A Conceptual Framework for Conducting Country and Economic Assessment of Aflatoxin Contamination. Volume I. Contract #

Transcription

1 A Conceptual Framework for Conducting Country and Economic Assessment of Aflatoxin Contamination Volume I Contract # January 8, 2013 Prepared for: Meridian Institute 1920 L Street, NW #500 Washington, D.C In support of: Partnership for Aflatoxin Control in Africa Submitted by: Abt Associates Inc Montgomery Avenue Suite 800 North Bethesda, MD 20814

2 Preface This conceptual framework for country and economic assessment was commissioned by Meridian Institute, which is supporting the Africa-led Partnership for Aflatoxin Control in Africa (PACA) with funding from the Bill & Melinda Gates Foundation and the UK Department for International Development (DFID). The framework suggests a new approach to assessing a country s situation and outlook for aflatoxin prevention and mitigation, to estimating the economic impacts of aflatoxin contamination, and to identifying priority areas for aflatoxin control using a country-led approach. The framework includes a review of the existing literature, provides guidelines for in-country engagement and interviews, and proposes a practical method for estimating economic impacts from aflatoxin contamination despite the usual data and resource constraints that developing countries face. This document is intended to have broad application for all developing countries, especially in Sub- Saharan Africa under PACA. It has already served as an initial guide for the work requested by the Meridian Institute on pilot country and economic assessments in Nigeria and Tanzania. Implementation of the framework requires a multi-disciplinary team of national technical consultants who are already working on aflatoxins as researchers or regulators and can be potential champions of the work. Ideally, the team should include an economist with economic impact assessment experience, an epidemiologist, a risk assessor, and a GIS specialist. Mr. John Lamb was the Project Director for the team at Abt Associates that developed the conceptual framework. Dr. Tulika Narayan and Ms. Angela Stene were principal investigators who worked closely with the economic analysis team that included Dr. Anna Belova and Ms. Lauren Brown. Jacqueline Haskell provided valuable research assistance. The authors wish to thank Dr. Sam Bozeman from Abt Associates, participants at the Tanzania and Nigeria stakeholder workshops, Meridian Institute and Gates Foundation for their comments on earlier draft. Abt Associates Inc. Front Matter pg. i

3 Abt Associates Inc. Front Matter pg. ii

4 Estimating Economic Impact of Aflatoxin Contamination A Conceptual Framework Table of Contents Preface... i 1 Introduction Overview of the Conceptual Framework Identification of the Key Crops of Concern (Step 1) Prevalence of Aflatoxin-Causing Fungus (Step 2) Direct Evidence of Aflatoxin Prevalence Geographic Information System (GIS) Analysis of Environmental Conditions Risk Characterization of Aflatoxin Exposure and Contamination (Step 3) Final Uses of Aflatoxin-Susceptible Crops Risk of Contamination along the Value Chain of Selected Crops Economic Impacts Resulting from Aflatoxin Contamination (Step 4) Economic Impact Resulting from Market Losses Domestic Market Impacts International Trade Impacts Economic Impact Resulting from Consumption of Aflatoxin-Contaminated Feed by Livestock Economic Impact Resulting from Human Consumption Quantifying Effects of Aflatoxin Exposure on HCC Incidence Dose-Response Assessment Exposure Assessment Risk Characterization Aggregating Health Damages and Establishing Their Economic Value DALY Calculation WTP Transfer Calculation Summary of the Limitations of the Health Impact Model Aggregate Economic Impacts: Sources of Uncertainty and Uncertainty Analysis Identification of Opportunities for Aflatoxin Control (Step 5) The Regulatory Environment Pertaining to Aflatoxins Ongoing Awareness Raising, and Outreach Initiatives Control Strategies Communication Strategy Consideration Stakeholder Workshops (Step 6) Conclusion References Abt Associates Inc. Front Matter pg. iii

5 List of Tables Table 6-1: Response of Domestic Animals to Aflatoxins Table 6-2: Aflatoxin Standards for Livestock Table 6-3: Sources of Data for the JEFAC-Recommended Cancer Potency Values Table 6-4: Sensitivity Analysis to Address Uncertainty in Prevalence and Historical Dietary Patterns and Historical Aflatoxin Exposure List of Figures Figure 4-1: Identifying Potential Hot Spots Using Environmental Determinants of Aflatoxins (hypothetical mapping) Figure 5-1: Final Uses of Aflatoxin-Contaminated Crop Figure 6-1: Impact of Aflatoxin Contamination on Domestic Market Figure 6-2: Approach to Estimating the Economic Impact of Aflatoxin Consumption Figure 6-3: Economic Impacts and Sources of Uncertainty Abt Associates Inc. Front Matter pg. iv

6 List of Acronyms BTC COI DALY ECOWAS EU FAO FDA GAP GDP GEMS/Food GI GIS GNP HAZ HBV HCC HCV HIV LSMS-ISA PCR MOA TB UNComtrade USDA ERS WAZ WB WHO WTP YLD YLL Bridge-to-cross Cost of Illness Disability Adjusted Life Year Economic Community of West African States European Union Food and Agricultural Organization of the United Nations U.S. Food and Drug Administration Good agricultural practices Gross domestic product WHO Global Environment Monitoring System - Food Monitoring and Assessment Program Gastrointestinal Geographic information systems Gross national product Height for age Z scores Hepatitis B virus Hepatocellular carcinoma Hepatitis C virus Human immunodeficiency virus Living Standards Measurement Survey Integrated Surveys in Agriculture Polymerase chain reaction Ministry of Agriculture Tuberculosis United Nations Commodity Trade Statistics Database United States Department of Agriculture s Economic Research Service Weight for age Z scores The World Bank World Health Organization Willingness To Pay Years Lived with Disability Years of Life Lost Abt Associates Inc. Front Matter pg. v

7 Abt Associates Inc. Front Matter pg. vi

8 1 Introduction Aflatoxins are a family of extremely toxic, mutagenic, and carcinogenic compounds produced mainly by Aspergillus flavus and Aspergillus parasiticus (both of which are widely found in the soil) that can contaminate crops (Diener et al., 1987; Kurtzman et al., 1987). Toxigenic A. flavus isolates produce aflatoxins B1 and B2, and toxigenic A. parasiticus isolates produce aflatoxins B1, B2, G1, and G2 (Abbas et al., 2006). These fungi can colonize a wide variety of food commodities including maize (corn), sorghum, millet, oilseeds, spices, groundnuts (peanuts), tree nuts, and dried fruit (Strosnider et al., 2006), as well as rice in storage. Aspergillus spp. depends on environmental conditions in order to thrive. Drought stress has been found to increase the number of Aspergillus spores in the air, increasing the chance of infection in crops (Sanders et al., 1993). Drought and other stresses that affect plant growth during pollination also increase the level of aflatoxins produced by the Aspergillus fungi, exacerbating the problem. In addition, moisture at the time of harvest is also shown to increase aflatoxin levels. Aspergillus growth is optimal when temperatures are between 80 and 100 degrees Fahrenheit with a relative humidity around 85 percent, corresponding to 18 percent grain moisture (LSU AgCenter, 2011). Thus, aflatoxins disproportionately affect food in tropical and subtropical regions of the world, which includes the majority of developing countries. These countries also have poor field and storage practices that exacerbate the problem of aflatoxin contamination. Aflatoxins are known to cause serious health effects in humans, resulting in increased epidemiological disease burden, human suffering, and loss of productivity and income, as well as damage to the economy. The health hazards associated with aflatoxin exposure include aflatoxicosis, liver cancer, immune suppression, and nutritional interference (Williams et al., 2004). The literature concerned with economic impact as a result of aflatoxin exposure in humans has focused on liver cancer (Wu and Khlangwiset, 2010; Liu and Wu, 2010) and stunting (Khlangwiset et al., 2011b). Aflatoxins also impact livestock poultry, pigs, and cattle and can result in economic impacts from increased disease burden, reduction in productivity, loss of marketability and selling value, and sometimes indirect effects through human consumption of contaminated livestock products. This paper proposes a conceptual framework and approach for estimating the aggregate economic impact of aflatoxin contamination for any country, along with practical ways of estimating this impact with available secondary data. Since aflatoxins are prevalent in key developing country staples (e.g., maize, sorghum), poorer households are more likely to consume a larger proportion of these crops, implying that an aflatoxin contamination problem can have significant implications for distributional justice. Although such issues go beyond the scope of this paper, distributional justice should be an important policy concern. Regulations that set minimum standards for aflatoxin levels in food and feed can increase the distributional gap because the poor are more likely to eat contaminated grain rather than sell it at lower prices or discard it. In addition, if aflatoxin control strategies are costly, then the poor may be constrained in adopting these strategies, which means that their net return from farming may decline and they may also experience adverse health impacts. Even a well-intentioned awareness campaign can mean reduced prices for aflatoxin-contaminated food, which can result in direct market losses for the poor (who cannot afford control strategies) and potentially more severe health impacts because of farmers own consumption of low-price-yielding contaminated grain. Therefore, policies and regulations to control aflatoxins require particular care in accounting for the distributional impact. Shephard (2008) and Williams (2008) note that regulations alone do little to Abt Associates Inc. Introduction pg. 1-1

9 help reduce aflatoxins and their related health effects in developing countries. It is important to make control strategies available with potential subsidies to the very poor. The remainder of the conceptual framework is organized as follows. Chapter 2 provides an overview of the conceptual framework. The subsequent chapters elaborate on each of the steps laid out in the overview. Chapter 3 discusses how to identify the key crops on which the country and economic assessment should focus. Chapter 4 presents the approaches to estimate the prevalence of aflatoxins in a country. Chapter 5 describes the approach to characterize the risk of aflatoxin contamination in the country. Chapter 6 presents the approach to estimate the economic impact resulting from aflatoxin contamination. Chapter 7 presents the approach to identify and prioritize aflatoxin control strategies appropriate for the country. Chapter 8 presents the conclusion. Appendixes are contained in Volume II of this conceptual framework. Abt Associates Inc. Introduction pg. 1-2

10 2 Overview of the Conceptual Framework This framework presents a practical approach to the conduct of country and economic assessments (henceforth, country assessment) for aflatoxin contamination and control. Key objectives include identifying the core risk of aflatoxin contamination, estimating the key economic impacts resulting from such contamination, and identifying opportunities for aflatoxin control. The framework is designed to be replicable in any country even with modest resource allocations and limited prior experience. It provides a simple template to capture information available from existing data, documents, and resources, while highlighting information gaps that need to be filled. The core steps in conducting a country assessment include: Step 1: Identify Key Crops of Concern. To optimize resources, it is desirable to focus the country assessments on crops that are known to have high aflatoxin contamination in the target country, and are either produced or consumed in large quantities and/or contribute significantly to gross national product. If information on aflatoxin contamination is not available, then the focus can be on the crops that are known for their susceptibility to high aflatoxin contamination globally and are produced and consumed in large quantities in the country of interest. Step 2: Determine the Prevalence of Aflatoxin. Once the focus crops are identified, the next step is to conduct an in-depth review of the data on the distribution and degree of aflatoxin contamination in those crops. Here, we review both available secondary data and published studies for evidence. Without information on prevalence it is hard to make a case for aflatoxin control and to arrive at robust estimates of economic impact. Therefore, if resources permit and data are lacking, actual testing for aflatoxin levels should be conducted in areas that are primary producers of the crop of interest. Step 3: Characterize Risks of Aflatoxin Contamination and Exposure. In this step, the core risk of aflatoxin contamination is established (i.e., whether the largest impact is expected to be on the country s agriculture and food security, trade, or health). Final uses of aflatoxin-susceptible crops determine how the economic impacts are distributed, which is helpful in narrowing down the focus of the analysis to the most significant areas of concern. Therefore, in this step we assess the main uses of the commodity in the country whether for direct consumption, domestic sale, or international trade. In addition, since aflatoxins can affect the entire supply chain, we examine the core aflatoxin risks all along value chains of selected crops, beginning with pre-harvest and post-harvest contamination that directly impact agriculture, then considering risks of contamination and exposure in domestic commerce and international trade, and finally considering factors that directly affect human health. Step 4: Estimate Economic Impact from Aflatoxin Contamination. In this step we estimate the economic impacts on agriculture and food security, economic impacts resulting from market losses in both domestic and international markets, and economic impact resulting from the consumption of aflatoxin-contaminated food by humans. Depending on the finding from step 3, the analysis can focus on the most significant impacts (e.g., health impacts). Step 5: Identify Opportunities for Aflatoxin Control. In the fifth step, we describe the institutional, legal, and regulatory framework that can support aflatoxin control in a country, and identify Abt Associates Inc. Overview of the Conceptual Framework pg. 2-1

11 opportunities for improvement in that enabling environment. Then we consider other promising solutions for prevention or mitigation, taking into account the national context. Step 6: Conduct Stakeholder Workshop to Validate findings, Identify Priority Actions and Establish Country Ownership. In this final step, a multi-sectoral workshop is conducted with key stakeholders representing agriculture, trade, health from the public and private sectors to discuss the draft assessment. Key stakeholders (which include solutions providers, researchers and legal and regulatory experts) make presentations that augment the discussion to identify current prevention, control and mitigation opportunities and gaps. Breakout sessions with small groups work to identify and sketch out priority action steps. Abt Associates Inc. Overview of the Conceptual Framework pg. 2-2

12 3 Identification of the Key Crops of Concern (Step 1) The crops commonly affected by aflatoxins include maize, groundnuts, cottonseed, sorghum, millet, rice, Brazil nuts, pecans, walnuts, pistachio nuts, sesame, and spices (particularly chilies), and products made from these crops. To minimize the expense involved in estimating the economic impact of aflatoxin contamination, assessments can focus on the crops that are known to have an aflatoxin problem in the country and are the most significant nationally in terms of amount of production, consumption, and/or value of exports. Production Volume Export Volume Consumption Calorie Conversion Data Requirements and Sources FAOSTAT ( CountrySTAT ( USDA ERS ( FAOSTAT ( CountrySTAT ( UNComtrade ( USDA ERS ( WHO Global Environment Monitoring System/Food Monitoring and Assessment Program ( LSMS-ISA ( National Household Budget Surveys Food and Agricultural Organization (FAO) of the United Nations ( Most countries keep a record of annual production of crops and exports through surveys conducted by a department of statistics located in the Central Bank or ministry of planning, agriculture, industry, or trade. For example, in Tanzania, the National Bureau of Statistics conducts the Agriculture Census and also conducts agriculture surveys. FAO also has time series and cross-sectional data relating to hunger, food, and agriculture for 245 countries from 1961 to the most recent year. These data include information on trade, production, and commodity balance. In addition, food and agricultural data are available for 17 African countries from FAO s CountrySTAT, which is a web-based information portal for food and agriculture statistics at the national and subnational levels (CountrySTAT, 2012). It provides access to statistics on trade and consumption. The United States Department of Agriculture s Economic Research Service (USDA ERS) also maintains data on production, consumption, and exports of key crops in various countries. For consumption data, the more relevant statistic is the per-person average daily intake of food. Nationally representative data on consumption are available from the Living Standards Measurement Survey (LSMS-ISA, 2012) and household budget surveys. The consumption data need to be converted to calories to assess the relative contribution of aflatoxin-susceptible crops to the total calorie intake. If nationally representative data are not available on consumption of crops, another source for estimating the average daily per-capita intake is WHO s Global Environment Monitoring System - Food Monitoring and Assessment Program (GEMS/Food), which has developed dietary intakes for countries grouped into 13 clusters. As part of WHO s mandate to assess the potential exposure of populations to chemicals in food, GEMS/Food has been responsible for estimating regional dietary patterns of raw and semi-processed food commodities. These estimates are based on FAO food balance sheets for 183 countries using data from Abt Associates Inc. Identification of the Key Crops of Concern pg. 3-1

13 Once these data are gathered, crops that can be potentially affected by aflatoxins can be ranked by volume of production, feed consumption, human consumption (average daily intake), or value of exports. As a general rule, the greater the production, consumption, or value of exports, the greater will be the likely economic impact of aflatoxin contamination in the crops. The decision as to which crops are most important is largely a normative one, and it should also draw on the expert judgment of scientists who have been working on the aflatoxin problem, particularly those who have been working in that country. Abt Associates Inc. Identification of the Key Crops of Concern pg. 3-2

14 4 Prevalence of Aflatoxin-Causing Fungus (Step 2) After identifying the crop or crops of most interest, the following three factors collectively referred to as prevalence need to be determined: (1) the geographical distribution of the problem (areas of concern), (2) the extent of the problem (percentage of crop that is contaminated), and (3) the degree of contamination (contamination levels in parts per billion). Typically, countries have evidence only from limited geographical areas based on specific sampling done by researchers. Information on nationwide contamination is not available for any African country, and generating this information is expensive because prevalence varies over time with variable environmental conditions. At the same time, this information is an important input in identifying priority areas and estimating economic impacts. The first step in establishing prevalence is to conduct a literature review of existing studies that have established prevalence for the selected crops of concern (see Volume II, Appendix A for a summary of studies with prevalence information for maize, groundnuts, and sorghum in Africa). If this evidence is not adequate, then direct evidence on aflatoxin prevalence should ideally be established using primary data collection and testing. 4.1 Direct Evidence of Aflatoxin Prevalence The most direct and ideal approach to generate data on aflatoxin prevalence is to conduct a survey in the primary crop-growing regions that collects evidence of aflatoxin contamination in crops at all stages in the value chain (e.g., Mahuku and Nizlioki, 2011) including at the stage of final consumption. Biomarker measurement will conclusively establish the aflatoxin burden resulting from all crops. It is important to measure both aflatoxin contamination in products and aflatoxin contamination in food ready for consumption (or aflatoxin levels in blood serum). This is because direct evidence of aflatoxin contamination in crops is an important input in estimating the market impacts (and to assess the best control strategy), and yet this evidence is not sufficient to estimate the human health impacts because of the difficulty in estimating the actual consumption of aflatoxins. The extent of contamination in crops at the pre-harvest or post-harvest stage can be different from that in the food consumed. For example, households may sell the higher-quality crop and keep the lower-quality crop for self-consumption. Aflatoxin contamination can also be lower in food that is processed through milling, washing, and cooking for final consumption (Fandohan et al., 2005; Mutungi et al., 2007; Matumba et al., 2009). Sampling the actual food or using human biomarker data that are derived from blood or urine samples are more reliable measures of chronic exposure to aflatoxins (Williams et al., 2004). However, as mentioned above, these data are not useful for estimating the market impacts of aflatoxin contamination, if any. Consequently, both these types of data need to be gathered to estimate the full economic impacts. In the absence of resources to collect both types of data (market impacts or health impacts), the choice of which type of data to gather depends on the prior expectation of its contribution to economic impacts, as discussed in Section 2. Given the lack of awareness about aflatoxins in Africa, it is more likely that the contaminated crop will be consumed, implying that human health impacts are likely to be large and making a case for collecting good data on aflatoxin burden through sampling of food samples and biomarker data. Centers for Disease Control and Prevention (n.d.) provide an approach for such studies. Abt Associates Inc. Prevalence of Aflatoxin-Causing Fungus pg. 4-1

15 Data on aflatoxin contamination levels in crops can be collected using several methods: Pre-harvest sampling of crop in fields Pre-harvest sampling of soil in fields Post-harvest sampling of crop in storage Sampling of food and/or feed A critical issue that the sampling strategy has to take into account is that aflatoxins are not homogenously distributed in the field, or even within the maize cob. Another challenge is the fact that the presence of contamination varies over time. Mahuku et al. (2010) provide a good overview of a sampling strategy for both pre-harvest and post-harvest sampling of maize and peanuts. There is also a need to standardize the protocols for testing and reporting for better comparison of prevalence across countries. 1 Finally, in the absence of resources to collect primary data, data from existing prevalence studies can be reviewed to develop possible ranges of contamination. Thus far, Mahuku and Nizlioki (2011) have conducted the only nationwide study to assess the prevalence of aflatoxins in the maize value chain in Kenya and the peanut value chain in Mali; Monyo (n.d.) has conducted a nationwide study to assess the prevalence of aflatoxin contamination in maize and peanuts in Malawi. Other than these two systematic studies, to the best of our knowledge, the majority of the efforts to estimate aflatoxin prevalence were motivated by scientific query to understand the conditions that inhibit or nurture the growth of aflatoxin-causing fungus (see Volume II, Appendix A, for a bibliography of papers with aflatoxin prevalence data on maize, groundnuts, and sorghum for Africa). Scientists have conducted tests to understand the relationship between climatic conditions and aflatoxin contamination, to assess the impact of control strategies on aflatoxin prevalence, and to characterize the relationship between post-harvest storage conditions and aflatoxin prevalence. However, these studies gather data from limited geographic areas on aflatoxin contamination. This motley collection of scientific tests gives scattered evidence of the prevalence of aflatoxins in some African countries. Although these data may not be adequate to characterize aflatoxin prevalence for a given country, they can be used to construct ranges of economic impact estimates based on the ranges of contamination levels derived from these studies. 4.2 Geographic Information System (GIS) Analysis of Environmental Conditions If prevalence data from existing studies are not adequate, GIS analysis of available environmental variables that are known to be correlated with aflatoxin presence can help identify potential areas of concern. It is widely recognized in the literature that dry spells and high temperatures during planting and hot and humid temperature or precipitation during harvest time can lead to higher aflatoxin 1 Reporting protocols are particularly important when a large percentage of the samples have contamination below the Level of Detection (LOD) of the test used. Average contamination in the overall sample is estimated using a range of methods in the literature. Some studies only report the mean aflatoxin concentration in samples above LOD, other substitute a fixed value to contamination below LOD, and still others estimate a mean assuming censoring at LOD. This can lead to a lack of comparability of estimated average contamination across studies. Abt Associates Inc. Prevalence of Aflatoxin-Causing Fungus pg. 4-2

16 presence. Using the available data on these environmental variables, one can identify areas that are more likely to have experienced pre-harvest and post-harvest conditions for aflatoxin contamination similar to the approach of Monyo (n.d.) for assessing occurrence and distribution of aflatoxins in Malawi. (see Figure 4-1). Data Requirements and Sources for GIS Maps of Environmental Conditions Environmental Variables Data on environmental variables that are known to affect aflatoxin presence from the sample locations, including average minimum temperature, average maximum temperature, rainfall, humidity at planting and harvesting, land cover, elevation data, and other relevant data. WorldClim ( Boston University Landcover Maps (wwwmodis.bu.edu/landcover/); US Geological Survey (USGS) ( Legend Severe Drought during Planting Moderate Drought during Planting High Moisture during Harvest Medium Moisture during Harvest Figure 4-1: Identifying Potential Hot Spots Using Environmental Determinants of Aflatoxins (hypothetical mapping) Abt Associates Inc. Prevalence of Aflatoxin-Causing Fungus pg. 4-3

17 Abt Associates Inc. Prevalence of Aflatoxin-Causing Fungus pg. 4-4

18 5 Risk Characterization of Aflatoxin Exposure and Contamination (Step 3) This step involves two sub-steps: (1) assess the final uses of the aflatoxin-susceptible crop, where the aflatoxin-contaminated crop is grown, how it is used, and by whom it is used; and (2) assess the risk of contamination along the value chain of selected crops. The first assessment is important to establish the relative magnitude of human health impacts, impacts on livestock, and market losses (see Figure 5-1). If resources are limited, this assessment can help narrow the focus of the economic assessment to the most significant economic impacts. This analysis relies largely on secondary data and is supplemented by key-informant interviews. Production Sale to Market Own Consumption Livestock Feed Contaminated Products Contaminated Livestock Products Market Loss Supply shortage Discarded grain Litigation Human Health Impact Disease burden Reduced productivity Market Loss Reduced milk productivity Livestock disease burden Reduced prices of products Discarded products Figure 5-1: Final Uses of Aflatoxin-Contaminated Crop The second assessment is completed largely through in-country interviews with key informants: key central and local government officials, and stakeholders from the community including farmers, processors, traders and retailers of food and feed, and women. The interviews should be conducted in the city where the central government offices are located and in at least three local sites where selected crops are grown and traded. The in-country interviews are informed by initial desk review of available documents, and by analysis of any relevant country-level data that help researchers understand the risks of aflatoxin contamination along the value chain of a crop (e.g., LSMS-ISA (2012)). The assessments should be conducted with (ideally, led by) in-country consultants from institutions that are leading any efforts in aflatoxin research, control, or awareness raising. The two sub-steps are described more in detail below. Abt Associates Inc. Aflatoxin Risk Characterization pg. 5-1

19 5.1 Final Uses of Aflatoxin-Susceptible Crops This step requires determining the final uses of contaminated crop: How much of the contaminated crop is consumed by the farmers as own consumption? How much of the contaminated crop is fed to livestock of interest? How much of the contaminated crop is traded in the domestic and international market? The final use of the crop determines where the largest impact of contamination is likely to be and, correspondingly, the distribution of economic impacts between human health impacts and market impacts. For example: If the majority of the product is used as own consumption, then human health impacts could constitute the majority of economic impacts. If the majority of the product goes to the market, and there is lack of awareness about the aflatoxin problem, human health impacts will continue to be the most significant concern. If the domestic market recognizes the aflatoxin problem, then it will reject the product or reduce prices for aflatoxin-contaminated crops, resulting in direct market loss to farmers. If the farmers respond by destroying or discarding the grain, then the market losses will be high with lower human health impacts. In contrast, if the farmers respond by sorting the product and consuming the contaminated grain while directing the uncontaminated grain to the market, human health impacts will be large. Farmers may also choose to divert a larger quantity of contaminated crops to livestock feed, which can increase the economic impacts resulting from disease burden in livestock and, ultimately, even human health impacts resulting from consumption of contaminated milk. This type of analysis requires data on crop production, which are available from annual statistics from the ministry of agriculture or national statistics departments. In addition, FAO also publishes food balance sheets that give the relative use of important food security crops (or cereal crops). The key data gap is typically the amount of crop used for livestock feed (if relevant), which is available in some cases from the United Nations Commodity Trade Statistics Database (UNComtrade). In the absence of statistically representative data on this amount, the best approach is to obtain expert opinion from livestock extension agents and targeted interviews with farmers. Abt Associates Inc. Aflatoxin Risk Characterization pg. 5-2

20 Food Balance Sheet Data Requirements and Sources for Determining Final Uses of Crop Data on final uses of cereal products. FAOSTAT ( Production Volume Export Volume and Export Rejection Consumption Data on total domestic production of specific crops. Data on total exports of the specific crops, and the rejection of products because of aflatoxin contamination. Consumption, including own consumption and sales. CountrySTAT ( CountrySTAT ( UNComtrade ( USDA ERS ( ome?navid=data_statistics) UNComtrade ( WHO Global Environment Monitoring System/Food Monitoring and Assessment Program ( n/index1.html); LSMS-ISA ( Livestock Feed Consumption of crop by livestock. USDA ERS ( ome?navid=data_statistics) 5.2 Risk of Contamination along the Value Chain of Selected Crops The analysis of risks of contamination along value chain covers an assessment of risk and vulnerability factors affecting aflatoxin contamination and exposure in the pre-harvest stage, postharvest stage, storage, processing, transport, retail, and consumption of crops. This work begins with a desk review of the existing literature, which would highlight information gaps that are resolved through in-country interviews with key informants. The literature may reveal existing technologies, procedures, systems, or research on aflatoxin mitigation, which can be verified by the in-country assessment (see Volume II, Appendix B, for the most recent literature review conducted in 2012). This literature review will also reveal prevalence data on aflatoxins and information on institutions, projects, networks, and experts that should be consulted during the in-country assessment. Key-informant interviews, focus group discussions, and observation can then be used to identify risks associated with aflatoxins, as well as knowledge, attitudes, practices, and available solutions for all stakeholders, including farmers, traders, vendors and livestock handlers. Results from the qualitative research will be compiled and shared with national experts in aflatoxin detection and regulation, as well as experts in trade, agriculture, and public health and nutrition. The in-country interviews should be conducted with consultants from the country who can be instrumental in carrying forward the efforts initiated by the country assessment. Consultants should be leaders in the field of aflatoxin mitigation, and should be well positioned to use what is learned in the assessment to mobilize policy makers to develop an organized country response to aflatoxin mitigation through the Aflatoxin Stakeholder Workshop (discussed in Section 0). Abt Associates Inc. Aflatoxin Risk Characterization pg. 5-3

21 At the workshop, the literature review findings and qualitative assessment should be summarized and presented to a multi-sectoral group of policy makers so that a national and/or regional response to aflatoxins can be drafted. Where gaps found cannot be filled during the assessment process, priority areas for ongoing research and interventions can be noted as a key part of the action plan. The qualitative portion of the country assessment provides the bulk of the information for this step. Semi-structured interview guides are needed for the information gathering process (see Volume II, Appendix C, for detailed interview guides). These guides must be developed for each key informant to be interviewed. The broad categories of key informants may vary across countries but are expected to include: Key officials in the ministries of agriculture (and food security if there is one), livestock, trade, and health, including departments within these ministries that handle extension messaging, postharvest processing, nutrition messaging, and research. Local government officials at a minimum of three locations that produce selected crops. Trade associations for selected crops. Private sector entities representing processors, traders, and retailers of selected products. Farmer associations and farmer groups at a minimum of three locations that produce selected crops. Women s groups. Development partners implementing programs in improved agricultural production, processing, trade, and improved nutrition. A template for this assessment with key questions and a list of suggested respondents (if different from above), is presented below to identify awareness and risks of contamination along the value chain Pre-Harvest The pre-harvest, harvest, and post-harvest questions should be asked of farmers, farmer association heads, agricultural extension agents, retailers of agricultural inputs (improved seeds, fertilizer, irrigation equipment) and district-level coordinators for the Ministry of Agriculture. These questions can also be asked of medium- and large-scale farmers to get a sense for variations in awareness or practices and attitudes. What is the general awareness level of good agricultural practices (GAP)? What do farmers know regarding pre-harvest practices that may reduce Aspergillus infection, such as irrigation and drainage, proper land and soil preparation, use of high-performing seed, application of fertilizers, weeding practices, crop rotation? What are current practices related to the above? Does the country have any experience with bio-controls (such as Aflasafe )? If yes, what is the progress/status of the bio-control? What is the awareness of bio-controls effects on aflatoxin contamination? How many farmers are using a soil treatment? (Large scale? Medium sized? Contract farmers, subsistence farmers?) Why/why not? How many farmers use improved seeds? Did research reveal willingness to pay for information? Are there any marked gender differences in awareness or access to pre-harvest solutions for male vs. female Abt Associates Inc. Aflatoxin Risk Characterization pg. 5-4

22 farmers? Harvest Do farmers know/understand the importance of timely harvesting? Do they do this? Why/why not? Do men and women farmers have different practices for harvesting? Why/why not? If they know the risks of aflatoxins, are they more likely to harvest in a timely fashion? Post-Harvest Key literature findings on post-harvest handling Common post-harvest recommendations include sorting, cleaning, drying, packaging, adherence to hygiene and sanitary conditions in storage and transport and awareness raising about these practices (Hell et al., 2008). One study of rural aflatoxin mitigation among small farm holders (in Guinea) found that a package of recommended interventions led to a 50% reduction of aflatoxin biomarkers among the households in the intervention group as compared to the control group five months after the package was adopted (Turner et al., 2005). This package included: hand-sorting, storage in jute bags, education on improved sun drying, wooden pallets for drying, locally made natural fiber mats, and insecticides (Turner et al., 2005). The estimated cost of this intervention package was $50 (including $10 for the wooden pallet); a sizeable but potentially manageable cost where the gross national product (GNP) per capita is $1,100 (Turner et al., 2005). Key questions on post-harvest handling practices Are the aforementioned options (hand-sorting, jute bags, sun drying, wood pallets, fiber mats, and insecticides) recommended for this country? If yes, are wooden pallets, fiber mats, jute bags, and insecticides available and affordable? What is the cost of the aforementioned package in the country? Are farmers willing to pay for these inputs? Do farmers find these inputs affordable? How do farmers typically dry their crops? Does that differ regionally? Across gender lines or among mediumand large-scale farmers? Is there access to finance for farmers seeking loans to improve GAP and post-harvest handling options? Does access to finance/loans differ for male vs. female farmers? Why/why not? If farmers can get a loan, how much would they (male and female farmers) be willing to invest in GAP-related equipment/supplies? Are there local manufacturers of recommended drying, bag, insecticide, and storage inputs? If yes, who and where are they based? Storage In addition to the respondents outlined above, fabricators of storage equipment; storage researchers; or vendors/retailers of household, community, and larger (industrial) scale storage and warehouses should be asked questions on storage. Storage silos and community grain stores How do small-scale farmers typically store their harvest? Is grain dried to 15% moisture before it is stored? If yes, how? If no, why not? Are there sellers of dryers? Where? How much does it cost? Do communities buy these? Are there any methods of affordable improved storage (and drying)? What types of improved storage facilities are available? How often are they used? Are any types of affordable improved storage available? Are there gender differences in storage practices? If yes, why? Does the MoA see it as its mandate to help rural communities use and access improved storage? Abt Associates Inc. Aflatoxin Risk Characterization pg. 5-5

23 Awareness Raising What is the role of the Ministry of Agriculture (MOA) in aflatoxin mitigation? What is the MOA s role in preventing/reducing aflatoxins? Are there policy champions within MOA who see aflatoxin awareness raising, or prevention or mitigation, as part of the MOA s mandate? How does awareness raising occur at the regional level? Community level? Does the MOA disseminate knowledge about GAP? Does this messaging incorporate information about aflatoxins? Household- and Community-Level Food Processing Findings from the literature on community- and household-level food processing Some studies suggest that aflatoxins can be reduced by household- or community-level food processing through sorting, processing, and dehulling grain mechanically (Fandohan et al., 2005). Generally, temperatures that are not achieved during home cooking (195 degrees Celsius for aflatoxin reduction) would be needed to sufficiently affect aflatoxin levels (Fandohan et al., 2005). Other promising practices include wet and dry milling, grain cleaning, canning, roasting, baking, frying, and extrusion cooking. 2 Studies referenced in the USAID synthesis found that 23 percent of aflatoxins may be reduced by home preparation of a maize porridge. The authors note however that caution should be exercised, as even these reductions in aflatoxin levels may not bring the contaminants down to safe levels (USAID and Danya International, 2012). Respondents for this section should include caregivers (male and female) in rural households, as well as the agricultural and health extension workers that may engage households or communities. Are there any viable examples of household or community-based food processing that may lead to aflatoxin mitigation? Are households aware of aflatoxins? What are common household processing procedures undertaken in the urban, peri-urban, and rural areas? Are there divisions of labor along gender lines for household processing? What about potentially risky practices (e.g., using leftover water in which maize has steeped for cooking? Using groundnut cake left over from oil pressing for household consumption among children? Animals? Other groups?) Industrial Processing Findings from the literature Though there is no widespread government acceptance of any decontamination treatment intended to reduce aflatoxin B1 levels in contaminated animal feeding stuffs.ammoniation appears to have the most practical application for the decontamination of agricultural commodities (USAID and Danya International, 2012). In animal feed, an anticaking/binding agent such as "hydrated sodium calcium aluminosilicate" may reduce AFM1, the metabolized form of aflatoxin, which may be found in the milk of lactating animals that have been exposed to aflatoxins in food or feed (USAID and Danya International, 2012). 2 Extrusion cooking is often an industrial process that involves mixing the food content (e.g., peanuts) with a reagent at very high temperatures. A Food Navigator article cites a study in which aflatoxins in peanuts were reduced by 97% by an extrusion cooking process that mixed calcium chloride, lycene, and methylamine (Gray, 2011). Abt Associates Inc. Aflatoxin Risk Characterization pg. 5-6

24 Respondents for industrial processing should include formal and informal millers, processors, and packagers of common food products that are sold for domestic and international sale. Key remaining questions about industrial processing to mitigate aflatoxins Are there any successful, wide-scale industrial processing efforts in the country? If yes, what are these? What methods do stakeholders see as favorable/promising for processing? Are processors willing to invest in these methods? Are some already investing? How can this investment be promoted and encouraged for scale-up? The following template addresses public health and dietary-related risk factors and opportunities to mitigate aflatoxin exposure. It also discusses animal feed and then alternative use as one way to withdraw contaminated crops from the food supply. Public Health Public health questions should be asked of the Ministry of Health division responsible for vaccination. Questions on treating aflatoxicosis should be asked of experts involved in food safety, liver cancer, and gut health or enteric disease. What is the coverage of hepatitis B vaccination? Are there gender differences in vaccination levels of coverage? In the event of human exposure to high levels of aflatoxin contamination (e.g., aflatoxicosis), does the country have any experience with chemopreventive agents such as Oltipraz, green tea polyphenols, and sulforaphane, which can either detoxify or inhibit enzymes required for the activation of the carcinogen associated with the aflatoxins? Diet and Nutrition Information on dietary trends and food consumption will be available from the analysis in Step 1, and the analysis described in Section 5.1. The remaining questions should be asked of nutrition and agricultural experts. Questions about dietary trends/staple dependence by region What are the most important staples for humans in the country? By region? Which of these staples are susceptible to aflatoxin contamination? Though these questions should also be addressed by the literature review, also ask nutrition and food safety experts these questions. Rural considerations What percentage of the population relies on purchased foods from a mill/processor that is likely to undergo aflatoxin inspection? What percentage of the population relies on local markets? Are there gender differences in consumption patterns that may affect human exposure to aflatoxins? Infant Feeding Practices Literature findings on possible effects of aflatoxin exposure on young infants A study in West Africa found that weaned children had approximately twofold higher mean AF-alb adduct [aflatoxin biomarkers] than those receiving a mixture of breast milk and solid foods and children who were underweight and stunted had 30 40% higher mean AF-alb levels than the remainder of the children (Gong, 2003). Though WHO recommends that infants up to 6 months of age be exclusively breastfed, premature introduction to complementary foods is common in many African countries, and weaning foods may also contain staples that are susceptible to aflatoxin contamination. Abt Associates Inc. Aflatoxin Risk Characterization pg. 5-7

25 Remaining questions to ask nutrition and child health experts within the Ministry of Health What percentage of the population is stunted? Is there a currently accepted Infant and Young Child Feeding Practices protocol that is being disseminated by the Ministry of Health? Non-governmental partners? What is the coverage of optimal breastfeeding (exclusive through 6 months of age)? Are there other harmful practices that may be increasing exposure to young infants and children? (e.g., cooking with water that was used for boiling maize, consuming groundnut cake? Monotonous diets that are based on staple products that are prone to aflatoxin contamination?) Are there any cultural differences in infant or child feeding for boys and girls that may affect aflatoxin exposure? Risk of Contamination for Animal Feed These questions should be asked of animal feed companies, Ministry of Agriculture animal scientists, livestock associations, commercial sector livestock growers, agricultural extension agents, and industries involved in the sale or import of binding agents. Animal feed contamination questions What is the awareness level of aflatoxins in the animal feed industry? Do animal feed suppliers use an anti-binding agent to reduce the effects of aflatoxins in animals? Does the country have standards on maximum limits of aflatoxins in animal feed? Are there more recent studies/findings on aflatoxin contamination in animal feed? If yes, where? Are there any stakeholders taking action to mitigate aflatoxin contamination in animal feed? If yes, what? What efforts are currently being made to reduce aflatoxin exposure in animal feed? Do large-scale livestock entrepreneurs know about the risks of aflatoxins in animal feed? Are they doing anything to mitigate it? Alternative Uses for Contaminated Crops Literature findings The United States Food and Drug Agency allows for regulated use of some contaminated commodities to be safely added to animal feeds, depending on the animal s life cycle and stage of growth. For example, 300 ppb can be used for corn and peanut products intended for finishing (i.e., feedlot) beef cattle; 300 ppb for cottonseed meal intended for beef cattle, swine, or poultry (regardless of age or breeding status); 200 ppb for corn or peanut products intended for finishing swine of 100 pounds or greater. For a full list of these regulations see the guidance provided here: Additional questions to ask of animal feed experts and regulatory specialists involved in animal feed and bio-fuel Do any industries currently use contaminated crops for alternative uses (e.g., bio-fuel?) Is there currently any type of established alternative use (e.g., bio-fuel) established for contaminated products? Is there any potential market that could be set up as an alternative use for contaminated products? Are there any safe practices for blending mildly contaminated crops for animal feeds? Is there a market for this type of blended product? Abt Associates Inc. Aflatoxin Risk Characterization pg. 5-8

26 6 Economic Impacts Resulting from Aflatoxin Contamination (Step 4) The focus of the economic impact analysis is on estimating the social costs borne by the citizens of a specific country, not the global social costs. The ideal approach to estimating national-level impacts is a general equilibrium model, which requires information on allocation of resources and relationships among all economic actors (households, government, and industry) of the economy. (The human health impacts need to be estimated separately because they are a non-market good.) Within this framework, the economic impact of the aflatoxin problem would require characterization of the economy without aflatoxins and comparison with the status quo. The differences in the two states measured by the changes in income; prices; quantities consumed, produced, and exported, etc. can be characterized as changes in the welfare of producers and consumers of aflatoxin-contaminated products, which is a strong measure of the cost to society of the aflatoxin problem. Not surprisingly, a general equilibrium approach is resource-intensive and requires tools and data to model the economy and the relationships among the economic actors, which is typically not feasible. The framework proposed strives to take into account the need for developing countries to carry out similar work, even when resources and data are limited. Therefore, the approach outlined is based on a partial equilibrium analysis to assess the impact on specific sectors separately, without accounting for feedback among households, firms, and various sectors. In fact, the data may often be too limited to complete even a partial equilibrium analysis. Accordingly, while this framework outlines the ideal (partial equilibrium) approach, which would require additional primary and country-specific research, it focuses on approaches to leverage existing secondary data and conduct uncertainty and sensitivity analysis to provide policy makers with a range of possible economic impacts. In this way, the framework helps identify the key data gaps that, if addressed, can significantly reduce the uncertainty in the economic impact estimates. The conceptual framework is also based on estimating annual impacts in a typical year, rather than estimating an impact over a specific policy period. The literature thus far has estimated the economic impacts economic impacts resulting from human consumption of aflatoxin (hereafter referred to as health impacts), trade impacts, and market impacts separately. Wu and Khlangwiset (2010), Liu and Wu (2010), and Khlangwiset et al. (2011b) estimate human health impacts. Several papers estimate the export losses from aflatoxin contamination using standard trade models (Otsuki et al., 2001a; Otsuki et al., 2001b; Munasib and Roy, 2012). Wu (2004) directly estimates the export losses after making assumptions about the probability of rejection. There are no papers that estimate the impact of aflatoxin contamination on the domestic market. One research effort that is underway as part of the Aflacontrol project (Tiangco, 2011) proposes to estimate the impact of aflatoxin contamination of maize on farmers income and wealth. This paper builds on the literature and proposes approaches to estimate three types of economic impact resulting from aflatoxin contamination of crops: Economic impact resulting from losses in both international and domestic markets Economic impact resulting from consumption of contaminated feed by livestock Economic impact of human consumption Abt Associates Inc. Economic Impact of Contamination pg. 6-1

27 Each country s economic assessment can focus on estimating the most significant economic impacts resulting from aflatoxin contamination after assessing the results from Step 2, which determines the final uses of the selected crops. In developing country environments, the most significant impacts will typically be on human health. The next sections present the framework to estimate the three types of economic impacts. 6.1 Economic Impact Resulting from Market Losses Market losses from aflatoxin contamination can be separated into losses in the domestic market and losses in the international market (the latter is often more formal). In the domestic market, the direct economic impact of aflatoxin contamination in crops results mainly from a reduction in marketable volume, loss in value in the national markets, inadmissibility or rejection of products by the international market, and losses incurred from livestock disease and mortality (see Figure 5-1). As mentioned above, the contribution of market losses to the total economic impacts depends on the extent to which the domestic market differentiates aflatoxin-contaminated products. If the domestic market does not differentiate aflatoxin-contaminated products, the market losses from the contamination will be zero. The international market, on the other hand, recognizes aflatoxins as food contaminants and has strict regulations that define aflatoxin standards, which can vary from country to country (FAO, 1997; FAO, 2004). Codex Alimentarius has established standards for food and feed use, and nearly all developed countries have established analogous regulations to control aflatoxins in commodities. 3 Therefore, in the international market, products that do not meet the aflatoxin standards are either rejected at the border, rejected in channels of distribution, assigned a reduced price, or diverted to non-human or even non-fee uses. There may be additional opportunity costs over time that arise from not being able to participate in the international market because aflatoxin standards present a barrier to entry. The sections below present an approach to estimate market losses from both international and domestic markets. The market loss resulting from livestock consumption of aflatoxin-contaminated feed is discussed in Section Domestic Market Impacts Domestic market impacts will be negligible if there is lack of awareness about the aflatoxin problem with no differential pricing of uncontaminated versus contaminated product. With awareness, the market will distinguish the aflatoxin-contaminated food (crop or livestock products) from the aflatoxin-free food, resulting in segmentation of markets across the two types, with separate (potentially zero) demand for aflatoxin-contaminated food. In the absence of control strategies for aflatoxins, the supply of aflatoxin-free food (and aflatoxin-contaminated food) is determined by weather outcomes so that the producers cannot adjust the supply of the aflatoxin-free food, resulting in a supply shock and increased prices. In the long run, the market should adjust to the exogenous, 3 The Codex Alimentarius Commission, established jointly by the Food and Agricultural Organization (FAO) and the World Health Organization (WHO), provides international guidelines for aflatoxins. The European Union (EU) has more stringent guidelines than those specified by the Codex Alimentarius. In addition, the United States, Canada, and some other countries have also specified their own standards. Abt Associates Inc. Economic Impact of Contamination pg. 6-2

28 climate-dependent supply shocks by moving production to other commodities that are less susceptible to aflatoxin contamination, and the resulting availability of substitutes might also affect the demand for the commodity. However, in low-income developing countries, commodities such as maize are grown for own consumption and are an integral part of the cultural diet; only the surplus is sold in the domestic market, implying that the long-run adjustment in supply and demand may be sluggish. Therefore, the short-run supply shock is a good approximation of the welfare impacts. There is likely to be a fair amount of uncertainty in these data, which should be modeled in estimating the economic impacts. In developed countries, there is significant awareness of the problem, and there are strict trade regulations on export of aflatoxin-contaminated grain to most major markets established with reference to Codex standards and enforced under the provisions of the World Trade Organization s Agreement on Sanitary and Phytosanitary Measures. Therefore, there is relatively little uncertainty about the response of international trade markets to the aflatoxin problem. By contrast, in many developing countries, and in most sub-saharan countries, there is limited awareness, regulation, and enforcement for either intra-regional trade or domestic commerce. To illustrate, consider the case of maize described in Figure 6-1. In the absence of knowledge about aflatoxin contamination, the supply of maize in a given year, S(q), is given by the intersection of the demand curve for maize, D(q), and the supply curve for maize. If a part of the supply is contaminated, and the market differentiates between the two types of maize, there will be welfare impacts. If there is zero demand for aflatoxin-contaminated maize (bad maize), then the market impact is the greatest. Aflatoxin contamination of part of the crop results in a supply shock for the available aflatoxin-free maize (good maize), which in turn results in an increase in the price for the aflatoxin-free food to P(q G ). The social welfare impact of aflatoxin contamination is the loss in producer and consumer surplus resulting from this shift in supply of good maize (equal to the green-shaded area in Figure 6-1). In reality, the market for bad maize will continue to exist, but the demand for it will be lower than the demand for good maize because of the known adverse impacts of aflatoxin contamination, resulting in reduced price. Given our assumption that there are no control strategies, the environmental conditions will determine the quantity of bad maize, given the quantity of maize produced in a given year. In Figure 6-1, this quantity is equal to q 0 -q G, which is the fixed supply of bad maize. The price at which this quantity of bad maize is sold will depend on the demand curve for bad maize. This demand needs to be characterized, but we can say a few things about its properties: First, the demand for bad maize will be zero if it is sold at the price of good maize. Second, the demand for bad maize at zero prices cannot be greater than the demand for good maize. These two conditions imply that the demand curve for bad maize will always be weakly below the demand curve for good maize. 4 The sale of bad maize results in a gain in welfare impacts, which is equal to the brown shaded area, so that the total impact of aflatoxin contamination is net welfare loss equal to difference between the greenshaded area and the brown-shaded area. Given the assumptions of the demand for bad maize, and the properties of the linear demand curve, one can show that there is always positive welfare loss (see Appendix D for the proof). The magnitude of this loss depends on the relative elasticity of the demand for good maize and the demand for bad maize. 4 Note that it is conceivable that the prevailing price of bad maize in the market can be higher than the price that would have prevailed if the entire supply were good (price P). Abt Associates Inc. Economic Impact of Contamination pg. 6-3

29 S(q) P(q G ) P(q 0 ) P(q 0 -q G ) D(q) q 0 -q G q G q 0 Quantity of (Good and Bad) Maize Figure 6-1: Impact of Aflatoxin Contamination on Domestic Market Therefore, estimating the domestic market impact from aflatoxin-contamination requires data to estimate the demand and supply system for both the aflatoxin-free and the aflatoxin-contaminated crop. The demand for the aflatoxin-free commodity can be characterized by the general demand for the commodity in markets without awareness about the product. However, if there is awareness of aflatoxin contamination, the demand for the aflatoxin-contaminated commodity also needs to be characterized. In the absence of data to characterize the demand for aflatoxin-contaminated grain, we can estimate the upper-bound impact under the case where demand for aflatoxin-contaminated products is zero. This requires estimating the demand and supply system for the commodity, information on the proportion of the crop that is contaminated, and the resulting welfare losses from the supply shock. The demand and supply system can be estimated using time series data on quantities sold, price of the commodity, and other factors that (exclusively) affect the demand and supply of the commodity. The pilot assessments for Nigeria and Tanzania suggest that in developing countries it is likely that the market does not differentiate between aflatoxin-contaminated foods and aflatoxin-free foods. In such a scenario, there will be no economic impact resulting from market loss. Instead, the economic impact will be from adverse health impacts resulting from the consumption of aflatoxin-contaminated products. In-country interviews with key informants need to be conducted to understand the market s awareness of aflatoxins, whether the domestic market differentiates an aflatoxin-contaminated crop in terms of prices or rejection of product, and farmers response to the problem International Trade Impacts As early classical theorists Ricardo and Heckscher point out, gains from trade stem from specialization in production according to a country s comparative advantage. This improves Abt Associates Inc. Economic Impact of Contamination pg. 6-4