Elsevier

Food and Chemical Toxicology

Volume 48, Issues 8–9, August–September 2010, Pages 2103-2108
Food and Chemical Toxicology

Dietary fumonisin exposure in a rural population of South Africa

https://doi.org/10.1016/j.fct.2010.05.011Get rights and content

Abstract

A validated culturally specific dietary assessment method was used to determine the habitual maize intakes of black Xhosa-speaking Africans living in the Centane region of the Eastern Cape Province to assess their exposure to the carcinogenic fumonisin mycotoxins. The mean total dry weight maize intakes of home-grown, commercial or combined (both maize sources) were 474, 344, 462 g day−1, respectively. When considering the total mean levels of fumonisin in home-grown maize (1142 μg kg−1) and commercial maize (222 μg kg−1), the probable daily intakes (PDI’s), expressed as μg kg−1 body weight day−1 were 12.1 (95%CI: 0.3–4926.5) and 1.3 (95%CI: 1.0–1.8) for men and 6.7 (95%CI: 1.0–457.8) and 1.1 (95%CI: 0.9–1.3) for women, consuming home-grown and commercial maize, respectively. Based on the different maize-based beer drinking frequencies the PDI’s varied between 6.9 and 12.0 μg kg−1/drinking event. Depending on the maize intake patterns an exposure “window” exists where fumonisin exposure is below the recommended group provisional maximum tolerable daily intake (PMTDI) for fumonisins of 2 μg kg−1 bw day−1. The assessment of fumonisin exposure and development of preventative strategies depend, not only the accurate determination of total fumonisin levels in maize, but also on the distinct dietary patterns of a specific population.

Introduction

The fumonisin B (FB) mycotoxins are ubiquitous contaminants of maize mainly produced by the fungi Fusarium verticillioides and F. proliferatum (Rheeder et al., 2002). They are known to cause several diseases in animals and are associated with a high incidence of human oesophageal and liver cancer in certain geographical areas of the world (Rheeder et al., 1992, Ueno et al., 1997), as well as the development of neural tube defects (Marasas et al., 2004). To date about 28 fumonisins have been identified (Rheeder et al., 2002). FB1, the most abundant occurs together with FB2 and FB3 mainly in maize with levels varying with season and geographical location (Shephard et al., 1996, Rheeder et al., 2002). The fumonisins have been classified as group 2B carcinogens (possibly carcinogenic to humans) by the International Agency for Research on Cancer (IARC, 2002). A group provisional maximum tolerable daily intake (PMTDI) for fumonisins (B1, B2 and B3) of 2 μg kg−1 bw day−1 was established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), using a no observed adverse effect level (NOAEL) of 0.2 mg kg−1 bw day−1 for nephrotoxicity in rats and a safety factor of 100 (Bolger et al., 2001).

The risk of exposure to mycotoxins in human populations residing in developing countries are considered to be far greater where the implementation of legislative control is compromised due to many economic, political and environmental factors (Wagacha and Muthomi, 2008, WHO, 2006). In South Africa, the former Transkei region of the Eastern Cape Province (EC) is a rural area characterised by a high prevalence of poverty and underdevelopment. The majority of the inhabitants are dependent on governmental pensions and grants while migrant labourers provide an additional income (D’Haese and Van Huylenbroeck, 2005, Nel and Davies, 1999). Subsistence farming is a major source of food security where the daily intake of maize is part of a culturally distinct dietary pattern and ethnic tradition. Home-grown maize from these areas is known to be contaminated with high levels of fumonisin and therefore poses an important health risk (Shephard et al., 2007). Commercial maize also consumed in these areas, generally contains far lower fumonisin levels, but could still pose a risk if consumed in large quantities. The determination of fumonisin exposure, which forms an integral part of the human risk assessment process, is therefore of critical importance. However, the lack of any regulations or monitoring of fumonisin levels in South African maize intended for human consumption further contributes to the uncertainty when determining risk (Gelderblom et al., 2008, Marasas et al., 2008).

The accuracy of assessing mycotoxin exposure is not only dependent on standardised analytical methods to determine the level of contamination in the food matrix, but also on detailed dietary intakes using effective and validated dietary assessment instruments (Kroes et al., 2002). In South Africa the national food consumption survey together with a few demographic-specific consumption studies provide limited data on maize consumption in rural areas (National Food Consumption Survey, 2000, Nel and Steyn, 2002). In a population at risk to fumonisin exposure, the maize intakes together with the maize-dietary practices will influence exposure. Factors such as the sources of maize, mixture of maize with other food components, seasonal variations of these components, socio-economic status, cultural traditions, food preparations, food availability and accessibility will impact on maize consumption. To address the methodological challenges of estimating dietary mycotoxin intake, a culturally specific dietary assessment tool, the Ratio And Portion size Photo (RAPP) tool was developed and validated among a black Xhosa-speaking African rural population (Wolmarans and Wentzel-Viljoen, 2008).

In the present study, the RAPP tool was used to assess maize consumption patterns and consequently fumonisin exposure in Centane, an area in the EC of South Africa where maize is consumed as a major dietary staple. This rural area is known for its high incidence of oesophageal cancer (OC) while the home-grown maize is highly contaminated with the fumonisin B mycotoxins (Somdyala et al., 2003, Shephard et al., 2007).

Section snippets

Study population

Ethical approval for the study was granted by the South African Medical Research Council Ethics Committee. Three hundred and fifteen apparently healthy volunteers between the ages of 18 and 70 were recruited after informed and signed consent. Volunteers were recruited from 21 rural villages within the magisterial area of Centane, Amathole District Municipality in the EC. A field laboratory was set up at three local trading stores along a central road, providing easy access to participants.

Characteristics of the study population

The mean values of the different parameters are the geometric mean with the 95% confidence interval (CI). Eighty-three percent of the study population (n = 315) were women (n = 261). Anthropometric variables included a mean body mass index of 27 kg/m2 (95% CI: 26–28) and a mean weight of 68 kg (95% CI: 67–70). The mean age and years of residence in the EC were 42 years (95% CI: 41–44) and 40 years (95%CI: 38–41), respectively. Socio-economic parameters indicated that a river or dam was the main source

Discussion

Human exposure to fumonisins in a rural area of Centane involves comprehensive analysis not only of the level of fumonisin contamination but also of the distinct maize-dietary patterns. Typical maize-dietary practises of people living in these rural areas includes hand grinding utilising “grinding” rocks or stamping of home-grown maize to produce maize meal or samp (Rose, 1972, Grobbelaar and Bateman, 1991). The resultant maize meal is either used for the preparation of porridges with different

Conflict of Interest

The authors declare that there are no conflicts of interest.

Acknowledgements

The authors would like to thank the funders of this study, the Cancer Association of South Africa (CANSA) and the Medical Research Council (MRC). The following persons: Ms. Lorna Thomas, research nurse; Mr. John Mokotary, driver and technical assistant as well as the fieldworkers Ms. Nokhutula Kulati, Ms. Bongiwe Kulati, Ms. Nobobele Mpetsheni and Ms. Beauty Stampu. Also, a special thanks to the Hulley family, trading store owners in Centane and the staff of the Trennery’s Hotel, Qolora for

References (31)

  • M. D’Haese et al.

    The rise of supermarkets and changing expenditure patterns of poor rural households case study in the Transkei area, South Africa

    Food Pol.

    (2005)
  • J. Ewing

    Detecting alcoholism: the CAGE questionnaire

    JAMA

    (1984)
  • Gelderblom, W.C.A., Riedel, S., Burger, H-M., Abel, S., Marasas, W.F.O., 2008. Carcinogenesis by the fumonisins:...
  • J.P. Grobbelaar et al.

    Hut lung: a domestically acquired pneumoconiosis of mixed aetiology in rural women

    Thorax

    (1991)
  • IARC, International Agency for Research on Cancer, 2002. Fumonisin B1. In: IARC Monographs on the Evaluation of...
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      Subsequent studies in Centane have arrived at similar intake values. Shephard et al. (2007), using weighed food quantities, calculated mean maize intakes of 483 g/adult male per day and 428 g/adult female per day, whereas Burger et al. (2010), using a culturally specific ratio and portion size photo (RAPP) tool, estimated intakes among the group consuming both commercial and home-grown maize to be 632 g/day for males and 440 g/day for females. Another estimate, based on the data of Nel and Steyn (2002) from other rural areas of South Africa and a number of assumptions to convert cooked food into dry maize intake, arrived at a daily maize consumption of 461 g/person (Shephard et al., 2007).

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