Heavy metals concentration in food crops irrigated with pesticides and their associated human health risks in Paki, Kaduna State, Nigeria

Figures & data

Figure 1. The location of the sampling points in the study.

Table 1. Details of Atomic absorption spectrometry instrumentation and condition of operation

Heavy metal	Wavelength (nm)	Slit width (nm)	Lamp current (ma)	Flame type
Cd	228.9	0.7	8.0	Air/Ace thane
Pb	283.2	0.7	8.0	Air/Ace thane
Cr	357.9	0.7	8.0	Air/Ace thane
Cu	324.7	0.7	6.0	Air/Ace thane
Zn	213.9	0.7	8.0	Air/Ace thane

Table 2. Mean Heavy Metals (mg/kg) Concentrations Dry Weight in Food Crops

Sampling Site	Name of Sample	Botanical Name	Hausa Name	Heavy metals mg/kg
				Cd	Pb	Cr	Cu	Zn
Kaduna	Onion	Allium cepa	Albasa	Mean±SD	Mean±SD	Mean±SD	Mean±SD	Mean±SD
	Root			0.17 ± 0.01a	2.33 ± 0.73a	0.67 ± 0.17a	17.83±a	21.33 ± 0.17b
	Stem			ND	ND	ND	ND	ND
	Leaf			0.18 ± 0.00a	1.17 ± 0.17a	ND	10.00±a	15.17 ± 0.33a
	Bulb			1.16 ± 0.03b	4.33 ± 0.33b	1.25 ± 0.06b	15.33±a	23.33 ± 0.16b
	Tomato	Solanum lycopersicum	Tomatur
	Root			0.11 ± 0.01b	2.67 ± 1.00a	0.67 ± 0.16a	11.58 ± 0.22b	17.92 ± 0.21a
	Stem			0.21 ± 0.02b	3.33 ± 0.66a	0.50 ± 0.50a	9.08 ± 0.66b	36.58 ± 0.38a
	Leaf			0.67 ± 0.06a	1.75 ± 0.91a	0.25 ± 0.25a	3.17 ± 0.17a	14.08 ± 0.88a
	Fruit			0.87 ± 0.33a	3.08 ± 0.25a	0.50 ± 0.04a	12.33 ± 0.50b	34.25 ± 0.27a
	Carrot	Daucus carota	Karas
	Root			ND	ND	ND	ND	ND
	Stem			ND	ND	ND	ND	ND
	Leaf			ND	ND	ND	ND	ND
	Taproot			1.18 ± 0.04	4.50 ± 0.50	1.50 ± 0.03	21.3 ± 0.44	19.00 ± 0.29
	Cucumber	Cucumis sativus	Kokwamba
	Root			0.30 ± 0.00a	0.67 ± 0.17a	ND	7.83 ± 0.17a	15.67 ± 0.44a
	Stem			ND	ND	ND	ND	ND
	Leaf			0.27 ± 0.02a	5.33 ± 0.16c	0.67 ± 0.17	15.8 ± 0.60b	44.00 ± 0.29c
	Fruit			0.98 ± 0.29b	1.83 ± 0.17b	ND	22.5 ± 1.76c	37.50 ± 0.29b
	Cabbage	Brassica oleracea	Kabeji
	Root			ND	ND	ND	ND	ND
	Stem			ND	ND	ND	ND	ND
	Leaf			0.88 ± 0.17	0.50 ± 0.29	ND	10.8 ± 1.33	22.50 ± 0.29
		FAO/WHO, 2019 limits		0.2	0.3	2.3	40	60

Note: NB: Mean values indicated by the same letter is not significantly different p > 0.05 across rows, ND=Not Detected.

Table 3. Mean Heavy Metals Concentrations (mg/kg) dry weight in Food Crops

Sampling Site	Name of Sample	Botanical Name	Hausa Name	Heavy metals mg/kg
				Cd	Pb	Cr	Cu	Zn
	Maize	Zea mays	Masara	Mean±SD	Mean±SD	Mean±SD	Mean±SD	Mean±SD
	Root			ND	ND	ND	ND	ND
	Stem			0.13 ± 0.01a	4.00 ± 0.29a	1.17 ± 0.17	31.8 ± 0.44a	17.33 ± 0.17a
	Leaf			ND	ND	ND	ND	ND
	Fruit			1.33 ± 0.04b	0.67 ± 0.44b	ND	16.3 ± 0.17b	39.67 ± 0.25b
		FAO/WHO, 2019 limits		0.2	0.3	2.3	40	60

Note: NB: Mean values indicated by the same letter is not significantly different p > 0.05 across rows, ND=Not Detected.

Table 4. Heavy Metals Concentrations (mg/kg) in Soil Sample of Each Crop

Sampling Site	Soil from the land of	Botanical Name	Hausa Name	Heavy metals mg/kg
				Cd	Pb	Cr	Cu	Zn
				Mean±SD	Mean±SD	Mean±SD	Mean±SD	Mean±SD
Kaduna	Onion	Allium cepa	Albasa	0.33 ± 0.07a	3.08 ± 0.05b	0.5 ± 0.02a	4.83 ± 0.20a	61.3 ± 0.29a
	Tomato	Solanum lycopersicum	Tomatur	0.92 ± 0.12a	2.76 ± 0.33b	0.5 ± 0.03a	18.33 ± 0.47ab	38.8 ± 0.29a
	Carrot	Daucus carota	Karas	1.17 ± 0.17b	1.83 ± 0.20ab	1.1 ± 0.17b	31.50 ± 0.29b	22.0 ± 0.15a
	Cucumber	Cucumis sativus	Kokwamba	1.17 ± 0.17b	2.17 ± 0.16ab	1.00 ± 0.02b	31.00 ± 0.50b	19.1 ± 0.17a
	Cabbage	Brassica oleracea	Kabeji	ND	2.67 ± 0.17b	0.50 ± 0.02a	6.50 ± 0.58a	12.3 ± 0.12a
	Maize Control	Zea mays Soil	Masara Soil	ND 0.16 ± 0.02c	0.83 ± 0.33a 0.20 ± 0.04c	0.50 ± 0.01a 0.03 ± 0.01c	15.17 ± 0.17ab 1.53 ± 0.03c	5.00 ± 0.09a 2.73 ± 1.36c
		Unep et al. (2013) Limits		10	200	200	50	250

NB: Mean values indicated by the same letter is not significantly different p > 0.05 across rows, ND=Not Detected.

Table 5. Estimated Bioaccumulation Factor of Heavy Metals of the Studied Crops

Sampling Site	Name of Sample	Botanical Name	Hausa Name	BAF
				Cd	Pb	Cr	Cu	Zn
Kaduna	Onion	Allium cepa	Albasa	3.52	0.85	1.92	2.98	0.32
	Tomato	Solanum lycopersicum	Tomatur	0.95	0.98	0.96	0.49	0.66
	Carrot	Daucus carota	Karas	1.01	2.45	1.29	0.68	0.86
	Cucumber	Cucumis sativus	Kokwamba	0.84	1.20	0.67	0.50	1.69
	Cabbage	Brassica oleracea	Kabeji	ND	0.19	ND	1.66	1.82
	Maize	Zea mays	Masara	ND	2.80	2.34	1.07	5.7

Note: Bioaccumulation factor value>1 denotes greater metal uptake ND=Not Detected

Table 6. Pearson correlation coefficient of heavy metals in the investigated food crops samples

Metals	Cd	Pb	Cr	Cu
Cd
Pb	0.557*
Cr	0.585*	0.614*
Cu	0.190	0.131	0.468*
Zn	−0.048	0.092	−0.143	−0.048

Note: N.B Correlation coefficient with an asterisk (*) is significant at p < 0.05

Table 7. Computed Hazard Quotient and Hazard Index of Adult upon Consumption of the Studied Food Crops

Name of Sample	Botanical Name	Hausa Name	Hazard Quotient					Hazard Index
			Cd	Pb	Cr	Cu	Zn
Onion	Allium cepa	Albasa	0.141327	0.13188	5.08E–02	0.04669	0.00947	0.38014
Tomato	Solanum lycopersicum	Tomatur	0.105995	0.09381	0.02E–06	0.03756	0.01391	0.27158
Carrot	Daucus carota	Karas	0.143763	0.13706	6.09E–02	0.06488	0.00772	0.41433
Cucumber	Cucumis sativus	Kokwamba	0.119397	0.05574	0.00000	0.06853	0.01523	0.25890
Cabbage	Brassica oleracea	Kabeji	0.107213	0.01523	0.00000	0.03290	0.00914	0.16448
Maize	Zea mays	Masara	0.162038	0.02041	0.00000	0.04965	0.01611	0.24820

Table 8. Computed Hazard Quotient and Hazard Index of children upon Consumption of the Studied Food Crops

Name of Sample	Botanical Name	Hausa Name	Hazard Quotient					Hazard Index
			Cd	Pb	Cr	Cu	Zn
Onion	Allium cepa	Albasa	2.157906	0.269427	0.103706	0.095388	0.019356	2.64578
Tomato	Solanum lycopersicum	Tomatur	1.037886	0.191648	0.041482	0.076721	0.028415	1.37615
Carrot	Daucus carota	Karas	2.364488	0.280005	0.124447	0.132536	0.015763	2.91724
Cucumber	Cucumis sativus	Kokwamba	0.74668	0.113869	0.082964	0.140003	0.031112	1.11463
Cabbage	Brassica oleracea	Kabeji	0.540099	0.031112	0.082964	0.067201	0.018667	0.74004
Maize	Zea mays	Masara	0.248893	0.04169	0.082964	0.101424	0.032912	0.50788

Table 9. Estimated Target Cancer Risk (TCR) for Adult and Children

Crops		Adults		Children
Botanical Name	Hausa Name	Metals		Metals
		Cr	Pb	Cr	Pb
Allium cepa	Albasa	5.27538E–05	0.000895833	0.000107771	0.001830099
Solanum lycopersicum	Tomatur	3.75247E–05	0.000358333	7.66592E–05	0.000732039
Daucus carota	Karas	0.000054825	0.001075	0.000112002	0.002196118
Cucumis sativus	Kokwamba	2.22955E–05	ND	4.55475E–05	ND
Brassica oleracea	Kabeji	6.09167E–06	ND	1.24447E–05	ND
Zea mays	Masara	8.16283E–06	ND	1.66759E–05	ND

Table 10. Comparison of mean heavy metal concentration in crops from the present study with some previous studies

Country	Authors	Source of Contamination	Heavy metal Mg/kg
			Cd	Cr	Pb	Cu	Zn
Nigeria	Present study	Pesticides sources	0.88–1.33	0.25–1.50	0.50–5.33	3.17–31.8	14.08–44.00
Nigeria	Barau et al. (2018)	Pesticides sources	0.11–0.94	0.02–0.33	0.36–4.64	————-	3.95–17.19
India	Kulkarni (2017)	Sewage waste	0.30–0.62	0.16–0.32	0.23–0.64	1.1–2.3	————-
China	Dai et al. (2017)	Market survey	ND-0.619	———–	ND-1.822	————	————–
Pakistan	Khanum et al. (2017)	Waste/water irrigation	0.51–0.67	0.37–0.60	1.42–2.766	————	————-
Liberia	Ngumbu et al. (2016)	Market survey	0.04–0.13	———–	0.093–0.47	———–	————–
Nigeria	Patrick-Iwuanyanwu and Chioma (2017)	Market survey	0.02–1.48	0.89–2.4	0.016–1.38	————	————–
China	Zhong et al. (2017)	Agricultural farm	0–1.900	———–	0–3.820	————-	————
Indonesia	Siaka et al. (2014)	Waste/water irrigation	————	ND-152.8	11.11–374	4.34–150.5	5.12–90.69
Saudi Arabia	Balkhair and Asharaf (2016)	Waste irrigation	1.20	1.96	0.88	0.56	1.88
Ethiopia	Eliku and Leta (2017)	Waste/water irrigation	0.17–0.41	0.51–1.73	0.26–0.54	————-	2.07–14.4
Nigeria	Oti (2015)	Mine sites	0.10–12.4	0.01–1.02	0.22–6.72	12.6–82.1	34.2–162.1
	Organization (2019) limits		0.2	3.3	0.3	40	60

Table 11. Comparison of mean heavy metal concentration in soil sample from present study with some previous studies

Country	Authors	Source of Contamination	Heavy metal Mg/kg
			Cd	Cr	Pb	Cu	Zn
Nigeria	Present study	Pesticides	0.33–1.17	0.5–1.1	0.83–3.08	4.83–31.50	5.00–61.3
Nigeria	Barau et al. (2018)	Pesticides	0.03–0.22	0.01–0.02	2.77–4.31	———–	21-38-28.58
Pakistan	Khanum et al. (2017)	Waste/water irrigation	0.62–0.85	0.49–0.69	————	———-	————
India	Kumar et al. (2017)	Agricultura farms	————	————	0.25–2.31	0.30–2.10	0.47–4.74
China	G. Liu et al. (2014)	Near mining site	0.73	47.49	70.36	————–	————
Ethiopia	Eliku and Leta (2017)	Waste/water irrigation	0.52–0.93	10.0–21.8	13.6–27.3	11.9–30.3	44.4–88.5
Nigeria	Oti (2015)	Mine sites	126.0	2.12	116	812.2	995.2
	Unep et al. (2013) Limits		10	200	200	50	250

Table 12. Comparison of bioaccumulation factor (BAF), hazard quotient (HQ) intake in the present study with some previous studies

Variable	Country	Authors	Source of heavy metals	Heavy metals
				Cd	Cr	Pb	Cu	Zn
BAF	Nigeria	Present study	Pesticides	3.2–0.84	0.67–1.92	0.19–2.80	0.46–2.98	0.32–5.7
	Nigeria	Barau et al. (2018)	Pesticides	1.46–3.31	1.75–10.2	0.18–0.49	———-	0.14–0.19
	Pakistan	Khanum et al. (2017)	Waste/water irrigation		0.906	0.390	———-	————
	India	Kumar et al. (2017)	Agricultura farm	————–	————	0.04–5.21	0.09–1.0	1.42–37.3
	Ethiopia	Eliku and Leta (2017)	Waste/water irrigation	0.3–0.44	0.02–0.16	0.01–0.02	0.09–0.1	0.09–0.16
	Nigeria	Oti (2015)	Mine sites	0.16	0.65	0.01	0.15	0.25
	Saudi Arabia	Balkhair and Asharaf (2016)	Waste water irrigation	0.099–0.18	1.67–1.82	1.01–1.04	0.01–0.02	———-
HQ	Nigeria	Present study	Pesticides	0.10–0.162	5.08E-02-0.02	0.01–0.13	0.03–0.06	0.007–0.01
	Nigeria	Barau et al. (2018)	Pesticides	1.51–17.89	0.01–0.01	1.29–15.3	———-	0.08–1.06
	China	Dai et al. (2017)	Market vegetables	0.324	———-	0.398	———-	———–
	India	Kumar et al. (2017)	Agricultura farm	—————-	———–	0.5590	0.0581	0.1018
	Nigeria	Patrick-Iwuanyanwu and Chioma (2017)	Market survey	7.435	0.008	3.487	———–	———
	Saudi Arabia	Balkhair and Asharaf (2016)	Waste water irrigation	2.904	2.279	1.803	0.873	———
	Ethiopia	Eliku and Leta (2017)	Waste/water irrigation	0.190	0.001	0.076	0.034	0.02

Table 13. Comparison of Hazard index (HI) from present study with some previous studies

Parameter	Country	Authors	Source of heavy metals	Hazard index (HI)
HI	Nigeria	Present study	Pesticides	0.16–0.696
	Nigeria	Barau et al. (2018)	Pesticides	3.29–35.94
	China	Dai et al. (2017)	Market survey	0.00–2.08
	Nigeria	Patrick-Iwuanyanwu and Chioma (2017)	Market survey	0.370–8.871
	China	Zhong et al. (2017)	Agricultural farm	0.009–0.274
	Ethiopia	Eliku and Leta (2017)	Waste/water irrigation	0.028–0.071

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