Aflatoxins in peanuts and the prevalence of aflatoxin induced hepatocellular carcinoma in Busia and Kisii Central Districts, Kenya
Chengo, Nelson Menza
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Aflatoxin is a carcinogenic toxin produced mainly by Aspergillus jlavus and contaminates foods including peanuts. Aflatoxin is associated with liver failure, hepatocellular carcinoma (HCC) and death. Many people are exposed to chronic levels of aflatoxins through consumption of contaminated foods. In Kenya, most efforts have been focused on aflatoxin in maize while other highly predisposed foods such as peanuts have received little attention. Also limited studies have been done to link aflatoxin to HCC. This study identified aflatoxin producing Aspergillus species and the type and levels of aflatoxin contamination of various varieties of peanuts (Arachis hypogaea L.) in Busia and Kisii Central districts. It also determined the peanut producers' exposure to aflatoxins and the prevalence of aflatoxin induced HCC among patients from the study districts. Cross-sectional and retrospective study designs with systematic random sampling technique were adopted. One hundred and two (102) peanut and urine samples were collected from peanut growers in each district and transported to Cooppers Labs, Nairobi for analysis. Aspergillus species' were identified using plate technique of serially diluted samples on modified Rose Bengal agar. Types and levels of aflatoxins were analyzed using high performance liquid chromatography (HPLC) technique while aflatoxin B (AFB) gual in urine was determined using fluorescence Spectrophotometer. Analysis of records for patients from Busia and Kisii Central districts who attended Moi Teaching and Referral Hospital in January 2010 to December 2012 was done to determine the prevalence of HCC among the study population. The diagnosis of HCC was confirmed by the presence of AFB 1 guanine adducts in urine or AFB 1 albumin adduct in blood. The levels of total aflatoxin ranges were 0.1 to 2681lg/kg and 1.63 to 591.11lg/kg in peanuts from Busia and Kisii Central respectively. Majority of peanuts samples had levels within Kenya Bureau of Standards (KEBS) and European Union (EU) regulatory limits for total aflatoxins. Aflatoxin type Bl was the most dominant (t = 12.4, df= 3, P = 0.034). Overall, the occurrence of Aspergillus jlavus L strain and A. flavus S strain were significantly higher than other species identified (H = 15.55, df= 4, P = 0.004) in peanuts from the two districts. However, A. jlavus S-strain was the most dominant species (F=3.15, df=25, P=0.031) with an overall mean occurrence of 45.1%. Oil content in peanuts decreased with an increase in aflatoxin levels (r = -0.496, P = 0.031) except in peanuts of Uganda local red variety from Kisii Central. Overall, males in both districts had slightly higher incidences (9.8%) of exposure to urinary Aflatoxin B than females at 5.4%. The prevalence of aflatoxin induced HCC among the patients was 19.73%. There is need for urgent awareness through campaign among the peanuts producers on the aflatoxin levels and promote sound practices when handling peanuts. Continuous screening of patients with liver disorders should be done for early detection of HCC. The high levels of aflatoxins in peanuts suggest the necessity to screen other foods consumed in the study areas. The findings will form basis of policy development for aflatoxin contamination control and management of aflatoxin induced HCC in Kenya.