Silica is the best environmental protection substitute for plastic beads
Plastic beads are small plastic particles, usually less than 0.5mm (500 microns) in diameter. They are used in toothpastes, sunscreen, hand sanitizers and many other products, mainly to enhance friction. After the product is used, the plastic beads will be washed away and eventually enter the ocean and other ecosystems. Not only marine organisms, but also human bodies have detected the existence of plastic beads, so the use of plastic beads has been explicitly prohibited in many regions of the world.
A research team at Imperial College London assessed the environmental impact of 29 alternatives to plastic beads. They found that the naturally occurring rich mineral silicon dioxide was the best substitute, and its overall performance was better than that of plastic beads in all categories. The research results were published in Nature Sustainability.
They found that there are two main factors affecting the environmental reputation of materials: the amount of energy intensive processing they need (producing greenhouse gases), and the amount of land and water they need for plant materials.
Almond husk is usually considered as an ideal "natural" substitute, but it needs a lot of land and water to grow. If it is planted in water deficient areas, it is a bad environmental substitute. Citric acid requires much less water and land, but requires a lot of processing and energy for manufacturing. Silicon dioxide, the best substitute, is inert, non-toxic and natural, so it is easy to purchase and process, and is unlikely to cause long-term negative effects.
However, the research team also pointed out that the "best" alternative depends on the specific situation. For example, the titanium dioxide used in toothpaste has a relatively large impact on the environment, and it is also used in sunscreen, while the substitute may not have the same health benefits to prevent skin cancer