Cadmium concentrations in Canadian durum exports decreased with the adoption of low accumulating cultivars

Figures & data

Figure 1. Cadmium content of bulk export shipments of Canada Western Amber Durum (CWAD) and Canada Western Red Spring (CWRS) between 1992 and 2020. Boxes represent 25–75th percentiles; whiskers represent 10–90th percentiles. Lines within boxes indicate median concentrations.

Table 1. Cadmium concentrations (mg/kg) in Canada Western Amber Durum bulk export shipments.

Shipment year	N	Median	Mean	Range	90th Percentile
1992–1993	142	0.130	0.131	0.092–0.167	0.151
1993–1994	173	0.127	0.126	0.095–0.164	0.140
1994–1995	263	0.117	0.118	0.085–0.163	0.138
1995–1996	21	0.116	0.116	0.095–0.142	0.128
1996–1997	74	0.114	0.118	0.091–0.165	0.141
1997–1998	63	0.118	0.117	0.049–0.150	0.140
1998–1999	66	0.137	0.139	0.110–0.183	0.158
1999–2000	41	0.127	0.129	0.099–0.170	0.148
2000–2001	19	0.118	0.114	0.082–0.148	0.135
2001–2002	38	0.145	0.147	0.102–0.226	0.180
2002–2003	36	0.154	0.155	0.118–0.209	0.183
2003–2004	26	0.160	0.156	0.122–0.192	0.173
2004–2005	100	0.150	0.147	0.095–0.247	0.171
2005–2006	254	0.134	0.137	0.044–0.369	0.163
2006–2007	274	0.134	0.134	0.054–0.412	0.159
2007–2008	173	0.111	0.112	0.051–0.187	0.135
2008–2009	147	0.109	0.114	0.082–0.229	0.132
2009–2010	37	0.115	0.124	0.085–0.209	0.189
2010–2011	8	0.085	0.084	0.063–0.103	0.098
2011–2012	37	0.077	0.079	0.052–0.138	0.092
2012–2013	52	0.072	0.076	0.058–0.184	0.084
2013–2014	67	0.071	0.072	0.052–0.107	0.079
2014–2015	31	0.066	0.069	0.057–0.092	0.085
2015–2016	25	0.079	0.079	0.058–0.101	0.091
2016–2017	15	0.071	0.068	0.045–0.088	0.081
2017–2018	9	0.058	0.060	0.049–0.072	0.068
2018–2019	19	0.072	0.071	0.060–0.082	0.079
2019–2020	29	0.070	0.074	0.055–0.123	0.088

Table 2. Cadmium concentrations (mg/kg) in Canada Western Red Spring bulk export shipments.

Shipment year	N	Mean	Median	Range	90th Percentile
1994–1995	273	0.034	0.033	0.022–0.054	0.040
1995–1996	28	0.036	0.037	0.016–0.050	0.044
1996–1997	30	0.033	0.032	0.024–0.050	0.040
1997–1998	37	0.033	0.033	0.013–0.044	0.041
1998–1999	34	0.041	0.039	0.029–0.093	0.047
1999–2000	51	0.036	0.035	0.020–0.056	0.049
2000–2001	27	0.028	0.028	0.018–0.053	0.034
2001–2002	72	0.035	0.035	0.025–0.059	0.043
2002–2003	37	0.039	0.039	0.029–0.057	0.048
2003–2004	81	0.035	0.035	0.017–0.052	0.041
2004–2005	108	0.039	0.039	0.022–0.060	0.047
2005–2006	51	0.034	0.033	0.022–0.050	0.043
2006–2007	48	0.035	0.035	0.025–0.050	0.043
2007–2008	65	0.032	0.031	0.020–0.046	0.039
2008–2009	65	0.033	0.033	0.019–0.046	0.040
2009–2010	75	0.035	0.034	0.023–0.053	0.041
2010–2011	26	0.030	0.029	0.023–0.037	0.037
2011–2012	71	0.030	0.030	0.018–0.045	0.038
2012–2013	137	0.034	0.033	0.020–0.047	0.041
2013–2014	74	0.034	0.032	0.021–0.131	0.042
2014–2015	29	0.034	0.036	0.024–0.044	0.040
2015–2016	52	0.038	0.036	0.025–0.059	0.049
2016–2017	31	0.036	0.036	0.026–0.051	0.042
2017–2018	20	0.031	0.030	0.025–0.038	0.035
2018–2019	24	0.035	0.035	0.025–0.050	0.045

Figure 2. Predominant Canada Western Amber Durum cultivars grown in the provinces of Manitoba, Saskatchewan and Alberta from 1998 to 2018. Data are unavailable for the 2015 growing year. Insured acres of each cultivar listed comprised greater than 5% of total insured acres in at least one year from 1998 to 2019. The grey ‘Others’ category includes cultivars comprising less than 5% of total insured acres, cultivars that were not in the current list of Canadian Grain Commission designated varieties for a given growing year, and cultivars whose name was not provided. Cultivars represented by shades of green were registered in 2004 and later, and are low cadmium accumulators. Cultivars represented by shades of blue were registered from 1984 to 2002, and are high cadmium accumulators.

Figure 3. Cadmium concentrations in Canada Western Amber Durum used as check cultivars in Co-operative Registration Trials. Cultivars represented by shades of green were registered in 2004 and later, and are low cadmium accumulators. Cultivars represented by shades of blue were registered from 1984 to 2004, and are high cadmium accumulators.

Table 3. Cadmium measured in wheat and durum grown in various locations.

Growing location	Sample source	Range of Cd (mg/kg)	Range represents	Reference
Wheat
USA	Commercial blends from mills	0.10 ± 0.02^a	Mean ± standard deviation	Zook et al. (1970)
USA	Field surveys in 11 states in 1 growing year	<0.002–0.207 0.022–0.074^b	Individual fields means from each state	Wolnik et al. (1983)
Italy	Harvest survey in 1 growing year	0.018–0.076	Cultivar/province composites	Conti et al. (2000)
Western Canada	Harvest survey in 3 provinces over 3 growing years	0.032–0.036^b	Annual mean of all individual samples	Gawalko et al. (2002)
Mato Grosso, Brazil	Field experiment in 1 growing year	<0.015–0.083^b	Mean of triplicate field plot samples of a single cultivar	Corguinha et al. (2015)
France	‘Reference area’ away from lead smelter in 1 growing year	0.09–0.14	Individual sampling point	Douay et al. (2008)
Belgium	Harvest survey over 4 growing years	0.063 ± 0.022^a	Mean ± standard deviation of individual samples	Harcz et al. (2007)
Jiangsu Province, China	Harvest survey in 1 growing year	0.010–0.275	Individual sampling point	Yang et al. (2020)
Durum
USA	Commercial blends from mills	0.13 ± 0.01^a	Composite	Zook et al. (1970)
Western Canada	Field experiments at 2 locations over 2 growing years	0.042–0.183^b	Means of variety/location/growing combinations	Clarke et al. (1997)
Italy	Harvest survey cultivar/province composites in 1 growing year	0.016–0.088	Cultivar/province composites	Conti et al. (2000)

^aMean ± standard deviation.

^bRange of means.

Table A1. Comparison of results from the analysis of replicate test portions (N) of certified and in-house reference materials for cadmium (mean ± standard deviation, mg/kg) by atomic absorption spectroscopy (AA) and inductively coupled plasma mass spectrometry (ICP-MS).

Reference material	N	Reference Cd value	AA	ICP-MS
NIST apple leaves SRM 1515	9	0.013 ± 0.002	0.012 ± 0.001	0.014 ± 0.001
NIST rice flour SRM 1568a	8	0.020 ± 0.002	0.019 ± 0.001	0.020 ± 0.002
NIST wheat flour SRM 1567a	8	0.024 ± 0.002	0.022 ± 0.001	0.023 ± 0.002
In-house reference Canada Western Red Spring wheat	21	0.041 ± 0.008	0.038 ± 0.002	0.039 ± 0.002
In-house reference Canada Western Amber Durum	19	0.141 ± 0.014	0.141 ± 0.008	0.140 ± 0.006
In-house reference solin	18	0.278 ± 0.028	0.270 ± 0.015	0.268 ± 0.009

Reference values were provided for the commercially-available certified reference materials (NIST materials). Reference values for the in-house reference materials were calculated as the mean ± standard deviation (wheat n = 34; durum n = 37; solin n = 28) of results from 6 rounds of analysis by 7 independent laboratories.

Zook EG, Greene FE, Morris ER. 1970. Nutrient composition of selected wheats and wheat products. VI. Distribution of manganese, copper, nickel, zinc, magnesium, lead, tin, cadmium, chromium, and selenium as determined by atomic absorption spectroscopy and colorimetry. Cereal Chem. 47:720–731.

 Google Scholar

Wolnik KA, Fricke FL, Capar SG, Braude GL, Meyer MW, Satzger RD, Bonnin E. 1983. Elements in major raw agricultural crops in the United States. 1. Cadmium and lead in lettuce, peanuts, potatoes, soybeans, sweet corn, and wheat. J Agric Food Chem. 31(6):1240–1244.

 PubMed Web of Science ®Google Scholar

Conti ME, Cubadda F, Carcea M. 2000. Trace metals in soft and durum wheat from Italy. Food Addit Contam. 17(1):45–53.

 PubMed Web of Science ®Google Scholar

Gawalko EJ, Garrett RG, Nowicki TW. 2002. Cadmium, copper, iron, manganese, selenium, and zinc in Canadian spring wheat. Commun Soil Sci Plant Anal. 33(15–18):3121–3133.

 Web of Science ®Google Scholar

Corguinha APB, Souza GAd, Gonçalves VC, Carvalho CA, Lima WEAd, Martins FAD, Yamanaka CH, Francisco EAB, Guilherme LRG. 2015. Assessing arsenic, cadmium, and lead contents in major crops in Brazil for food safety purposes. J Food Compos Anal. 37:143–150.

 Web of Science ®Google Scholar

Douay F, Roussel H, Pruvot C, Waterlot C. 2008. Impact of a smelter closedown on metal contents of wheat cultivated in the neighbourhood. Environ Sci Pollut Res Int. 15(2):162–169.

 PubMed Web of Science ®Google Scholar

Harcz P, De Temmerman L, De Voghel S, Waegeneers N, Wilmart O, Vromman V, Schmit JF, Moons E, Van Peteghem C, De Saeger S, et al. 2007. Contaminants in organically and conventionally produced winter wheat (Triticum aestivum) in Belgium. Food Addit Contam. 24(7):713–720.

 PubMed Web of Science ®Google Scholar

Yang JI, Cang L, Wang X, Xu HT, Zhou DM. 2020. Field survey study on the difference in Cd accumulation capacity of rice and wheat in rice-wheat rotation area. J Soils Sediments. 20(4):2082–2092.

 Web of Science ®Google Scholar

Clarke JM, Leisle D, Kopytko GL. 1997. Inheritance of cadmium concentration in five durum wheat crosses. Crop Sci. 37(6):1722–1726.

 Web of Science ®Google Scholar