GenX and PFAS Uptake by Food Plants

Kathyrn L. Holden, Yuanbo Li, Yue Zhi, Stephen W. Broome, Detlef Knappe, and Owen W. DuckworthDepartment of Crop and Soil Sciences

Department of Civil, Construction, and Environmental EngineeringNorth Carolina State University

Department of Crop and Soil SciencesGenualdi, deJager, Begley, FDA (2019)

Potential food crops uptake and human exposure

Plant uptake is an important process to transport PFAS to food chain.

Accumulation?

PFAS

Spiking concentrations: 10 ng/g

Approach

Lettuce

5% compost

20% compost

10% compost

Shoot

Pore water

Root

SoilSampling: 45 d

0% compost

60% field capacity

Compost increase the soil organic carbon content

Soil pH (H2O) TOCa (%) CECb (cmol/kg) Clay (%) Silt (%) Sand (%)0% compost 6.1 0.57 3.6 5.2 7.9 86.9

5% compost 5.9 0.75 5.1 4.1 8.0 87.9

10% compost 6.1 1.44 8.5 4.6 8.1 87.3

20% compost 6.3 2.02 11.5 5.1 7.2 87.7

aTOC: Total organic carbon

Greenhouse experimentCompound CAS supplier PFMOAA 21837-98-9 fluoryxHFPO-DA/GenX 13252-13-6 SynquestPFBS 375-73-5 SynquestPFHxS 355-46-4 SynquestPFOS 1763-23-1 Synquest6:2 FtS 27619-97-2 fluoryx4:2 FtS 757124-72-4 Synquest8:2 FtS 39108-34-4 Synquest

LettuceOrganic compost was made from wheat straw and cow manure

Sample extraction and analysis

Extraction LC-MS/MSDried and ground

Pore water:

Soil and lettuce plant:

4:2FTS 6:2FTS 8:2FTS GenX PFBS PFHxS PFMOAA PFOS0

500

1000

1500

5000

10000

15000

20000

25000

30000

35000

40000

Pore

wat

er co

ncen

tratio

n (n

g/L)

0% compost 5% compost 10% compost 20% compost

Increasing compost content decrease the bioavailable PFAS concentrations in soil by 68-96%.

Soil pore water

96%

79%

89%

84%

79%

68%

94%

78%

PFAS concentration in soil pore water

Preliminary Data

Genx uptake ─ fill the data gap

0

50

100

150

200

250

300

350

Conc

entra

tion (

ng/g,

dw)

Lettuce shoots (n = 3)

0% compost 5% compost 10% compost 20% compost

0

20

40

60

80

100

120

140

160

Lettuce roots (n = 3)

Conc

entra

tion (

ng/g,

dw) 0% compost

5% compost 10% compost 20% compost

54.3-82.8% decreasing 53.4-87.5% decreasing

Genx uptake into plant was first studied. Genx concentration was decreased by up to 82.8% in shoots

and 87.5% in roots by compost addition.

54%

O

OHO

F F

FF

FF

F

FFF

F

72% 83% 53%

74% 88%

Preliminary Data

Next Steps: Digging Deeper• Surveying real food

products• Understanding

fundamental soil chemistry

Department of Crop and Soil Sciences

Department of Crop and Soil Sciences

WaterSoilBlueberriesCornOkraPecansPotatoesSquashPeachesTomatoesGrapesField BeansGreen Beans

ApplesBlackberriesPearsPeasTurnipsSweet potatoesFigsEggsCucumbersLettuceRadishCeleryPickles

Collection of produce from local residents

Department of Crop and Soil Sciences

Is it safe to eat the food I grow in my garden?Currently, there is no recommendation against eating local produce. DEQ and DHHS arecontinuing to review the scientific literature related to plant uptake of GenX and otherchemicals in the same family (per‐ and polyfluoroalkyl substances, or “PFAS”). Studieshave shown that some other chemicals in the PFAS family can be found in variableamounts in plants and vegetables, but the amount depends on the particular chemicaland the plant type. Direct testing of garden produce for GenX has not been conducted by

NC DEQ, and to our knowledge results of such testing are not available from other sourcesat this time. A study conducted by the Minnesota Department of Health found that the a

mount of exposure to five other PFAS compounds from plants and vegetable sources wasmuch lower than the amount of exposure through drinking water, and concluded that thebenefits of growing and eating homegrown produce outweighed the potential risk fromlow levels of PFAS (https://deq.nc.gov/news/key‐issues/genx‐investigation)

AcknowledgementsThanks to Josh Henson, Yinan Ding, and Becca Weed.

Funding: PFAST Network Team 5, NC Policy Collaboratory Supplement, and USEPA