How Dirty Is the Stuff You Touch Every Day? (Your Toothbrush Might Surprise You)

Quick: which is dirtier — your toilet seat or your toothbrush? Most people guess wrong.

We spend a lot of energy scrubbing the bathroom, but the objects we touch most often rarely get the same attention. Microbiologists have been swabbing everyday items for years, and the results are a little humbling. Here's what the research actually shows — and why it matters for what's sitting next to your sink.

Bacteria load on household items

A well-known study by microbiologist Dr. Charles Gerba at the University of Arizona counted bacteria on common surfaces, using the same method for each one:

• Toilet seat: about 49 bacteria per square inch
• Computer keyboard: about 3,295 bacteria per square inch
• Office phone: about 25,127 bacteria per square inch

Why is the toilet seat so low? Because it's one of the few surfaces people disinfect regularly. Things we touch all day with our hands — and rarely clean — build up far more.

Then there's your toothbrush

In a study published in the Australian Dental Journal, researchers gave volunteers new toothbrushes and collected them after three weeks of normal use. Each brush carried between 10,000 and 1,000,000 bacteria — on a brush head smaller than a square inch.

Before you throw yours away: most of these bacteria come from your own mouth, and a used toothbrush is supposed to have some. That's normal. The interesting part is where that brush goes next.

Every morning, it touches your toothpaste tube

Squeezing toothpaste onto a brush usually means pressing the bristles right against the tube's opening. A study that swabbed the openings of toothpaste tubes after 30 days of use found about 250 bacterial colonies on tubes used by one person — and about 710 on tubes shared by a family. That's roughly three times as many when four or five brushes are touching the same spot every day.

To be clear, that study looked at the outside of the opening, not the paste inside, and it didn't find that anyone got sick. But it's a good reminder that a shared tube is a shared surface.

Why tube toothpaste needs preservatives

Regular toothpaste is a paste because it contains water. Anything with water in it can grow bacteria and mould over its shelf life, so water-based toothpastes need preservatives to stay stable from the factory to the last squeeze.

Toothpaste tablets work differently. They're pressed dry, with no water, so there's nothing for preservatives to protect against. NovaTabz tablets don't contain any.

One tablet each

With tablets, there's no shared nozzle. Everyone takes their own tablet, chews it briefly, and brushes with a wet toothbrush as usual. Nobody's brush ever touches the jar.

Tip: tip a tablet into your palm (or straight into your mouth) instead of reaching into the jar with wet fingers. Keep the lid closed between uses so the tablets stay dry.

Simple habits for a cleaner routine

• Rinse your toothbrush well after brushing and let it air-dry upright.
• Don't store brushes so their heads touch each other.
• Replace your toothbrush every three months, or sooner if the bristles fray.
• Wash your toothbrush holder regularly — in an NSF International home study, it ranked as the third-germiest item in the house.
• Keep toothbrushes away from the toilet, or close the lid before flushing.
• Never share toothbrushes.

Your new morning routine starts here: shop NovaTabz toothpaste tablets.

Sources

• Gerba, C. — University of Arizona study on bacteria on office and household surfaces (reported in The Register, 2004)
• Taji, S. & Rogers, A. (1998). The microbial contamination of toothbrushes. A pilot study. Australian Dental Journal, 43(2), 128–130. Abstract
• Microbial Contamination of Tooth Paste Tube Orifice. Indian Journal of Public Health Research & Development. Abstract
• NSF International (2011). Germiest Items in the Home

Disclaimer: The information provided in this article is for educational and informational purposes only and is not intended as professional medical or dental advice, diagnosis, or treatment. Always seek the advice of your dentist, physician, or other qualified health provider with any questions you may have regarding a medical or dental condition.