1. Exposure Modelling Day 1.
Adam Peters and Graham Merrington
2017

2. Exposure Conceptual model Wastewater Discharges Emission Scenarios
2017

3. Exposure Modelling ECHA Guidance for Risk Assessment R16
Based on the approaches previously used for the risk assessment of chemicals in Europe (EU TGD)
Complete approach for exposure assessment defined in R16
EUSES implements the same procedures
Requires minimal input information
Molecular weight, vapour pressure, water solubility, log KOW
Avoids making simple mistakes
Spreadsheet versions can be developed
2017

4. Emissions Data Typically for prospective risk assessment
How much of this substance will be released into the environment from this process, operation, or application?
Quantities in use?
Containment and potential for dispersal?
Specific equipment, use at specified sites only, indoor or outdoor use, professional use only, wide spread dispersive use
Routes of emission
Air, water, soil (usually only indirectly via deposition from air and spreading of sewage sludges)
2017

5. Sewage and Wastewater Treatment
Typical for large industrial sites
Treatment may be on-site, off-site (municipal), or both
Concentrations of chemicals in many wastewaters may not be limited by water solubility
Fate during treatment
Degradation, volatilisation, partitioning to sludge, and aqueous phase emitted as effluent
2017

6. Discharges to surface waters
Discharge of sewage effluent into receiving water
Takes account of dilution and partitioning to SPM
May also need to consider duration and frequency of emission
Peak concentrations or annual averages?
2016

7. Emission Scenarios Continuous emission from an industrial site
Review of consented discharge
Intermittent emission from an industrial site
Batch processes or development work
Accidental emission directly into the environment
Spillages, fires, shipwreck
Land application of materials exempt from waste management licencing
Residual medicines in manures
2017

8. Emission Source Mass of substance used Frequency of use, emission days
Fraction emitted
Treatment efficiency
Effluent flow rate
2017

9. Spatial Scales Local Regional Continental
e.g. the area surrounding an industrial site, farm, or waste management facility
Regional
Usually taken to be a whole country, but could be smaller, e.g. a county
Likely to include a number of similar operations
Continental
Aggregation of several regions
2017

10. Background Concentrations
May arise from widespread use and emission of substances
Legacy substances still found in the environment
Also relevant to naturally occurring substances
Sometimes considered for compliance assessment of metals
Only likely to be relevant for marginal failures
2017

11. Sewage Treatment Removal of BOD & suspended solids
Also degradation of some organic chemicals
Other removal processes
Adsorption to sludge –partitioning substances
Volatilisation – volatile substances
Degree of degradation and removal can be highly variable between different works
Limited useful information
SIMPLETreat estimates
2017

12. Soil Exposures Atmospheric deposition of air emissions
Land spreading of sewage sludges
Land spreading of other waste materials
Particular Issues
Averaging period for exposure duration
Relevant soil depth
Accumulation models
2017

13. Emission to Environment
Wastewater discharge into a river
Concentration of substance in discharge
Size (flow rate) of discharge relative to river?
Partitioning of substance in river
Deposition to sediments
Resulting dissolved concentration in river after dilution
Are local sediments likely to become contaminated?
Are there any potential concerns for local predators?
Are there any potential concerns for local fishermen?
2017

14. 2016