Research 2005–2007 Comprehensive Assessment of Maize Aflatoxin Levels in Eastern Kenya, and Michael A. McGeehin1 Johnni H. Daniel,1 Lauren W. Lewis,1 Yanique A. Redwood,1 Stephanie Kieszak,1 Robert F. Breiman,2 W. Dana Flanders,1 Carlos Bell,3 John Mwihia,4 George Ogana,4 Sopiato Likimani,5 Masja Straetemans,6 1Centers for Disease Control and Prevention, Atlanta, Georgia, USA; 2Centers for Disease Control and Prevention, Kenya, Nairobi, Kenya; 3Food and Drug Administration, Rockville, Maryland, USA; 4Kenya National Public Health Laboratory, Nairobi, Kenya; 5Kenya Ministry of Public Health and Sanitation, Nairobi, Kenya; 6KNCV Tuberculosis Foundation, The Hague, the Netherlands Background : Aflatoxin, a potent fungal toxin, contaminates 25% of crops worldwide. Since 2004, 477 aflatoxin poisonings associated with eating contaminated maize have been documented in Eastern Kenya, with a case-fatality rate of 40%. o Bjective : We characterized maize aflatoxin contamination during the high-risk season (April–June) after the major harvests in 2005, 2006 (aflatoxicosis outbreak years), and 2007 (a non- outbreak year). Methods : Households were randomly selected each year from the region in Kenya where outbreaks have consistently occurred. At each household, we obtained at least one maize sample (n = 716) for aflatoxin analysis using immunoaffinity methods and administered a questionnaire to determine the source (i.e., homegrown, purchased, or relief) and amount of maize in the household. r esult : During the years of outbreaks in 2005 and 2006, 41% and 51% of maize samples, respectively, had aflatoxin levels above the Kenyan regulatory limit of 20 ppb in grains that were for human consumption. In 2007 (non-outbreak year), 16% of samples were above the 20-ppb limit. In addition, geometric mean (GM) aflatoxin levels were significantly higher in 2005 (GM = 12.92, maximum = 48,000 ppb) and 2006 (GM = 26.03, maximum = 24,400 ppb) compared with 2007 (GM = 1.95, maximum = 2,500 ppb) (p-value < 0.001). In all 3 years combined, maize afla- toxin levels were significantly higher in homegrown maize (GM = 17.96) when compared with pur- chased maize (GM = 3.64) or relief maize (GM = 0.73) (p-value < 0.0001). c onclusi : Aflatoxin contamination is extreme within this region, and homegrown maize is the primary source of contamination. Prevention measures should focus on reducing homegrown maize contamination at the household level to avert future outbreaks. k ey words : aflatoxicosis, aflatoxin, contamination, Kenya, maize. Environ Health Perspect 119:1794–1799 (2011). http://dx.doi.org/10.1289/ehp.1003044 [Online 15 August 2011] Household Budget Survey 2005/2006). The districts lie in a drought-prone region that consists of small-scale subsistence farms and where maize is the main crop produced and consumed (Lewis et al. 2005). The first recorded outbreak in this area was in 1981, resulting in 20 cases and 12 deaths. Consumption of contaminated maize was established as the source of aflatoxin expo- sure. The maize grains from households where severe and fatal illness had occurred contained aflatoxin levels up to 12,000 ppb (Ngindu et al. 1982). In April 2004, the most severe aflatoxicosis outbreak ever reported occurred in this region. That outbreak resulted in 317 cases and 125 deaths and was due to con- tamination of improperly stored maize (Azziz- Baumgartner et al. 2005; CDC 2004). Epidemiologic investigations of these previous outbreaks identified consistent characteristics of aflatoxicosis outbreaks in the region. Maize was the established source of aflatoxin exposure, and the season between April and June (4–8 weeks after the major crop has been harvested and stored) was established as the high-risk season when acute aflatoxicosis outbreaks consistently occurred (Azziz- Baumgartner et al. 2005; Mwihia et al. 2008; Ngindu et al. 1982; CDC 2004). Historically, outbreaks have highlighted the extreme aflatoxin exposure in this region. However, the extent of aflatoxin contamination is unknown, and community awareness of aflatoxin and aflatoxicosis and other factors that may influence exposure in the affected geographic locations have not been well characterized. Address correspondence to J.H. Daniel, Centers for Disease Control and Prevention, National Center for Environmental Health, Health Studies Branch, 4770 Buford Hwy MS F-57, Atlanta, GA 30341 USA. Telephone: (770) 488-3415. Fax: (770) 488- 3450. E-mail: bez2@cdc.gov We thank the Ministry of Public Health and Sanitation (formerly the Kenya Ministry of Health), Centers for Disease Control and Prevention, Kenya Country Office, the Kenya Field Epidemiology Training Program, A. Dahiye, and A. Guracha. The Division of Environmental Hazards and Health Effects and the U.S. Centers for Disease Control and Prevention’s National Center for Environmental Health provided funding. The authors declare they have no actual or poten- tial competing financial interests. Received 1 October 2010; accepted 15 August 2011. ovlume 119 | number 12 | December 2011 • Environmental Health Perspectives Aflatoxins are a group of mycotoxins produced mainly by Aspergillus spp. fungi that grow on various crops such as maize, nuts, and other grains (Patten 1981). Chronic dietary exposure to low doses of aflatoxins is a known risk factor for liver can- cer and may also affect protein metabolism and immunity, thus worsening infectious diseases and malnutrition (Williams et al. 2004). Ingesting highly contaminated prod- ucts results in severe, acute hepatitis known as aflatoxicosis; symptoms include vomit- ing, jaundice, and abdominal pain and can lead to fulminant liver failure and death. No specific treatment has been found for acute aflatoxicosis. With supportive care, the case fatality rate for acute poisoning ranges from 25 to 40% (Azziz-Baumgartner et al. 2005; Eaton and Groopman 1993). Multiple risk factors increase human exposure to dietary aflatoxins. Inadequate drying and storage under damp conditions are primary factors that lead to aflatoxin pro- duction and grain contamination (Wilson and Payne 1994). In addition, drought con- ditions and insect invasion can weaken crops and make them susceptible to contamination (Sinha and Sinha 1992). 1794 Subsistence farmers in developing coun- tries are perhaps the most at risk. They often lack the capacity to protect crops against afla- toxin contamination. In addition, food inse- curity due to drought and other causes of crop failure seem to contribute to behaviors that increase risk of exposure. Finally, 60–85% of the population in the developing world are subsistence farmers and are not protected by commercial food safety regulation (Wild 2007). As a result, there are considerable dis- parities in aflatoxin exposure between people living in developed and developing countries. Perhaps the most extreme exposure to aflatoxin documented globally occurs in the southern region of Kenya’s Eastern prov- ince [Azziz-Baumgartner et al. 2005; Centers for Disease Control and Prevention (CDC) 2004; Lewis et al. 2005; Ngindu et al. 1982]. Outbreaks of acute aflatoxicosis recur in the region, specifically, in two adjacent districts, Makueni and Kitui, that have consistently been the epicenter of aflatoxicosis outbreaks in the region (Azziz-Baumgartner et al. 2005; Ngindu et al. 1982). Makueni and Kitui are located approximately 130 km southeast of Nairobi and have a combined estimated population of 1,591,343 (Kenya Integrated