pfas exposure and toxicology update...sep 25, 2019 · andrew smith, sm, scd state toxicologist...

Andrew Smith, SM, ScD

State Toxicologist

Maine Center for Disease Control and Prevention

September 25, 2019

PFAS Exposure and Toxicology Update

PFAS Task Force Meeting

TOPICS

• What we know about PFAS exposure for “typical” child / adult

• What soil screening levels and soil monitoring data may tell us about exposure to Maine residents

• Update on toxicity values and water guidelines and standards

Maine Department of Health and Human Services

Source:

National Report on Human Exposure to Environmental Chemicals – US CDC: https://www.cdc.gov/exposurereport/index.html

Trends in PFAS Serum LevelsNational Perspective


Source:


Differences in PFAS Serum Levels by Age Group


Estimated Daily

Intake

1.5 ng/kg/day(105 ng/day)

0.4 ng/kg/day(28 ng/day)

Source:


Estimated PFOS Daily Exposure based on Serum Levels


Source:

Egeghy & Lorber. Journal of Exposure Science and Environmental Epidemiology (2011) 21, 150–168

Estimates of Major Sources of PFOS Exposure for the “Typical” Child / Adult


2-Year Old Adult

Range of

2015/2016

exposureRange of

2013/2014

3-5 yo

exposure

Source: US FDA 2019. Analytical Results for PFAS in 2019 Total Diet Study Sampling (Parts Per Trillion).

https://www.fda.gov/media/127852/download. Fruits and vegetables, breads and baked goods, and dairy were all < LLOQ.

Current PFOS Levels in Food(FDA 2019 Data)


0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Tilapia,

baked

Turkey

ground,

pan-cooked

Shrimp,

boiled

Catfish,

pan-cooked

Salmon,

baked

Lamb chop,

pan-cooked

Cod, baked Chicken

thigh,

rosted

Beef steak,

broiled

Frankfurter,

boiled

PF

OS

Co

nce

ntr

atio

n (

ng

/g, w

w)

Results from PFAS in FDA's 2019 Total Diet Study Sampling

6-oz meal

per week

15-20

ng/day

6-oz meal

per week

4-6 ng/day

Thoughts on “Typical” Exposures

• Exposure to PFOS and PFOA have decreased 70-80 % since 2000.

• Diet for adults and Diet/Household dust for small children appear to be major sources of exposure

• For diet, seafood/meats appear to be major sources of exposure, especially seafood.


Source:

Egeghy & Lorber. Journal of Exposure Science and Environmental Epidemiology (2011) 21, 150–168

Potential Exposure from Contaminated Environments


Intake

for RfDs

Intake

from

Water at

70 ng/L

AdultAdult

PFOS / PFOA

1700 µg/kg, dw

Remedial Action Guidelines: Based on USEPA RfD of 20 ng/kg/day, 95th

percentile incidental soil ingestion rate for a 1-6 year old child, 256 days / year.

PFOS Soil Screening Levels (SLs) for Residential Soil Exposure Pathway - 2018


PFOS

5.2 µg/kg

PFOA

2.5 µg/kg

Based on Chapter 418 risk standard of 0.5 HI, USEPA RSL tap water model modified

with use of SESOIL soil to groundwater model, and USEPA RfD , no RSC.

PFOS Soil SLs for Soil-to-Groundwater Exposure Pathway


Ground water impacts from biosolids use?


Composite Soil

Sample

18 µg/kg PFOS

3.5 µg/kg PFOA

Monitoring

Well Sample

170 ng/L PFOS

340 ng/L PFOA

What would be a PFOS soil screening level for the dairy farming scenario?

Soil → Hay/Corn → Cow → Milk → Child


USEPA PRGR Soil Screening Level Equation

Agronomic Pathway

�� =��

�� × �� × �� × �� × �� +�� + �� × �� × ��

Plant uptake and

soil loading

Fraction of time exposed

to contaminated feed

Animal ingestion rates

Transfer Factor

from Intake to

Milk

Source:

Modified equation from U.S. EPA Preliminary Remediation Goals for Radionuclides, consumption of milk back calculated to soil -

https://epa-prgs.ornl.gov/radionuclides/users_guide.html

Fraction of time exposed

to contaminated soil

Milk Action

Level

“Adulterated”


Example Soil SL Calculation for Hay

Source:



13,800 ng/kg dw

(13.8 µg/kg dw) 204 ng/kg

0.02

day/kg

6.5

kg/day

�� =��

�� × �� × �� × �� × �� +�� + �� × �� × ��

1

0.07 0.0340.13

kg/day

1

0.68 kg/day

1 0.5

0.065 kg/day


Example Soil SL Calculation for Corn Silage

Source:



�� =��

�� × �� × �� × �� × �� +��

204 ng/kg

5,900 - 31,300 ng/kg dw

(5.9 - 31.7 µg/kg dw)

0.02

day/kg

8.7

kg/day

1

0.036 - 0.165 0.0014 - 0.034

1


Example Soil Screening Levels

for Dairy Farm Scenarios

EPA “Subsistence Dairy Farm”

• Diet: Hay (65%) Corn (20%) Grain (15%)

SSL = 4 – 6 µg/kg, dw

Average Maine Dairy Farm

• Diet: Hay (28%) Corn (37%) Grain (35%)

SSL = 4 – 10 µg/kg, dw


PFOS Levels for Stoneridge Farm

151

759

99.5

878

ND

98.2

62.7

6.7

0.6

5.4

1.8

4.7

0.7

ND

Soil / Hay in µg/kg, dw

Water / Milk in ng/L

4.6

3.6

130

42


Model Estimated PFOS Milk Levels based on

Stoneridge Farms Soil Levels

Stoneridge Farms PFOS site-wide soil level

estimates (ug/kg dry weight)

Model estimated PFOS milk

(ng/L)

123

(arithmetic average)4,100

25

(geometric mean)840

Initial average measured PFOS milk levels at Stoneridge Farms = 1,117 ng/L


Thoughts on “Site” Exposures

Still thinking on this …….


?

Update on Toxicity Values for PFOS

Agency Endpoint Species

Human

equivalent

dose

(ng/kg/day)

Cumulative

uncertainty

factor

Reference

dose

(ng/kg/day)

FederalEPA Developmental effects Rats 510 30 20

ATSDR Developmental effects Rats 515 300 2*

States

ME, VT, CT† Developmental effects Rats 510 30 20

MA Developmental effects Rats 510 100 5*

MN Immune effects Mice 307 100 3

NH Immune effects Mice 302 100 3

MI Immune effects Mice 86 30 3*

NJ, NY, CA Immune effects Mice 55 30 2*

InternationalHealth Canada Liver effects Rats 1500 25 60

EFSA Changes in cholesterol Humans 2 1 2

* Proposed/Draft. † ME, VT, CT all using EPA’s toxicity value (FDA is also using EPA’s toxicity value).


Cancer (10-5)

Risk Specific Dose

0.4 ng/kg/day

Other Drinking Water Guidelines for PFOS

* Proposed / Draft

Agency

Reference

dose

(ng/kg/day) Receptor

Drinking

water

intake

(L/kg/day)

Relative

source

contribution

(%)

Drinking

water

guideline

(ng/L)

FederalEPA 20 Lactating woman 0.054 20 70

ATSDR 2 Infant, birth to 1 yr 0.143 No RSC 14

States

VT 20 Bottle-fed infant 0.175 20 20

MA 5 Lactating woman 0.054 20 20*

MI 3 Breastfed infant 0.047 50 16*

MN 3 Breastfed infant 0.047 50 15

NH 3 Breastfed infant 0.047 50 15

NJ 2 Adult 0.029 20 13*

NY 2 Infant 0.151 60 10*

CA 2 Lifetime 0.053 20 7*

International Health Canada 60 Adult 0.021 20 600


Update on Toxicity Values for PFOA


Agency Endpoint Species

Human

equivalent

dose

(ng/kg/day)

Cumulative

uncertainty

factor

Reference

dose

(ng/kg/day)

FederalEPA Developmental effects Mice 5300 300 20

ATSDR Developmental effects Mice 821 300 3*

States

ME, VT, CT Developmental effects Mice 5300 300 20

MN Developmental effects Mice 5300 300 18

MA Developmental effects Mice 5300 1000 5*

MI Developmental effects Mice 1163 300 4*

NH Liver effects Mice 610 100 6

NJ Liver effects Mice 609 300 2*

NY Liver effects Mice - - 2*

CA Liver effects Mice 136 300 0.5*

InternationalHealth Canada Liver effects Rats 521 25 21

EFSA Changes in cholesterol Humans 1 1 1

Cancer (10-5)

Risk Specific Dose

0.1 ng/kg/day

* Proposed/Draft. † ME, VT, CT all using EPA’s toxicity value

Other Drinking Water Guidelines for PFOA


* Proposed / Draft

Agency

Reference

dose

(ng/kg/day) Receptor

Drinking

water

intake

(L/kg/day)

Relative

source

contribution

Drinking

water

guideline

(ng/L)

FederalEPA 20 Lactating woman 0.054 20 70

ATSDR 3 Infant birth to 1 yr 0.143 No RSC 21

States

VT 20 Bottle-fed infant 0.175 20 20

MA 5 Lactating woman 0.054 20 20*

MN 18 Breastfed infant 0.047 50 35

NJ 2 Adult 0.029 20 14*

NH 6 Breastfed infant 0.047 50 12

NY 2 Infant 0.151 60 10*

MI 4 Breastfed infant 0.047 50 8*

CA 0.5 Lifetime 0.053 20 2*

International Health Canada 21 Adult 0.021 20 200

Deriving a PFOS Toxicity Value for Immune System Effects


Benchmark Dose Modeling (BMD) of Dong et al., 2011 study of

decreased immune response in mice to sheep red blood cells

IgM

(n

g/m

l)

Serum PFOS (mg/L)

Toxicity Values for other PFAS


RfD = 4 ng/kg/day

Thomas Simones, PhDToxicologist

Maine Center for Disease Control and Prevention

[email protected]

Questions?

Andrew Smith, SM, ScD

State Toxicologist

Maine Center for Disease

Control and Prevention

[email protected]

pfas exposure and toxicology update...sep 25, 2019 · andrew smith, sm, scd state toxicologist...

Documents