# Contamination of durum wheat by cadmium : lessons from the field

Christophe Nguyen, Emmanuelle Gourdain, Guénolé Grignon, Bruno

Barrier-Guillot, Benoit Meleard

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## ► To cite this version:

Christophe Nguyen, Emmanuelle Gourdain, Guénolé Grignon, Bruno Barrier-Guillot, Benoit Meleard. Contamination of durum wheat by cadmium: lessons from the field. ICOBTE 2017, Jul 2017, Zurich, Switzerland. 1 p. hal-01605302

HAL Id: hal-01605302

https://hal.science/hal-01605302

Submitted on 5 Jun 2020

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# Contamination of Durum Wheat by Cadmium : Lessons from the Field

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Christophe Nguyenª, E. Gourdainᵇ, M. Jacquardᵇ, G. Grignonᵇ, B. Barrier-Guillotᵇ and B. Méléardᵇ

ª Interactions soil-plant-atmosphere INRA - BSA, France - ᵇ Arvalis, Institut du Végétal, France
christophe.nguyen@inra.fr

## Cadmium (Cd)

Very toxic (carcinogenic) - Accumulated by crops due to root uptake from soil - European regulatory limits for contents in some foodstuffs (EC 1881/2006) - Dietary exposure to Cd too high in Europe (Efsa, 2009) - Wheat = major contributor to dietary exposure to Cd

**Project of lowering regulatory limit for Cd in wheat (DGSanco, 2011)**

### Cd in French durum wheat compared to current and possible new regulatory limits

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### Cd in durum wheat grain : Phytoavailability of Cd in soil > cultivar differences

### N fertilization increases Cd in durum wheat grain Spliting N dose can help limiting contamination

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Location : CV =54%
Between cultivars|location : x1.5

Cultivar : CV =10%
Between locations|cultivar : x6.8

Field factorial trials comparing cultivars for different soils

Contrary to Canada, in France, cultivars are not yet selected for the low Cd accumulation allele (Zimmerl et al., 2014)

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NH₄NO₃ fertilization increased more importantly grain Cd than yield and protein content

Increase proteins but not Cd in grains = Split N quantity
NH₄⁺ assumed to desorb Cd and/or acidify soil solution

### Risk assessment for the contamination of durum wheat grain by Cd

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1 Cdtot

2 Cdtot + pHeau

3 Cdtot + pHeau + Clay

4 Cdtot + pHeau + Silt_F

5 Cdtot + pHeau + Silt_C

6 Cdtot + pHeau + Corg

7 Cdtot + pHeau + Calc

8 Cdtot + pHeau + Clay + Silt_F

9 Cdtot + pHeau + Clay + Silt_C

10 Cdtot + pHeau + Clay + Calc

11 Cdtot + pHeau + Clay + Calc

12 Cdtot + pHeau + Silt_F + Silt_C

13 Cdtot + pHeau + Silt_F + Corg

Limit 0.15 mg Cd/kg

$p(\text{pred}=-|\text{-}) = 0.96$

$p(-|\text{pred}=-) = 0.94$

<figure><img src="image_9.png" /></figure>

14 Cdtot + pHeau + Silt_F + Calc

15 Cdtot + pHeau + Silt_C + Corg

16 Cdtot + pHeau + Silt_C + Calc

17 Cdtot + pHeau + Corg + Calc

18 Cdtot + pHeau + Clay + Silt_F + Silt_C

19 Cdtot + pHeau + Clay + Silt_F + Corg

20 Cdtot + pHeau + Clay + Silt_F + Calc

21 Cdtot + pHeau + Clay + Silt_C + Corg

22 Cdtot + pHeau + Clay + Silt_C + Calc

23 Cdtot + pHeau + Clay + Corg + Calc

24 Cdtot + pHeau + Clay + Silt_F + Silt_C + Corg

25 Cdtot + pHeau + Clay + Silt_F + Silt_C + Calc

26 Cdtot + pHeau + Clay + Silt_F + Silt_C + Corg + Calc

Which model(s) ?

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**Increase grain Cd** : Cdtot, Clay and Silk (buffer power)

**Decrease grain Cd** : pH (solubility, speciation), Corg (sorption), Calc (sorption, precipitation)

<figure><img src="image_11.png" /></figure>

Limit 0.10 mg Cd/kg

$p(\text{pred}=-|\text{-}) = 0.92$

$p(-|\text{pred}=-) = 0.85$

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Probability (grain Cd > limit) = f(Cdtot : total soil Cd, pH : soil pH, Corg : soil organic carbon, Calc : soil calcareous, Clay : soil clay, Silk_C, Silk_F : coarse & fine silk)

Field data : n=408
(2008-2016, French production of durum wheat)

### Model performances for field applications

The models predict correctly more than **91%** of the cases

Conform (-)

Detection
p(pred=+|+)
p(pred=-|-)

High

Non conform (+)

Weak

Good

Good

Weak

Reliability
p(+|pred=+)
p(-|pred=-)

High

Models are sensitive & accurate

Trade-off between detection and reliability

More data are needed to improve models