Skip to main content

Risk Assessment of Heavy-Metal Contamination on Vegetables Grown in Long-Term Wastewater Irrigated Urban Farming Sites in Accra, Ghana

Abstract

Assessment was done of heavy-metal contamination and its related health risks in urban vegetable farming in Accra. Samples of irrigation water (n=120), soil (n=144) and five different kinds of vegetable (n=240) were collected and analyzed for copper, zinc, lead, cadmium, chromium, nickel and cobalt. All water, soil and vegetable samples contained detectable concentrations of each of the seven heavy metals except for irrigation water which had no detectable chromium, cadmium and cobalt. All heavy-metal levels were below permissible limits except lead on vegetables which was 1.8–3.5 times higher. Health risk assessments showed for all elements that normal consumption of each of the vegetables assessed poses no risk. The highest hazard index obtained was 42 % for wastewater irrigated cabbage. Though within permissible limits, cabbage and ayoyo had the highest potential risk. Compared with previous studies on the same sites, the data show that the risk from heavy metals is less significance than that from pathogen contamination which has positive implications for risk mitigation.

This is a preview of subscription content, access via your institution.

Fig. 1

Notes

  1. 1.

    We noticed in several references that dry weight concentrations were compared with MRLs which referred to fresh weight, resulting in exaggerated risk assessments.

References

  1. Affum HA, Oduro-Afriyie K, Nartey VK, Adomako D, Nyarko BJB (2008) Bio-monitoring of airborne heavy metals along a major road in Accra, Ghana. Environ Monit Assess 137:15–24

    Article  CAS  Google Scholar 

  2. Agency for toxic substances and disease registry (ATSDR) (2012) Minimal risk levels (MRLs) for hazardous substances. Accessed on 17/7/212 at: http://www.atsdr.cdc.gov/mrls/mrllist.asp

  3. Akrong OM (2009) The influence of quality of irrigation water and postharvest handling on bacterial contamination and heavy metal accumulation on lettuce cultivated in urban Accra. Unpublished thesis, Environmental Sciences Department, University of Ghana, Accra

  4. American Public Health Association, American Water Works Association, Water Environment Federation (APHA-AWWA-WEF) (2001) Standard methods for the examination of water and wastewater, 22nd edn, Washington, DC

  5. Amoah P, Drechsel P, Abaidoo RC, Henseler M (2007) Irrigated urban vegetable production in Ghana: microbiological contamination in farms and markets and associated consumer risk groups. J Water Health 5(3):455–466

    Article  CAS  Google Scholar 

  6. Amoah P, Keraita B, Drechsel P, Abaidoo R, Konradsen F, Akple M (2011) Low cost options for health risk reduction where crops are irrigated with polluted water in west Africa. IWMI research Report no 141 Colombo, Sri Lanka

  7. Ayers RS, Westcot DW (1985) Water quality for agriculture. FAO Irrigation and Drainage Paper 29. Rome

  8. Bakare S, Denloye AA, Olaniyan FO (2004) Cadmium, lead and mercury in fresh and boiled leafy vegetables grown in Lagos, Nigeria. Environ Technol 25(12):1367–1370

    Article  CAS  Google Scholar 

  9. Borowski K, Schmaling A (1996) An integrated microwave digestion system for the modern laboratory. Milestone Inc America laboratory

  10. Cui YJ, Zhu YG, Zhai RH, Chen DY, Huang YZ, Qui Y, Liang JZ (2004) Transfer of metals from near a smelter in Nanning, China. Environ Int 30:785–791

    Article  CAS  Google Scholar 

  11. Drechsel P, Graefe S, Sonou M, Cofie OO (2006) Informal irrigation in urban West Africa: An overview. IWMI research report series, vol 102. IWMI, Colombo. 34 pp. http://www.iwmi.cgiar.org/Publications/IWMI_Research_Reports/PDF/pub102/RR102.pdf (accessed 7 August 2012)

    Google Scholar 

  12. Eriyamremu GE, Asagba SO, Akpoborie A, Ojeabur SI (2005) Evaluation of lead and cadmium levels in some commonly consumed vegetables in the Niger-Delta oil area of Nigeria. Bull Environ Contam Toxicol 75:278–283

    Article  CAS  Google Scholar 

  13. European Commission (EC) (2006) Standards for lead, cadmium and mercury. Commission Regulation (EC) No 1881/2006. Accessed on 18/7/2012 at: http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:2006R1881:20100701:EN:PDF

  14. Ewers U (1991) Standards, guidelines and legislative regulations concerning metals and their compounds. In: Merian E (ed) Metals and their compounds in the environment, relevance. VCH, Weinheim, pp 458–468

    Google Scholar 

  15. FAO/WHO (2010) Evaluations of the joint FAO/WHO expert committee on food additives (JECFA). Accessed 18/7/2012. http://apps.who.int/ipsc/database/evaluations/chemical.aspx?chemID=3511

  16. Jassir MS, Shaker A, Khalip MA (2005) Deposition of heavy metals on green leafy vegetables sold on roadsides of Riyadh city, Saudi Arabia. Bull Environ Contam Toxicol 75:1020–1027

    Article  Google Scholar 

  17. Kylander ME, Rauch S, Morrison GM, Andam K (2003) Impact of automobile emissions on the levels of platinum and lead in Accra, Ghana. J Environ Monit 5:91–95

    Article  CAS  Google Scholar 

  18. Mapanda F, Mangwayana EN, Nyamangara J, Giller KE (2005) The effect of long term irrigation using wastewater on heavy metal contents of soils under vegetables in Harare, Zimbabwe. Agric Ecosyst Environ 107:151–165

    Article  CAS  Google Scholar 

  19. Mapanda F, Mangwayana EN, Nyamangara J, Giller KE (2007) Uptake of heavy metals by vegetables irrigated using wastewater and the subsequent risks in Harare, Zimbabwe. Phys Chem Earth Parts A/B/C 32(15–18):1399–1405

    Article  Google Scholar 

  20. McBride MB (2003) Toxic metals in sewage sludge-amended soils: has promotion of beneficial use discounted the risks? Adv Environ Res 8:5–19

    Article  CAS  Google Scholar 

  21. Muchuweti M, Birkett JW, Chinyanga E, Zvauya R, Scrimshaw MD, Lester JN (2006) Heavy metal content of vegetables irrigated with mixtures of wastewater and sewage sludge in Zimbabwe: implications for human health. Agric Ecosyst Environ 112:41–48

    Article  CAS  Google Scholar 

  22. Obuobie E, Keraita B, Danso G, Amoah P, Cofie OO, Raschid-Sally L, Drechsel P (2006) Irrigated urban vegetable production in Ghana: characteristics, benefits and risks. IWMI, Accra; accessed on 18/7/2012 at www.cityfarmer.org/GhanaIrrigateVegis.html

  23. Odai SN, Mensah E, Sipitey D, Ryo S, Awuah E (2008) Heavy metals uptake by vegetables cultivated on urban waste dumpsites: case study of Kumasi, Ghana. Res J Environ Toxicol 2:92–99

    Article  CAS  Google Scholar 

  24. Ogwuegbu MOC, Muhanga W (2005) Investigation of lead concentration in the blood of people in the copper belt province of Zambia. J Environ 1:66–75

    Google Scholar 

  25. Sharma RK, Agrawal M, Marshall F (2006) Heavy metals contamination in vegetables grown in wastewater irrigated areas of Varanasi, India. Bull Environ Contam Toxicol 77:312–318

    Article  CAS  Google Scholar 

  26. Sharma RK, Agrawal M, Marshall FM (2007) Heavy metals contamination of soil and vegetables in suburban areas of Varanasi,India. Ecotoxicol Environ Saf 66:258–266

    Article  CAS  Google Scholar 

  27. Sharma S, Prasad FM (2009) Accumulation of lead and cadmium in soil and vegetable crops along major highways in Agra (India). E-J Chem 7(4):1174–1183

    Article  Google Scholar 

  28. Singh A, Sharma RK, Agrawal M, Marshall FM (2010) Risk assessment of heavy metal toxicity through contaminated vegetables from wastewater irrigated areas in Varanasi India. Trop Ecol 51(2):375–387

    CAS  Google Scholar 

  29. Suruchi, Khanna P (2011) Assessment of heavy metal contamination in different vegetables grown in and around urban areas. Res J Environ Toxicol 5:162–179

    Article  CAS  Google Scholar 

  30. Umweltbundesamt (1992) Klaerschlammverordnung. www.umweltbundesamt.de/boden-und-altlasten/boden/downloads/Klaerschlammverordnung.pdf (accessed 18 July 2012)

  31. US Environmental Protection Agency (USEPA) (1996) Review of national air quality standards for ozone, assessment of scientific technical information. OAQPS Staff Paper, EPA 452/R-96-007; USEPA Air Quality Criteria for Ozone and related Photochemical Oxidants EPA/600/P-93/004Af

  32. Weigert P (1991) Metal loads of food of vegetable origin including mushrooms. In: Marian E (ed) Metals and their compounds in the environment, occurrence, analysis and biological relevance. VCH, Weinheim, pp 458–468

    Google Scholar 

  33. Weldegebriel Y, Chandravanshi BS, Wondimu T (2012) Concentration levels of metals in vegetables grown in soils irrigated with river water in Addis Ababa, Ethiopia. Ecotoxicol Environ Saf 77:57–63

    Article  CAS  Google Scholar 

  34. WHO (2005). Nickel in drinking-water. WHO/SDE/WSH/05.08/55 Accessed on 17/7/2012 at http://www.who.int/water_sanitation_health/gdwqrevision/nickel2005.pdf

Download references

Acknowledgements

We duly acknowledge support from the International Water Management Institute (IWMI), the Carnegie Corporation of New York Project and the Office of Research, Innovation and Development (ORID), University of Ghana, Accra.

Author information

Affiliations

Authors

Corresponding author

Correspondence to Bernard Keraita.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Lente, I., Keraita, B., Drechsel, P. et al. Risk Assessment of Heavy-Metal Contamination on Vegetables Grown in Long-Term Wastewater Irrigated Urban Farming Sites in Accra, Ghana. Water Qual Expo Health 4, 179–186 (2012). https://doi.org/10.1007/s12403-012-0077-8

Download citation

Keywords

  • Heavy-metal contamination
  • Urban vegetable farming
  • Wastewater
  • Human health
  • Ghana