Chemicals and their properties Day 1. Adam Peters and Graham Merrington 2017

Identification Chemical Properties Environmental Fate Information Sources Missing Information Example Chemicals Summary 2017

Identification Chemicals or Substances? Unique structure or complex mixture? Ambiguity in chemical identification Multiple CAS numbers , stereo isomers Commercial products (mixtures) CAS or EC numbers (EINECS, ELINCS) IUPAC name, Trade name, Common name Identify most suitable CAS/EC number and name for searching 2017

Chemical Properties Partition coefficient Water solubility Log KOW, partitioning, accumulation, Water solubility Environmental mobility, bioavailability Vapour pressure Environmental mobility, long range transport Potential for ionisation? May be predictable from the chemical structure if not available (USEPA EPISuite) 2017

Environmental Fate Partitioning Degradation Bioaccumulation KOC, KD, KP, soil, suspended sediment Henry’s Law Constant Degradation Photolysis Hydrolysis Biodegradation, primary or ultimate Bioaccumulation KOW, BCF, BAF, BMF 2017

Finding Information Is an EQS available? Searching databases Use the EQS as the basis for effects information, additional information on fate may still be required Searching databases ECHA dissemination portal IUCLID, ESR risk assessments OECD HPV programme USEPA ECOTOX Open literature… 2016

Missing Information QSAR estimates Requires structure USEPA EPI Suite models Requires structure Many structures in database SMILES code Requires some expert chemical knowledge Validity of applied models Comparison against measured data Peer review of outputs by experienced staff 2017

Partitioning and Fate How will a substance behave in the environment? Volatile, transport and exposure via air, rapid removal and dispersion Water soluble, transport and exposure via water, available for biodegradation Highly insoluble, high partition coefficient, binds strongly to soils and sediments, low availability for biodegradation, resistant to degradation, accumulates in organisms 2017

Predicting Fate Fugacity modelling – Don Mackay Affinity of a substance for different phases Air, soil, water, sediment, biota Simplistic systems and routes of entry Level I, single input, equilibrium Level II, continuous inputs, transformation Level III, compartment specific inputs 2017

Example Chemicals Example substances which will be used throughout the course to demonstrate the complete risk assessment process for a diverse range of substances You will be obtaining, and assessing, information on some substances yourselves 2017

Approaches Risk assessment approach taken may define some of the information requirements Many models require a selection of specific input parameters In many cases the selection of the most appropriate value for each input parameter will need to be justified and recorded 2017

2016