2020 GLHHFTS Fish Tissue Data Dictionary for Mercury, PCBs, and PFAS Results

November 2023

The Office of Science and Technology (OST) is providing the fish tissue results from the 2020 Great Lakes
Human Health Fish Fillet Tissue Study (GLHHFFTS). The specific chemical analyses include:

•	Mercury (total)

•	Polychlorinated biphenyls (PCBs) (all 209 congeners)

•	Per- and polyfluoroalkyl substances (PFAS) (40 compounds)

This document represents the "data dictionary" for each type of chemical contaminant analysis. The field
names and descriptions for the analytical results are similar for each type of chemical analysis, but results from
some analyses include additional information that may not apply to all analysis types. OST is also providing
information on the fish composite samples collected during the study and used to prepare the fillet tissue
samples that were analyzed. The fish sample information for each contaminant data file is identical, so only
one version of the dictionary for the sample information is provided after the dictionary for the results for each
type of contaminant analysis.

Data Tab for Mercury, PCBs, and PFAS

Field Name

Description

EPA Region

The EPA Region in which the sample was collected.

State

USPS 2-letter abbreviation for the state in which the sample was collected.

Lake

Name of the Great Lake from which the sample was collected.

Site ID

The identifier assigned by EPA to the site. The first three characters are "NGL," the next two
are the site selection year (20), followed by the State abbreviation and the 4-digit site location.

EPA Sample ID

Unique 6-digit number assigned by EPA.

Tissue Type

An indication of the tissue used for the analysis. For the 2020 GLHHFFTS, all of the samples
were prepared from composited fillet tissue.

% Lipids

The lipid content of the sample, measured independently of the chemical analysis.



An identifier for the analytical method used for each chemical. For the mercury and PCB
results, the identifiers refer to the following standardized EPA methods:



EPA Method 163 IE, Mercury in Water by Oxidation, Purge and Trap, and Cold Vapor
Atomic Fluorescence Spectrometry, EPA-821-R-02-019, August 2002.

Method

EPA Method 1668C, Chlorinated Biphenyl Congeners in Water, Soil, Sediment, Biosolids, and
Tissue by HRGC/HRMS, EPA-820-R-10-005, April 2010.

For the PFAS results, there were no EPA methods for analysis of fish tissue at the time of the
study, so fillet samples were analyzed by an in-house procedure developed by the commercial
laboratory, utilizing liquid chromatography with tandem mass spectrometric detection
(LC/MS/MS).



Common name or abbreviation for the chemical.

Chemical

For PCBs, the abbreviation "PCB" is followed by the congener number (i.e., "PCB-7"). It is not
practical to completely separate all 209 PCB congeners from one another during analysis, so
congeners that elute from the gas chromatograph together are listed with a forward slash
between each congener, in increasing congener number order, e.g., PCB-12/PCB-13. "Total
PCBs" is the name given to the sum of the results for all 209 of the congeners (which includes
the coeluting congener groups) reported in the fillet sample. This value was calculated by OST,
using zero for any congener result that was "not detected" at the method detection limit.

For PFAS, the chemical names are the commonly used abbreviations for the anion form of the
chemical (e.g., the "ate" form). The full names of the PFAS chemicals are given in a table later
in this document.

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2020 GLHHFTS Fish Tissue Data Dictionary for Mercury, PCBs, and PFAS Results

November 2023

Data Tab for Mercury, PCBs, and PFAS

Field Name

Description

CAS Number

Chemical Abstracts Service Registry Number assigned by CAS to the chemical. CAS Numbers
do not exist for the groups of coeluting PCB congeners. For PFAS, this is the CAS Number of
the parent acid or amide form, because the anions do not have separate CAS Numbers.



Concentration of the chemical, if detected. If this field is blank, then the chemical was not
detected in the fillet sample. In order to accommodate the range of concentrations in these
samples, all the results are presented with the same number of decimal places for a chemical
(mercury) or chemical class (PCBs and PFAS).

Amount

For mercury, the amount field is presented to 1 decimal place.

For the PCBs, the amount fields are presented to 5 decimal places.

For PFAS, the amount field is presented to 3 decimal places.

However, these results have at most 3 significant figures, regardless of the number of decimal
places (for example, a PFAS value of 19.000 does not imply 5 significant figures).



The nominal method detection limit for the chemical, based on the procedure in 40 CFR part
136, not adjusted for actual sample size, in the units shown in the Units column.

MDL

For mercury, MDLs are reported to 2 decimal places.
For PCBs, MDLs are reported to 6 decimal places.
For PFAS, MDLs are reported to 3 decimal places.

QL

The nominal quantitation limit (QL) or "Minimum Level" for the chemical, based on the lowest
calibration standard analyzed, not adjusted for sample size, in the units shown in the Units
column.

Units 1

The weight/weight units of nanograms per gram or ng/g

Units 2

The "parts per billion" notation ppb, which is equivalent to ng/g

Lab Flag

The data qualifier flag(s) applied by the laboratory. For mercury, no lab qualifier flags were
required.

U = Chemical not detected
J = Result between the MDL and the QL
B = Chemical also present in the method blank
D = Result is from a diluted analysis

K = Ion abundance ratio is outside of the acceptance limits, but the chemical meets all the

other identification criteria
NQ = Not quantified

SCC Code

Qualifiers applied by the Sample Control Center staff at GDIT during data validation. The
individual SCC codes applied to the PCB and PFAS results are identified and defined in the
tables of SCC codes below. For mercury, no SCC codes were required.

Comments

A text translation of the SCC code combinations applied to each result.

Sort Order

Applies only to PCBs and PFAS. A field used to sort the chemical names in a consistent order
within each chemical group.

For PCBs, the values in this field range from 1 to 169.

For PFAS, the values in this field range from 1 to 40.

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2020 GLHHFTS Fish Tissue Data Dictionary for Mercury, PCBs, and PFAS Results

November 2023

Sample Information Tab

Field Name

Description

EPA Region

The EPA Region in which the sample was collected.

State

USPS 2-letter abbreviation for the state in which the sample was collected.

Site ID

The identifier assigned by EPA to the site. The first three characters are "NGL," the next
two are the site selection year (20), followed by the State abbreviation and the 4-digit site
location.

Lake

Name of the Great Lake from which the sample was collected.

Latitude

Latitude, in decimal format, to 5 decimal places.

Longitude

Longitude, in decimal format, to 5 decimal places.

EPA Sample ID

Unique 6-digit number assigned by EPA.

Sample Collection Date

Actual sampling date, in MM/DD/YYYY format.

Sample Specimen ID

The 6-digit EPA Sample ID, followed by a decimal point and a value between 1 and 10.
The decimal portion identifies the number assigned to the individual fish specimen in the
composite sample.

Spec Sort

A specimen sorting field designed to account for the fact that samples with more than 9
specimens do not sort properly (i.e., XX. 10 sorts before XX.2).

Species - Scientific
Name

Latin name (Genus and species) based on Nelson et al. (2004), Common and Scientific
Names of Fishes from the United States, Canada, and Mexico, Sixth Edition.

Species - Common
Name

Generally accepted common name based on Nelson et al. (2004).

Family

Latin name of the Family based on Nelson et al. (2004).

Tissue Type

The type of fish tissue used to prepare the sample. For the GLHHFFTS, all of the
samples were prepared from fillet tissue.

Total Length (mm)

Length of each individual specimen in millimeters (mm).

Included in Fillet
Composite?

This field indicates if the specimen was included in the tissue sample for analysis or not.
The options are either "Yes" or "No" and the rationale is explained in the "Instructions"
field to the far right.

Predator or Bottom
Dweller

Classification of the species as either:
P = Predator species, or
BD = Bottom-dweller species

Composite
Classification

Routine vs. Non-routine composite, based on the fish composite sample criteria specified
in the human health fish sampling procedures.

Deviation

For non-routine composites, the nature of the deviation from the criteria (e.g., number of
fish, fish length, or both).

Fillet Sample
Preparation Instructions

Instructions from EPA/OW/OST to the sample preparation laboratory regarding which
specimens to include in the fillet composite sample for analysis, based on specimen
length, species, etc.

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2020 GLHHFTS Fish Tissue Data Dictionary for Mercury, PCBs, and PFAS Results

November 2023

Individual SCC Codes Applied to the PCB Results

SCC Code

Comments

Implication

B, RMAX

Blank Contamination,
Result is a Maximum
Value

Blank contamination was observed and the target chemical was reported
in the sample at a concentration between 5 and 10 times higher than the
blank value. The result was considered to be of acceptable quality, but
data users are cautioned that it may be a maximum value due to possible
influence of contamination.

B, RNAF

Blank Contamination,
Result is Not Affected

Blank contamination was present but was not considered to adversely
impact the sample result. The presence of the chemical in the blank is not
considered to adversely affect the data in cases where the sample results
are more than 10 times the associated blank results or where the chemical
is not detected in associated samples.

HRPD, J

High RPD, Estimated

The relative percent difference (RPD) between the results in the parent
sample and the laboratory duplicate is above the acceptance limit. This
may be due to inhomogeneity in the bulk sample or analytical variability.
When high RPD was observed for a chemical, all the detected results for
that chemical in any of the samples in the batch with the duplicate sample
were qualified as estimated values.

HRPD, RNAF

High RPD, Result is
Not

Affected

The relative percent difference (RPD) between the results in the parent
sample and the laboratory duplicate is above the acceptance limit. This
may be due to inhomogeneity in the bulk sample or analytical variability.
However, when high RPD was observed for a chemical, the non-detected
results for that chemical were not affected, and the RNAF flag was
applied.

J

Estimated

When applied alone, this code indicates that the result is at or above the
MDL, but below the QL. This flag also may be applied in conjunction
with other flags to indicate the potential for greater uncertainty.

Note: Commas are used to separate related parts of a single code (e.g., "B, RNAF" is considered one code), while
semicolons are used to separate different codes (e.g., "B, RNAF; J" is the combination of two codes).

Individual SCC Codes Applied to the PFAS Results

SCC Code

Comments

Implication

B, RMAX

Blank Contamination,
Result is a Maximum
Value

Blank contamination was observed and the target chemical was reported
in the sample at a concentration between 5 and 10 times higher than the
blank value. The result was considered to be of acceptable quality, but
data users are cautioned that it may be a maximum value due to possible
influence of contamination.

B, RNAF

Blank Contamination,
Result is Not Affected

Blank contamination was present but was not considered to adversely
impact the sample result. The presence of the chemical in the blank is not
considered to adversely affect the data in cases where the sample results
are more than 10 times the associated blank results or where the chemical
is not detected in associated samples.

B, RNON

Blank Contamination,
Result Reported as a
Non-detect

When the sample result is less than five times the blank result, there are
no means by which to ascertain whether or not the presence of the
chemical may be attributed to contamination. Therefore, the result is
reported in the database as a non-detect at the MDL, adjusted for sample
size and dilution.

HIAR, J

High Ion Abundance
Ratio, Estimated

Each chemical is identified and quantified based on the instrumental
response for two specific ions and the ratio of those two ions was above
the upper acceptance limit, suggesting a potential interference that may
affect the sample result. Therefore, the result also is flagged as an
estimated value.

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2020 GLHHFTS Fish Tissue Data Dictionary for Mercury, PCBs, and PFAS Results

November 2023

Individual SCC Codes Applied to the PFAS Results

SCC Code

Comments

Implication

HLBL, J

High Labeled
Compound Recovery,
Estimated

The labeled analog of the target chemical was recovered above
acceptance criteria, suggesting the possible presence of matrix
interferences. Isolated instances of high recovery are not uncommon, and
patterns across multiple samples are more of a concern.

HLBL, RNAF

High Labeled
Compound Recovery,
Result is Not Affected

The labeled analog of the target chemical was recovered above
acceptance criteria, suggesting the possible presence of matrix
interferences. Isolated instances of high recovery are not uncommon, and
patterns across multiple samples are more of a concern. If the chemical
was not detected in a field sample, there is no concern and the RNAF is
added to the HLBL flag.

HLCS, RNAF

High Lab Control
Sample Recovery,
Result is Not Affected

The recovery in the LCS was high, but the chemical was not detected in
the associated fillet tissue sample, so there was no high bias concern and
the RNAF flag was applied.

HVER, J

High CALVER,
Estimated

The results for the calibration verification associated with the chemical
were above the acceptance limit, suggesting a possible high bias.
Detected chemicals also are considered estimated values.

HVER, RNAF

High CALVER, Result
is Not Affected

The results for the calibration verification associated with the chemical
were above the acceptance limit, suggesting a possible high bias. If the
chemical was not detected in a field sample, there is no concern and the
RNAF is added to the HVER flag

J

Estimated

When applied alone, this code indicates that the result is at or above the
MDL, but below the QL. This flag also may be applied in conjunction
with other flags to indicate the potential for greater uncertainty.

LLBL

Low Labeled
Compound Recovery

The labeled analog of the target chemical was recovered below
acceptance criteria, suggesting the possible presence of matrix
interferences or incomplete recovery of both the labeled compound and
target chemical during the extract cleanup processes used in the
analytical procedure. The use of isotope dilution quantitation
automatically corrects the results for the target chemical, even when the
labeled compound recovery is below expectations. This flag is applied
when the chemical associated with the labeled analog is not detected in
the sample.

LLBL, J

Low Labeled
Compound Recovery,
Estimated

The labeled analog of the target chemical was recovered below
acceptance criteria, suggesting the possible presence of matrix
interferences or incomplete recovery of both the labeled compound and
target chemical during the extract cleanup processes used in the
analytical procedure. The use of isotope dilution quantitation
automatically corrects the results for the target chemical, even when the
labeled compound recovery is below expectations. When the chemical
associated with the labeled analog is detected in the sample, the result is
also flagged as an estimated value.

LLCS

Low LCS result

The lab control sample (LCS) was a clean reference matrix. If recovery in
the LCS was low, there may be a low bias for that chemical. When low
LCS recovery was observed for a chemical, the results for that chemical
were qualified in all of the samples in the batch with the LCS.

LVER, J

Low CALVER,
Estimated

The results for the calibration verification associated with the chemical
were below the acceptance limit, suggesting a possible low bias. Detected
chemicals also are considered estimated values.

NQ

Not Quantified

The chemical could not be quantified by isotope dilution and was
reported as a non-detect at the MDL.

Note: Commas are used to separate related parts of a single code (e.g., "B, RNAF is considered one code), while
semicolons are used to separate different codes (e.g., "B, RNAF; J" is the combination of two codes).

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2020 GLHHFTS Fish Tissue Data Dictionary for Mercury, PCBs, and PFAS Results

November 2023

PFAS Abbrc\ ialion | PFAS Name
IViiluoroalkv 1 carbowlic acids

PFBA

Perfluorobutanoic acid

PFPeA

Perfluoropentanoic acid

PFHxA

Perfluorohexanoic acid

PFHpA

Perfluoroheptanoic acid

PFOA

Perfluorooctanoic acid

PFNA

Perfluorononanoic acid

PFDA

Perfluorodecanoic acid

PFUnA

Perfluoroundecanoic acid

PFDoA

Perfluorododecanoic acid

PFTrDA

Perfluorotridecanoic acid

PFTeDA

Perfluorotetradecanoic acid

Perfluoroalkvl sulfonic acids

PFBS

Perfluorobutanesulfonic acid

PFPeS

Perfluoropentansulfonic acid

PFHxS

Perfluorohexanesulfonic acid

PFHpS

Perfluoroheptanesulfonic acid

PFOS

Perfluorooctanesulfonic acid

PFNS

Perfluorononanesulfonic acid

PFDS

Perfluorodecanesulfonic acid

PFDoS

Perfluorododecanesulfonic acid

Fliioroiclomcr sulfonic acids

4:2FTS

\I I. \I I. 211. 2/f-Perfluorohexane sulfonic acid

6:2FTS

\I I. \I I. 211. 2/f-Perfluorooctane sulfonic acid

8:2FTS

1 //. \ II. 211. 2//- Pc rfl norodccanc sulfonic acid

PciTluorooclanc siilfonaniides

PFOSA

Perfluorooctanesulfonamide

NMeFOSA

N-methyl perfluorooctanesulfonamide

NEtFOSA

N-ethyl perfluorooctanesulfonamide

I'ei'fluorooclanc siilfonaniidoacclic acids

NMeFOSAA

N-methyl perfluorooctanesulfonamidoacetic acid

NEtFOSAA

N-ethyl perfluorooctanesulfonamidoacetic acid



I'ei'Nuorooclane sullonaniide elhanols

NMcFOSE

N-mclhvl perfluorooclancsulfonamidoelhanol

NElFOSE

N-elhvl perfluorooclancsulfonamidoelhanol

Per- and Polvfluorocthcr carboxvlic acids

HFPO-DA

Hexafluoropropylene oxide dimer acid

ADONA

4.8 - D io \a-3 //-pc rfl no ro no na no i c acid

PFMPA

Perfluoro-3-methoxypropanoic acid

PFMBA

Perfluoro-4-methoxybutanoic acid

NFDHA

Nonafluoro-3,6-dioxaheptanoic acid

I'llhcr sulfonic acids

9C1-PF30NS

9-Chlorohexadecafluoro-3 -oxanonane-1 -sulfonic acid

llCl-PF30UdS

1 l-Chloroeicosafluoro-3-oxaundecane-l-sulfonic acid

PFEESA

Perfluoro(2-ethoxyethane)sulfonic acid

l-'liioroiclomcr carbow lie acids

3:3FTCA

3-Perfluoropropyl propanoic acid

5:3FTCA

2 / /. 2 / /. 3 / /. 3 / /- Pc rfl no ro o c t a no i c acid

7:3FTCA

3-Perfluoroheptyl propanoic acid

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