Ohio Northern University
CE 3231 - Introduction to Environmental Engineering and Science
Introduction
Chemistry, Microbiology & Material Balance
Water & Air Pollution
Partition Coefficients and Modeling
Real data characterizing risk is difficult and expensive to come across. As
thousands of chemicals enter the market place each year, models help
estimate the risk based upon compound structure and physical-chemical
properties. Here, we examine how partition coefficients are used to make
decisions.
Env Risk Management
Readings for This Class:
Exposure Assessment
 pathways of exposure
 calculating CDI
Lecture 32
Partition Coefficents and Modeling Risk
(Risk III)
Risk & Risk Assessment
 Topics Covered Include:
 New Chemicals Review
 Risk Models
 Partitioning Coefficients

Octanol water

Vapor pressure
New Chemicals Review Program – Premanufacture Notice
US Environmental Protection Agency
Office of Pollution Prevention and Toxics
Toxic Substance Control Act – Section 5
Program Goal
Serve as a “gatekeeper to help manage the
potential risk from chemicals new to the
marketplace.”
New Chemicals
Review Program
Risk Evaluations
Risk Based
- potential health risks
- toxicological investigations
Exposure Based
- potential exposure risks
- chemical property investigations
- fate modeling: ranks outcomes I to IV
New Chemicals
Review Program
Physical/Chemical Properties
Boiling Point
Vapor
Pressure
Estimate
Concentration
in Air
Estimate
Inhalation
Exposure
Melting Point
Estimate
Henry’s Law
Constant
Estimate
Concentration
in Water
Estimate
Volatilization
from water
Water Solubility
(estimate)
Octanol/Water
Partition
Coefficient
(Kow, P)
Estimate
Absorption
through skin,
lungs and GI
Estimate
Removal in
Wastewater
Treatment
Soil/Sorption
Coefficent (Koc)
(estimate)
Estimate
Bioconcentration
Estimate
Toxicity
Estimate
Migration
through Soil to
Groundwater
Estimate Risk to Human Health and the Environment
New Chemicals
Review Program
CAS Number : 000105-55-5
Chem Name : n-boulanger
Mol Formula: StRuCtUrE
Mol Weight : 186
Melting Pt : -10 deg C
Boiling Pt : 128 deg C
Water Solubility:
Value : 0.01 mg/L
Temp : 37 deg C
Type : EXP
Log Kow (logP):
Value : 3.57
Type : EXP
Vapor Pressure:
Value : 210 mm Hg
Temp : 25 deg C
Type : EXP
Henry's Law Constant:
Value : 6.85E-004 atm-m3/mole
Temp : 25 deg C
Type : EST
Illustrating Example
N-boulanger is used to formulate air fresheners.
Octanol/Water Partitioning
• Reported as log Kow or log P
• Used to estimate water solubility, soil sediment adsorption, biological
absorption (dermal, oral, GI, inhalation), bioaccumulation, and toxicity
• model for partitioning within body
New Chemicals
Review Program
Octanol/Water Partitioning
80% of PMN process is determined through use of log Kow
- fuels QSARs (Quantitative Structural Activity Relationships) or EPA’s
ECOSAR (Ecological Structural Activity Relationship) used during the
evaluation
Experimental Determination
1. Shake Flask Method
2. Slow Stir
3. Generator Column via HPLC
New Chemicals
Review Program
Octanol/Water Partitioning
Non-experimental Estimation Methods
1. Fragment/segment summation
2. Correlations with molecular descriptors (shape,
volume,…) with known chemistries
3. Correlations with Reversed Phase HPLC Retention
Times of known chemistries
4. 3 dimensional structure
New Chemicals
Review Program
The Agency
prefers
experimentally
derived
Kow values.
Whenever
non-experimental
methods will be
estimated, the
most conservative
value will be used!
Log Kow drives partitioning between the substance and biological tissues
New Chemicals
Review Program
Vapor Pressure
• rate of vapor condensation = vaporization
rate of liquid
• determined experimentally through
automated instruments, an isoteniscope, or
gas saturation procedure
• strongly hints at air fraction
• can be correlated for most compounds
New Chemicals
Review Program
Vapor Pressure
drives partitioning of
compound between
atmosphere.
New Chemicals
Review Program
CAS Number : 000105-55-5
Chem Name : n-boulanger
Mol Formula: StRuCtUrE
Mol Weight : 186
Melting Pt : -10 deg C
Boiling Pt : 128 deg C
Water Solubility:
Value : 0.01 mg/L
Temp : 37 deg C
Type : EXP
Log Kow:
Value : 3.57
Type : EXP
Vapor Pressure:
Value : 210 mm Hg
Temp : 25 deg C
Type : EXP
Henry's Law Constant:
Value : 6.85E-004 atm-m3/mole
Temp : 25 deg C
Type : EST
Putting Values into Context
N-boulanger is used to formulate air fresheners.
Putting Numbers into Context
Henry's Constant Ranges (atm m3/mol)
Aqueous Solubility Ranges
High
moderate
low
non volatile
low volatility
moderate volatility
high volatility
> 500 mM
100 - 500 mM
< 100 mM
< 3x10-7
3x10-7 to 1x10-5
1x10-5 to 1x10-3
> 1x10-3
Vapor Pressure Ranges (mmHg) @ 20-30 deg F
Very highly volatile
highly volatile
moderately volatile
low volatility
non volatile
> 10-3
10-4 to 10-3
10-5 to 10-4
10-5 to 10-6
< 10-7
logP considered a problem when logKow > 5 (will bioaccumulate)
logP from 2 to 5 considered likely to bioaccumulate
logP from 0 to 2 potential to bioaccumulate
Putting Values into Context
CAS Number : 000105-55-5
Chem Name : n-boulanger
Mol Formula: StRuCtUrE
Mol Weight : 186
Melting Pt : -60 deg C
Boiling Pt : 128 deg C
Water Solubility:
Value : 0.01 mg/L
Temp : 37 deg C
Type : EXP
Log Kow:
Value : 3.57
Type : EXP
Vapor Pressure:
Value : 210 mm Hg
Temp : 25 deg C
Type : EXP
Henry's Law Constant:
Value : 6.85E-004 atm-m3/mole
Temp : 25 deg C
Type : EST
Aqueous Solubility Ranges
High
moderate
low
> 500 mM
100 - 500 mM
< 100 mM
CAS Number : 000105-55-5
Chem Name : n-boulanger
Mol Formula: StRuCtUrE
Mol Weight : 186
Melting Pt : -60 deg C
Boiling Pt : 128 deg C
Water Solubility:
Value : 0.01 mg/L
Temp : 37 deg C
Type : EXP
Log Kow:
Value : 3.57
Type : EXP
Vapor Pressure:
Value : 210 mm Hg
Temp : 25 deg C
Type : EXP
Henry's Law Constant:
Value : 6.85E-004 atm-m3/mole
Temp : 25 deg C
Type : EST
Putting Values into Context
logKow considered a problem when logKow > 5 (will bioaccumulate)
logKow from 2 to 5 considered likely to bioaccumulate
logKow from 0 to 2 potential to bioaccumulate
CAS Number : 000105-55-5
Chem Name : n-boulanger
Mol Formula: StRuCtUrE
Mol Weight : 186
Melting Pt : -60 deg C
Boiling Pt : 128 deg C
Water Solubility:
Value : 0.01 mg/L
Temp : 37 deg C
Type : EXP
Log Kow:
Value : 3.57
Type : EXP
Vapor Pressure:
Value : 210 mm Hg
Temp : 25 deg C
Type : EXP
Henry's Law Constant:
Value : 6.85E-004 atm-m3/mole
Temp : 25 deg C
Type : EST
Putting Values into Context
Vapor Pressure Ranges (mmHg) @ 20-30 deg F
Very highly volatile
highly volatile
moderately volatile
low volatility
non volatile
> 10-3
10-4 to 10-3
10-5 to 10-4
10-5 to 10-6
< 10-7
CAS Number : 000105-55-5
Chem Name : n-boulanger
Mol Formula: StRuCtUrE
Mol Weight : 186
Melting Pt : -60 deg C
Boiling Pt : 128 deg C
Water Solubility:
Value : 0.01 mg/L
Temp : 37 deg C
Type : EXP
Log Kow:
Value : 3.57
Type : EXP
Vapor Pressure:
Value : 210 mm Hg
Temp : 25 deg C
Type : EXP
Henry's Law Constant:
Value : 6.85E-004 atm-m3/mole
Temp : 25 deg C
Type : EST
Putting Values into Context
Henry's Constant Ranges (atm m3/mol)
non volatile
low volatility
moderate volatility
high volatility
< 3x10-7
3x10-7 to 1x10-5
1x10-5 to 1x10-3
> 1x10-3
Putting Values into Context
CAS Number : 000105-55-5
Chem Name : n-boulanger
Mol Formula: StRuCtUrE
Mol Weight : 186
Melting Pt : -60 deg C
LIQUID
Boiling Pt : 128 deg C
Water Solubility:
Value : 0.01 mg/L
LOW SOLUBILITY
Temp : 37 deg C
Type : EXP
Log Kow:
Value : 3.57
LIKELY TO BIOACCUMULATE
Type : EXP
Vapor Pressure:
Value : 210 mm Hg
VERY HIGHLY VOLATILE
Temp : 25 deg C
Type : EXP
Henry's Law Constant:
Value : 6.85E-004 atm-m3/mole
Temp : 25 deg C
MODERATELY VOLATILE
Type : EST
Fate considers reactions too!
1. Biologically mediated degradation
2. Hydrolysis
3. Photolysis (direct or indirect)
All the models EPA uses to determine
reactions are based upon the
physical/chemical parameters reported in
the PMN
New Chemicals
Review Program
Putting Numbers into Context
Henry's Constant Ranges (atm m3/mol)
Aqueous Solubility Ranges
High
moderate
low
non volatile
low volatility
moderate volatility
high volatility
> 500 mM
100 - 500 mM
< 100 mM
< 3x10-7
3x10-7 to 1x10-5
1x10-5 to 1x10-3
> 1x10-3
Vapor Pressure Ranges (mmHg) @ 20-30 deg F
Very highly volatile
highly volatile
moderately volatile
low volatility
non volatile
> 10-3
10-4 to 10-3
10-5 to 10-4
10-5 to 10-6
< 10-7
logP considered a problem when logKow > 5 (will bioaccumulate)
logP from 2 to 5 considered likely to bioaccumulate
logP from 0 to 2 potential to bioaccumulate
New Chemicals Process
1. Gatekeeper for new chemicals
2. Dependent upon partitioning
3. Physical/chemical properties key
4. Modeling approach
“…we’re busy alright. I can send you
home with about 500 submissions
right now. Do you have a U-Haul?...”
New Chemicals
Review Program