You probably don’t think much about your toothbrush, but the one you choose actually makes a big difference to the environment. A group of researchers carried out the first lifecycle assessment of toothbrushes to measure their environmental footprint, with electric ones not doing too well.

Healthcare is a major emitter of environmental pollutants that adversely affect health, but awareness of these effects remains low both in the industry and in the general consumer population. There’s currently little evidence or guidance regarding the sustainability of specific healthcare interventions, services, or devices.

A team at Trinity College Dublin (TCD) collaborated with the Eastman Dental Institute at University College London and analyzed the carbon footprint and human health impact of the electric toothbrush, the standard plastic brush, the plastic brush with a replaceable head and the bamboo brush.

The electric toothbrush performed consistently poorly compared to the three types of manual toothbrushes and had the greatest impact in 15 out of 16 environmental categories measured. On the other hand, the bamboo and replaceable-head plastic toothbrushes, if recycled, had the lowest impact in all categories.

“There are billions of toothbrushes used and discarded every year. Our research shows that electric toothbrushes are actually harmful to the planet and to the people involved in the manufacturing process and distribution,” said Brett Duane, lead researcher and professor at TCD, in a statement.

The study showed that the electric toothbrush has an impact of 10 hours in disability-adjusted life years (DALYs) for those associated with its manufacturing, five times higher than a standard plastic toothbrush. One DALY can be thought of as one lost year of “healthy” life.

The bamboo toothbrush is also not the most sustainable option on your shopping list, the researchers argued. Using them just stops land from being put to better use such as helping biodiversity, or in growing forests to offset carbon emissions. This leaves the plastic toothbrush as the best option, but only if part of a recycling process.

Plastic brushes that can be recycled don’t take up a lot of land and they don’t need lots of water to manufacture. Overall, the most important thing is to keep the plastic in the recycling chain. We need a system where plastic toothbrushes can be collected like batteries and then recycled into new products, the researchers argued.

The findings could be used to inform individual consumer choice, oral health recommendations, procurement of toothbrushes for public health programs, and toothbrush manufacturers, the researchers argued. The lifecycle assessment could even drive healthcare providers to a more sustainable system.

The study was published in the British Dental Journal.