Chemical similarity: structuring risk and hazard assessment

Wassenaar, P.N.H. (2022)

Doctoral Thesis

At the moment, over 350.000 chemicals are registered worldwide for production and use. Their application, however, may harm human health and the environment. To manage the safety of chemicals, particular chemical legislations are in place, which make use of risk and hazard assessments. However, there are several challenges for current risk and hazard assessments, including i) a lack of (reliable) data, and ii) a relative slow and inefficient evaluation and regulation process. In this thesis, I investigate specifically whether more extensive and targeted use of chemical similarity within risk and hazard assessment has the potential to improve these aspects. Chemical similarity could be a valuable factor as similarities between two chemicals could be a sign of similar physicochemical and/or toxic properties. The separate sections within this thesis specifically focus on chemical similarity in relation to screening, data generation and evaluation of substances. The results of this thesis indicate that chemical similarity could be used to identify and evaluate hazardous properties of single and groups of chemicals. Accordingly, I promote more extensive use of chemical similarity within risk and hazard assessment as it has the ability to circumvent several issues related to a lack of data and evaluation efficiency.

• Substances of very high concern
• Screening
• In silico
• Computational toxicology
• Hazard assessment
• Risk assessment
• PBT-assessment
• Grouping of chemicals
• Read-across

• All authors: Wassenaar, P.N.H.
• Supervisor: Peijnenburg, W.J.G.M.; Vijver, M.G.
• Committee: Tukker, A.; Bodegom, P.M. van; Suh, S.; Rijn, J.N. van; Benfenati, E.; Papa, E.
• Qualification: Doctor (dr.)
• Awarding Institution: Institute of Environmental Sciences (CML), Faculty of Science, Leiden University
• Date: 2022-04-19
• ISBN (print): 9789051917000