CdCd, , PbPb and Zn oral and Zn oral

bioaccessibility in urban soils in bioaccessibility in urban soils in

the vicinity of two lead and zinc the vicinity of two lead and zinc

smelterssmelters

RousselRoussel H.H., , WaterlotWaterlot C., C., PruvotPruvot C., Douay F.C., Douay F.

Laboratory of Soils and Environment, Institut Supérieur d’Agriculture, 48 boulevard Vauban, Lille - France

ContextContext

•• HistoricHistoric

contaminationcontamination

� Metaleurop Nord (Noyelles-Godault) = Lead smelter

� Umicore (Auby) = Zinc smelter

Pb isoconcentrationcurves (mg/kg)

ContextContext

Agricultural topsoils

ContextContext•• High contamination of urban soils used for High contamination of urban soils used for

recreational purposes or vegetables recreational purposes or vegetables

production.production.

0

5

10

15

20

25

30

35

40

45

50

Ag As Bi Cd Co Cr Cu Hg In Ni Pb Sb Se Sn Th Tl U Zn

ME

UM

ContextContext

•• Ratio of Ratio of UrbanUrban vs vs RegionalRegional agricultural agricultural topsoilstopsoils

•• Ratio of Ratio of UrbanUrban vs vs Local agricultural Local agricultural topsoilstopsoils

METALEUROP (Pb smelter)

UMICORE (Zn smelter)

0

1

2

3

4

5

6

7

8

Ag As Bi Cd Co Cr Cu Hg In Ni Pb Sb Se Sn Th Tl U Zn

ME

UM

(Douay et al. 2008)

ContextContext

•• SoilSoil ingestion ingestion withwith hand to hand to mouthmouth transfertransfer

7

Lead blood level (> 100 µg L-1)

� 10 to 15 % of children (2 to 4 years old, from 1994 to 2002)

� up to 30 % under the prevailing winds

� 2.4 % in 2004 after smelter closedown

But the actual mean lead blood level is still over the national mean value (42 µg L-1 instead of 27 µg L-1 respectively)

ContextContext

AimsAims

••Evaluate Bioaccessibility of Evaluate Bioaccessibility of CdCd, , PbPb and Zn in and Zn in

urban soils for human health risk assessmenturban soils for human health risk assessment

••Differentiate bioaccessibility between smeltersDifferentiate bioaccessibility between smelters

••Understand the impact of soils Understand the impact of soils physicophysico--chemical chemical

parametersparameters

••Predict Bioaccessibility with multiple parameter Predict Bioaccessibility with multiple parameter

equationsequations

MaterialsMaterials and and methodsmethods27 urban topsoils were sampled

•20 soils

around

Metaleurop

Nord (ME)

•7 soils around

Umicore (U)

•12 lawns and

15 kitchen

gardens

MaterialsMaterials and and methodsmethods

•Pooled (5 to 13 elementary samples)

topsoil samples (0-25 cm) taken with a

stainless steel auger.

•Total Cd, Pb, Zn concentrations, in vitro

bioaccessibility tests, CEC, pH,

Carbonates, Organic matter, etc.

MaterialsMaterials and and methodsmethods

30.86.35.217.2cmol+ kg-1CEC

2.6800.1040.7110.912g kg-1P2O5

8.166.670.417.42g kg-1Total CaCO3

12313.730.856.6g kg-1Total nitrogen

101.51.033.429.2g kg-1Organic carbon

8.26.70.47.4pH

62.91311.526.1%Sand

69.927.49.553.1%Silt

28.88.15.420.8%Clay

MaxMinSDMean

•• PhysicoPhysico--chemicalchemical parametersparameters

MaterialsMaterials and and methodsmethods

6908.2325.91761.61941.2mg kg-1Total Zn

3025.695.1760.5983.8mg kg-1Total Pb

31.433.158.3914.96mg kg-1Total Cd

MaxMinSDMean

•• PhysicoPhysico--chemicalchemical parametersparameters

MaterialsMaterials and and methodsmethods•• In vitroIn vitro Bioaccessibility test (following Bioaccessibility test (following

BARGE UBM protocol)BARGE UBM protocol)

0.6 g soil

............................................................ ........................

+ 9 mL Saliva

+ 13.5 mL Gastric juice pH = 1.2 - 1.7

....................................

(pH = 6.5+_ 0.5)

Manualshaking

5 - 15 min

Chyme

..........................Residual soil

1h00 - 37°C

End-over-endrotation

Centrifugation3000 g - 5 min

Gastric extraction

Filtration 27µm(Whatman n°41)

Analysis AAS

Gastro-intestinal

extraction

+ 27 mL jus Duodenal+ 9 mL Bile

Centrifugation3000 g - 5 min

End-over-endrotation

4h00 - 37°C

Residual soil

..............Chyme

............

(pH = 6.3+_ 0.5)

Filtration 27µm(Whatman n°41)

Analysis AAS

............

ResultsResults

•• ReferenceReference NIST 2710NIST 2710

Total (mg kg-1)

(Ellickson et al., 2001) (Denys et al., 2007)(Oomen

et al.,2004)This study

Gastric Intestinal Gastric Intestinal Intestinal Gastric Intestinal

Cd 21,8 55-65 57.1 ±±±±2.8 27.2 ±±±± 8.3

Pb 5532 76.1 ± 11 10.7 ± 2.3 79 ± 4 25 ± 1 30-35 55 ±±±± 6.7 30.6 ±±±± 2.5

Zn 6952 20.5 ±±±± 3.8 11.1 ±±±± 1.2

ResultsResults•• Percentage of bioaccessible fraction of Percentage of bioaccessible fraction of CdCd, ,

PbPb and Zn expressed as a percentage of and Zn expressed as a percentage of total concentration in soil. total concentration in soil.

46.663.258.684.676.180.9Max

8.413.716.216.632.857.1Min

10.411.410.317.010.66.5SD

23.032.031.247.261.568.1Mean

ZnPbCdZnPbCd

Gastro-intestinalGastric

Results

• No clear differences of bioaccessibility (related to total concentration) among smelters

y = 0.4201x

R2 = 0.9028

y = 0.2919x

R2 = 0.8502

0

2

4

6

8

10

12

14

16

18

0 5 10 15 20 25 30 35

Cd

Cd total (mg/kg)

Cd b

ioaccessib

le (

mg/k

g)

y = 0.3812x

R2 = 0.9217

y = 0.3503x

R2 = 0.8654

0

200

400

600

800

1000

1200

0 500 1000 1500 2000 2500 3000 3500

Pb total (mg/kg)

Pb b

ioaccessib

le (

mg/k

g)

y = 0.3827x

R2 = 0.9267

y = 0.2869x

R2 = 0.8358

0

500

1000

1500

2000

2500

3000

0 1000 2000 3000 4000 5000 6000 7000 8000

Zn total (mg/kg)

Zn b

ioaccessib

le (

mg/k

g)

Pb

Zn

Umicore

Metaleurop

ResultsResults

•• Relationships Relationships between between bioaccessible bioaccessible CdCd, , PbPb and Zn and total and Zn and total concentrations in concentrations in soils. soils.

Cd

y = 0.6928x - 0.1677

R2 = 0.9645

y = 0.3734x - 0.7023

R2 = 0.8141

0

5

10

15

20

25

30

0 5 10 15 20 25 30 35

Cd total (mg kg -1)

Cd

bio

accessib

le (

mg

kg

-

1)

Zny = 0.6738x -212.79R2 = 0.9376

y = 0.4159x - 226.97

R2 = 0.9474

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 1000 2000 3000 4000 5000 6000 7000 8000

Zn total (mg kg -1)

Zn

bio

accessib

le (

mg

kg

-1)

Pby = 0.626x - 4.3255

R2 = 0.9584

y = 0.3907x - 49.419

R2 = 0.8896

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 500 1000 1500 2000 2500 3000 3500

Pb total (mg kg -1)

Pb

bio

accessib

le (

mg

kg

-1)

R²=0.89

R²=0.81

R²=0.95

Gastric

Gastro-intestinal

Results

P<0.0010.975Bioacc Zn=0.412*[Zntot]-14.58*[Clay]-

86.42*[P2O5]-1.59*[CaCO3]+208.5

Zn

P<0.0010.944Bioacc Pb=0.395*[Pbtot]-1.04*[CaCO3]-

24.92*[Ntot]-81.75*pH+658.51

Pb

P<0.0010.87Bioacc Cd= 0.414*[Cdtot]-0.140*[CEC]-

0.009*[CaCO3]-0.45*[P2O5]+1.77

Cd

R²Equation

• Relationship between predicted bioaccessible

concentrations of Cd, Pb and Zn and soil parameters

given by stepwise regression models.

R²=0.89

R²=0.81

R²=0.95

DiscussionDiscussion

•• HOWEVER... As shown by Denys and coHOWEVER... As shown by Denys and co--authors (2007) carbonates can be positively authors (2007) carbonates can be positively related with bioaccessibility (PbCOrelated with bioaccessibility (PbCO33))

•• Urban Urban vsvs. minig soils behave differently (Pb . minig soils behave differently (Pb bioaccessibility between 40bioaccessibility between 40--84% and 84% and 1010--60% in 60% in CabocheCaboche and coand co--authors presentation Wed authors presentation Wed a.ma.m).).

•• Stepwise multiple regression showed that total Stepwise multiple regression showed that total

concentration was positively correlated to concentration was positively correlated to

bioaccessibility and bioaccessibility and PP22OO55, CEC, Clay, pH or , CEC, Clay, pH or

CaCOCaCO33 where negatively related.where negatively related.

ConclusionConclusion

•• Real importance of the source Real importance of the source

of contamination (speciation) and of contamination (speciation) and

the receiving matrix (soil quality)the receiving matrix (soil quality)

Post Doctoral position Post Doctoral position

availableavailableOral bioavailability assessment Oral bioavailability assessment

of trace elements in soils and of trace elements in soils and

dust from an area heavily dust from an area heavily

contaminated by a former lead contaminated by a former lead

smeltersmelter

ThankThank youyou for for youryour attention !attention !