Extraction of ochratoxin A in bread samples by the QuEChERS methodology.

A QuEChERS method for the extraction of ochratoxin A (OTA) from bread samples was evaluated. A factorial design (2(3)) was used to find the optimal QuEChERS parameters (extraction time, extraction solvent volume and sample mass). Extracts were analysed by LC with fluorescence detection. The optimal extraction conditions were: 5 g of sample, 15 mL of acetonitrile and 3 min of agitation. The extraction procedure was validated by systematic recovery experiments at three levels. The recoveries obtained ranged from 94.8% (at 1.0 µg kg(-1)) to 96.6% (at 3.0 µg kg(-1)). The limit of quantification of the method was 0.05 µg kg(-1). The optimised procedure was applied to 20 samples of different bread types ("Carcaça", "Broa de Milho", and "Broa de Avintes") highly consumed in Portugal. None of the samples exceeded the established European legal limit of 3 µg kg(-1).

Human ochratoxin a biomarkers--from exposure to effect.

Ochratoxin A (OTA) is a nephrotoxic mycotoxin that has received particular attention because of the toxic effects, widespread occurrence in contaminated food and feed chain, suspected causal effect on nephropathies, and, more recently, possibility of exposure by inhalation in domicile and occupational settings. Biomarkers have been used not only to ascertain the role of OTA in inducing chronic renal failure diseases, but also as a means to portray general populations' risk to the mycotoxin. Biomonitoring can thus be used to assess internal OTA exposure, with no need to recognize the main source of exposure. And so it presents undeniable advantages over the monitoring of external dose. With a just right understanding of biomarkers, it is possible to follow the trail from exposure right to effect, and so contribute both to surveillance plans and etiological studies. In recognition of the long serum half-life and the renal elimination of OTA, most of the studies present serum/plasma and/or urine analyses as markers of exposure. In this review and for each of these main matrices, a comparison over the advantages and disadvantages is offered. Although currently limited, an overview of the current knowledge on OTA biomarkers and the influential role of the individual characteristics, namely gender and age, along with season and geographical location is given. Attention is also given to the ongoing debate over the existence of OTA-DNA adducts, a biomarker of effective dose regarded as an alternative to biomarkers of internal dose. Although unspecific, OTA effect biomarkers are also reviewed.

Evaluation of organochlorine pesticides in serum from students in Coimbra, Portugal: 1997-2001.

In 1997, 1999, 2000, and 2001, in an attempt to evaluate the contamination level of a Portuguese population, organochlorine pesticide residues were evaluated in human serum from students of the University of Coimbra. Concentrations of selected organochlorine pollutants (alpha-, beta-, and gamma-HCH, aldrin, dieldrin, HE, HCB, p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD) and endosulfan sulfate was measured with gas chromatography-electron capture detector. Our objective is to point out the general levels of pesticide contamination and the differences between the four populations; and together with this, if a connection could be established with gender or the residence area of the subjects. Endosulfan sulfate, p,p'-DDE, o,p'-DDT, and p,p'-DDD were the most frequently identified residues. Endosulfan sulfate present the highest concentrations for all subjects, 42.6 microg/l, with concentrations ranging from undetected to 1295.5 microg/l. Between DDT, isomers, and analogues, o,p'-DDT, and p,p'-DDT presented the highest levels, 24.8 and 21.9 microg/l, respectively. Mean total DDT levels were higher than mean total HCH levels. For summation operator-DDT, the highest levels were found among female gender and urban samples. An opposite situation was found in summation operator-HCH: males presented higher levels than females. The mean concentration of organochlorine pesticide residues, present in the student populations, showed that it is among the highest levels of contamination, when compared with others from Europe, Asia, and America.