Roger Brewer, PhD (roger.brewer@doh.hawaii.gov)
Hawai′i Department of Health
State Risk Assessor Association
(October 20, 2020)
Untangling the PFASs Web - Perspectives on
Fate, Risk and Screening Levels from Hawaii
1

PFASs in Hawaii
Maui Airport PFAS Plume
PFAS Makeup – Fire Training Area
PFAS Makeup – Downgradient Area
• Low risk (not drinking water);
• Potential discharge to shoreline;
• Two areas tested;
• One or two sources?
• Ok to only focus on PFOS- and PFOA-?
• Expanded action levels needed.
Draft!
Draft!
PFOS-
41%
PFHxS-
22%
PFHxA-
22%
PFBS-
10%
Other 5%
Relative Percent of Total PFASs
Downgradient
Area
Fire Training
Area
250’
? Downgradient
Area
PFHxA-
41%
PFBS-
35%
PFHxS-
20%
PFOS- 0.41% Other 3%
Relative Percent of Total PFASs
2

Outline
• Nature and use of PFASs (brief);
• Targeted PFASs (nomenclature, occurrence, lab analysis);
• Potential environmental concerns;
• Development of soil and groundwater action/screening
levels;
• Fire training site case study;
• Looming Issues:
• Leaching from soil (models vs lab tests);
• Wastewater, biosolids and uptake into food crops;
• Collection of representative sample data.
3
Risk Assessor: Someone who does precision guesswork based on
unreliable data provided by those of questionable knowledge.
See also Wizard, Magician.
(unknown - adapted from a T-Shirt)

Interim Soil and Water Environmental Action Levels (EALs)
for Perfluoroalkyl and Polyfluoroalkyl Substances (PFASs),
July 20, 2020 (public review draft, updated in Fall 2020):
https://health.hawaii.gov/heer/guidance/additional-guidance-
documents/
Evaluation of Environmental Hazards at Sites with
Contaminated Soil and Groundwater (EALs):
https://health.hawaii.gov/heer/guidance/ehe-and-eals/
ITRC 2020: Per- and Polyfluoroalkyl Substances (PFAS)
Washington Dept of Ecology (Draft Oct 2020): Per- and
Polyfluoroalkyl Substances Chemical Action Plan
References
4
HIDOH Recorded Webinars:
https://health.hawaii.gov/heer/guidance/heer-webinars/

• Used since 1940s;
• Water- and oil-resistant textiles and papers;
• Non-stick cookware;
• Fire suppression foams;
• Metal plating and etching fluids;
• Emerging awareness of toxicity in 1970s;
• Persistent in the environment and
difficult/expensive to treat.
Use of PFASs
5

PFASs Forms and Nomenclature
[names: “Perfluoro” + # Carbon Atoms (penta, hexa, etc.) + Functional Group
Sulfonic Acids & Sulfonates Carboxylic Acids & Carboxylates
Other
HFPO-DA (GenX) 5:3 FTCA (alcohol)
Plus PFASs Precursors
Perfluoro octanoate (PFOA-)
Perfluoro octane sulfonate (PFOS-)
Perfluoro octane sulfonic acid (PFOS) Perfluoro octanoic acid (PFOA)
6

Targeted PFASs:
Protonated (H+) Acids versus Anions
Huh???
ITRC 2020 PFAS Document:
“Most PFAAs are present in environmental and human matrices
in their anionic form.”
“Although laboratories may be reporting… the (protonated) acid
form of their name, they are actually measuring the anionic
form…”
“Physical and chemical properties (of protonated acid vs anion
forms) are different, and it is important to know which form is
(present in the environment)… when attempting to explain…
environmental behavior… through mathematical fate and
transport modeling (i.e., assessment of risk and development of
screening levels)”
Conflict Between Lab Data
and Assessment of Risk?
7

Risk
Assessment
Reporting by
Laboratory
Occurrence
in Nature
Toxicity
Studies
Why do labs report PFAS data as protonated acids?
• Laboratories process samples in a manner that converts any H+ acid
forms of compounds present to anion forms (methods can’t distinguish
protonated acid forms from anion forms);
• As a default, measured anion-based concentration of compounds
converted to equivalent protonated acid concentrations for final reporting
[Cacid = Canion x (MWacid/MWanion)];
• Because… USEPA lab SOPs list protonated (H+) acid forms (e.g.,
Method 533, Method 537.1, based on testing of industrial chemicals?);
• Inconsequential in terms of reported concentration (< +0.1%) but
important implications for accurate evaluation of fate and transport, risk
assessment and risk communication;
• “What is the concentration of perfuoro octane sulfonic acid in drinking
water?” “Zero!”
• Toxicity studies based on a mix of acid forms and anion forms.
8

• Present action levels in terms of anion forms of compounds (dominant
form in nature);
• Add a superscript "-" after the abbreviation to denote reference to
anion form;
• “PFOS” = Perfluoro octane sulfonic acid;
• “PFOS-” = Perfluoro octane sulfonate;
• Use physiochemical constants for anion forms to develop action levels -
affects solubility (higher), volatility (lower) and sorption (variable);
• Clarify that toxicity factors from studies based on doses of protonated
acid form of compound also applicable to anion form and vice versa
(difference in administerd dose inconsequential, < -0.1%).
First Lesson: Stick to the Anions…
(Planned Edits to HDOH July 2020 PFASs Guidance)
Risk
Assessment
Reporting by
Laboratory
Occurrence
in Nature
Toxicity
Studies 9

• Identify specific PFASs to target for investigations;
• Identify potential environmental concerns;
• Compile physiochemical constants and toxicity factors;
• Input into fate and transport and exposure risk models;
• Compile aquatic toxicity action levels (chronic and acute);
• Action levels optional for use (NOT promulgated
“standards”) - alternative, site-specific action levels can
be presented for review and approval.
Development of PFAS Soil and Groundwater
Action/Screening Levels
10

The “Big Nine” and Environmental Sources (minimum)
California
“Big Nine”
Fire Fighting
Training Areas
Landfill
Leachate
Wastewater
& Biosolids
PFBS- X x X
PFHxS- X x X
PFOS- X x X
PFPeA- ? X X
PFHxA- X X X
PFHpA- ? X X
PFOA- X X X
PFNA- x x ?
PFDA- ? ? ?
PFAS Precursors ? X X
PFOS- & PFOA-
• Typical focus of risk assessments and published action levels;
• Not the dominant PFAS at many sites;
• Action levels for other PFASs needed.
11

Plant
Uptake
Irrigation
12

PFASs with Toxicity Factors
And Physiochemical Constants
HH Toxicity Factors (main) *Compounds (18)
USEPA (2014, 2016, 2018) PFBS, PFOS-, PFOA, HFPO-DA
Michigan (2019) PFHxS-, PFHxA, PFNA
Minnesota (2018) PFBA-
Texas (2016) PFOSA- (+RfCs for 8 PFASs)
Europe (RIVM 2018)
PFHpS, PFDS, PFPeA, PFHpA,
PFDA, PFUnA, PFDoDA,
PFTrDA, PFTeDA
*Physiochemical
Constants
USEPA, European Chemical
Agency, ITRC, etc.
*HDOH July 2020 EALs to be updated to reflect constants for anionic forms
*RfD based primarily on studies for protonated acid form of compound? 13

Aquatic Toxicity (acute and chronic)
(limited action levels available)
Reference Compounds (5)
Giesey et al (2010) PFBS-
Australia (2018) PFOS-, PFOA-
European Chemical
Agency (2018)
PFHxA-
UNDEP (2028)
Environment
PFHxS- (assumed = PFOS-)
• Several states compiling toxicity data (e.g., Washington);
• Similar “protonated acid vs anion” toxicity study issue;
• Drinking water action level used as temporary surrogate for if
aquatic toxicity if latter not available;
• Laboratory bioassay tests recommended if exceeded. 14

Hawai’i Groundwater Action Levels (Draft! 10/20)
(Drinking Water: RSC = 20%, noncancer HQ = 0.5)
Compound
Drinking Water
Toxicity
(ug/L)
Chronic Aquatic
Toxicity
(ug/L)
Acute Aquatic
Toxicity
(ug/L)
PFBS- 40 13,000 130,000
PFHxS- 0.019 0.130 31
PFHpS- 0.020 0.020 0.020
PFOS- 0.040 0.130 31
PFDS- 0.020 0.020 0.020
PFBA- 7.6 7.6 7.6
PFPeA- 0.800 0.800 0.800
PFHxA- 4.0 5,000 48,000
PFHpA- 0.040 0.040 0.040
PFOA- 0.040 8.5 22
PFNA- 0.004 0.004 0.004
PFDA- 0.004 0.004 0.004
PFUnDA- 0.010 0.010 0.010
PFDoDA- 0.013 0.013 0.013
PFTrDA- 0.013 0.013 0.013
PFTeDA- 0.130 0.130 0.13
PFOSA 0.024 0.024 0.024
HFPO-DA- 0.160 0.160 0.160
15

Compound
Direct Exposure Leaching to Groundwater
Residential
(mg/kg)
C/I
(mg/kg)
DW
(mg/kg)
Non-DW
(mg/kg)
PFBS- 25 1,100 0.21 65
PFHxS- 0.012 0.55 0.002 0.012
PFHpS- 0.013 0.56 0.004 0.004
PFOS- 0.025 1.1 0.007 0.024
PFDS- 0.013 0.56 0.013 0.013
PFBA- 4.8 210 0.099 0.099
PFPeA- 0.51 23 0.003 0.003
PFHxA- 2.5 110 0.013 17
PFHpA- 0.025 1.1 0.0003 0.0003
PFOA- 0.025 1.1 0.001 0.26
PFNA- 0.003 0.12 0.0008 0.0008
PFDA- 0.003 0.11 0.0005 0.0005
PFUnDA- 0.006 0.28 0.004 0.004
PFDoDA- 0.008 0.38 (use lab test) (use lab test)
PFTrDA- 0.008 0.38 (use lab test) (use lab test)
PFTeDA- 0.084 3.8 (use lab test) (use lab test)
PFOSA 0.015 0.68 50 50
HFPO-DA- 0.10 4.5 0.0003 0.0003
Hawai’i Soil Action Levels (Draft! 10/20)
(Soil Direct Exposure: RSC = 20%, noncancer HQ = 0.5)
16

High Toxicity
High Mobility
Low Toxicity
Low Mobility
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CEL…
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
[CELLRANGE]
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.00E+00 1.00E+02 1.00E+04 1.00E+06
PFASs Toxicity vs Mobility
High
Med
Low
RfD
(mg/kg-day)
Koc (cm3/g)
Increasing
Toxicity
Increasing Mobility
<1.0E-05
<1.0E-03
Low Toxicity
High Mobility
High Toxicity
Low Mobility
17
R
i
s
k

HFPO-DA- HFPO-DA- HFPO-DA-
PFHxA- PFHxA- PFHxA-
PFPeA- PFPeA- PFPeA-
PFBS- PFBS- PFBS-
PFHpA- PFHpA- PFHpA-
PFBA- PFBA- PFBA-
PFOA- PFOA-
PFHxS- PFHxS-
PFDA- PFDA-
PFNA- PFNA-
PFOS- PFOS-
PFHpS- PFHpS-
PFUnDA-
PFDS-
PFOSA-
PFDoDA-
PFTrDA-
PFTeDA-
Hypothetical PFASs Groundwater Plume Separation
(based on sorption and mobility)
Plume Leading Edge
Immediately
Downgradient
Source
Area
• High sorption PFASs concentrated in and near
source area;
• Low sorption PFASs at leading edge of plume;
• Very different PFAS compositions in source
area vs leading edge of the same plume.
Decreasing
Mobility
GW
18

PFASs in Hawaii
Maui Airport PFAS Plume
• Single groundwater plume?
• Most PFOS- trapped in source area?
• Downgradient area dominated by more
mobile PFASs (except PFHxS?);
• Fails aquatic toxicity action levels (install
more monitoring wells, check springs, etc.);
• DW action levels also exceeded.
Downgradient
Area
Fire Training
Area
250’
?
PFAS Makeup – Fire Training Area
PFAS Makeup – Downgradient Area
Draft!
Draft!
PFOS-
41%
PFHxS-
22%
PFHxA-
22%
PFBS-
10%
Other 5%
Relative Percent of Total PFASs
PFHxA-
41%
PFBS-
35%
PFHxS-
20%
PFOS- 0.41% Other 3%
Relative Percent of Total PFASs
19

PFOS-,
42%
PFHxS-,
46%
PFHxA-,
0.2%
PFBS-,
0.01%
Other,
9.7%
Relative PFAS Risk
Draft!
Draft!
PFAS Risk – Fire Training Area
PFAS Risk – Downgradient Area
20
PFAS Makeup – Fire Training Area
PFAS Makeup – Downgradient Area
Draft!
Draft!
PFOS-
41%
PFHxS-
22%
PFHxA-
22%
PFBS-
10%
Other 5%
Relative PFAS Makeup
PFHxA-
41%
PFBS-
35%
PFHxS-
20%
PFOS- 0.41% Other 3%
Relative PFASs Makeup
Twice as much PFOS- but
PFHxS- twice as toxic
PFHxA-,
0.9%
PFBS-, 0.1%
PFHxS-, 92%
PFOS-, 0.9%
Other, 5.9%
Relative PFAS Risk
Twice as much PFHxA-
but PFHxS- 200X as toxic

Plant
Uptake
Irrigation
Plant Uptake:
Field Studies
Needed
Leaching From Soil:
Laboratory Leaching
Tests (SPLP, Soil
Column Method 1314)
21

Leaching Models vs Laboratory Tests
Csoil = Cgw x [(6207 x H) + (0.166 x Koc)]
x
1. Concentration in groundwater
x
x
groundwater plume
x
2. Concentration in leachate
at groundwater interface
1m
• Specify targeted area and volume of soil for assessment (every drop?);
• SESOIL over predicts contaminant desorption and concentration in leachate;
• Synthetic Precipitation Leaching Procedure (SPLP) batch more accurately
estimates Kd and leaching hazards (see HDOH 2017)
• Better: “LEAF” Method 1314 soil column leaching tests.
3. Concentration in source leachate
22
4. Concentration in soil
(applies to specified volume)

PFASs Uptake Into Food Crops and Livestock Feed
Uptake from
Groundwater/Irrigation
Uptake from Soil
PFAS-contaminated
Crops?
PFAS-contaminated
soil (e.g., from biosolids)
PFAS-contaminated
water (e.g., leaching,
treated wastewater)
23

PFASs in Wastewater
Wastewater Source
*Total PFASs
(ng/L)
Example Source
Products
Domestic <100 (?)
Food packaging, dust,
household equipment
PFAS non-
intensive industry
100-1,000
Chrome plating,
hospital waste
PFAS intensive
industry
>1,000
Water proofing
agents, AFFF
Vo et al., 2019, Poly‐and perfluoroalkyl substances in water and wastewater: A
comprehensive review from sources to remediation: Journal of Water Process
Engineering 36 (2020) 101393
24
*Wastewater influent can be dominated by PFAS precursors;
increase in terminal anion forms in effluent due to oxidation.

Sludge and Biosolids Production:
• Approximately 75-100 tons of wastewater sludge (dry weight) generated
per one million people per day (after Univ Michigan, 2019);
• USA: 54% processed as “biosolids” and sold as soil amendment on 1%
of cropland (https://oecotextiles.blog/2015/08/25/are-biosolids-safe/);
• Significant increase in crop yield (nutrients, organic matter);
• Big problem if landfills and farmers start refusing to accept it…
10 tons (10 cubic yards)
PFASs in Wastewater Sludge & Biosolids
25

PFBS-
16%
PFBA-
16%
PFHxA-
10%
NEtFOSAA-
10%
PFOA-
9%
NMeFOSAA-
9%
PFOS-
9%
PFPeA-
7%
Other
15%
Example PFASs Makeup of Biosolids
(New Hampshire 2020, draft data
Average Biosolids Total PFASs 40 ug/kg)
For example only!
26

PFASs Distribution in Strawberry Plant
(lab study; after Higgins 2017)
Data from: Blaine et al., 2014b. ES&T. 48: 14361-14368.
1000
1500
2000
3000
2500
PFASs
(ng/g
dw
)
for
the
4
g/L
Applied
Dose
PFOS-
PFHxS-
PFBS-
PFNA-
PFOA-
PFHpA-
PFHxA-
PFPeA-
PFBA-
500
0
Root Shoot Fruit
PFBA-
PFPeA
PFHxA-
PFPeA-
PFHxA-
PFPeA-
PFHpA-
PFOA-
PFBS-
• Carboxylates > sulfonates;
• Longer-chain PFASs in shoot or root crops;
• Shorter-chain PFASs in fruit crops. 27

Soil and Groundwater/Irrigation Water
Plant Uptake Action Levels
Soil/Groundwater AL =
(Food Action Level/
Bioaccumulation Factor)
28
Plant:Soil BAF?
Plant:Water BAF?
Groundwater Action Level?
Soil Action Level?
Food Action Level?
BAF
Bioaccumulation Factor =
(Conc. in Plant/
Conc. in Soil or Water)

Dietary Action Levels
Default Pacific-Asian Diet – Child
(grams per day; HDOH 2010)
Cereals, 166g
Whole Milk,
158g
Fish, 57g
Fruits, 31g
Meat and
Products, 27g
Beverages
(excluding DW),
26g
Vegetables,
23g
Milk Products, 21g
Other,
54g
Total Daily Diet:
Food = 563 grams
Water = 0.78 liters
Soil: 200 mg
• Multiple ways to split up between food groups.
For example only!
29

Example PFASs Whole-Diet Action Levels
Compound
Target Average
Daily Dose
(BW=15kg,
RSC=0.8; HQ=0.5)
(ng/day)
Whole Diet
Action Level
(ng/kg)
PFBS-
120,000 213,333
PFHxS-
58 103
PFHpS-
60 107
PFOS-
120 213
PFDS-
60 107
PFBA-
22,800 40,533
PFPeA-
2,400 4,267
PFHxA-
12,000 21,333
PFHpA-
120 213
PFOA-
120 213
PFNA-
13 23
PFDA-
12 21
For example only!
30
Whole Diet AL=
Target ADDPFOS
-/
0.563 kg/day
Alternative: Assume
PFASs restricted to
a smaller number of
food groups
PFOS- Target ADD =
300 ng/day x 0.8 x 0.5

The Big Mystery - Soil and Water
PFASs Bioaccumulation Factors
Plant: Soil BAF?
Plant: Water BAF?
For example only!
• Published BAFs highly variable
within and between studies;
• Factors include soil type &
microbiome, plant species,
fertilizers, etc.;
• Also likely a sampling problem:
“Multi Increment” type sample
data required for both soil and
crops (not discrete!).
31
Groundwater Action Level?
Soil Action Level?
PFOS- Corn = 120 ng/kg
BAF
Bioaccumulation Factor =
(Conc. in Plant/
Conc. in Soil or Water)

32
• Data for a discrete sample points and means for multiple points
are random within a (largely) unknown range.
Total Discrete Sample
Variability
Collection of Representative Sample Data
-Why Discrete Sample Data “Don’t Work”-

33
Study Site
Range 95% UCL
(mg/kg) Range RSD
Site A
(arsenic)
403 to 776 34% to 67%
Site B
(lead)
201 to 439 20% to 86%
Site C
(PCBs)
9.4 to >1,000,000 124% to 315%
Implications for Risk Assessment: Mean Varies
Between Independent Sets of Discrete Sample Data
• Mean for single data set is random within an unknown range;
• Sample collection error in estimated mean can’t be quantified;
• Statistical analysis of single data set only evaluates the precision of the
statistical test employed to estimate a mean for the data set provided;
• Yields a false sense of data precision.
Replicate Data Sets (10 samples per set, 20 iterations)

Simple Solution: Decision Unit & Multi Increment Sample
Investigation Methods (HDOH 2016+)
x
x
x
x
x
x
x
x x
x
x
x
x
x
x
x
x
x x
x
x
x
x
X Sample Increment Points
• “What is the true (mean) concentration of the contaminant in the targeted
“Decision Unit” area and volume of soil (sediment, air, water, food, etc.)?”;
• For soil, collect a single, Multi Increment Sample by combining 20-40g
“increments” from 30 to 75 points (default = 50, minimum 1-2kg total mass);
• Sample carefully processed and subsampled at laboratory’
• Collect plant samples in similar manner;
• Collect replicate samples (triplicates) in some DUs to test total data precision.

Discrete Sample Data Reliability &
Decision Unit and Multi Increment Sample
Investigation Methods
35
Presentations and Training webinars (SRA July 2019):
http://eha-web.doh.hawaii.gov/eha-cma/Leaders/HEER/Webinar
Envirostat, Inc.: Chuck Ramsey (www.envirostat.org)
Four-day, detailed introduction to sampling theory and
Multi Increment Sample investigation methods (food,
drugs, soil, sediment, air, water, etc.)
HDOH, 2016, Technical Guidance Manual (Sections 3, 4 & 5): Hawai‘i
Department of Health, Office of Hazard Evaluation and Emergency
Response, http://www.hawaiidoh.org/
Brewer et al., 2017, A critical review of discrete soil sample reliability:
Journal of Soil and Sediment Contamination.
Part 1 - Field study Results: http://dx.doi.org/10.1080/15320383.2017.1244171
Part 2 – Implications: http://dx.doi.org/10.1080/15320383.2017.1244172

• Indoor Air:Subslab Vapor Attenuation
factors based on collection of a single,
1-6L vapor sample beneath each
building slab;
• Vapor sample from another point
would yield a different concentration;
• Database not scientifically defensible
for development of generic attenuation
factors;
• Can’t be “fixed” by statistical analysis;
• Useful but failed scientific study.
Frequency
Range of random noise/error
in subslab vapor sample data
Erroneous
95% UCL SSAF =0.03
Similar Problems With USEPA Vapor Intrusion Database
Brewer, R., Nagashima, J., Rigby, M., Schmidt, M. and O'Neill, H. (2014),
Estimation of Generic Subslab Attenuation Factors for Vapor Intrusion
Investigations. Groundwater Monitoring & Remediation, 34: 79–92.
http://onlinelibrary.wiley.com/doi/10.1111/gwmr.12086/full 36
Subslab AF =
Conc. Indoor Air
Conc. Soil Vapor
USEPA 2015

37
Better: Collection of Representative Subslab Vapor Samples
(“Large Volume Purge” sampling methods)
LVP PCE Results (HDOH 2017):
Sample #1: 17,000 µg/m3
Sample #2: 36,000 µg/m3
Sample #3: 50,000 µg/m3
Sample #4: 51,000 µg/m3
Sample #5: 54,000 µg/m3
• Replicate five-day intrusion of vapors through a hypothetical vapor entry
point in slab (default = slab center);
• Continuous Summa sample drawn from each of five, 3,500 to 7,000 liter
purges from vapor point (default daily vapor entry rate);
• Hypothetical risk only - Still don’t know if sample data are representative of
vapors actually intruding the building (better but not reliable for SSAFs).
X
LVP Point
Reference: HDOH Technical Guidance Manual, Section 7 (Field study report and
recorded webinars available at: https://health.hawaii.gov/heer/guidance/heer-webinars/)

Summary
• EALs generated for 18 PFASs;
• Significantly expands other state & USEPA guidance;
• Able to more reliable screen PFAS sites for potential
environmental risks;
• Limited focus PFOS- and PFOA- could miss potential risks from
other PFASs present;
• Lingering concerns:
• Leaching from soil and impacts to groundwater;
• Uptake into edible plants from fields amended with biosolids
and or irrigated with treated wastewater;
• Updated PFASs action levels anticipated Fall 2020;
• Possible plant uptake studies in 2021 (coordinate with other states;
• Demonstration of both soil sample and plant sample data
representativeness critical.
USA:
Est. 2,000
trucks/day
38
Roger Brewer, PhD (roger.brewer@doh.hawaii.gov)
Hawai′i Department of Health