Aflatoxin Country Assessments A Progress Report

Transcription

1 Aflatoxin Country Assessments A Progress Report August 31, 2012 Submitted by: Abt Associates Inc. Background This progress report summarizes progress on work to develop country aflatoxin assessments for Nigeria and Tanzania to inform country-led aflatoxin mitigation strategies. The report covers the methodology, status and key highlights to date. The country assessments evaluate the status quo, economic impact, and the challenges and opportunities for mitigation as they relate to aflatoxin s effects on food security, human health, and trade. In doing so, the assessments focus on the crops and commodities most affected by aflatoxin, and characterize the current risks from aflatoxin contamination to food security, human health, and trade. The economic assessments estimate losses in both the domestic and international markets, as well as economic impacts resulting from the human consumption of aflatoxin-contaminated crops. Finally, the assessments explore the opportunities for prevention, control, and mitigation actions. The success of such actions will be influenced by the regulatory environment pertaining to aflatoxins; aflatoxin control readiness; and current and promising technologies/practices for aflatoxin mitigation, which are evaluated in the assessments. The assessments also summarize ongoing and promising aflatoxin communication initiatives. Pilot Countries: Nigeria and Tanzania In early 2012 Nigeria and Tanzania were selected for piloting a country and economic assessment methodology, as countries that have a known aflatoxin problem and whose governments have an active interest in addressing the problem. These countries will offer a snapshot for the countries, the East African Community (EAC) and the Economic Community of West African States (ECOWAS), and PACA of the burden and effects of aflatoxin on food security, human health, and trade in two regions of Africa. The project sponsors felt that the diversity in topography, agro-climatic zones, aflatoxin prevalence, data availability, and institutional responses to aflatoxin in these two countries would help inform national responses elsewhere on the African continent. Research Methodology The country assessments first assess the key crops of concern to focus assessment resources on crops that may be most affected by aflatoxin contamination. Next, the assessments characterize the types of risks to food security, human health, and trade associated with the crops, and also the relative risks within those domains. This step takes into account the availability and quality of evidence on the prevalence of aflatoxin contamination. The country assessments then analyze current consumption patterns, the calorie contribution of the crop to diets, the importance of the crop as a source of income, and the value of domestic and international trade. In determining the health impacts, the prevalence of hepatitis B (HBV) is assessed, as it affects the risk of getting cancer. In addition, the assessments evaluate knowledge, attitudes, and practices concerning aflatoxin given their impact on the extent of aflatoxin exposure. These factors are also key inputs for estimating the economic impact of aflatoxin contamination given the status quo. The second part of the assessments reviews the existing policies, stakeholders, and opportunities for prevention, mitigation, and control of aflatoxin. Abt Associates Inc. 1

2 The research teams collected data from published and unpublished papers, policies, standards, and regulations affecting aflatoxin detection and control. In addition to papers, the assessments rely on available survey data and primary data collection through semi-structured interviews with key stakeholders (including aflatoxin prevalence sampling for Tanzania) to fill data gaps. The research teams collected primary information in the central government offices along with performing in-depth field research in three locations each in Nigeria and Tanzania. The locations were chosen based on crop growing patterns, representation of agro-ecological zones, probability of contamination (in the case of Tanzania), or available information on prevalence (in the case of Nigeria) and inputs from country experts. The teams interviewed public sector officials and private sector trade and agro-enterprise operators, as well as health practitioners, policy makers, households, and farmers at the central and local levels in both countries. Current Status of the Assessments The research teams have carried out the in-field assessments for Nigeria and Tanzania. In both countries, the researchers interviewed numerous stakeholders, from field (local level) to central level to identify awareness, behaviors, attitudes, practices, challenges and opportunities for action; and to gather data and vet assumptions for the economic impact analysis. The data synthesis for economic impact analysis is at a more advanced stage for Tanzania. For Nigeria the data are ready, but it would be premature to report findings because the team is at the midpoint of the analysis. The research teams will consolidate results from each research effort into major findings and recommendations for stakeholder review. In October/November 2012, workshops will bring together stakeholders to prioritize action steps for immediate and long-term response, while identifying key activities that will require external and domestic funding. Tanzania Summary of Main Findings to Date Crops of Concern Of the crops that are susceptible to aflatoxin contamination, cassava, groundnuts, maize, and cashew should be the crops of most concern to Tanzania. Maize is the most important in terms of its calorie contribution in the diet of an average Tanzanian household, followed by cassava, which is the focus of the International Institute of Tropical Agriculture s (IITA s) ongoing work on mycotoxins (see Exhibit 1). Groundnuts are potentially important because they are promoted in Tanzania as an ingredient in weaning foods. Abt Associates Inc. 2

3 Exhibit 1: Pie Chart: Calorie Contribution of Key Aflatoxin-Susceptible Crops in Tanzania (Percentage of Weekly Household Consumption) 51% 9% 2% 37% Cashew Cassava Groundnuts Maize Milk All other crops Notes: Estimated from the Tanzania 2008/9 Living Standards Measurements Study Integrated Surveys on Agriculture (LSMS-ISA). In contrast, FAO estimates that maize accounts for 33% of the calorific value per capita. In terms of production, both cassava and maize are important, with 6.2 million tons and 4.2 million tons of production, respectively, in Maize is also the most widely grown crop in Tanzania, produced by 4.5 million farm households representing about 82% of all Tanzanian farmers, according to the National Sample Census of Agriculture. In terms of international trade value, cashew is the most important crop, accounting for $128 million in exports in 2011, while maize and groundnuts accounted for only $8 million and $2 million, respectively, in Because cashew is successfully exported from Tanzania, it is likely that aflatoxin contamination is addressed by the industry. Although cashews are not the focus of this assessment, the final report will include information on how the industry has managed aflatoxin contamination especially given that the contamination has been an impediment to exporting groundnuts. Given the importance of maize in consumption and the level of its production, and accounting for the resources available for this activity, the country assessment concentrated on maize and groundnuts, with discussion of groundnuts more in the context of its consumption as a complementary food for children. Risk Characterization 1% Prevalence of Aflatoxin: Available evidence on aflatoxin prevalence (where prevalence is defined as the percentage of crop affected and the degree to which it is affected) for maize and groundnuts in Tanzania is very limited and dated. However, several ongoing efforts are measuring aflatoxin prevalence in maize, groundnuts, and cassava. These include: (1) Ministry of Agriculture, Food and Cooperatives which is measuring aflatoxins in groundnuts, with support from McKnight Foundation; (2) Tanzania Food and Drug Authority (TFDA) which, with support from VLIR-UOS, is working in collaboration with Ghent University (Belgium) and Sokoine University of Agriculture to measure aflatoxins in maize and (3) TFDA, working with support from Luvenhulme-Royal Society, is collaborating with University of Leeds (UK) to measure aflatoxins in maize flour. These efforts have already generated aflatoxin data for samples totaling approximately 208 for maize, 520 for cassava, and as yet an unknown number of samples for groundnuts (between 2009 and 2012). The country assessment effort will complement this testing to add regions that were not already covered by these efforts and is funding aflatoxin testing of 180 maize samples and 125 groundnut samples; the results of these tests will be available in September These efforts will be summarized in the country Abt Associates Inc. 3

4 assessments and used as input to estimate the extent of aflatoxin exposure and economic impact resulting from this exposure. Food Security, Human Health, and Trade Relative Risks: The degree to which aflatoxin contamination impacts food security, human health, and trade depends on the relative use of the commodity as a source of consumption and income. In particular, it depends on the commodity s share in the calorific requirements for the household, and its share as a source of income through domestic and international trade, and the extent of awareness about the problem both by households and markets. Using the Tanzania Living Standards Measurements Study Integrated Surveys on Agriculture (LSMS-ISA), a nationally and zonally representative survey that gathers detailed information on agricultural production, consumption, and household characteristics - the research team estimated the fate and transport of maize after production. The results suggest that on average agricultural households in Tanzania produce 500 kilograms of maize, of which 18% is sold in the market, 3% is lost in post-harvest, and an estimated 77% is used for own consumption (see Exhibit 2). 1 FAO agricultural data also suggest that trade in maize is low and that domestic consumption accounts for a large percentage of maize production (export is only 3% of apparent consumption). This implies that the biggest concern regarding aflatoxin contamination of maize is likely to be its human health impact resulting from consumption of maize. Exhibit 2: Maize Consumption, Sale, and Non-Food Uses 2% 1% 3% 18% Sales to market Own consumption Feed Seed Post-harvest losses 77% Notes: Estimated using LSMS-ISA, 2008/9 data. FAO estimates that domestic consumption accounted for as much as 98% of maize production in Tanzania averaging over (FAO 2009 Food Balance Sheet and Agriculture Production Data). The available data do not indicate what happens to aflatoxin-contaminated maize, and the awareness about aflatoxins both by households and by the markets. The in-depth field assessment explored these issues and found little or no awareness of aflatoxin contamination at the household level or the domestic market level. At the household level, visibly damaged maize is set aside and is either fed to the livestock or consumed by humans if the household experiences food shortages. All the chaff generated from own consumption, which typically has a higher concentration of aflatoxin, is fed to 1 Own consumption was estimated after deducting sales and post-harvest losses from production because production data were gathered for the entire year and own consumption data were only based on a weekly recall, which can vary significantly over the year. The percentages for the use for seed and feed are based on another report since LSMS-ISA did not collect this information. Abt Associates Inc. 4

5 the livestock. The domestic market has minimal requirements for maize quality, and the farmers sort the grain enough to get their maize accepted by millers. For maize there is largely no testing or awareness of aflatoxin contamination, even in more developed maize markets. This implies that farmers do not actually face any tangible losses in the domestic market because of aflatoxin contamination. (We are still finalizing our findings and estimates for the impact on international trade; however, we expect the impact to be minimal because of the almost continuous bans on maize export by Tanzanian government, and the consequent low volume of trade.) All of these findings suggest that the largest impact of aflatoxin contamination of maize will be on human health. Economic Impact Human Health: The estimates for economic impact resulting from human consumption are preliminary and are calculated only for the liver cancer endpoint. (The final assessment will include the economic impact resulting from stunting). These preliminary estimates rely on aflatoxin prevalence estimates from 1987 and 1988 data as an example of potential impact given the current consumption patterns, distribution of population by age and sex, prevalence of HBV, and the known risk of cancer among HBV-negative and HBV-positive populations. These estimates will be updated when the latest data on prevalence is made available by end of September. There is significant uncertainty in the reported estimates. First, the data on aflatoxin prevalence are very sparse (data availability will improve before the results are finalized). Second, there is uncertainty in the cancer potency factors for HBV-negative and HBV-positive populations. The final assessments will include improved characterization of some of these uncertainties, and will also develop estimates by zones of the country; these will differ because of the variability in the maize and groundnut consumption patterns. Our preliminary estimates suggest that if aflatoxin contamination in maize and groundnuts averages 3.6 parts per billion (ppb) in maize and 65 ppb in groundnuts, it will result in a loss of 10,000 disability-adjusted life years (DALY), or healthy life years, annually, because of liver cancer cases. Using the Value of Statistical Life (VSL) estimates based on Hammitt & Robinson (2011) for Tanzania and assuming that all cases diagnosed with cancer result in death within the same year, the economic impact of aflatoxin contamination can range from $20 million to $127 million annually (see Exhibit 3 in the Appendix for details). Food Security: We are analyzing the LSMS-ISA to assess the extent to which maize contributes to household incomes by income levels, which determine households overall access or ability to purchase their overall food requirements. Given that 63% of the maize consumed comes from own production, and accounts for 37% of the total calorie requirement of households (Exhibit 1), aflatoxin contamination can dramatically impact food availability for agricultural households. Trade: The overall market impact of aflatoxin contamination of maize and groundnuts is expected to be low because of the small volume and value of international trade in these commodities, the lack of aflatoxin testing in informal domestic trade, and the almost continuous bans on maize export by the Tanzanian government. In the domestic market, there is little or no awareness of aflatoxin contamination, implying that the economic impact of aflatoxin contamination from domestic and international trade is currently small. That said, there are economic implications resulting from the trade volumes that could have been realized for groundnuts (less so for maize given the export bans) if there were more aflatoxin awareness and mitigation in Tanzania. Our work to estimate trade impacts is ongoing. Abt Associates Inc. 5

6 Opportunities for Mitigation Action We will update this section based on a consensus-building workshop to be held in October/November 2012 in both countries. To date, the following opportunities for mitigation have been identified through consultation with stakeholders in Tanzania. Learn more about the prevalence of aflatoxin in the food and feed destined for export or domestic use. Develop laboratory capacity for aflatoxin testing and human resources capacity for risk assessment including the ability to perform aflatoxins exposure assessment using biomarkers. Develop a stakeholder coordination committee for aflatoxin and a focal point organization for aflatoxin. Human Health: Generate awareness about aflatoxin contamination and mitigation options to reduce aflatoxin exposure from consumption at the household levels. Develop direct guidance on aflatoxin and include it in the implementation plan for the newly drafted National Nutrition Strategy. TFNC is developing information on infant and young child feeding practices that can include specific information on aflatoxin contamination and prevention. Manage a biomarker studies database and increase biomarker testing of aflatoxin. Conduct analysis that informs standards setting and guidance for aflatoxins risk assessment and management in terms of laboratory facilities and human resources. The Tanzania Bureau of Standards (TBS) called for more analysis to establish aflatoxin standards that take into account the country-specific differences. TFDA also plans to include aflatoxins management principles in the draft of Food Safety Policy currently being formulated under the Ministry of Health and Social Welfare. Food Security: Post-harvest management and utilization of food. Promote good agricultural practices (GAP) and improve the connection between GAP and food safety. Explore opportunities to provide access to commercial bio-control (Aflasafe ). Develop guidance and manuals on aflatoxin under the National Agricultural Policy that is being drafted. Establish crop-specific boards for both groundnuts and maize that will be concerned with the management of quality in the domestic market. Nigeria Summary of Main Findings to Date Risk Characterization Crops of Concern: Maize is the most consumed staple nationally in Nigeria, constituting 20% of staples consumed (Maziya-Dixon et al, 2004). Cassava (16.5%), rice (14.9%), cowpea grain (11.8%), and groundnuts (11.1%) were the other most frequently consumed crops nationally, while groundnuts also have important market/export value. In Nigeria, the research team s primary field investigation confirmed secondary sources suggesting that weaning foods are commonly maize based but may also Abt Associates Inc. 6

7 contain groundnuts, sorghum, millet, and guinea corn (Onofiok and Nnanyelugo, 1998), of which aflatoxin B1 is of risk in each. The final report will include more up-to-date information. Given the limited resources, the economic assessment for Nigeria will be focused on maize and groundnuts given that maize is an important staple and groundnuts can contain a high concentration of aflatoxins. Prevalence of Aflatoxin: Nigeria has a wealth of peer-reviewed and non-published data that analyze aflatoxin prevalence in maize and groundnut samples, as well as several other crops. An excerpt from a particularly relevant publication is included in Exhibit 4 (see the Appendix). Food Security, Human Health, and Trade Relative Risks: The analysis for the relative risk that aflatoxin contamination presents to food security, human health, and trade in Nigeria is pending because our analysis of the survey data is ongoing, as is the analysis for food security that examines the extent to which maize and groundnuts are important in consumption and as a source of income for households. Economic Impact Human Health: The analysis is ongoing, but one recent study found that the average exposure of Nigerians to aflatoxin was ng/kgbw/day. 2 Based on this level, researchers estimated that the excess annual liver cancer incidence for Nigeria was cases per 100,000 in HBV-negative populations and cases per 100,000 in HBV-positive populations (Liu and Wu, 2010). Another study estimated that the burden of stunting in Nigeria from consuming maize and groundnuts contaminated with aflatoxins is estimated to be percent of all stunted children under age 5 in 2010 (Klangwiset 2011). Trade: Commodities that have received international attention most recently due to unsafe aflatoxin levels include sesame and melon seeds, which received Japanese and EU delegations in 2012 to collaborate with export authorities in addressing aflatoxin levels in these export commodities. Exhibit 5 in the Appendix shows EU alerts of import rejections of Nigeria-originating commodities due to aflatoxin from 2007 to Opportunities for Prevention, Control, and Mitigation in Nigeria We will update this section based on a consensus-building workshop to be held in October/November 2012 in both countries. This overview offers some of the recommendations that have been voiced by stakeholders during the field research to date. Trade: Increase voluntary inspection of export products. Incentivize companies through ease/priority of export or even tax advantages can help get products certified for export. Increase collaboration among all port and customs institutions (National Quarantine Service, Ports Inspectorate Division (mandate), Establishment Inspection Division of NAFDAC, and the Standards Organization of Nigeria) to help reduce redundancies, clarify quality assurance responsibilities, and ensure that institutions are working together to monitor the quality of commodities and products that enter and exit Nigeria s trade ports. Human Health: 2 Nano grams per kilogram of body weight per day. Abt Associates Inc. 7

8 Promote dietary diversity. Boost immunization coverage for HBV. Conduct screening and surveillance for HBV and liver cancer. Promote optimal breastfeeding, which can reduce exposure as compared to infants who are prematurely weaned (before 6 months of age) (Gong 2003). Raise demand for overall food safety and quality and reduce consumption of, foods that have been found to have elevated risk of unsafe aflatoxin exposure, such as kulikuli (groundnut paste). Increase collaboration between local health and agricultural extension workers to strengthen the link between safe food and health and promote the adoption of GAP, which are integral to reducing aflatoxins in the food and feed supply. Food Security: The implications of aflatoxin mitigation may inadvertently affect food security, given that aflatoxin control calls for more rigorous sorting and withdrawal of contaminated products. Strategies for combating this include: Improve production and cultivation potential of farmers through increasing use of, access to, and availability of the inputs that can improve crop yields and hardiness while also reducing risk of the development of unsafe levels of aflatoxins. Use mobile phones to send SMS vouchers to rural farmers for partially subsidized and improved seeds, for distribution by a rurally based agro-dealer. 3 Support development of the Abuja Securities and Commodities Exchange (established in 2006), which seeks to promote formal exchange and quality assurance. The exchange also seeks to build six regional warehouses with aflatoxin testing capacity, as well as proper drying and storage methods. Increasing and promoting domestic and international trade through use of this system has potential to greatly increase the quality of food destined for both domestic consumption and export. Other promising innovations include the development of gamma irradiation labs, though more research is needed in this area to find a balance between safe doses and aflatoxin eradication. With their limited resources, stakeholders interviewed to date have favored preventive measures over investing in exploration of alternative uses of commodities with unsafe levels of aflatoxin (biofuel and finishing feed for cattle bound for slaughter) at this time. 3 Interview conducted August 17, 2012, with Mr. Auphonsus Onwuemelca, Director of the Agricultural Extension Services within the Ministry of Agriculture. Abt Associates Inc. 8

9 References Atehnkeng et al Distribution and Toxicity of Aspergillus Species Isolated from Maize Kernels from Three Agro-Ecological Zones of Nigeria. International Journal of Food Microbiology 122: FAO (Food and Agriculture Organization). 2009a. FAO Food Balance Sheet. Rome. FAO (Food and Agriculture Organization). 2009b. FAO Agricultural Production Data. Rome. Gong, Y.Y., S. Egal, A. Hounsa, P.C. Turner, A.J. Hall, K. Cardwell, C.P. Wild Determinants of Aflatoxin Exposure in Young Children from Benin and Togo, West Africa: the Critical Role of Weaning. International Journal of Epidemiology 32: Hammitt, James K., and Lisa A. Robinson The Income Elasticity of the Value per Statistical Life: Transferring Estimates between High and Low Income Populations. Journal of Benefit-Cost Analysis 2(1): Article 1. Khlangwiset, Pornsri. March 30, Reducing the Risks of Aflatoxin Through Public Health Interventions. PhD Dissertation. University of Pittsburgh. [Accessed April 3, 2012]. Liu, Y. and Wu, F Global Burden of Aflatoxin-Induced Hepatocellular Carcinoma: A Risk Assessment. Environmental Health Perspectives 118(6): Maziya-Dixon, B., I.O. Akinyele, E.B. Oguntona, S. Nokoe, R.A. Sanusi, and E. Harris Nigeria Food Consumption and Nutrition Survey IITA. [Accessed April 5, 2012]. Minot, Nicholas. January Staple Food Prices in Tanzania. Food Security Collaborative Working Paper Number Michigan State University, Department of Agricultural, Food, and Resource Economics. Onofiok and Nnanyelugo. n/d Weaning foods in West Africa: Nutritional Problems and Possible Solutions. [Accessed August 31, 2012] Abt Associates Inc. 9

10 Appendix Exhibit 3: Economic Impact Resulting from Liver Cancer (HCC) Incidents Attributable to Aflatoxin Contamination in Maize and Groundnuts Average Consumption Total Aflatoxin-related HCC Health Effects Sex Maize (g/day) Groundnut (g/day) Average Aggregate Aflatoxin Exposure (ng/kgbodywt/day) HCC Cases (Cancers per year) Disability Adjusted Life Years Lost (DALY per year) Low (thous. of 2007$ per year) VSL High (thous. of 2007$ per year) Females (0-251) 366 (3-1,561) 4,800 (40-20,300) 9,500 (70-40,600) 60,300 ( ,600) Males (0-277) 404 (3-1,712) 5,300 (40-22,300) 10,500 (80-44,500) 66,600 ( ,400) Total (0-264) 770 (6-3,273) 10,000 (80-42,600) 20,000 (200-85,100) 127,000 (1, ,000) Notes: Figures in parentheses reflect the lower and upper bound of the 95% confidence interval characterizing the uncertainty in aflatoxin prevalence. Estimation assumptions and method: (1) Consumption of maize and groundnuts is estimated from LSMS-ISA 2008/9 and converted to aggregate aflatoxin exposure using available prevalence data. (3) Probability of liver cancer incidence was estimated separately for HBV negative and HBV positive populations (not shown in table). It was used in conjunction with age- and sex-specific HBV prevalence data for East sub-saharan Africa and a 2010 Tanzania population estimates (by age and sex) to calculate the annual number of HCC incidents resulting from aflatoxin contamination in maize and groundnuts. (5) WHO DALY estimate for one liver cancer case is used to calculate the total DALYs lost per year for Tanzania. (6) Hammitt and Robinson (2011) low and high estimates of value of a statistical life (VSL) for Tanzania were used to quantify the annual economic impact of liver cancer assuming that mortality results within one year of HCC diagnosis. Abt Associates Inc. 10

11 Exhibit 4: Aflatoxin Contamination in Maize Samples Collected from Farmers Stores in Districts in the Three Agro-Ecological Zones in Nigeria Concentration of Aflatoxin B 1 (ng g -1 ) Agro-Ecological Zone (AEZ) / District Mean Median Range Derived Savannah Ado-Ekiti Lafia ,722 Lokoja Makurdi Ogbomosho ,105 Southern Guinea Savannah Abuja Akwanga Bida ,874 Minna Mokwa ,102 Northern Guinea Savannah Zaria Source: Athenkeng et al. (2008). Exhibit 5: EU Alerts of Border Rejections/Detainment of Nigeria-Originating Imports Due to Aflatoxin Contamination ( ) Year Peanuts Kulikuli (1) G.nut oil Maize Cereal products Melon (2) Ogbono (3) Durum beans Spices Ginger Ehuru seeds (4) Total Source: EU notifications were provided by Mrs. Folasade of NAFDAC s Mycotoxin Laboratory on 8/30/12. Notes: (1) Groundnut/peanut paste; (2) Melon seeds are very popular in stews and have receive a high level of EU attention this year for high aflatoxin levels; (3) Ogbono is a mango-like seed, commonly used in soups and stews; (4) Ehuru seeds are sold as spices. Abt Associates Inc. 11