Some chemicals may harm our health. Normally, the longer a chemical has been on the market and the more widely it has been used, the more we know about its toxicity. But for nanomaterials, this is not always the case as their use has rapidly increased in society. It is important to carry out studies on nanomaterials to find out if they’re safe and, if not, to find ways to protect our health.
Studying the toxicity of a chemical is done using validated test protocols. For nanomaterials, these studies mainly focus on:
- Acute effects. These occur as irritation or corrosion of the skin, or as irritation of the eyes, nose or throat. Such effects are often studied by applying a test material on reconstructed human tissues or on animals. Some nanomaterials can also cause more harmful effects if swallowed, breathed in, or if our skin gets exposed. Life-threatening effects are mainly tested on animals, but tests with cell cultures can also indicate high toxicity.
- Allergic effects. Sensitisation studies check whether a nanomaterial can cause allergic reactions, for example, through skin contact. Some of these effects can already be studied using non-animal methods. Nanomaterials can also cause respiratory sensitisation, like asthma. Currently, there are no regulatory accepted animal test methods to test for respiratory sensitisation. So data from humans that have such symptoms is used to confirm that a chemical is causing this effect.
- Target organ effects. These are effects that can impact how a specific organ functions, or cause changes in the structure of organ tissue, in the worst case resulting in cancer. The effects may also be local, such as lung effects after a nanomaterial has been breathed in. For the most harmful effects to occur, repeated exposure for weeks or months is normally needed. Target organ toxicity is mainly studied on rats.
- Mutagenic effects. Mutations are changes to the genetic material of cells or organisms. Studies investigating whether a nanomaterial is likely to cause mutations are often carried out using cultured cells. A nanomaterial with mutagenic effects is, in many cases, also likely to cause cancer.
- Reproductive effects. Reproductive effects include changes in fertility or disrupting the development of foetuses. For women, this can mean difficulties getting pregnant, and for men, changes in sperm cells. Reproductive and developmental toxicity studies are still carried out on animals, sometimes over more than one generation.
In the EU, the hazardous properties of nanomaterials must be assessed, and their safe use needs to be ensured.
For the hazardous ones, several regulatory measures can be taken to protect our health. For example, they may need an EU-wide harmonised hazard classification. This also requires that information about the hazard is included on the labels of products that contain them.