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

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. Department of the Interior U.S. Geological Survey

The Challenge Anthropogenic versus Geogenic p g g

The Challenge For Particulate Matter Research (PM) Anthropogenic – Human impact on the environment ( (e.g., chemicals, pesticides, h i l ti id 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

The Challenge Geogenic or naturally occurring earth materials such as soils, dusts and ash may contain known h t i k or potential toxicants. Exposure levels needed Exposure levels needed to trigger disease and causal links to disease are lacking for many materials

The Challenge g Occupational Environmental exposures exposures  Single element or  Element mixture mixture (metals)  Concentration  Concentration  Route of Exposure  Route of Exposure  Duration of  Duration of Exposure Exposure  Matrix composition and effects

The Challenge Particle Characteristics of Particle Characteristics of Toxicological Interest  Particle mineralogy  Particle size distribution  Particle morphology  Chemical composition (bulk, and of  Ch i l iti (b lk d f different phases)  Particle biosolubility, bioreactivity,  P ti l bi l bilit bi ti it bioaccessibility along inhalation, ingestion exposure pathways p p y

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 (% Bioaccess. = (conc. leachate/total conc.)* 100) (% Bi ( l h t /t t l )* 100)  Fast & Inexpensive  Gastric (pH 1 5) 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

IVBA

The North American Soil Geochemical Landscapes Project. Examine size fraction (<2mm or <250µm) and variations/controls in/on bioaccessibility  N-S transect  Randomly selected  0  0 – 5 cm soil 5 il  Split, half sieved to <2mm and half to <250µm and half to 250µm  Simulated gastric leach (pH 1.5, temperature 37 ° f for 1 hour) 1 h ) (Morman et al. 2009. Applied Geochemistry, v. 24 8) Geochemistry, v. 24 8)

Results - Total Chemistry (mg/kg) As Cd Cr Ni Pb Both Transects 20 8.2 6030 2820 318 Max <1 <0.1 2 2 3 Min 4.5 0.2 29 14 19 Median N-S Transect 11 0.8 79 63 93 Max <1 <1 <0.1 <0 1 4 4 4 4 7 7 Min Mi 3 0.3 31 16 17 Median Selected Samples 11 0.7 50 30 93 Max 1 <0.1 9 5 9 Min 4 0.3 34 14 17 Median

Results 120 No significant difference in g median concentration values between size 100 fractions for total chemistry fractions for total chemistry ssibility or % bioaccessibility. 80 Regression analysis % Bioacces showed no correlation with 60 several ‘controls’ on mobility (soil pH, clay mobility (soil pH, clay 40 40 % content, organic C,) Cd, Ni and Pb 20 demonstrated weak correlation to total 0 µm) µm) µm) concentration µm) µm) mm) m) m) m) m) Ni (<2 mm Pb (<250 µ As (<250 µ Cr (<250 µ Ni (<250 µ Cd (<2 m Cd (<250 Pb (<2 m As (<2 m Cr (<2 m

Arsenic 12.00 2% 2% As <2 mm (total, mg/kg) 10.00 5% 8.00 7% As <2 mm (mg leached/ 2% kg solid) g/kg 6 00 6.00 mg 4% 2% As <250 µm (total, mg/kg) 4.00 7% 10% 5% 2.00 As <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

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

Cadmium 0 50 0.50 Cd <2 mm 0.45 (total, mg/kg) 61% 58% 54% 58% 57% 55% 0.40 60% 60% 57% 68% 0.35 Cd <2 mm 65% (mg leached/ 59% 71% 0.30 kg solid) 66% 104% kg mg/k 0.25 30% Cd <250 µm 0.20 (total, mg/kg) 65% 44% 0.15 55% 55% 66% 86% 0.10 Cd <250 µm (mg leached/ 0.05 kg solid) 0.00

Chromium 60.00 1% Cr <2 mm 1% 2% 2% (total, mg/kg) 2% 1% 50.00 2% 0.4% 0 4% 2% 1% 0.3% 40.00 Cr <2 mm (mg leached/ 0.7% kg solid) kg mg/k 30.00 5% Cr <250 µm 0.8% 2% 3% (total, mg/kg) 20.00 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

Interferences on Cr Values  Cr measured at 52 Cr or 53 Cr  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 40 Ar 12 C and 37 Cl 16 O 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 NH 3 as the reaction gas can eliminate these interferences giving an accurate concentration for Cr background levels in the fluids  NH 3 at 0.9 and RPq at 0.65 NH 3 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 Q DRC-ICP-MS Lung Fluid Blank 110 ppb 0.9 ppb Gastric Fluid Blank 92 ppb 1.5 ppb

Nickel 35.00 Ni <2 mm (total, mg/kg) 16% 30.00 16% 15% 19% 25.00 25% 23% Ni <2 mm (mg leached/ 9% kg solid) 20.00 kg 9% 13% mg/k 3% 14% 9% 15% 13% 15.00 Ni <250 µm 24% (total, mg/kg) 34% 15% 10 00 10.00 5% 4% Ni <250 µm 8% 5.00 (mg leached/ kg solid) 0.00 H H H H H H H H H H P P P P P P P P P P - - - - - - - - - - 1 2 4 1 1 1 3 1 d 3 - - - - - - - - - 3 4 1 2 d 0 d 7 6 2 - - - 3 2 3 3 2 2 4 2 8 4 - - 0 0 2 0 3 3 1 9 0 3 2

Lead 30.00 Pb <2 mm 28% (total, mg/kg) 26% 23% 8% 18% 18% 22% 22% 16% 45% 14% 10% 20.00 44% Pb <2 mm 21% (mg leached/ 44% kg solid) 24% /kg mg/ 19% 19% 16% 22% Pb <250 µm 17% (total, mg/kg) 29% 10.00 25% Pb <250 µm (mg leached/ kg solid) 0.00 H H H H H H H H H H P P P P P P P P P P - - - - - - - - - - 1 2 4 1 1 1 3 1 d 3 - - - - - - - - 3 - 4 1 2 d 0 d 7 6 2 - - - 3 2 3 3 2 2 4 2 8 4 - - 0 0 2 0 3 3 1 9 0 3 2

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.

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