They’re not green (Image: Domani/Stock.XCHNG)

ANTIBACTERIAL nanoparticles may have more of an impact on the environment than we thought, including potentially raising levels of greenhouse gases.

Silver nanoparticles are used as an antibacterial agent in a wide range of products, from odour-free socks to wound-healing bandages (see diagram). They can find their way into waste water, and have been shown to reduce the activity of bacteria used to remove ammonia when the water is treated.

So far most of the research on the environmental impact of nanoparticles has been carried out on single microbe or plant species within the …