Bioaccessibility studies using in vitro extraction methods on soils - - PowerPoint PPT Presentation

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Bioaccessibility studies using in vitro extraction methods on soils - - PowerPoint PPT Presentation

Dec 13, 2023 642 likes •865 views

Bioaccessibility studies using in vitro extraction methods on soils vitro extraction methods on soils of North America Suzette A. Morman, RN, MSc., MPH smorman@usgs.gov (303) 236-1205 David B. Smith, PhD gplumlee@usgs.gov (303) 236-1204 U.S.

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SLIDE 1

Bioaccessibility studies using in vitro extraction methods on soils vitro extraction methods on soils

  • f North America

Suzette A. Morman, RN, MSc., MPH smorman@usgs.gov (303) 236-1205 David B. Smith, PhD gplumlee@usgs.gov (303) 236-1204

U.S. Department of the Interior U.S. Geological Survey

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SLIDE 2

The Challenge Anthropogenic versus Geogenic p g g

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SLIDE 3

The Challenge

For Particulate Matter Research (PM) Anthropogenic – Human

impact on the environment ( h i l ti id (e.g., chemicals, pesticides, energy production, and mining)

Geogenic – produced g

p from the Earth by natural processes ( e.g., volcanic ash, windborne ash from wildfires, and mineral dusts) , )

Geoanthropogenic -

produced from natural sources by processes that are modified or enhanced by human activities, e.g., dusts from lakebeds dried by human removal of water)

Aral Sea

http://earthobservatory.nasa.gov/IOTD/view.ph p?id=39944

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SLIDE 4

The Challenge

Geogenic or naturally

  • ccurring earth materials

such as soils, dusts and h t i k ash may contain known

  • r potential toxicants.

Exposure levels needed Exposure levels needed to trigger disease and causal links to disease are lacking for many materials

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SLIDE 5

The Challenge

g Occupational Environmental exposures

  • Single element or

exposures

  • Element mixture

mixture

  • Concentration

(metals)

  • Concentration
  • Route of Exposure
  • Duration of
  • Route of Exposure
  • Duration of

Exposure Exposure

  • Matrix composition

and effects

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SLIDE 6

The Challenge Particle Characteristics of Particle Characteristics of Toxicological Interest

  • Particle mineralogy
  • Particle size distribution
  • Particle morphology
  • Ch

i l iti (b lk d f

  • Chemical composition (bulk, and of

different phases)

  • P

ti l bi l bilit bi ti it

  • Particle biosolubility, bioreactivity,

bioaccessibility along inhalation, ingestion exposure pathways p p y

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SLIDE 7

In Vitro Bioaccessibility Tests (IVBA)

Bioaccessibility – The amount of a toxicant that is soluble in simulated body fluid and available for uptake body fluid and available for uptake. IVBA’s measure bioaccessibility in simulated body fluids

(% Bi ( l h t /t t l )* 100)

  • Fast & Inexpensive
  • Gastric (pH 1 5)

(% Bioaccess. = (conc. leachate/total conc.)* 100) Gastric (pH 1.5)

  • Gastric to Intestinal
  • Lung (pH 7.4)
  • Phagolysosomal (pH 4.5)

g y (p )

  • Linked to detailed mineralogical,

physical characterization of test materials

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SLIDE 8

IVBA

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SLIDE 9

The North American Soil Geochemical Landscapes Project. Examine size fraction (<2mm or <250µm) and variations/controls in/on bioaccessibility

  • N-S transect
  • Randomly selected

5 il

  • 0 – 5 cm soil
  • Split, half sieved to <2mm

and half to <250µm and half to 250µm

  • Simulated gastric leach

(pH 1.5, temperature 37° f 1 h ) for 1 hour) (Morman et al. 2009. Applied Geochemistry, v. 24 8) Geochemistry, v. 24 8)

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SLIDE 10

Results - Total Chemistry (mg/kg)

As Cd Cr Ni Pb

Both Transects Max

20 8.2 6030 2820 318

Min

<1 <0.1 2 2 3

Median

4.5 0.2 29 14 19

N-S Transect Max

11 0.8 79 63 93

Mi

<1 <0 1 4 4 7

Min

<1 <0.1 4 4 7

Median

3 0.3 31 16 17

Selected Samples Max

11 0.7 50 30 93

Min

1 <0.1 9 5 9

Median

4 0.3 34 14 17

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SLIDE 11

Results

120

No significant difference in

100

g median concentration values between size fractions for total chemistry

80

ssibility

fractions for total chemistry

  • r % bioaccessibility.

Regression analysis

40 60

% Bioacces

showed no correlation with several ‘controls’ on mobility (soil pH, clay

20 40

%

mobility (soil pH, clay content, organic C,) Cd, Ni and Pb

mm) µm) m) µm) m) µm) m) µm) m) µm)

demonstrated weak correlation to total concentration

Cd (<2 m Cd (<250 Pb (<2 m Pb (<250 µ Ni (<2 mm Ni (<250 µ As (<2 m As (<250 µ Cr (<2 m Cr (<250 µ

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SLIDE 12

12.00

2%

Arsenic

10.00 As <2 mm (total, mg/kg)

2% 5%

6 00 8.00

g/kg

As <2 mm (mg leached/ kg solid)

2% 7%

4.00 6.00

mg

As <250 µm (total, mg/kg)

7% 2% 4%

2.00 As <250 µm (mg leached/ kg solid)

10% 5%

0.00 38-4-1-PH 34-1-2-PH 32-4-PH 31-2d-1-PH 30-1-PH 29-3d-1-PH 027-3-PH 026-1-PH 024-3d-PH 022-3-PH

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SLIDE 13

Arsenic

Morman S et al 2008 Geological Societ of America Meeting Morman,S., et al, 2008, Geological Society of America Meeting abstracts with Program, Vol. 40, No. 6, p78

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SLIDE 14

0 50

Cadmium

0.40 0.45 0.50

Cd <2 mm (total, mg/kg)

58% 54% 61% 58% 60% 57% 55%

0.30 0.35

kg

Cd <2 mm (mg leached/ kg solid)

65% 104% 68% 60% 71% 57% 59% 66%

0.15 0.20 0.25

mg/k

Cd <250 µm (total, mg/kg)

30% 65% 55% 44%

0.05 0.10

Cd <250 µm (mg leached/ kg solid)

66% 55% 86%

0.00

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SLIDE 15

60.00

Chromium

50.00 Cr <2 mm (total, mg/kg)

2% 2% 2% 2% 0 4% 1% 1% 1%

40.00

kg

Cr <2 mm (mg leached/ kg solid)

2% 1% 0.4% 0.7% 0.3%

20.00 30.00

mg/k

Cr <250 µm (total, mg/kg)

0.8% 2% 3% 5%

10.00 Cr <250 µm (mg leached/ kg solid) 0.00 38-4-1-PH 34-1-2-PH 32-4-PH 31-2d-1-PH 30-1-PH 29-3d-1-PH 027-3-PH 026-1-PH 024-3d-PH 022-3-PH

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SLIDE 16

Interferences on Cr Values

  • Cr measured at 52Cr or 53Cr
  • Using normal quadrupole ICP-MS false positives can result due
  • Using normal quadrupole ICP-MS false positives can result due

to interferences at these masses from 40Ar12C and 37Cl16O which are formed in the plasma

  • Use of Dynamic Reaction Cell (DRC) ICP-MS with NH as the

Use of Dynamic Reaction Cell (DRC) ICP-MS with NH3 as the reaction gas can eliminate these interferences giving an accurate concentration for Cr background levels in the fluids

  • NH3 at 0.9 and RPq at 0.65

NH3 at 0.9 and RPq at 0.65

  • Both solutions were run in both modes during the same analysis

Cr Concentration Normal Q-ICP-MS DRC-ICP-MS Q Lung Fluid Blank 110 ppb 0.9 ppb Gastric Fluid Blank 92 ppb 1.5 ppb

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SLIDE 17

35.00

Nickel

30.00 Ni <2 mm (total, mg/kg)

15% 16% 19% 16%

20.00 25.00

kg

Ni <2 mm (mg leached/ kg solid)

9% 9% 25% 23% 13%

10 00 15.00

mg/k

Ni <250 µm (total, mg/kg)

3% 24% 34% 15% 13% 14% 9% 15%

5.00 10.00 Ni <250 µm (mg leached/ kg solid)

5% 8% 4%

0.00 3 8

  • 4
  • 1
  • P

H 3 4

  • 1
  • 2
  • P

H 3 2

  • 4
  • P

H 3 1

  • 2

d

  • 1
  • P

H 3

  • 1
  • P

H 2 9

  • 3

d

  • 1
  • P

H 2 7

  • 3
  • P

H 2 6

  • 1
  • P

H 2 4

  • 3

d

  • P

H 2 2

  • 3
  • P

H

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SLIDE 18

30.00

Lead

Pb <2 mm (total, mg/kg)

28% 26% 8% 18% 22% 23%

20.00

/kg

Pb <2 mm (mg leached/ kg solid)

19% 10% 18% 14% 24% 21% 22% 16% 45% 44% 44%

10.00

mg/

Pb <250 µm (total, mg/kg)

22% 25% 19% 16% 29% 17%

Pb <250 µm (mg leached/ kg solid) 0.00 3 8

  • 4
  • 1
  • P

H 3 4

  • 1
  • 2
  • P

H 3 2

  • 4
  • P

H 3 1

  • 2

d

  • 1
  • P

H 3

  • 1
  • P

H 2 9

  • 3

d

  • 1
  • P

H 2 7

  • 3
  • P

H 2 6

  • 1
  • P

H 2 4

  • 3

d

  • P

H 2 2

  • 3
  • P

H

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SLIDE 19

Conclusions

  • No significant difference between soil size

fractions for metals examined

  • No strong correlations with usual controls on

element mobility in soils

  • IVBA’s are a useful tool within context - particle

characteristics, source apportionment etc.

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SLIDE 20

Thanks

Geoff Plumlee Paul Lamothe Ruth Wolf Geoff Plumlee, Paul Lamothe, Ruth Wolf and Monique Adams