Sources and levels of human exposure to aflatoxins in Makueni county, Kenya

Abstract

Afllatoxicosis is a disease of great socioeconomic and public health importance. Several studies have been conducted in Kenya to establish the aflatoxin levels in food commodities especially during outbreaks where lives have been lost. Makueni County has had several of these outbreaks; however, no study has been done to establish the level of aflatoxin exposure in humans in this County. Most of the focus has been on the outbreaks ignoring the danger posed by chronic exposure. A cross sectional study was carried out in Makueni County to: 1) establish the level of human exposure to aflatoxins in Makueni County. 2) to assess the associated pre- and post- harvest practices that pre-dispose cereals to aflatoxin contamination in the County. This study was stratified into three locations of Nguumo, Ukia and Wote in, Makindu, Kaiti and Wote divisions, respectively. These study sites were selected on the basis of dairy cattle population, maize growing and presence of children less than five years. Three- hundred- and-ten households (310) were proportionately selected in the three locations. A questionnaire was administered to the household head in the sampled households to establish household knowledge, attitudes and practices about aflatoxins. Samples consisting of maize, sorghum and millets, cow milk, goat milk and breast milk were collected for total aflatoxin analysis using an ELISA test. Urine from each index child under the age of 5 years in each household was collected twice six months apart and tested for aflatoxin using the ELISA test; anthropometric measurements (weight, and height) of the children were taken during these two visits. The mean household size was six persons (5.9) across the three divisions. The main source of earnings was from sale of maize and fruits. The level of education was averagely primary. xv Anthropometric measures showed overall stunting at 28%. Overall underweight children were 20.2% of the sampled 258 children. However as there were no controls, the stunting and the underweight seen could not totally be attributed to aflatoxins. Ninety- two- point- eight percent (92.8%) of the households knew how to identify spoilt maize. Of the 278 households, 61.1% identified spoilt maize by change in colour of the grains, 14.3% by insect damage, and 5.7% by seeing rotten grains, 5% by mouldy grains, and 2.5% by smell. Concerning risks posed by spoilt maize, 78.6% were aware of some danger with 38.9% quoting stomach problems, 16.8% aflatoxins, 10% disease, 9.6% death and others cancer and liver problems. On whether mouldy feeds fed to dairy cows was safe, 53.6% knew it was not safe, 19.6% thought it was safe and 26.8% did not know. Of the 597 cereal samples collected, 83.4% had aflatoxins, 55.1% had levels up to 10ppb and 28.3% had levels above 10ppb. A high proportion (81.7%) of the maize samples were contaminated with aflatoxin with 27% of the samples having values ranging from 10ppb to 288.7ppb.The sorghum and millet samples had similar levels (86.5%) of aflatoxin contamination with 29.8% having values above 10ppb. The per capita consumption of maize in the study area was 0.30Kg/person/day, while the average aflatoxin exposure evel from maize was 6.94μg/person/day. The aflatoxin exposure level in Makindu was significantly (p<0.05) higher than in the other two divisions. From the 98 human breast milk samples collected, 86.9% were positive for aflatoxin M1 with levels ranging from 0.215ppt to 47.5ppt. Of the 209 cow milk samples collected 88% were positive for aflatoxin (range 0.002ppt to 273.8ppt) and 93% of the 54 goat milk samples were positive for aflatoxin (range 0.84ppt to35.8ppt). Per capita consumption for milk was 329.2ml/person/day while the exposure level through milk was 0.006ppt/person/day; exposure to children through breast milk was 5.5μg/child/day. A high proportion (79.2%) of the 250 urine samples collected on the first visit, were positive xvi for Aflatoxin M1 (range 0.302ppt to 10415.1ppt). On the second visit, 126 samples were collected and 63.2% were positive (range 79.2ppt to2193ppt). None of the potential risk factors for aflatoxin contamination considered were significant at 5% level of significance. However division appeared to be associated with aflatoxin contamination; Makindu Division had a significantly (p<0.05) higher exposure levels of aflatoxin (OR=1.4) relative to Kaiti and Wote Divisions. It is recommended that extension messages targeting harvesting, drying, disposal of spoilt grains and shelling methods be availed to Makueni County and disseminated through women groups, churches and school farmers’ clubs in order to address chronic exposure occasioned by consumption of aflatoxin contaminated foods in the daily diets.