Are All Tampons Toxic? Dissecting the NEW 2024 Study Making Headlines

**Note from the author: Updates coming soon

I understand the panic and concern raised by women around me in real life and online. Well, hold onto your strings, ladies. In the spirit of demonstrating the power of media-driven medical misinformation, we're taking things to a molecular level.

Let's review some of the data presented by UC Berkeley that is making headlines nationwide:

A recent study out of UC Berkeley finds metalloids present in 100% of tested tampons.

That sounds really, really serious. Without being explicitly trained on the interpretation of published research, you could be easily convinced of its significance. However, if you take the time to get past the medical jargon and statistical analyses, it is evident that the researchers understand the incredible limitations of their study -- going so far as to acknowledge its inconclusivity and statistical insignificance. Nonetheless, it is true - metalloids were detected in 100% of the tampon products that were studied. First, we aim to understand how metals and metalloids such as zinc, arsenic, lead, and many more get into our tampons in the first place.

How is this possible? Should I worry?

No, this is not an immediate cause for concern. Metals are not only found naturally in cotton samples, but are also intentionally

added to tampons.

• Naturally-Occuring Metals: organic contamination of plant materials

  • "Metals may be present in tampons within the the absorbent core materials (e.g., cotton, rayon, viscose);

  • Naturally occurring metals are taken up from soil and may be present within crops.

• Additive Metals: intentional and unintentional contamination

  • Unintentional addition of metals: applied to plants (present a fertilizer and/or pesticides)

  • Intentional addition of metals: serves various purposes within the tampon

    • Antimicrobial purposes:Ca, Co, Cr, Cu, Ni, and Zn may be added.

  • less risk of bacterial growth = less risk of Toxic Shock Syndrome

  • Arguably safer to add one of these agents

    • Odor control purposes: Ca, Co, Cu, Ni, Zn, Fe, and Mn may be added

    • Lubricant (for smooth insertion): Ca, Sr, Zn may be added

    • **The metals found in the highest concentrations (Ca and Zn) are the metals most often added to tampons due to their odor control, lubricant, and antimicrobial properties. Similar products include zinc-infused period panties.

...Shocking. Tampons that are designed to have metals within them in fact contain metals.

Breaking it Down: What The Media Got Wrong

Upon reviewing the literature, here are some of the inflammatory statements which I found to be dangerously misleading:

"There are several health risks associated with heavy metal toxicity. The plausible presence of metals in tampons is concerning not only given the known adverse effects of metals exposure on health...but also the characteristics of the vaginal epithelium that allow for efficient chemical absorption into systemic circulation.. Critical evidence for systemic exposure to toxins with tampon use is provided by the toxic shock syndrome outbreak of the early 1980s. In that epidemic, the Rely tampon [interacted]with menstrual blood and vaginal microbiota over time to result in overgrowth of the bacteria Staphylococcus aureus and its toxin in the vagina. The toxin crossed the vaginal epithelium, entered systemic circulation, and produced a range of serious symptoms in individuals, including hypotensive shock and even death..."

Spooky stuff. However, if you get past all of the scary and confusing mathematical formulas in the "methods" section, you may come across the true conclusion to UC Berkeley's research: "This study does not provide information about potential bio-accessibility of tampon metals and thus we cannot estimate health risks (if any) from tampon use."

Statistical Insignificance

• "We drew conclusions... based on robustness of the results and the strength of the association rather than relying upon statistical significance alone.We did not conduct formal statistical tests due to small sample size, and we did not have sufficient observations to perform formal statistical tests."

• Major issue: sample size, only 30 tampons were tested

  • 2 samples from each tampon. n=60 (total samples)

• No "p-value" given: p-values are a calculated measure of statistical significance. When p >0.05 the data is inconclusive; the results collected/conclusions drawn are not applicable outside of this study.
  

**TLDR; this data can not be used to make generalizations; it lacks the ability to provide any definitive conclusions. 

We could stop right here and end this article, but to quiet any naysayers, I'll continue.

Misleading Results & Statements

In reality, the only meaningful information from this study is that the 30 tampons tested appear to be contain detectable levels of certain metals/metalloids. We should further investigate particle transport across the vaginal mucosa/epithelium to better understand the potential for systemic absorption of any given molecule, and coincidentally the associated potential health risks.

• "All of the metals we assessed were present in quantifiable concentrations in tampons . For 12 out of the 16 metals, we found concentrations greater than the MDL in 100 % of tampon samples."

• MDL (method detectable limit) is a misleading representation of data. To the untrained eye, MDL can be easily perceived as a "maximum recommended level" or some sort of safety limitation.

  • MDL = the smallest amount that the test can detect with 99% confidence.

  • In other words, a metalloid level greater than the MDL only confirms presence of a particle - does not have any direct relationship to the absorption of particles into the bloodstream.

• Primary Outcome: Results were listed as metal concentrations (ng/g) in tampon samples

  • For reference, the average tampon weighs approximately 1 gram.

• Putting things into perspective: blood arsenic concentrations greater than 12 ng/mL of blood indicate significant toxin exposure. (CDC)

  • Arsenic average value measured in UC Berkeley study: 2.5ng per 1 tampon.

  • Even if 100% of the present arsenic was absorbed (which is essentially impossible) the blood level would be so miniscule it would not be able to be detected by any available blood test / would not have any immediate clinical significance.

• "The plausible presence of metals in tampons is concerning not only given the known adverse effects of metals exposure on health...but also the characteristics of the vaginal epithelium that allow for efficient chemical absorption into systemic circulation... Critical evidence for systemic exposure to toxins with tampon use is provided by the toxic shock syndrome outbreak of the early 1980s."

  • Misleading claims of permeability: there are numerous barriers to systemic absorption, and this is why we are able to treat many conditions vaginally with limited risk of systemic effects.

• . Critical evidence for systemic exposure to toxins with tampon use is provided by the toxic shock syndrome outbreak of the early 1980s."

  • Fear mongering with Toxic Shock comparison misinterpreted as a sweeping generalization .

  • Panic inducing: this comparison could be taken to mean that metals cross into the bloodstream in a similar fashion as bacteria do in TSS, a potentially fatal infection related to use of a tampon for an excessive duration, leading to bacterial buildup and septic infection. However, bacterial transport across the vaginal mucosa has absolutely nothing to do with metalloid transport across the vaginal mucosa. Metals are not bacteria, and bacteria are not metals.
    

Are 100% organic tampons any better?

Eh... maybe. Although the difference may not make any measurable impact on our health, it may be true that organic tampons are exposed to less metalloids than their non-organic counterparts.

Theoretically, this could be due to the pesticides/fertilizer contributing to added metals in raw materials or by intentional addition of metals due to favorable qualities.

Organic vs. Non organic results of the study were conflicting:

• "We found significant differences between median metal concentrations for organic versus non-organic tampon samples for all metals except Cu, Hg, Ni, and Se. Median concentrations of Ba, Cd, Co, Pb, and Zn were lower in organic tampons compared to non-organic tampons (effect estimates ranging from −48,605.46 ng/g [95 % CI: −63,500.14, –33,710.77] for Zn to −9.93 ng/g [95 % CI: −13.62, −6.23] for Cd), while median concentrations of As, Ca, Cr, Fe, Mn, Sr, and V were higher in organic tampons compared to non-organic tampons (effect estimates ranging from 4.53 ng/g [95 % CI: 2.32, 6.75] for As to 78,980.41 ng/g [95 % CI: 55,016.32, 102,944.50] for Ca)"
  

In summary, stick to what works for you. Sustainable, traditional, organic, and inorganic options --for all intents and purposes -- are equally safe. There is no need to throw out your cabinet of period products, even after watching a "Tik Tok" which may have told you to do so.

**Unbeknownst to me (a native New Yorker) NY state law requires tampon manufacturers to list ingredients in all tampons sold in NY. Check your state laws; this may help to identify tampons with intentionally added chemicals, including metalloids.

Bonus: Can metalloids cross the vaginal mucosa and enter systemic circulation?

Throughout reviewing the research on this topic, I kept asking myself "what properties determine which chemicals can and can not be absorbed vaginally?". In practice, I know that most prescription vaginal treatments are intended to work locally, not systemically. In fact, vaginal drug delivery is an incredibly useful way to avoid systemic side effects, due to the limited ability of drugs to enter the bloodstream. Unfortunately, the UC Berkeley study avoided this question entirely-- perhaps because it would have illuminated their limitations. Purely out of curiosity, I began to seek an understanding: could metals even cross the vaginal epithelium?

Upon reviewing several clinical studies, I find no conclusive evidence that any measurable amount of metalloids (from tampon use) would enter the bloodstream. I want to urge that I can not be definitive on this conclusion, due to teh dynamic and interpersonal differences in anatomy, vaginal microbiome, pH levels, etc. Regardless, Here's a brief explanation of my reasoning:

• Mucosal Barrier: the most significant barrier to vaginal systemic absorption.

  • Natural physical protection from debris, bacteria, and more. Responsible for clearing microbes from the vagina.

  • Selective permeability to drugs and other molecules.

    • These mechanisms are mainly governed by mucus physicochemical properties such as pore size, viscoelasticity, pH, ionic strength, and charge,

  • The mucus layer contains a variety of bonds and intermolecular forces which determine plasma absorption: both covalent and noncovalent interactions (hydrophobic, electrostatic, hydrogen bonds, etc.)

    • Creates a unique mesh network filter that decreases penetration of molecules such as metalloids

    • CVM (cerivicovaginal mucus) pore size may be approximately = 340 ± 70 nm (average size 10-500nm)

• Molecular Size: molecules that can pass through vaginal epithelium: 20-80 nm

  • large molecular weight molecules permeate vaginal mucosa at a slower rate than smaller molecules. This is true for both hydrophilic and lipophilic molecules.

• Molecular Weight: MW >200 daltons significantly decreases absorption across the vaginal mucosa.

  • Example: molecular weight of lead (Pb) is 207.2 daltons (CDC)

  • Molecules exceeding 1000 daltons have negligible dissolution across the vaginal epithelium

• Polarity: lipophilic and hydrophilic molecules can pass, but lipophilic molecules have a much easier time crossing the vaginal epithelium.

  • Example: Arsenic (As) forms polar molecules (hydrophilic)

  • Hydrophobic/Lipophilic molecules typically exhibit low permeability across the mucus barrier due to interactions with the glycoproteins and lipids in the mucus

  • Even in small molecules, polarity / hydrophilicity complicates mucosal & epithelial diffusion.
    

Resources:

1. Shearston JA, Upson K, Gordon M, et al. Tampons as a source of exposure to metal(loid)s. Environ Int. 2024;190:108849. doi: 10.1016/j.envint.2024.108849

2. Leal J, Smyth HDC, Ghosh D. Physicochemical properties of mucus and their impact on transmucosal drug delivery. Int J Pharm. 2017;532(1):555-572. doi:10.1016/j.ijpharm.2017.09.018

3. Shapiro RL, DeLong K, Zulfiqar F, Carter D, Better M, Ensign LM. In vitro and ex vivo models for evaluating vaginal drug delivery systems. Adv Drug Deliv Rev. 2022;191:114543. doi: 10.1016/j.addr.2022.114543

4. Zierden HC, Josyula A, Shapiro RL, Hsueh HT, Hanes J, Ensign LM. Avoiding a Sticky Situation: Bypassing the Mucus Barrier for Improved Local Drug Delivery. Trends Mol Med. 2021;27(5):436-450. doi: 10.1016/j.molmed.2020.12.001. Epub 2021 Jan 4.

5. Subi MTM, Selvasudha N, Vasanthi HR. Vaginal drug delivery system: A promising route of drug administration for local and systemic diseases. Drug Discov Today. 2024;29(6):104012. doi: 10.1016/j.drudis.2024.104012

6. Lock JY, Carlson TL, Carrier RL. Mucus models to evaluate the diffusion of drugs and particles. Adv Drug Deliv Rev. 2018;124:34-49. doi: 10.1016/j.addr.2017.11.001. Epub 2017 Nov 5.

7. Van Eyk AD, Van Der Bijl P, Moll LM. Physicochemical Characteristics of Molecules and Their Diffusion across Human Vaginal Mucosa. European Journal of Inflammation. 2008;6(2):65-71. doi:10.1177/1721727X0800600203