall, F., & Orton, D. (2008). Allergic axillary dermatitis due to hydrogenated castor oil in a deodorant. Contact dermatitis, 58(3), 168-169.

Zekorn, R. (1997). Zinc ricinoleate: The basis of its deodorizing activity.Cosmetics and toiletries, 112(11), 37-40.