Fumonisin exposure and the sphinganine/sphingosine ratio in urine, serum and buccal cells in adults from Burkina Faso, West Africa

Abstract

Fumonisins are mycotoxins that frequently contaminate maize, a dietary staple in Burkina Faso. Fumonisins have been linked with both the incidence of oesophageal cancer, and to neural tube defects. However, epidemiological studies of these associations are hampered by lack of validated exposure biomarkers. One candidate biomarker is the sphinganine/sphingosine (Sa/So) ratio in biological samples. Twenty husband-wife pairs aged 20-40 were recruited from Dingasso-1, western Burkina Faso. Plate ready food was sampled over three consecutive days (day one to three) for fumonisin B1 and B2, to provide a measure of total fumonisin intake. The Sa/So ratio was determined in (1) first morning urines taken on days two to four, (2) buccal cells and (3) serum on days one and four only. Fumonisin intake was moderate (mean 0.81 µg/kg bw/day (range 0.01-2.40 µg/kg bw/day) compared to exposures reported in China and South Africa. For each person the mean fumonisin intake over three days was compared to the mean Sa, So and Sa/So ratio in urine, buccal cells and serum. A modest positive trend between mean fumonisin intake and mean serum Sa/So was observed (P=0.067). When individuals were dichotomised based on the median fumonisin intake (<0.75 µg/kg bw/day), the serum Sa/So ratio was moderately higher (P=0.044) in the high intake group (geometric mean 0.64; 95% CI: 0.54, 0.75) compared to the low intake group (0.49; 95% CI: 0.41, 0.59). Neither urinary nor buccal cell Sa/So ratio was associated with mean fumonisin intake. Neither mean individual Sa nor So level for urine, buccal cells or urine was associated with mean individual fumonisin intake. The study population was exposed to moderate levels of fumonisin with limited evidence of altered Sa/So ratio. Further work on serum Sa/So ratio is merited in comparison with other biomarker approaches such as urinary fumonisin B1 or sphingolipid 1-phosphate metabolites.

Mycotoxins and human disease: a largely ignored global health issue

“…Elevated ratios have been reported in tissues and body fluids from many species in a dose-and time-dependent manner (84,(88)(89)(90). This led to the ratio being examined in human populations in France (91), South Africa and Kenya (85,92), Italy, Argentina, Brazil (93), China (94) and Burkina Faso (95). For the majority of studies there was little evidence of altered ratio with FB exposure, although a slight increase was reported in urinary Sa:So ratio in male volunteers in China eating home-grown maize (94).…”

Biomonitoring of Fusarium spp. Mycotoxins: Perspectives for an Individual Exposure Assessment Tool

“…Moreover, the ratios have been assessed in simultaneous matrices as buccal cells, urine and serum in population from Burkina Faso, without showing any association between urinary Sa : So ratios and fumonisin intake, but suggesting a positive trend between fumonisin intake and Sa : So ratios in serum (Nikiema et al, 2008).…”

“…This biomarker was validated initially in Wistar rats by Solfrizzo et al (1997) and recently in F344 rats by Cai et al (2007), obtaining more sensitive results in urine than in serum for acute and sub-chronic exposure to FB 1 . Furthermore, several studies have been conducted to assess the effectiveness of this biomarker on human population without successful results to obtain an accurate validation due to the low sensitivity when applied to individuals (Van der Westhuizen et al, 1999Abnet et al, 2001;Qiu and Liu 2001;Solfrizzo et al, 2004;Missmer et al, 2006;Nikiema et al, 2008).…”

Development and Limitations of Exposure Biomarkers to Dietary Contaminants Mycotoxins

“…In one study, following the identification of a high-risk village in Burkina Faso, a survey of 20 husband–wife pairs aged 20–40 was conducted [ 42 , 43 ]. Plate-ready food was sampled over three consecutive days, and the Sa/So ratio was determined in urine and buccal cells on days two to four, and serum on days one and four.…”