The Life & Deaths of a Toothbrush (Part 2)
Post by Sebastian Carpenter, CeCe Liu, Joe Nangle & Ji Young Ohn for Prof. Jonathan Chapman’s “Design That Lasts”, CMU School of Design, Spring 2021
This post is part of a 2-part series. Please take a look at Part 1 before diving in here.
Is something missing from this airline salad?
If you answered “precisely one olive — for good reason”, you may be either a) crazy or b) aware of Robert L. Crandall.
An icon in the aviation industry and former CEO of American Airlines, he was responsible for the first frequent flyer program, modernization of airline reservations, and more.
But that’s not what interested us in Crandall. Instead, it was his determination that removing a single olive from American’s inflight meal service would save the airline $40,000 annually (Deutsch, 2001).
This legendary 1980’s anecdote played a significant factor in driving our design decisions and philosophy about the perils of single-use toothbrushes, especially those supplied in complimentary airline toiletry kits.
Although olive-cutting might focus on cost-cutting, we saw bigger implications, and the underlying principles influenced our design approach.
Olive Math
While Crandall’s idea reduced spending directly on olives, it also pulled less obvious levers.
An olive weighs between 3 and 5 grams (Bjarnadottir, 2019). Removing one per salad on a Boeing 787–10 with seating capacity of 300 passengers flying New York to London, then, means propelling 824 to 1,330 fewer grams of olives across the Atlantic Ocean at jet speed.
While a mere kilogram reduction might seem insignificant in the context of a single flight, the fuel savings from transporting less mass across the skies can be significant when scaled to an entire airline or industry.
United Airlines also yielded impressive results with a minor change: by printing their inflight magazine on lighter paper, a reduction of 28 grams, United expects to save “643,000 liters of fuel and $300,000 a year” (Ziemelis, 2019).
To take United’s math a little further, we also considered the carbon impact of this reduction. 643,000 liters of jet fuel is roughly 516.22 tons (My6EB, 2020), and for each ton of jet fuel burned, 3.15 tons of CO2 are emitted (GreenAir, 2021). So, United’s paper-thinning also prevented ~1,626 tons of CO2 emissions.
With these considerations in mind, we began to explore how even small changes to the toothbrush in each complimentary toiletry kit could add up.
Material Selection
The typical airline toothbrush consists of an ABS or polypropylene handle with nylon bristles. For something that likely gets used only once, or is even disposed unused, this presents a huge environmental overhead on the material extraction frontend, transportation, and the centuries-long decomposition backend.
Instead, we sought to incorporate materials that could create a closed loop. Larger components should be reusable, and for the portions that can’t be reused (or that escape the loop), the toothbrush must be entirely compostable. Critically, the object must be compostable as a monolith, rather than, for instance, requiring users to “simply” remove non-compostable bristles with pliers, as some “compostable” toothbrushes do.
Our design consists of three parts: A reusable handle attached to disposable head with disposable bristles, both designed for single (or minimal) use.
- The handle: of bamboo, a fast-growing grass quickly becoming the standard material for handles in compostable toothbrushes. These bamboo handles are reusable for at least 180 cycles, potentially more.
- The head: of two potential materials — a bioplastic (likely PLA) or a food-grade soy wax. Both can be cast in a mold, a necessity for manufacturing. Biodegradable options exist, although nearly all bioplastics must be industrially composted (Gibbens, 2018). The necessity for industrial compost is not an issue so long as the toothbrush stays within the closed loop; but it might become a problem if pieces escape the loop and are disposed in landfill.
- The bristles: while we explored a number of alternatives to explicit bristles (including testing crude prototypes with both sponge and luffa heads), traditional bristles prevailed as the best choice to preserve function and comfort. Two biodegradable options, both in use in existing toothbrush products, seem viable — boar hair and bamboo charcoal fibers (our preference as a vegan option).
The plastic head and bristles are removable from the handle and would be composted as a single unit. The handle could then be cleaned and assembled into a fresh toothbrush. The unit is packaged in paper or cardboard and includes a solid toothpaste tablet, making the entire unit biodegradable and minimizing packaging.
With a PLA head and bamboo bristles and handle, the entire unit (less packaging and toothpaste tablet) weighs just 2.8 grams, approximately one olive less than today’s standard (8.2 grams).
Product Considerations
After multiple iterations, we arrived at a final form: a 3.5” long modular travel toothbrush. We reduced the handle length and proportions significantly to reduce material mass. We also reduced the number of bristles and adopted a simple brush-head attachment mechanism for assembly and disassembly.
The final form is soft, intimate, and comforting.
User Scenario
Recognizing that many passengers never use their toothbrush, we also propose eliminating it from the standard toiletry kit (which weighs 70 grams!), further reducing the number carried per flight. Instead, passengers could dispense a toothbrush as needed outside lavatories, and return it back to the dispenser to close the loop after brushing. We picture a scenario like this:
Each toothbrush is separated within the dispenser upon disposal. Once separated, each component can enter the appropriate cycle: the handles cleaned and sterilized, then assembled into a new unit; brush-heads to industrial compost.
And, critically, in the “worst case scenario,” our brush would break down in landfill in under a millennium.
Works Cited
- “Bamboo Toothbrush.” Isshah. Isshah. url: http://www.isshah.com/index.php?route=product/product&product_id=132
- Bjarnadottir, Adda. “Olives 101: Nutrition Facts and Health Benefits.” Healthline. 21 May 2019. Healthline Media. url: https://www.healthline.com/nutrition/foods/olives
- Deutsch, Claudia H. “. . . And to Penny-Pinching Wizardry.” The New York Times, Issue May 6, 2001, Section 3, Page 1. 6 May 2001. The New York Times Company. url: https://www.nytimes.com/2001/05/06/business/and-to-penny-pinching-wizardry.html
- “Fuel Conversions.” myE6B. Aviation Mobile Apps. url: http://mye6b.com/Fuel/
- Gibbens, Sarah. “What You Need to Know About Plant-Based Plastics.” National Geographic. 15 November 2019. The National Geographic Society. url: https://www.nationalgeographic.com/environment/article/are-bioplastics-made-from-plants-better-for-environment-ocean-plastic
- “Glossary.” Greenair Archives. Greenair Communications. url: https://www.greenaironline.com/news.php?viewStory=217
- “Natural Bristle Bamboo Toothbrush — 6-Pack.” Gaia Guy. Gaia Guy. url: https://www.gaiaguy.com/products/natural-bristle-bamboo-toothbrush-6-pack
- “Proper Care & Disposal.” Brush with Bamboo. Brush with Bamboo. url: https://www.brushwithbamboo.com/proper-care-disposal/
9. Žiemelis, Gediminas. “How Your Heavy Coat Can Cut Airline’s Profit?” Aviation Voice. 1 August 2019. Aviation Voice. url: https://aviationvoice.com/how-your-heavy-coat-can-cut-airlines-profit-201908011139/
