@ Khalid, materials which by themselves are not very harmful could be toxic if they are inhaled in the form of nanoparticles. The effects of inhaled nanoparticles in the body may include lung inflammation and heart problems. Toxicity of nanoparticles depends on their surface properties, coating, structure, size, and ability to aggregate. If nanoparticles have poor solubility they can cause cancer. Nanoparticles have been shown to lead to brain damage in fish and dogs. Nanotechnology has also led to a rise in pollutants, including air and water contamination. Nano pollution is the term for contamination brought on by nanotechnology. For living things, this form of pollution is extremely harmful.

Mostly think of nanoparticles as new materials. We often don't know what will happen. For example, gold nanoparticles of a certain size interact with DNA and cause problems. Of course bulk gold is no problem. Note that we have been surrounded by some nanoparticles for a very long time.... any wood fire generates carbon nanoparticles. As with chemicals testing is needed. Not all nanoparticles will be harmful but we need to determine which are a problem.

In electrochemical sensors, risks associated with nanotechnology include potential health and environmental hazards due to the unknown toxicity of nanomaterials used in the sensor fabrication, as well as concerns about their long-term effects. Scientists are actively working to address these risks and develop guidelines for safe and responsible use of nanotechnology.