Trial to Establish Causal Linkage Between Mycotoxin Exposure and Child Stunting

Laura Smith inspecting corn

Mycotoxins are naturally occurring secondhand metabolites produced by molds that contaminate staple crops that populations depend on, like maize, in rural Sub-Saharan Africa. Currently, aflatoxin is the most studied mycotoxin, due to the intermittent outbreaks of high aflatoxin exposure that leads to acute aflatoxicosis. Despite this, there is still little research into chronic, low-level aflatoxin exposure during fetal and early-life development and its effects on child growth and stunting.

In many rural Sub-Saharan African regions, like the Kongwa District of Dodoma, Tanzania, there is no routine assessment of mycotoxin exposure and few active mitigation policies/programs to lessen the burden of mycotoxin exposure. Populations in these regions are also predisposed to higher mycotoxin exposure, as diets are largely based on staple crops prone to mycotoxin contamination, and are frequently exposed to low-to-moderate levels of mycotoxin.

Our cluster randomized controlled study will investigate the causal relationship between mycotoxin exposure and child stunting in infants and young children living in rural Tanzania. Formative research has described infant food contamination in the region and tested intervention techniques for efficacy and acceptability. The results to those pilot studies will be published in the near future. Recruitment will begin in March, 2019. Clusters will be randomized to two groups: 1.) infant and young child feeding (IYCF) counseling and 2.) IYCF counseling with the provision of mycotoxin free baby food. We hypothesize the second intervention will reduce the level of exposure to mycotoxins and thus reduce levels of stunting. Primarily, the mycotoxins aflatoxin and fumonisin will be considered in this study, as they are the most potent mycotoxins to be widely studied and that are known to be highly prevalent in the African food supply. The mycotoxin deoxynivalenol will also be considered as a covariate. Dr. Laura Smith is a co-investigator on this trial. The project is funded by the Bill and Melinda Gates Foundation (OPP1155626).

Publications and Presentations

Smith LE, Stasiewicz M, Hestrin R, Morales S, Mutiga S, Nelson R.J. Examining environmental drivers of spatial variability in aflatoxin accumulation in Kenyan maize: Potential utility in risk prediction models. African Journal of Food, Agriculture, Nutrition and Development. 2016 Aug.​

Abstract

Maize, a staple food in most African countries, is prone to contamination by aflatoxins, toxic secondary metabolites mainly produced byAspergillus flavus and A. parasiticus. Aflatoxins are known to cause liver cancer, and chronic exposure has been linked to other adverse health outcomes including growth faltering in children. To mitigate exposure in maize-dependent populations, there is need to identify the factors associated with aflatoxin contamination. This is difficult, however, because of high sampling cost and lack of affordable and accurate analytical methods. Publicly available, remotely-sensed data on vegetation, precipitation, and soil properties could be useful in predicting locations at risk for aflatoxin contamination in maize. This study investigates the utility of publicly available remotely-sensed data on rainfall, vegetation cover (indicated by normalized difference vegetation index or NDVI), and soil characteristics as potential predictors of aflatoxin contamination in Kenyan maize. Aflatoxin was analyzed in maize samples (n=2466) that were collected in 2009 and 2010 at 243 local hammer mills in eastern and western Kenya. Overall, 60% of maize samples had detectable aflatoxin. Global positioning system coordinates of each mill location were linked to remotely-sensed, spatially explicit indicators of average monthly NDVI, total monthly rainfall, and soil properties. Higher rainfall and vegetation cover during the maize pre-flowering period were significantly associated with higher prevalence of aflatoxin contamination. Conversely, higher rainfall and vegetation cover during the maize flowering and post-flowering periods (not including harvest) were associated with lower prevalence of aflatoxin contamination. Water stress throughout the growing season may cause increased plant susceptibility to fungal colonization and aflatoxin accumulation. Soil organic carbon content, pH, total exchangeable bases, salinity, texture, and soil type were significantly associated with aflatoxin. In conclusion, this study shows that remotely-sensed data can be regressed on available aflatoxin data highlighting important potential predictors that could reduce the cost of data collection and the cost of aflatoxin risk forecasting models.

Our Team

Laura Smith

Laura Smith

Assistant Professor

Epidemiology and Environmental Health

Rebecca J. Stoltzfus, PhD - Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA

Francis Ngure, PhD - Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA

Rebecca Nelson, PhD - School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY, USA

Erica Phillips, MD - Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical College

Paul Turner, PhD - Maryland Institute for Applied Environmental Health, School of Public Health, University of Maryland, College Park, Maryland.

Clara Mollay, PhD Student- School of Life Science and Bioengineering, Nelson Mandela African Institution of Science and Technology (NM-AIST), Arusha, Tanzania

Neema Kassim, PhD- School of Life Science and Bioengineering, Nelson Mandela African Institution of Science and Technology (NM-AIST), Arusha, Tanzania

Edna Makule, PhD - School of Life Science and Bioengineering, Nelson Mandela African Institution of Science and Technology (NM-AIST), Arusha, Tanzania