Total Fumonisin Research Articles

HPLC determination of fumonisin mycotoxins in maize: A comparative study of naphthalene-2,3-dicarboxaldehyde and o-phthaldialdehyde derivatization reagents for fluorescence and diode array detection

Fumonisins are mycotoxins produced by various species of Fusarium and occur naturally in contaminated maize and maize-based foods. Ingestion of fumonisins has considerable health implications for humans and animals. Since fumonisins lack a useful chromophore or fluorophore, their determination in maize is routinely achieved via HPLC with fluorescence detection (FLD) after precolumn derivatization. This study optimized naphthalene-2,3-dicarboxaldehyde (NDA) derivatization of fumonisins in naturally contaminated maize following strong anion exchange (SAX) solid phase extraction (SPE) clean-up and utilizing diode array detection (DAD) as a practical alternative simultaneously to FLD. The limit of detection (LOD) for fumonisin B 1 (FB 1), fumonisin B 2 (FB 2) and fumonisin B 3 (FB 3) with FLD was 0.11 ng, 0.50 ng and 0.27 ng, respectively, and with DAD it was 13.8 ng, 12.5 ng and 6.6 ng, respectively injected on column. The coefficient of variation (CV, n = 6) for FB 1, FB 2 and FB 3 in a naturally contaminated samples obtained with FLD was 2.6%, 1.8% and 5.3%, respectively, compared to 6.0%, 3.4% and 9.5%, respectively, obtained with DAD. Subsequently the optimized NDA derivatization was compared to the widely used o-phthaldialdehyde (OPA) derivatization agent as well as alternative sample clean-up with immunoaffinity column (IAC) by analyzing naturally contaminated maize samples ( n = 15) ranging in total fumonisin (TFB = FB 1 + FB 2 + FB 3) levels from 106 to 6000 μg/kg. After immunoaffinity column clean-up of extracted samples, the recoveries of spiked maize samples for NDA-FLD of FB 1, FB 2 and FB 3 were 62%, 94% and 64%, respectively. NDA proved to be an effective derivatization reagent of fumonisin in naturally contaminated maize samples following IAC clean-up, except for DAD at TFB levels below 1000 μg/kg. In contrast NDA derivatization following SAX clean-up produced results comparable to OPA only for levels below 1000 μg/kg. Aside from the difference in detection limits, FLD and DAD produced comparable results irrespective of the clean-up method or the derivatization agent.

Effects of agrochemical treatments on the occurrence of Fusarium ear rot and fumonisin contamination of maize in Southern Italy

The efficacy of agrochemical treatments, based on three different fungicides combined with an insecticide, was tested in southern Italy for two years on three maize hybrids to control Fusarium ear rot of maize and the accumulation in the maize kernels of the carcinogenic mycotoxins fumonisins. Insect damage incidence and severity, disease incidence and severity, identification of Fusarium species and levels of fumonisin contamination in kernels were determined. Field trials showed in both years that natural colonization of maize kernels by the fumonisin producing species Fusarium proliferatum and F. verticillioides (up to 81.5 and 26.5%, respectively) and total fumonisin contamination (up to 68.2 μg g −1) were highly severe. For all hybrids and in both years, the treatment with the insecticide applied alone reduced the insect damage severity consistently and the content of fumonisins in the kernel only in half of the cases, whereas fungicide treatments applied in combination with the insecticide showed a further significant reduction of fumonisin contamination in the three hybrids and in both years.

Levels of total fumonisins in maize samples from Italy during 2006–2008

We analysed a total of 2258 grain samples over a 3-year period (2006–2008) from 93 storage centers in the principal maize cultivation area of Italy to establish the levels of fumonisin contamination. Fumonisin concentrations were measured using ELISA (RIDASCREEN) fumonisin test kits. Mean levels of contamination were remarkably high in each year, with the highest value in 2006 (10.9 mg/kg) and the lowest in 2008 (4.8 mg/kg). Similarly, for each year, variations were quite large: from <LOQ to 77.0 mg/kg, < LOQ to 26.3, and 0.1 to 19.0 mg/kg, respectively, in 2006, 2007 and 2008. The highest fumonisin concentration was found in samples harvested in Veneto (11.1 mg/kg) and Friuli Venezia Giulia (8.9 mg/kg), while the lowest were recorded in Emilia Romagna and Piemonte (4.6 mg/kg).

Mango Malformation: I. Toxin Production Associated with Fusarium Pathogens

Eight Fusarium species i.e. F. subglutinans, F. solani, F. oxyspoum, F. sterilihyphosum, F. proliferatum, F. monili-forme, F. avena and F. chlamydspore isolated from mango malformed disease were tested for their ability to cause mango malformation disease and their production of moniliformin and total fumonisins (FB1 + FB2) using HPLC. A evaluated for moniliformin production, seven isolates were toxin producers, the production levels ranging from 0.51 to 8.90 µg/ml. The higher levels were produced by Fusarium subglutinans (8.51 µg/ml). Moderate concentrations of moniliformin was produced by F.moniliforme (6.90 µg/ml), F. oxysporum (6.30 µg/ml), F. proliferatum (4.10 μg/ml) and F. sterilihyphosum (1.10 μg/ml). Separation and identification of Fumonisin that was isolated from the pathogen- causing disease are made by (HPLC). A evaluated for total fumonisin production (FB1 + FB2), seven isolates were toxin producers, the production levels ranging from 0.10 to 8.30 µg/ml. The higher levels were produced by F. monili-forme (8.30 µg/ml. Moderate concentrations of fumonisin was produced by F .proliferatum (0.64 µg/ml) and F. subglutinans (0.50 µg/ml). Strong positive correlations between moniliformin and total fumonisins (FB1 + FB2) activities and malformation disease incidence by F. subglutinans, F. solani, F. oxyspoum, F. sterilihyphosum, F. proliferatum was observed.

Quantization of total fumonisins produced by Fusarium verticillioides strains in some maize and sorghum genotypes by ELISA

Fusarium verticillioides is one of the most prevalent Fusarium species on maize and sorghum, causing Fusarium ear rot and sorghum grain mold in warm and humid regions of Iran. The pathogen produces potent mycotoxins known as fumonisins. In order to determine mycotoxin (fumonisins) production on different maize and sorghum genotypes, a field trial was carried out based on a randomized complete block design with 10 treatments and three replications for each crop at Gorgan station in 2010. The ears of corn plants were inoculated by spore suspension of the mixture of some virulent F. verticillioides isolates using an ear inoculation method (Nail Punch). The sorghum panicles were also inoculated by spraying of spore suspension isolates at f lowering stage. All infected kernels were evaluated by ELISA kits (AgraQuant Fumonisin Kit; Romer Labs, Austria) for their total fumonisins production at the physiological maturing stage. All genotypes showed statistically significant difference in their fumonisin production in Gorgan. The results of fumonisins analysis obtained from ELISA test showed that lines 1 (Resistant) and 3 (Susceptible) with 2.4 ppm and 13.7 ppm had the least and highest amount of total fumonisins respectively among all maize genotypes. Also among all sorghum genotypes, genotypes 10 and 6 with 0.2 ppm and 4.8 ppm had the least and the highest amount of total fumonisins respectively. The results of this experiment demonstrated that fumonisin production level in maize kernels (maybe as maize kernels are the main host of this fungus) was significantly higher than sorghum kernels in Gorgan region.

Fumonisin B1 and B2 in dry dog food: preliminary study on commercial samples

A reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the identification and quantification of fumonisin B1 (FB1) and fumonisin B2 (FB2) in complete and complementary formulations of dry dog foods has been optimised and validated. The sample preparation consists of an extraction step followed by immunoaffinity clean-up. Method performance characteristics were evaluated spiking blank samples on multiple levels in four replicates. The method showed appropriate performance characteristic: good values of recovery (&gt;95.9%) and precision (RSD &lt;6.8%), as well as satisfying linearity of calibration curves (r2≥0.99). The limit of quantification (LOQ) and detection (LOD) were 0.100 µg/g and 0.005 µg/g, respectively, both in complete and complementary dry dog foods and both for FB1 and FB2. This method was applied to 41 commercial samples in order to test its efficacy and gain some preliminary data about fumonisin contamination in dog food available in the Italian market. FB1 and FB2 were detected in all samples analysed and, in particular, 63.41% and 56.10% of the samples showed concentrations above the LOQ of FB1 and FB2, respectively. The levels of contamination quantified ranged between LOQ and 5.87 µg/g and 2.93 µg/g for FB1 and FB2, respectively. Among the complete dry dog foods, standard formulations generally showed an average fumonisins contamination higher than premium formulations. The guidance value of 5 µg/g set by Commission Recommendation 2006/576/EC for the sum of FB1 and FB2 was exceeded in two samples: one standard complete dry dog food showed a total fumonisin contamination of 5.19 µg/g and one complementary food a contamination of 8.80 µg/g.

A reversed phase high performance liquid chromatography method for the determination of fumonisins B 1 and B 2 in food and feed using monolithic column and positive confirmation by liquid chromatography/tandem mass spectrometry

The development of a reversed phase high performance liquid chromatography fluorescence method for the determination of the mycotoxins fumonisin B 1 and fumonisin B 2 by using silica-based monolithic column is described. The samples were first extracted using acetonitrile:water (50:50, v/v) and purified by using a C 18 solid phase extraction-based clean-up column. Then, pre-column derivatization for the analyte using ortho-phthaldialdehyde in the presence of 2-mercaptoethanol was carried out. The developed method involved optimization of mobile phase composition using methanol and phosphate buffer, injection volume, temperature and flow rate. The liquid chromatographic separation was performed using a reversed phase Chromolith ® RP-18e column (100 mm × 4.6 mm) at 30 °C and eluted with a mobile phase of a mixture of methanol and phosphate buffer pH 3.35 (78:22, v/v) at a flow rate of 1.0 mL min −1. The fumonisins separation was achieved in about 4 min, compared to approximately 20 min by using a C 18 particle-packed column. The fluorescence excitation and emission were at 335 nm and 440 nm, respectively. The limits of detections were 0.01–0.04 μg g −1 fumonisin B 1 and fumonisin B 2, respectively. Good recoveries were found for spiked samples (0.1, 0.5, 1.5 μg g −1 fumonisins B 1 and B 2), ranging from 84.0 to 106.0% for fumonisin B 1 and from 81.0 to 103.0% for fumonisin B 2. Fifty-three samples were analyzed including 39 food and feeds and 14 inoculated corn and rice. Results show that 12.8% of the food and feed samples were contaminated with fumonisin B 1 (range, 0.01–0.51 μg g −1) and fumonisin B 2 (0.05 μg g −1). The total fumonisins in these samples however, do not exceed the legal limits established by the European Union of 0.8 μg g −1. Of the 14 inoculated samples, 57.1% contained fumonisin B 1 (0.16–41.0 μg g −1) and fumonisin B 2 (range, 0.22–50.0 μg g −1). Positive confirmation of selected samples was carried out using liquid chromatography–tandem mass spectrometry, using triple quadrupole analyzer and operated in the multiple reaction monitoring mode.

Natural occurrence of fumonisins in corn puff in Argentina

Maize presents a substantial contamination by fumonisins (FB) throughout the world. In particular, Argentina presents a high frequency of positive samples and levels of up to 10,000μg/kg of total FB, depending on the harvest campaign studied. Corn puff, an extruded product of high consumption among children and adolescent populations, was analyzed with the aim of determining the presence and levels of fumonisins B1, B2 and B3. In the present study, 20 samples of different brands were collected from commercial stores. Two solvent systems, two types of agitation, and the number of extractions were tested in order to find the most suitable method to establish the level of fumonisins in corn puff. Extracts were analyzed by high performance liquid chromatography (HPLC) with fluorescence detection. A C18 column and precolumn derivatization with orthophtalaldialdehyde were utilized. The average of fumonisins found in 20 samples was 257.5μg/kg (n = 19), 70.4μg/kg (n = 14) and 73.3μg/kg (n = 6) for FB1, FB2 and FB3, on positive samples, respectively. These are the first analyses in Argentina of this type of product, highlighting the need to continue the studies in the processing industries because, despite the extrusion process that the raw material suffers, a sample was found with a contamination of 1,649μg/kg total fumonisins.

Differential gene expression in kernels and silks of maize lines with contrasting levels of ear rot resistance after Fusarium verticillioides infection

Fusarium verticillioides is the causal agent of ear rot in most maize-growing areas of southern Europe. F. verticillioides produces fumonisins commonly found at biologically significant concentrations in maize grain; the molecular interaction between the fungus and the plant is not well known, and little information is currently available about the defense response of maize against F. verticillioides infection. We attempted to identify genes that may be involved in Fusarium ear rot resistance using resistant and susceptible maize genotypes. Kernels of the resistant inbred showed significantly reduced incidence of infection by F. verticillioides, limited amounts of total fumonisin content and reduced fungal growth, as indicated by a lower copy number of β- tubulin 2 and FUM 21 genes of F. verticillioides. Gene expression data were obtained from microarray hybridizations using maize seeds infected with F. verticillioides, by comparing seeds at 0 and 48 h after infection. Differentially expressed sequences were identified and classified into 11 functional categories. Most of the differentially expressed genes were assigned to the category “cell rescue, defense and virulence” in both resistant and susceptible maize lines. These genes encode for PR proteins, detoxification enzymes and β-glucosidases. Most of the pathogenesis-related genes were differentially activated after F. veticillioides infection, depending on the resistance level of the maize genotypes. In kernels of the resistant line, the defense-related genes assayed were transcribed at high levels before infection and provided basic defense against the fungus. In the susceptible kernels, the defense-related genes were induced from a basal level, responding specifically to pathogen infection. The qRT-PCR in infected silks showed that PR1, PR5, PRm6 and thaumatin genes had lower expression ratios in the resistant line compared to the susceptible one.

Dietary fumonisin exposure in a rural population of South Africa

A validated culturally specific dietary assessment method was used to determine the habitual maize intakes of black Xhosa-speaking Africans living in the Centane region of the Eastern Cape Province to assess their exposure to the carcinogenic fumonisin mycotoxins. The mean total dry weight maize intakes of home-grown, commercial or combined (both maize sources) were 474, 344, 462 g day −1, respectively. When considering the total mean levels of fumonisin in home-grown maize (1142 μg kg −1) and commercial maize (222 μg kg −1), the probable daily intakes (PDI’s), expressed as μg kg −1 body weight day −1 were 12.1 (95%CI: 0.3–4926.5) and 1.3 (95%CI: 1.0–1.8) for men and 6.7 (95%CI: 1.0–457.8) and 1.1 (95%CI: 0.9–1.3) for women, consuming home-grown and commercial maize, respectively. Based on the different maize-based beer drinking frequencies the PDI’s varied between 6.9 and 12.0 μg kg −1/drinking event. Depending on the maize intake patterns an exposure “window” exists where fumonisin exposure is below the recommended group provisional maximum tolerable daily intake (PMTDI) for fumonisins of 2 μg kg −1 bw day −1. The assessment of fumonisin exposure and development of preventative strategies depend, not only the accurate determination of total fumonisin levels in maize, but also on the distinct dietary patterns of a specific population.

A rapid lateral flow test for the determination of total type B fumonisins in maize

A one-step lateral flow test was developed for the quantitative determination of total type B fumonisins in maize with a test range up to 4,000 microg/kg and a limit of detection of 199 microg/kg. The test presented gives a result within 4 min, including 1 min strip drying, and does not require any sample cleanup steps after a previous 3-min sample extraction. Quantitative readout with a compact photometric strip reader will also indicate the best suited measurement range when needed. The test is based on a competitive immunoassay format where a ready-to-use antibody-colloidal gold particle complex is mixed with 50 microL sample extract in a microwell and used as a signal reagent. The test strip is inserted into the well and the mixed content migrates onto the strip, which contains a test zone and a control zone. Mycotoxin-protein conjugate coated on the test zone captures free signal reagent, and colored particles concentrate, forming a visible line. The intensity of the test line is dependent on the total fumonisin concentration in the sample. Naturally contaminated quality-control maize material was used for matrix-matched calibration of photometric readout. The test presented is both quantitative and rapid, with no cross-reactivity to other mycotoxins. The applicability of the lateral flow test was shown by the screening of 23 naturally contaminated maize samples. Relative standard deviations ranged from 1.7 to 32.9%.

Factors associated with fumonisin contamination of maize in Uganda

AbstractBACKGROUND: During production and handling, maize is attacked by many Fusarium species, some of which are prolific producers of fumonisins. Contamination of maize with fumonisins is influenced by climate, agronomic and postharvest practices. This study investigated the factors associated with the occurrence of fumonisins in maize produced in three agroecological zones of Uganda.RESULTS: All the maize samples were positive for fumonisins with levels ranging from 0.27 to 10 mg kg−1. A positive and significant correlation (P &lt; 0.01) was observed between fumonisin levels and agroecological zone. Maize from high altitude zone had significantly higher (P &lt; 0.05) mean total fumonisin content (4.93 mg kg−1) than maize from the mid altitude‐moist (4.53 mg kg−1) and mid altitude‐dry (4.50 mg kg−1) zones. Five farmer practices, namely intercropping, crop rotation, delayed harvesting, drying maize on bare ground and planting treated seeds were significantly associated with fumonisin production in maize. Intercropping, delayed harvesting and drying maize on bare ground increased fumonisin contamination whereas crop rotation and planting treated seeds reduced the contamination.CONCLUSION: All maize samples obtained from the three agroecological zones were contaminated with fumonisins. The study showed that some of the farmers' practices predispose maize to fumonisin contamination. The findings are important for future studies aimed at designing strategies to control and prevent contamination of maize with fumonisins. Copyright © 2009 Society of Chemical Industry

Difficulties in fumonisin determination: the issue of hidden fumonisins

In this paper, the results obtained by five independent methods for the quantification of fumonisins B(1), B(2), and B(3) in raw maize are reported. Five naturally contaminated maize samples and a reference material were analyzed in three different laboratories. Although each method was validated and common calibrants were used, a poor agreement about fumonisin contamination levels was obtained. In order to investigate the interactions among analyte and matrix leading to this lack of consistency, the occurrence of fumonisin derivatives was checked. Significant amounts of hidden fumonisins were detected for all the considered samples. Furthermore, the application of an in vitro digestion protocol to raw maize allowed for a higher recovery of native fumonisins, suggesting that the interaction occurring among analytes and matrix macromolecules is associative rather than covalent. Depending on the analytical method as well as the maize sample, only 37-68% of the total fumonisin concentrations were found to be extractable from the samples. These results are particularly impressive and significant in the case of the certified reference material, underlying the actual difficulties in ascertaining the trueness of a method for fumonisin determination, opening thus an important issue for risk assessment.

Free and bound fumonisins in gluten‐free food products

In this work a multiresidual LC-ESI-MS/MS method for the simultaneous detection of free and bound fumonisins is described, which allowed for a very low LOD and a very good recovery for all the analytes. The method was applied to the determination of free and bound fumonisins in several gluten-free products from the Italian market. Free fumonisins were found to occur in 90% of the samples: the overall median value was below the EU legal limit for foods for human consumption (800 microg/kg). Nonetheless, fumonisins occurred in several samples at concentrations above the legal limit, reaching also very strong contamination levels (maximum concentration level: 3310 microg/kg). Anyway, considering the limited diet of people suffering of the celiac disease or allergic to other wheat proteins, the incidence of fumonisin contamination may be envisaged as problematic. Furthermore, bound fumonisins were found to be present in all the analysed samples at similar or even higher amounts than the free forms. In many cases the sum of free and bound fumonisins exceeded the EU legal limit for total fumonisins also for those samples characterized by a low contamination of free fumonisins, thus opening a new important task to be addressed for the risk assessment in this field.

Incomplete Recoveries of Fumonisins Present in Naturally Contaminated Corn Foods from an Immunoaffinity Column

Following previous observations of apparent instability of fumonisin B1 in corn starch and corn meal, immunoaffinity column (IAC) cleanup, of the type used in the analysis of commercial starch-containing corn foods for fumonisins, was investigated. Foods analyzed for naturally occurring fumonisins B1, B2, and B3 included corn flour (3 different products), corn meal, and corn flakes. In 2 series of experiments, fractions were eluted by gravity or vacuum from narrow- or wide-bore Fumonitest IACs either with 2 x 2 mL methanol, followed by 2 mL methanol-water (8 + 2, v/v), or with 2 mL methanol, then 2 mL methanol-water (8 + 2, v/v). The ratio (%) of fumonisin B1 concentration in the first methanol eluate to the total concentration measured from all eluates in most cases varied from 25-70%. Incomplete recoveries were also observed for fumonisins B2 and B3. It is concluded that there can be a major underestimation of naturally occurring fumonisins in methods using only methanol elution for IAC cleanup, as in AOAC INTERNATIONAL Official Method 2001.04 (accuracy of these methods had been determined only by spiking the food with fumonisins). Elution with 2 x 2 mL methanol-water (8 + 2, v/v) was chosen as a practical procedure; means of 81-98% of the total fumonisin B1 concentration were found in the first eluate, except for corn flakes and 2 experiments with corn meal.

Fungal and mycotoxin contamination in Bt maize and non-Bt maize grown in Argentina

A Bt maize hybrid and its non-transgenic counterpart harvested during 2002/2003 and 2003/2004 harvest seasons from different locations within the maize-growing area in Argentina were compared for fungal and mycotoxin contamination.Fusariumspecies were the most prevalent on both genotypes with an isolation frequency &gt;60% across all locations. The percentage of infection was lower in Bt maize than in non-Bt maize (P&lt;0.05). There were no statistical differences in infection percentage due to genotype, fungicide treatment and their interactions. Fumonisins were detected in all of the samples from all locations and genotypes. Total fumonisin levels (fumonisins B1, B2and B3) in the Bt and the non-Bt hybrid were significantly different (P&lt;0.001), with lower toxin levels in the Bt maize in all locations but one evaluated during the two harvest season. There was no significant difference in deoxynivalenol levels between Bt and non-Bt maize. Application of the fungicide tebuconazole did not alter either the infection or the toxin levels in the Bt and non-Bt maize hybrid.

Comparison of enzyme linked immunoassay and high performance liquid chromatography for determination of fumonisin in dried figs

The occurrence of fumonisin in dried figs was investigated by Enzyme Linked Immunoassay (ELISA) and High Performance Liquid Chromatography (HPLC). Total fumonisins (FB1, FB2, FB3) in dried figs were determined using ELISA, whereas only fumonisin B1 (FB1) was determined by HPLC. In the period 2003-2004, one hundred and fifty five dried fig samples were taken during their drying in 7 different districts in the Aegean Region. Among a total of 115 samples, the incidence of total fumonisin in the dried figs was 82% within the range of 0.16 - 108.34 mg/g when determined by ELISA. In comparison, FB1 was detected in 86 samples (74.8%) within the range between 0.046 and 3.649 mg/g by HPLC. Correlation between ELISA and HPLC methods was observed for all samples. However, no correlation between methods was recorded for the samples with less than 1 mg/g Fumonisin B1 level (obtained by HPLC). Although there was a correlation between methods for all the samples, fumonisin levels obtained by ELISA were much higher than those obtained by HPLC. False positive results were obtained by ELISA in 11 out of 115 dried fig samples. The results indicated that ELISA can be used as a screening method for determining the occurence of fumonisin in dried figs.

Sphingoid base levels in humans consuming fumonisin-contaminated maize in rural areas of the former Transkei, South Africa: a cross-sectional study

High incidences of oesophageal cancer are associated with the consumption of subsistence-grown maize by rural populations in the former Transkei region of Eastern Cape Province, South Africa. This cross-sectional study was conducted in the north-eastern magisterial area of Bizana (a previously low oesophageal cancer incidence area) and the south-eastern area of Centane (a previously high incidence area). Plasma and urine samples of male and female participants were analysed for the sphingoid bases, sphinganine and sphingosine. Good home-grown and visibly mouldy maize samples, collected from the households of the participants, were analysed for fumonisin B1, B2 and B3. Plasma sphinganine/sphingosine ratios in males and females were significantly lower (p < 0.05) due to lower sphinganine levels in Bizana compared to Centane. In contrast, the urinary female and combined (males + females) sphinganine/sphingosine ratios were significantly higher (p < 0.05) in Bizana due to the significantly lower (p < 0.05) urinary sphingosine levels. Interestingly, urinary sphingoid base levels were significantly lower (p < 0.05) in males than females within each area. Based on the mean total fumonisin levels in good maize, the estimated mean probable daily intake (PDI) was 5.8 µg kg−1 body weight day−1 in Bizana during 2000 and 4.4 and 6.7 5.8 µg kg−1 body weight day−1 in Centane during 1997 and 2000, respectively, exceeding the maximum tolerable daily intake proposed by JECFA. However, there was no significant difference in the mean total fumonisin levels in the maize between the magisterial areas. The observed differences in plasma and urinary sphingoid base levels could not be ascribed as a biomarker of fumonisin exposure and further studies at an individual level are required.

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

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 (&lt;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.

Human exposure to fumonisins from home grown maize in Tanzania

Fumonisins contaminate maize worldwide resulting in unacceptable fumonisin exposures in people relying on maize as staple food. This study determined fumonisins B1 (FB1) and B2 (FB2) in maize from 120 rural households: 30 from each of four main maize producing regions of Tabora, Ruvuma, Iringa and Kilimanjaro in Tanzania in order to estimate total fumonisin (FB1 + FB2) exposures to adult individuals in the households. The average daily per capita maize consumption of 771 g, recommended by the Tanzania Food and Nutrition Centre (TFNC) for an adult relying on it as a main meal, and also average daily per capita maize consumptions of 129, 308 and 356 g documented for Tanzania, were used in the exposure estimation. The fumonisins were determined by HPLC using fluorescence detection. Total fumonisins exposure (µg/kg body weight (bw)/day) was determined by multiplying average daily per capita maize consumption (kg) by fumonisin level in maize (µg/kg) from a given household and then dividing by an average bw of an adult of 60 kg. Of the 120 samples, 52% were contaminated with fumonisins at levels of up to 11,048 µg/kg (median; 363 µg/kg). Based on the recommended maize consumption of 771 g/person/day, fumonisin exposures to adult individuals in 38% of the households would exceed the provisional maximum tolerable daily intake (PMTDI) of 2 µg/kg bw, recommended by the Joint FAO/WHO Expert Committee on Food Additives. At the least documented maize consumption of 129 g/person/day, fumonisin exposures in 16% of the households were still above the PMTDI. Reduction of the maize consumption level to 40 g/person/day is an impractical, and reduction of the maximum contamination level to 155 µg/kg is a possibly practical, option for effective minimisation of fumonisin exposures in these communities. A relatively larger study is needed in order to generate comprehensive data for the formulation of appropriate strategies to minimise fumonisin exposures in Tanzania.