We are constantly exposed to many chemicals, including nanomaterials, for example through the air we breathe, the food we eat, the clothes we wear, or the sports equipment we use. Because of their wide use in society and our increased exposure to them, it is important to understand any potentially harmful effects they might have on our health.

Assessing the potential health hazard of a nanomaterial is done through toxicological studies that focus on a specific organ, such as the liver, kidney or blood and route, such as ingestion, inhalation or skin absorption.

For example:

• Mutagenicity studies examine a chemical’s ability to cause changes to a cell’s genetic material.
• Inhalation toxicity studies evaluate effects of airborne nanomaterials after they get into the lungs.
• Reproductive toxicity studies look at effects on fertility and the development of offspring.
• Dermal studies consider the effects of nanomaterials absorbed through the skin.

Doing toxicological studies with nanomaterials is challenging. Due to their size and surface area, they can have poor absorption or low solubility, and their properties can be more difficult to analyse than other chemicals.

One of the main objectives in identifying a hazard is to establish the relationship between the dose of a substance and the severity of their effect (the ‘dose-effect relationship’). By doing toxicological studies, a dose threshold can be determined below which it is assumed that no adverse effect will occur. While above this threshold, the potential risk needs to be controlled and managed, by minimising our exposure to them.