Big Chem-EZ: What’s on top of my sink?

Editor’s Note: In 2020 (and 2021), there have been a lot of unanswered questions about life and living, so in our partnership with the Chemical Engineering Service Learning Class at Tulane University, taught by Dr. Julie Albert, we made it our aim to find questions we could answer. The series is called “Dear Big Chem-EZ” (think “Dear Abbey” but with less about “Why does my partner ignore me?” and more about “Can I actually drink my tap water?” and “What’s that smell outside my house?”).

You can look for new pieces every day this week and next because we love science, we love answers, and we love knowing what’s going on with our sinks! Let’s take a look! If you have questions you’d like answered, send them to thebigchemez@gmail.com.

Dear Big Chem-EZ,

I read your article about what’s under my sink. Now that I am constantly taking trips to the bathroom sink every time I come home, I am wondering about the stuff that’s on top of my sink. These hand soaps, toothpaste, and mouthwash have some long and dangerous sounding chemical names. How do they actually work?

Photo of typical personal care products seen on top of sink.

New Orleans was affected drastically by the coronavirus epidemic, and the first line of defense against spreading the disease has been handwashing with soap. Now that we spend more time around the sink throughout the day, it is natural to wonder how these chemicals in our personal care products work. More importantly, how does soap prevent the spread of the coronavirus? This article will explain the active ingredients in toothpaste, mouthwash, and soap so you’ll know what these long and hazardous sounding chemicals do in your everyday personal care products. It will also explain how hand soap kills off the coronavirus.

As you wake up every morning, the first thing you grab is a tube of toothpaste. The main ingredient in this product is sodium monofluorophoshate, which is an anticavity agent. Tooth decay happens when the bacteria that naturally exist in your mouth produce acid that destroys your enamel, which is the hard, outer covering that protects your teeth [4]. Sodium monofluorophoshate prevents tooth decay by reacting with a compound that exist on the enamel after an acid attack [3]. The resulting product of this reaction mimics the chemical makeup of the enamel to protect your teeth. Even though this fluoride compound is essential in preventing tooth decay, ingesting copious amounts is toxic. There are toothpastes that are fluoride-free, usually for young children, and use activated charcoal to absorb the bacteria [5].

After you brush your teeth, you usually go for a swish of mouth wash. A common active ingredient in mouthwash is cetylpyridinium chloride, which is a general antibacterial agent. Bacteria causes bad breath, but usually saliva can keep bacterial growth under control. However, when you wake up early in the morning, your mouth tends to be dry which causes morning breath. When cetylpyridinium chloride is dissolved in a liquid, it breaks into a positive portion and a negative portion. The positively charged portion is able puncture the negatively charged cell wall of the bacteria [2]. This could be thought of as puncturing a balloon. The positively charge portion also help this molecule bind to the enamel after the use of mouthwash, so it has antimicrobial functions after the rinse.

As you conclude your morning, you may still have to come back to the sink a few times to wash your hands. The main ingredient in most hand soap is sodium laureth sulfate, which is a surfactant. Surfactants are a class of chemicals that have a region that sticks to water and another region that sticks to oils [1]. Because of this special property, surfactants are active antibacterial agents. Bacteria have membranes that are made up of molecules that have the same property as surfactants. This allows the surfactant to insert itself between the bacterial membrane molecules and effectively break it apart. Luckily, the SARS-CoV-2 virus is an enveloped virus, which means all its vital components are contained in a capsule that is like the bacterial membranes. Once this capsule is destroyed, the virus is no longer active. Sulfate surfactants like sodium laureth sulfate have been known to cause skin irritation for some people [6]. There are ongoing studies to replace these sulfate surfactants with more mild amino acid surfactants that are derived from natural proteins [7].

We hope this sheds some light on some of the intimidating chemical agent names that are present in your everyday morning. Even though they might still be unpronounceable, they all have a function and have been engineered to keep you healthy and hygienic!

-Big Chem-EZ

[1] “Difference Between Types Of Soaps, Shampoos And Detergents.” Science ABC, 23 Oct. 2019, www.scienceabc.com/eyeopeners/whats-the-difference-between-various-types-of-soaps-shampoo-and-detergents.html.

[2] “Cetylpyridinium.” DrugBank, go.drugbank.com/drugs/DB11073.

[3] “Sodium Monofluorophosphate.” Wikipedia, Wikimedia Foundation, 29 Jan. 2020, en.wikipedia.org/wiki/Sodium_monofluorophosphate.

[4] Crest. “Cavities and Tooth Decay: Symptoms, Causes and Treatments.” Crest, Crest, 15 Apr. 2020, crest.com/en-us/oral-health/conditions/cavities-tooth-decay/cavities-tooth-decay-symptoms-causes-treatment.

[5] “How Does Charcoal Toothpaste Work?” Hello Products, 2 Apr. 2020, www.hello-products.com/friendly-blog/how-does-charcoal-toothpaste-work/.

[6] Bondi, Cara Am, et al. “Human and Environmental Toxicity of Sodium Lauryl Sulfate (SLS): Evidence for Safe Use in Household Cleaning Products.” Environmental Health Insights, Libertas Academica, 17 Nov. 2015, www.ncbi.nlm.nih.gov/pmc/articles/PMC4651417/.

[7] Perinelli, Diego R., et al. “Chemical–Physical Properties and Cytotoxicity of N -Decanoyl Amino Acid-Based Surfactants: Effect of Polar Heads.” Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 492, 2016, pp. 38–46., doi:10.1016/j.colsurfa.2015.12.009.