Bioaccumulation and Human Health Risk of Heavy Metals from Pesticides in Some Crops Grown in Plateau State, Nigeria †
1
Department of Biological Sciences, Bayero University, Kano, P.M.B., Kano 3011, Nigeria
2
Department of Applied Ecology, Abubakar Tafawa Balewa University, P.M.B., Bauchi 0248, Nigeria
3
Department of Biology Education, Aminu Saleh College of Education, P.M.B., 944 Azare, Bauchi 751101, Nigeria
*
Author to whom correspondence should be addressed.
†
Presented at the 1st International Electronic Conference on Plant Science, 1–15 December 2020; Available online: https://iecps2020.sciforum.net/.
Biol. Life Sci. Forum 2021, 4(1), 12; https://doi.org/10.3390/IECPS2020-08737
Published: 1 December 2020
(This article belongs to the Proceedings of The 1st International Electronic Conference on Plant Science)
Abstract
:The health risk assessment of heavy metals as the source of metal contamination in food crops fumigated exclusively with pesticides is mostly overlooked. This study determined the concentrations of heavy metals (Cd, Pb, Cr, Cu, and Zn) in some food crops fumigated with pesticides and their health risk to humans. The mean concentrations of heavy metals in different parts of the studied crops ranged from 0.12 to 2.03 for Zn, 1.73 to 23.34 for Pb, 1.60 to 1150.50 for Cu, 0.67 to 19.50 for Cr, and 0.09 to 6.14 mg/kg for Cd. The concentrations of Cd, Pb, and Cr in the investigated crops were above the WHO (2011) permissible limits and in decreasing trend of Cu > Pb > Cr > Cd > Zn. The bioaccumulation factor (BAF) > 1 values for Cd, Pb, and Zn and the BAF value were highest for copper (141.75) in Oryza sativa. Pollution indices showed all crops were contaminated with Cd, Pb, and Cr and were likely to pose a potential health risk to humans. The estimated daily intake of Cd and Pb from all the studied crops exceeded the USEPA (2006) oral reference dose daily limit. A hazard quotient > 1 was observed only from the consumption of Ozyza sativa (3.504) for Cu and could likely cause potential health risk in human. The hazard index indicated a health risk through the consumption of Oryza sativa (4.666), Zea mays (1.475), and Capsicum annuum (1.132) for all the studied metals. Therefore, there is a need for regular screening and monitoring of heavy metals from pesticides sources in food crops.
1. Introduction
Pesticides are extensively employed in agriculture to kill pests or unwanted organisms that may reduce crop yield and increase agricultural production [1]. Famers in northern Nigeria have largely depended on pesticides for the control of pests, weeds, and diseases [2]. This has led to a proliferation in the importation of new pesticide products into Nigeria whose chemical contents are not known or are mostly concealed by the manufacturer [1].The use of pesticides has been on the increase and these pesticides have been shown to contain heavy metals [1,3]. However, despite the banning of heavy metals in pesticides globally, a recent study revealed the presence of heavy metals in pesticides at levels above the recommended dilution rate in Europe [4]. Soil–plant heavy metal transfer is the main pathway for pollutants to enter the human body through the food chain.
There is a paucity of studies on heavy metal contamination of food crops exclusively fumigated with pesticides and the health risk to humans. Therefore this study was designed with the aim of determining the concentrations of heavy metals (Cd, Pb, Cr, Cu, and Zn) from pesticides in some crops and soils in Jos, Plateau State, Nigeria and their associated human health risk.
2. Materials and Methods
Samples of leaves, stems, roots, and fruits of tomato, pepper, onion, cabbage, carrot, cucumber, spinach, lettuce, and maize and corresponding soils, were collected from Naraguta Farm (A) in Plateau State, Nigeria (N 09°58.586, E 008°53.820) and Naraguta Farm B (N 09°58.562, E 008°53.230). Soils collected from some locations outside the agricultural farms that had had no pesticides application were used as controls. All samples were collected in a clean brown envelope, labelled, and transported to the ATBU Biology Laboratory and analyzed for Cr, Cu, Cd, Zn, and Pb using an atomic absorption spectrophotometer. Health risk assessment [5,6,7], hazard quotient [8], hazard index [8], estimated daily intake [7,8], and pollution index [8,9] were determined and results statistically analyzed by SPPS version 8.1. and two-way analysis of variance.
3. Results
Heavy Metals in the Plants and Soil and Their Factors
There was significant variation (p < 0.05) in the concentration of heavy metals in different parts of most of the studied crops (Table 1 and Table 2). The trend of heavy metals in the studied crops was in the decreasing order of Cu > Pb > Cr > Cd > Zn (Table 1 and Table 2). Cadmium, chromium, and lead concentrations in the all the studied crops were above the permissible limits except in Allium cepa (root, leaf, and bulb), Daucas carota (root and stem), Cucumis sativus (fruit), and Lactuca sativa (root, leaf) (Table 1 and Table 2). The concentrations of zinc in all the investigated crops were below the permissible limit. Copper was also below the permissible limit except in Cucumis sativus (stem, leaf, and fruit,), Zea mays (root, leaf, and fruit), and Oryza sativa (root, stem, and fruit) (Table 1 and Table 2).
The bioaccumulation factor (BAF) of heavy metals was BAF > 1 for Cd, Pb, and Zn and the BAF was in the decreasing order of Cu > Zn > Pb > Cd > Cr (Figure 1). Pollution indices (PI) were >1 for Cd and Pb in all crops and in most crops for Cr (Figure 2). The estimated daily intake of metal (EDI) for adults exceeded the USEPA, ref. [10] oral reference dose daily limit in all the crops for Cd and Pb (Table 3). The EDI for Cr, Zn, and Cu were below the USEPA [10] except in Solanum lycopersicum, Brassica oleracea, and Oryza sativa for Cu. (Table 3). EDI values were in decreasing order of Cu > Pb > Cr > Cd > Zn. Hazard quotient (HQ) values were not detected for Zn and >1 for Oryza sativa. (Table 4). The HI values for all crops were >1 (4.666) in Oryza sativa, (1.475) Zea mays, (1.132), and capsicum annuum.
4. Discussion and Conclusions
The contamination of food crops by heavy metals from pesticides sources is a major concern for food quality and safety. The concentrations of Cd, Pb, and Cr in all the studied crops fumigated with pesticides as the only source of contamination exceeded the WHO [11] permissible limits, while the concentration of heavy metals in the corresponding soils of all the studied crops were below the UNEP [12] limits for agricultural soils. Most of the studied crops showed BAF > 1 for Cd, Pb, and Zn and the BAF was in decreasing order of Cu > Zn > Pb > Cd > Cr. Pollution indices indicated that most of the studied crops were contaminated for Pb, Cd, and Cr. The estimated daily intake of metals showed that all the studied crops exceeded the daily oral reference dose limit and could cause risk to humans. The hazard quotient showed all the studied crops were safe for human consumption except Oryza sativa for Cu which may cause risk to humans. However, people may be experiencing a severe adverse health risk (HI) from all the studied metals for the consumption of Oryza sativa, Zea mays, and Capsicum annuum. Similar reports relating to this work include but are not limited to [13,14,15,16,17,18]. Thus, there is need for regular screening of heavy metals in pesticides. The predominant use of metal-based pesticides with high Cd, Pb, and Zn in the study areas could be responsible for the BAF > 1 values observed [3].
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Figure 1.
Bioaccumulation factor (BAF) of heavy metals in the edible parts of crops grown in Plateau State (2018).
Figure 1.
Bioaccumulation factor (BAF) of heavy metals in the edible parts of crops grown in Plateau State (2018).
Figure 2.
Pollution indices of heavy metals in the edible parts of crops grown in Plateau State (2018).
Figure 2.
Pollution indices of heavy metals in the edible parts of crops grown in Plateau State (2018).
Table 1.
Mean concentration of heavy metals in crops grown in Plateau State (2018).
| Sampling Site | Name of Sample | Botanical Name | Hausa Name | Heavy Metals mg/kg | ||||
|---|---|---|---|---|---|---|---|---|
| Cd | Pb | Cr | Cu | Zn | ||||
| Jos | Tomato | Solanum lycopersicum | Tomatur | |||||
| Root | 4.47 a | 2.32 a | 10.17 ab | 28.37 b | 1.02 c | |||
| Stem | 5.66 b | 4.48 a | 7.58 a | 18.94 a | 0.15 a | |||
| Leaf | 5.14 ab | 3.26 a | 9.83 ab | 39.25 c | 0.47 b | |||
| Fruit | 5.08 ab | 1.73 a | 10.92 b | 35.26 bc | 1.40 d | |||
| Pepper | Capsicum annuum | Attarugu | ||||||
| Root | 3.11 a | 14.88 b | 2.67 a | 12.28 a | 1.72 a | |||
| Stem | 3.25 a | 15.97 b | 5.58 b | 18.44 ab | 0.12 a | |||
| Leaf | 3.76 a | 9.51 a | 4.25 b | 20.71 ab | 1.01 a | |||
| Fruit | 3.33 a | 21.25 b | 5.00 b | 25.55 c | 0.97 a | |||
| Onion | Allium cepa | Albasa | ||||||
| Root | 2.58 a | 14.98 a | 1.67 a | 6.30 a | 1.90 b | |||
| Stem | ND | ND | ND | ND | ND | |||
| Leaf | 3.95 c | 18.60 a | 1.83 a | 12.42 b | 1.42 ab | |||
| Bulb | 2.72 a | 17.25 a | 2.00 a | 6.67 a | 0.58 a | |||
| Carrot | Daucus carota | Karas | ||||||
| Root | ND | ND | ND | ND | ND | |||
| Stem | 4.87 a | 18.33 b | 0.67 a | 12.08 b | 2.03 b | |||
| Leaf | 4.55 a | 19.78 b | 1.17 a | 23.43 c | 0.72 a | |||
| Fruit | 4.63 a | 3.77 a | 3.00 b | 1.60 a | ND | |||
| Spinach | Spinacia oleracea | Alayyaho | ||||||
| Root | 3.57 a | 14.91 a | 3.58 a | 12.21 b | ND | |||
| Stem | 3.91 a | 14.20 a | 3.75 ab | 10.68 a | 0.84 | |||
| Leaf | 3.21 a | 16.12 a | 4.17 c | 15.68 c | ND | |||
| Safe limits a | 0.2 | 0.3 | 2.3 | 40 | 60 |
a Source: FAO/WHO (2001). Mean followed with same letter across the column are not significantly different (p > 0.05).
Table 2.
Mean concentration of heavy metals in crops grown in Plateau State (2018).
| Sampling Site | Name of Sample | Botanical Name | Hausa Name | Heavy Metals mg/kg | ||||
|---|---|---|---|---|---|---|---|---|
| Cd | Pb | Cr | Cu | Zn | ||||
| Jos | Lettuce | Lactuca sativa | Salad | |||||
| Root | 0.66 b | 17.03 c | 1.25 a | 8.34 a | ND | |||
| Stem | 0.09 a | 15.13 a | 2.25 c | 6.75 a | ND | |||
| Leaf | 1.43 c | 17.21 c | 1.92 ab | 14.61 b | ND | |||
| Cabbage | Brassica oleracea | Kabeji | ||||||
| Root | 2.87 b | 22.52 c | 1.83 a | 11.45 b | 0.27 | |||
| Stem | 0.55 a | 15.38 b | 3.17 a | 3.07 a | ND | |||
| Leaf | 5.03 c | 5.50 a | 2.67 a | 0.38 a | ND | |||
| Cucumber | Cucumis sativus | Kwawamba | ||||||
| Root | ND | ND | ND | ND | ND | |||
| Stem | 1.43 a | 15.75 ab | 3.67 c | 214.48 c | ND | |||
| Leaf | 1.92 a | 16.13 c | 2.83 b | 16.52 a | ND | |||
| Fruit | 1.38 a | 12.78 a | 1.83 a | 26.08 b | ND | |||
| Maize | Zea mays | Masara | ||||||
| Root | 3.53 a | 12.42 a | 18.92 b | 111.80 b | ND | |||
| Stem | 5.53 b | 15.68 a | 9.00 a | 1.78 a | ND | |||
| Leaf | 6.14 b | 15.37 a | 9.08 a | 30.78 a | ND | |||
| Fruit | 5.53 b | 15.68 a | 8.08 a | 105.80 b | ND | |||
| Rice | Oryza sativa | Shinkafa | ||||||
| Root | 3.68 a | 13.55 a | 12.42 a | 92.55 a | 1.00 a | |||
| Stem | 3.92 a | 18.70 ab | 6.17 a | 37.13 a | 0.97 a | |||
| leaf | ND | ND | ND | ND | ND | |||
| Fruit | 3.68 a | 23.34 c | 19.50 a | 1150.50 b | 0.93 a | |||
| Safe limits a | 0.2 | 0.3 | 2.3 | 40 | 60 |
a Source: FAO/WHO (2001). Mean followed with same letter across the column are not significantly different (p > 0.05).
Table 3.
Estimated daily intake of metals (EDI) (mg/kg/bw/day) through consumption of crops grown in Plateau State (2018).
Table 3.
Estimated daily intake of metals (EDI) (mg/kg/bw/day) through consumption of crops grown in Plateau State (2018).
| Name of Sample | Botanical Name | Hausa Name | Estimated Daily Intake | ||||
|---|---|---|---|---|---|---|---|
| Cd | Pb | Cr | Cu | Zn | |||
| Tomato | Solanum lycopersicum | Tomatur | 0.007 | 0.053 | 0.016 | 0.051 | 0.002 |
| Pepper | Capsicum annuum | Attarugu | 0.005 | 0.647 | 0.007 | 0.037 | 0.001 |
| Onion | Allium cepa | Albasa | 0.004 | 0.525 | 0.003 | 0.010 | 0.001 |
| Carrot | Daucus carota | Karas | 0.007 | 0.115 | 0.004 | 0.002 | 0.000 |
| Spinach | Spinacia oleracea | Alayyaho | 0.005 | 0.491 | 0.006 | 0.022 | 0.000 |
| Lettuce | Lactuca sativa | Salad | 0.002 | 0.524 | 0.003 | 0.021 | 0.000 |
| Cabbage | Brassica oleracea | Kabeji | 0.007 | 0.168 | 0.004 | 0.001 | 0.000 |
| Cucumber | Cucumis sativus | Kokwamba | 0.002 | 0.389 | 0.003 | 0.037 | 0.000 |
| Maize | Zea mays | Masara | 0.008 | 0.478 | 0.012 | 0.152 | 0.000 |
| Rice | Oryza sativa | Shinkafa | 0.005 | 0.711 | 0.028 | 1.649 | 0.001 |
| RfD a | 0.001 | 0.004 | 1.5 | 0.04 | 0.30 |
a Source: USEPA, (2006).
Table 4.
Hazard quotient and hazard index for adult population through the consumption of crops grown in Plateau State (2018).
Table 4.
Hazard quotient and hazard index for adult population through the consumption of crops grown in Plateau State (2018).
| Name of Sample | Botanical Name | Hausa Name | Hazard Quotient (HQ) | Hazard Index (HI) | ||||
|---|---|---|---|---|---|---|---|---|
| Cd | Pb | Cr | Cu | Zn | ||||
| Tomato | Solanum lycopersicum | Tomatur | 0.619 | 0.053 | 0.001 | 0.107 | ND | 0.780 |
| Pepper | Capsicum annuum | Attarugu | 0.406 | 0.647 | ND | 0.078 | ND | 1.132 |
| Onion | Allium cepa | Albasa | 0.331 | 0.525 | ND | 0.020 | ND | 0.877 |
| Carrot | Daucus carota | Karas | 0.564 | 0.115 | ND | 0.005 | ND | 0.684 |
| Spinach | Spinacia oleracea | Alayyaho | 0.391 | 0.491 | ND | 0.048 | ND | 0.930 |
| Lettuce | Lactuca sativa | Salad | 0.174 | 0.524 | ND | 0.044 | ND | 0.742 |
| Cabbage | Brassica oleracea | Kabeji | 0.613 | 0.168 | ND | 0.001 | ND | 0.782 |
| Cucumber | Cucumis sativus | Kokwamba | 0.169 | 0.389 | ND | 0.079 | ND | 0.637 |
| Maize | Zea mays | Masara | 0.674 | 0.478 | 0.001 | 0.322 | ND | 1.475 |
| Rice | Oryza sativa | Shinkafa | 0.449 | 0.711 | 0.002 | 3.504 | ND | 4.666 |
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MDPI and ACS Style
Usman, B.; Ahmad, A.; Jibrin, N.A.; Gaya, E.A.; Jibrin, M. Bioaccumulation and Human Health Risk of Heavy Metals from Pesticides in Some Crops Grown in Plateau State, Nigeria. Biol. Life Sci. Forum 2021, 4, 12. https://doi.org/10.3390/IECPS2020-08737
AMA Style
Usman B, Ahmad A, Jibrin NA, Gaya EA, Jibrin M. Bioaccumulation and Human Health Risk of Heavy Metals from Pesticides in Some Crops Grown in Plateau State, Nigeria. Biology and Life Sciences Forum. 2021; 4(1):12. https://doi.org/10.3390/IECPS2020-08737
Chicago/Turabian StyleUsman, Bawa, AbdulHameed Ahmad, Nayaya A. Jibrin, Ezra A. Gaya, and Maryam Jibrin. 2021. "Bioaccumulation and Human Health Risk of Heavy Metals from Pesticides in Some Crops Grown in Plateau State, Nigeria" Biology and Life Sciences Forum 4, no. 1: 12. https://doi.org/10.3390/IECPS2020-08737
APA StyleUsman, B., Ahmad, A., Jibrin, N. A., Gaya, E. A., & Jibrin, M. (2021). Bioaccumulation and Human Health Risk of Heavy Metals from Pesticides in Some Crops Grown in Plateau State, Nigeria. Biology and Life Sciences Forum, 4(1), 12. https://doi.org/10.3390/IECPS2020-08737
