Predicting the properties of nanomaterials
To speed up the testing of nanomaterials and ultimately our understanding of their potentially hazardous effects, researchers can use a read-across approach. Read-across uses information from similar source substances where data exists to predict the properties of target substances where little information has been generated or is missing.
Read-across can be used for individual substances, including nanomaterials, under the REACH Regulation but it can also be applied to groups of substances and nanoforms to determine any trends between them. If the grouping of substances and read-across has been done correctly, experimental testing can be reduced as there is no need to test each target substance separately.
Using existing data to fill gaps
The read-across approach is particularly useful when generating data for regulatory purposes so that authorities have sufficient information to make decisions on chemicals and ensure their safe use.
Grouping is possible:
- Between different nanoforms of a substance
- Between other substances in the same size range
- Potentially between various forms of a substance from their bulk form to their nanoforms
Grouping was initially developed for chemicals and was further applied for nanoforms.
Defining the properties of nanomaterials
Nanomaterials can be manufactured and modified to have different characteristics. They cover size, shape, crystallinity and surface treatment. The latter is the process of coating the surface of the nanomaterial. For instance, some multi-walled carbon nanotubes can be coated to make them attach to organs and deliver pharmaceuticals more efficiently.
Registering chemicals under REACH using read-across
The REACH Regulation requires data on substances produced over 1 tonne per year. For nanoforms it can be difficult to reach this amount as the requirement refers to the overall tonnage of the nanoforms and other forms of a substance and not to the individual nanoform.
Nanoforms are often produced in much lower quantities, ranging from a few grams up to 100 kilos a year depending on their uses and markets.
Companies need to justify the use of read-across when registering their chemicals under REACH. This is done with a scientifically justified explanation of why the grouping of nanoforms is possible, supported by available data, for example on hazard or fate for both the source and the target substances.
Developing frameworks for read-across
During the last decade, many advances have been made to test if read-across for nanoforms is possible and to what information is needed for a reliable read-across approach.
ECHA and the OECD have published guidance to give a frame and boundaries on how to apply read-across while ensuring regulatory validity and acceptance.
Research projects, such as GRACIOUS, have developed a framework mainly for industry to apply read-across under REACH, but also to support sustainable product development.
While progress has been made, more needs to be done to further strengthen the validity and recognition of read-across between different nanoforms.