Assessment of dietary exposure to ochratoxin A in the UK using a duplicate diet approach and analysis of urine and plasma samples

Abstract

The approach to assess exposure to ochratoxin A from the diet by the analysis of human plasma and urine samples has been developed. Composite duplicate diet samples from 50 individuals and corresponding plasma and urine samples were obtained over 30 days. Samples were analysed using sensitive methods capable of measuring ochratoxin A at 0.001 ng g(-1) in food, 0.1 ng ml(-1) in plasma and 0.01 ng ml(-1) in urine. Analysis of the foods indicated ochratoxin A levels contributing to an average intake in the range 0.26-3.54 ng kg(-1) bw day(-1) over the 30 days. Ochratoxin A was found in all plasma samples and in 46 urine samples. The correlation between the plasma ochratoxin A levels and ochratoxin A consumption was not significant (95% confidence limit). However, a significant correlation was found between ochratoxin A consumption and the urine ochratoxin A concentration expressed as the total amount excreted. This new work offers the possibility of using ochratoxin A in urine as a simple and reliable biomarker to estimate exposure to this mycotoxin.

Biomarkers of human exposure to ochratoxin A

“…Several studies -in Canada (Frohlich et al 1991, Scott et al 1998, Lebanon (Assaf et al 2004), Japan (Ueno et al 1998), Norway (Skaug 2003), Germany (Gareis et al 2000), northern Spain (Jiménez et al 1998), Italy (Tuscany) (Palli et al 1999) and Tunisia ) -found no difference with age in positive levels of OTA in human blood (adults). However, in a UK dietary exposure study (Gilbert et al 2001), plasma concentrations of OTA did appear to depend on age, with higher levels in 30-44 year-olds compared to <30 year-olds and >45 year-olds and this was significant for a screening sample taken 30 days before the start of the study. However, the amount of OTA consumed in food had no significant relationship with age.…”

“…Mean coefficients of variation of 36 and 27% between weeks were noted in analyses of serum from two villages in Bulgaria (Petkova-Bocharova et al 2003). These studies indicate that single analyses are insufficient to determine individual plasma levels and composites should be used (Gilbert et al 2001). On the other hand, four analyses of serum of one person in Switzerland over one year gave the same result (Zimmerli & Dick 1995).…”

A direct assessment of mycotoxin biomarkers in human urine samples by liquid chromatography tandem mass spectrometry

“…Gilbert et al [12], found a positive correlation between the urinary concentration of OTA and the consumption of OTA, while Munoz et al [13] reported the presence of OTA and its major metabolite ochratoxin alpha (OTα) in 100% of the samples analyzed. OTα which is produced from the hydrolysis of OTA by the gut microflora in the intestine was the major metabolite detected in the urine of rats [14].…”

The role of biomarkers in evaluating human health concerns from fungal contaminants in food

“…Urinary fD þ DG has now been observed in studies from the UK, France, Sweden and China (100) , and independently in Spain and Italy (105,106) , whilst urinary DG was observed in Austrians (103) . All of the mycotoxin biomarker approaches discussed here are summarised in Table 1; ochratoxin A is additionally included for completeness, as the only other mycotoxin for which biomarker development has been reported (107) . Summaries of aflatoxin biomarker surveys are in numerous reviews; here only aflatoxin-albumin biomarkers are presented from studies of West African infants and children (Table 2), as these relate to latter sections of this review.…”