Are silver nanoparticles harmful?

Commonly used

Nanotechnology is increasingly used in consumer products, medicines and building products. The potential risks of using engineered nanoparticles need to be monitored so that the industry can develop products that are safe for humans and nature.

Previous research has shown that nanoparticles can cross both the blood-brain barrier and blood-testes barrier in mice and rats, and are taken up by cells. This study aimed to see if silver and titanium dioxide nanoparticles had any effect on human and mice testicular cells.

The researchers found that silver nanoparticles had a toxic effect on cells, suppressing cellular growth and multiplication and causing cell death depending on concentrations and duration of exposure. The effect was weaker for titanium dioxide nanoparticles, although both types did cause cell type-specific DNA damage, with possible implications on reproduction as well as human and environmental health.

"It seems that the type of nanoparticle, and not the size alone, may be the limiting factor" says Nana Asare, primary author of the study published in Toxicology.

Further studies using in vivo models are needed to study the impact of nanoparticles on reproductive health.

The researchers used cells from a human testicular carcinoma cell line and testicular cells from two strains of mice, one of which is genetically modified to serve as a representative model for human male reproductive toxicity. The cells were exposed to titanium dioxide nanoparticles (21nm) and two different sizes of silver nanoparticles (20 nm and 200nm) over different concentrations and time periods. Both sizes of silver nanoparticles inhibited normal cell function and caused more cell death than the titanium dioxide nanoparticles. In particular, the 200 nm silver particles caused a concentration-dependent increase in DNA damage in the human cells.

Nano facts

• Nanotechnology is technology on the atomic and molecular scale
• A nanometre (nm) is one billionth of a metre
• A nanoparticle is a particle with one or more external dimensions in the size range 1 nm -- 100 nm
• The aspect ratio between a nanoparticle and a football is similar to that between a football and Earth
• Nanotechnology is working on a scale of 100 nm (which corresponds approximately to the size of a virus) down to the size of atoms, about 0.1 nm
• Nano-scale materials and processes are present in nature, ranging from free molecules in gases and liquids to proteins and organic processes
• Some substances are produced unintentionally, such as welding dust and diesel particulates