The determination of fumonisin B1 in human faeces: a short term marker for assessment of exposure

Fumonisin B1 (FB1) is a compound that occurs frequently in rural foods and feeds, creating health hazards. When ingested, FB1 does not appear to change in structure and is mostly excreted unchanged in faeces within 24 h. Twenty human stool samples obtained from rural school children of Vulamehlo, south of Durban (South Africa), were analysed for FB1, as well as 23 urban control samples obtained from various households within the Durban metropolitan area. The samples were freeze-dried and ground to a fine powder. A fraction of each sample was extracted three times with aqueous ethylenediaminetetraacetic acid at pH 5.2. The pooled extracts were purified using reversed phase C18 solid phase extraction cartridges. Analytical high performance liquid chromatography was used to quantitate the amount of FB1 as an o-phthaldialdehyde (OPA) derivative in the extracts. The rural (35%) and the urban samples (9%) showed the presence of FB ranging from 790 to 19 560 ng g-1 of freeze dried stool. It was concluded that this method could be used as a routine biomarker for short term human exposure to FB1 in contaminated food.