International Journal of Hygiene and Environmental Health
Contribution of soil, water and food consumption to metal exposure of children from geological enriched environments in the coastal zone of Lake Victoria, Kenya
Introduction
Human exposure to metals such as cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), zinc (Zn), cobalt (Co) and titanium (Ti), are well documented (e.g. Dipietro et al., 1989, Nriagu, 1996, Luoma and Rainbow, 2008, Tian et al., 2011). Non-essential metals such as Pb, Cd and Cr can elicit toxic effects even at low exposure doses. Also for Ti, no essential metabolic role has yet been described (Kanztzis, 1981). On the other hand, Cu is an essential metal and a component of various enzymes, is involved in collagen synthesis and in the normal development of connective tissues, nerves and immune system (Amaral et al., 2008). Also Zn and Co are essential and are involved in multiple functions such as enzymes structure and activities, protein transport, hormonal functions and specific receptor sites, which are crucial for the well functioning of biological systems (Apostoli, 2002). Whether metals are classified as essential or non-essential, they can be toxic at acute high exposure levels (Cai et al., 2005, Waalkes, 2003, Amaral et al., 2008). Moreover, increasing evidence also points to negative health effects from cumulative, lower level of exposures to some metals (Hu, 2002, Quandt et al., 2010). Children are more vulnerable to metal exposures, which may lead to several pediatrics effects including neurodevelopment disorders. Ingestion of metals by children may occur through consumption of water, soil and food from a metal rich environment (Moreno et al., 2010).
The Lake Victoria basin in Kenya is volcanic in nature and contains rich deposits of metals from geological origin (Ogola et al., 2002, Kenya Geological Survey, 2008). Compounding the problem of metal pollution in the region is the continuous operation of small scale and artisanal gold miners over the last few decades (http://www.youtube.com/watch?v=PVIVj4NYAlQ&feature=player_embedded). Previous studies have established high concentrations of metals such as Cd, Cr, Zn, Cu, Ti and Co in the in water, soil and sediments of Lake Victoria (Campbell et al., 2003, Campbell et al., 2004, Lalah et al., 2008, Mbabazi et al., 2010, Oyoo-Okoth et al., 2010a, Oyoo-Okoth et al., 2010b, Oyoo-Okoth et al., 2010c). In the most commonly consumed fish species, the silver sardines (Rastrineobola argentea), Mbabazi and Wasswa (2010), Oyoo-Okoth et al., 2010a, Oyoo-Okoth et al., 2010b, Oyoo-Okoth et al., 2010c and Oyoo-Okoth et al. (2012) have documented high concentrations of some of these metals. Yet, nearly all food items consumed in these regions are grown locally. Consumption of crops grown locally and fish from the region may increase the metal transfer from the geologically enriched environment to the children through food transfer mechanism. Yet no study is available on the contribution of geological metals to the enrichment of soils, water and overall food items grown locally and how these metals may be transferred to humans through food consumption.
The aim of the present study was to assess the contribution of soil, water and food consumption to the metal burden of children aged 10 years and younger in the geologically enriched coastal zone of Lake Victoria, Kenya. To this purpose, we investigated the relationship between the metal body burden of the children with the metal concentrations in soil, water, and food consumed. Body tissues such as hair have been very useful in biomonitoring human exposure to metals (Nowak, 1998, Harkins and Susten, 2003, Pereira et al., 2000, Amaral et al., 2008, Wang et al., 2009, Li et al., 2011). We hypothesized that the metal concentrations in hair are characteristic signatures for metal intake from the soil, water and from food consumed.
Section snippets
Study area and sampling sites
Lake Victoria (Fig. 1), the second largest freshwater body in the world (area 68,800 km2), is generally shallow (mean depth 40 m) and lies in a catchment of about 184,000 km2 and is shared by three riparian states (Kenya, Tanzania and Uganda). Four sites were selected for this study. Site S1 (Kisumu) which has a population of about 164,000 living near the shore of Lake Victoria, site S2 (Kendu-Bay), which has a population of about 75,000 and site S3 (Karungu) with a population of about 56,000 (
Metal body burden
The GMs ± 0.95*Confidence Interval of the analysed metals in hair samples per site are shown in Fig. 2. The GMs of the Cd concentration in the hair ranged from 0.5 to 1.5 μg/g in the exposed sites, which was five times higher than the reference site (0.1–0.3 μg/g). The concentration of Cr ranged from 0.4 to 1.6 μg/g at exposed sites, which was five times higher than at the reference site (0.1–0.4 μg/g), while GMs of Cu ranged from 16 to 38 μg/g and 6 to 18 μg/g at the exposed and non exposed sites
Discussion
In Africa, studies on natural metal pollution due to metal rich geological environments (e.g. Banza et al., 2009) are rare, although there is growing evidence that pollution is increasing on the continent (Nriagu, 1992). In some areas within the Lake Victoria region of Kenya, soils and water catchments show remarkable high concentrations of metals that may cause metal exposure to the local populations. This study assessed the contribution of soil, water and food consumption to metal body burden
Conclusions
This study provides evidence that children residing in geologically enriched environments are exposed to potentially high concentrations of geological metals through food consumption and exposure to metal rich soils. Although children working in the artisanal mines without any safety gadgets are likely to have direct exposures to these metals, our data suggest that even children who do not work in the artisanal mine may be exposed to geologically enriched metals through soil and food
Acknowledgements
This study was supported by The Netherlands Government through NWO-WOTRO (grant no. W 01.83.2004.023). We are very grateful for the assistance of Mr. Kuloba of ILRI for metal analysis and Tonny Odero of Kenya Marine and Fisheries Research Institute (KEMFRI) for their assistance in the sampling and a laboratory for sample preparation. We also thank the local fishermen in Kenya who provided their boats and assistance during the sampling time in Lake Victoria. The authors also thank the volunteers
References (49)
- et al.
Essential and non-essential trace metals in scalp hair of men chronically exposed to volcanogenic metals in the Azores, Portugal
Environ. Int.
(2008) Element in environmental and occupational medicine
J. Chromatogr. B
(2002)- et al.
High human exposure to cobalt and other metals in Katanga, a mining area of the Democratic Republic of Congo
Environ. Res.
(2009) - et al.
Trace element concentrations in hair of healthy centenarian
Sci. Total Environ.
(2011) - et al.
Estimating human exposure through multiple pathways from air, water, and soil
Regul. Toxicol. Pharmacol.
(1991) - et al.
Bimonitoring of metals in children living in a mine tailings z one of Southern Mexico: a pilot study
Int. J. Hyg. Environ. Health
(2010) Contents and relationship of elements in human hair for a non-industrialised population in Poland
Sci. Total Environ.
(1998)- et al.
Relationship of lead and cadmium to essential elements in hair, teeth, and nails of environmentally exposed people
Ecotoxicol. Environ. Saf.
(2000) Toxic metal pollution in Africa
Sci. Total Environ.
(1992)- et al.
Metal specific partitioning in a parasite-host assemblage of the cestode Ligula intestinalis and the cyprinid fish Rastrineobola argentea
Sci. Total Environ.
(2010)
Parasites modify sub-cellular partitioning of metals in the gut of fish
Aquat. Toxicol.
Monitoring exposure to heavy metals among children in Lake Victoria, Kenya: environmental and fish matrix
Ecotoxicol. Environ. Saf.
Heavy metals exposures among Mexican farmworkers in eastern North Carolina
Environ. Res.
Application of double focusing sector field inductively coupled plasma-mass spectrometry multi-elemental characterization of human hair and nail: part II. A study of inhabitants of Northern Sweden
Sci. Total Environ.
Mercury hair concentration and dietary exposure among Inuit preschool children in Nunavut, Canada
Environ. Int.
Cadmium carcinogenesis
Mutat. Res.
Use of scalp hair as indicator of human exposure to heavy metals in an electronic waste recycling area
Environ. Pollut.
Contaminants: Joint FAO/WHO Standards Program. Codex Alimentarius, vol. XVII
Essentiality, toxicology and chelation therapy of zinc and copper
Curr. Med. Chem.
Biomagnification of mercury in fish from Thruston Bay, Napoleon Gulf, Lake Victoria (East Africa)
Afr. J. Aquat. Sci.
Variation and distribution of total mercury in water, sediment and soil from northern Lake Victoria, East Africa
Biogeochemistry
Heavy metal concentrations in nine species of fishes caught in coastal waters off Ann-Ping, S.W. Taiwan
J. Food Drug Anal.
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