A review of modeling pesticides in freshwaters: Current status, progress achieved and desirable improvements.

This study comprises a critical review of modeling of pesticides in surface waters. The aim was to update the status of the use of models to simulate the fate of pesticides from diffuse sources. ISI papers were selected on Scopus and the information concerning the study areas, type of pesticides (herbicides, fungicides and insecticides), the model, and the methodology adopted (i.e., calibration and/or validation, spatial and temporal scales) were analyzed. The studies were carried out in Europe (55.5%), North America (22.3%), Asia (13.9%) and South America (8.3%). The Soil and Water Assessment Tool proved to be the most used model (45.95%). Herbicides were the most modeled pesticides (71.4%), followed by insecticides (18.2%) and fungicides (10.4%). The main herbicides modeled were atrazine, metolachlor, isoproturon, glyphosate, and acetochlor. Insecticides such as chlorpyrifos and metaldehyde. Chlorothalonil, and fungicides (i.e., tebuconazole) were the most widely investigated. Based on published studies, it was found that modeling approaches for assessing the fate of pesticides are constantly evolving and the model algorithms work well with diverse watershed conditions, management strategies, and pesticide properties. Several papers reported concentrations of pesticides exceeding ecotoxicological thresholds revealing that water contamination with pesticides used in agriculture and urban areas is a priority issue of current global concern.

Modelling soil erosion in a Mediterranean watershed: Comparison between SWAT and AnnAGNPS models.

In this study, the simulations generated by two of the most widely used hydrological basin-scale models, the Annualized Agricultural Non-Point Source (AnnAGNPS) and the Soil and Water Assessment Tool (SWAT), were compared in a Mediterranean watershed, the Carapelle (Apulia, Southern Italy). Input data requirements, time and efforts needed for input preparation, strength and weakness points of each model, ease of use and limitations were evaluated in order to give information to users. Models were calibrated and validated at monthly time scale for hydrology and sediment load using a four year period of observations (streamflow and suspended sediment concentrations). In the driest year, the specific sediment load measured at the outlet was 0.89 t ha-1 yr-1, while the simulated values were 0.83 t ha-1 yr-1 and 1.99 t ha-1 yr-1 for SWAT and AnnAGNPS, respectively. In the wettest year, the specific measured sediment load was 7.45 t ha-1 yr-1, and the simulated values were 8.27 t ha-1 yr-1 and 6.23 t ha-1 yr-1 for SWAT and AnnAGNPS, respectively. Both models showed from fair to a very good correlation between observed and simulated streamflow and satisfactory for sediment load. Results showed that most of the basin is under moderate (1.4-10 t ha-1 yr-1) and high-risk erosion (> 10 t ha-1 yr-1). The sediment yield predicted by the SWAT and AnnAGNPS models were compared with estimates of soil erosion simulated by models for Europe (PESERA and RUSLE2015). The average gross erosion estimated by the RUSLE2015 model (12.5 t ha-1 yr-1) resulted comparable with the average specific sediment yield estimated by SWAT (8.8 t ha-1 yr-1) and AnnAGNPS (5.6 t ha-1 yr-1), while it was found that the average soil erosion estimated by PESERA is lower than the other estimates (1.2 t ha-1 yr-1).

Effect of alkaline cooking of maize on the content of fumonisins B1 and B2 and their hydrolysed forms.

The effect of nixtamalization on the content of fumonisins (FBs), hydrolysed (HFBs) and partially hydrolysed (PHFBs) fumonisins in maize was investigated at laboratory-scale. Maize naturally contaminated with FBs and PHFBs was cooked with lime. Starting raw maize, steeping and washing waters and final masa fractions were analysed for toxin content. Control-cooking experiments without lime were also carried out. The nixtamalization reduced the amount of FBs and PHFBs in masa and converted them to HFBs. However, the three forms of fumonisins collected in all fractions amounted to 183%, indicating that nixtamalization made available forms of matrix-associated fumonisins that were then converted to their hydrolysed forms. Control-cooking enhanced FBs and PHFBs reduction, due to the solubility of fumonisins in water during the steeping process, but did not form HFBs. These findings indicate that benefits associated with enhancing the nutritional value of nixtamalized maize are also associated with a safer product in terms of fumonisin contamination.

Dose-dependent lipid peroxidation induction on ex vivo intestine tracts exposed to chyme samples from fumonisins contaminated corn samples.

Fumonisins (FBs), Fusarium mycotoxins common food contaminant, are a potent inducer of oxidative stress and lipid peroxidation in intestinal cells. In order to verify this toxic effect in intestine tract, the aim was to assess lipid peroxidation (as malondialdehyde MDA increased levels) on intestine rat samples exposed to chyme samples from in vitro digestion of FBs contaminated corn samples. Naturally (9.61±3.2 µg/gr), artificially (726±94 µg/gr) and spiked corn samples at EU permitted FBs levels were digested and added to luminal side of Ussing chamber for 120 min. Fumonisins-free corn sample was used as control. The MDA increase was observed just in 83% of intestine samples exposed at EU FBs levels and the digestion process seems to reduce this incidence (50% of samples). Malondialdehyde levels were FBs dose- and subject-related and ranged from 0.07±0.01 to 3.59±0.6 nmol/mg. Highest incidence and MDA % increment (I) were found when intestine tracts were exposed to chymes from artificially corn sample. The induction of lipid peroxidation induced by FBs could be due to interactions between FBs and intestinal membranes, with consequent modifications in membrane permeability and oxygen diffusion-concentration, as suggested by other authors.

Influence on functional parameters of intestinal tract induced by short-term exposure to fumonisins contaminated corn chyme samples.

The gut is a possible target toward mycotoxin fumonisins (FBs) exposure. The study aims to investigate the effects induced by FBs contaminated-corn chyme samples on functional parameters of human and rat intestine by using Ussing chamber. Fumonisins-contaminated corn and processed corn samples were undergone to in vitro digestion process and then added to luminal side. A reduction (about 90%) of short circuit current (Isc µA/cm(2)) during exposure of human colon tissues to fumonisins-free corn chyme samples was observed, probably related to increased chyme osmolality. This hyperosmotic stress could drain water towards the luminal compartment, modifying Na(+) and Cl(-) transports. The presence of FBs in corn chyme samples, independently to their concentration, did not affect significantly the Isc, probably related to their interference towards epithelial Na(+) transport, as assessed by using a specific inhibitor (Amiloride). The rat colon tract represents a more accessible model to study FBs toxicity showing a similar functional response to human. In the rat small intestine a significant reduction (about 15%) of Isc parameter during exposure to uncontaminated or FBs contaminated corn chyme samples was observed; therefore such model was not suitable to assess the FBs toxicity, probably because the prevalent glucose and amino acids electrogenic absorption overwhelmed the FBs influence on ionic transport.

Comparison of methods and optimisation of the analysis of fumonisins B1 and B2 in masa flour, an alkaline cooked corn product.

A comparison study of different extraction and clean-up procedures for the liquid chromatographic analysis of fumonisins B(1) (FB(1)) and B(2) (FB(2)) in corn masa flour was performed. The procedures included extraction (heat or room temperature) with acidic conditions or EDTA-containing solvents, and clean-up by immunoaffinity or C18 solid-phase extraction columns. Thereafter an analytical method was optimised using extraction with an acidic mixture of methanol-acetonitrile-citrate/phosphate buffer, clean-up through the immunoaffinity column and determination of fumonisins by liquid chromatography with automated pre-column derivatisation with o-phthaldialdehyde reagent. Recovery experiments performed on yellow, white and blue masa flours at spiking levels of 400, 800 and 1200 µg kg(-1) FB(1) and of 100, 200 and 300 µg kg(-1) FB(2) gave overall mean recoveries of 99% (±6%) for FB(1) and 88% (±6%) for FB(2). Good recoveries (higher than 90% for both FB(1) and FB(2)) were also obtained with corn tortilla chips. The limits of quantification of the method (signal-to-noise ratio of 10) were 25 µg kg(-1) for FB(1) and 17 µg kg(-1) for FB(2). The method was tested on different commercial corn masa flours as well as on white and yellow corn tortilla chips, showing fumonisin contamination levels (FB(1) + FB(2)) up to 1800 µg kg(-1) (FB(1) + FB(2)) in masa flour and 960 µg kg(-1) in tortilla chips. Over 30% of masa flours originating from Mexico exceeded the European Union maximum permitted level.

Determination of fumonisins B1 and B2 in corn by LC/MS with immunoaffinity column cleanup: interlaboratory study.

An interlaboratory validation study was conducted to establish the method performance characteristics of an immunoaffinity column (IAC) cleanup procedure followed by LC/MS for the determination of fumonisins B1 (FB1) and B2 (FB2) and combined FB1 + FB2 in corn. The test portion is extracted with acetonitrile-methanol-water (25 + 25 + 50). The extract is filtered, diluted with phosphate-buffered saline solution, and applied to an IAC. FB1 and FB2 are removed with methanol, followed by water, then directly determined by RPLC with MS detection using selected-ion monitoring of two characteristic ions in each case. Naturally contaminated corn samples were milled to a fine powder and mixed to produce three samples with target levels of combined FB1 + FB2 ranging from 350 to 4000 microg/kg. Of 15 initially participating laboratories, two failed to report results and another did not follow the prescribed method. Thus, valid results were obtained from 12 participants located in 11 countries. Statistical analysis of the results produced RSDr values of 4.6-11.9, 1.9-12.6, and 1.4-11.5% for FB1, FB2, and combined FB1 + FB2, respectively; the corresponding RSDR values were 19.8-23.8, 18.2-25.5, and 18.8-23.2%. The three concentration levels of combined FB1 + FB2 were 534, 1194, and 1954 microg/kg. HorRat values for r and R were all < 2.0, indicating that the method is suitable as a regulatory method for the enforcement of European Union limits for fumonisins in corn.

Rapid and non-invasive analysis of deoxynivalenol in durum and common wheat by Fourier-Transform Near Infrared (FT-NIR) spectroscopy.

Fourier transform near-infrared spectroscopy (FT-NIR) was used for rapid and non-invasive analysis of deoxynivalenol (DON) in durum and common wheat. The relevance of using ground wheat samples with a homogeneous particle size distribution to minimize measurement variations and avoid DON segregation among particles of different sizes was established. Calibration models for durum wheat, common wheat and durum + common wheat samples, with particle size <500 microm, were obtained by using partial least squares (PLS) regression with an external validation technique. Values of root mean square error of prediction (RMSEP, 306-379 microg kg(-1)) were comparable and not too far from values of root mean square error of cross-validation (RMSECV, 470-555 microg kg(-1)). Coefficients of determination (r(2)) indicated an "approximate to good" level of prediction of the DON content by FT-NIR spectroscopy in the PLS calibration models (r(2) = 0.71-0.83), and a "good" discrimination between low and high DON contents in the PLS validation models (r(2) = 0.58-0.63). A "limited to good" practical utility of the models was ascertained by range error ratio (RER) values higher than 6. A qualitative model, based on 197 calibration samples, was developed to discriminate between blank and naturally contaminated wheat samples by setting a cut-off at 300 microg kg(-1) DON to separate the two classes. The model correctly classified 69% of the 65 validation samples with most misclassified samples (16 of 20) showing DON contamination levels quite close to the cut-off level. These findings suggest that FT-NIR analysis is suitable for the determination of DON in unprocessed wheat at levels far below the maximum permitted limits set by the European Commission.

Fitness for purpose--ochratoxin A analytical developments.

Laboratory accreditation involving third party auditing, the use of validated methods and participation in laboratory proficiency testing are essential elements for laboratory quality assurance in relation to ochratoxin A (OTA) analysis. A number of methods, mainly based on liquid chromatography (LC) with fluorescence detection (FD), coupled with immunoaffinity column or solid phase extraction cleanup, have been collaboratively validated and adopted as official standards for OTA determination in a variety of foods, including cereals, coffee, wine and beer. Enzyme-linked immunosorbent assays (ELISA) kits are widely used as screening methods for the occurrence of OTA in food. Novel technologies using anti-OTA antibodies (electrochemical immunosensors, fluorescence polarisation, lateral flow devices, enzyme-based flow through membranes, and surface plasmon resonance biosensors) have been proposed for rapid analysis of OTA in food and beverages, and may be applied for in situ measurements. Validation of these immunochemical methods and commercial kits is required. Liquid chromatography-mass spectrometry represents an adequate alternative to LC-FD particularly in the area of multi-mycotoxin analysis. OTA specific molecularly imprinted polymers are currently considered for cleanup as a potential and cheaper alternative to immunoaffinity or solid-phase extraction sorbents.

Comparison of urinary sphingolipids in human populations with high and low maize consumption as a possible biomarker of fumonisin dietary exposure.

The increased sphinganine/sphingosine (SA/SO) ratio has previously been shown as a biomarker of fumonisin exposure in experimental animals and has been proposed as a tool to assess human exposure to fumonisin mainly occurring through the dietary consumption of fumonisin contaminated maize-based foods. Sphinganine and sphingosine were measured in urines of humans resident in two areas of North Argentina and South Brazil with high maize consumption and compared with urine samples collected in areas with very low or no maize consumption, such as Central Argentina and Southern Italy. The pattern of SA/SO values in the two groups with no maize consumption (assumed as controls) was similar, with all SA/SO values lower than one. Mean SA/SO ratio was 1.27 in urine of subjects with high maize consumption (n = 123) and 0.36 in controls (n = 66) and the difference was statistically significant (p<0.001). The mean fumonisin level in maize samples collected in North Argentina and South Brazil was 0.35 mg kg(-1) (n = 40). Although a similar maize and fumonisin intake was recorded for the two groups of populations, the mean SA/SO ratio in South Brazil (1.57) was significantly higher (p<0.05) than that of North Argentina (0.69). These data suggest that the higher SA/SO values observed in South Brazil cannot be associated with high fumonisin exposure and further studies are necessary to provide convincing evidence for using the SA/SO ratio as a biomarker of human fumonisin exposure.

Effect of processing on fumonisin concentration in corn flakes.

The stability of fumonisin B1 and fumonisin B2 during processing of corn flakes was investigated with three different methods for analysis of the naturally contaminated raw material (corn flour), intermediate product (extruded, but not roasted corn flakes), and final product (roasted corn flakes). Only one method, using immunoaffinity column clean-up, provided reliable results in the determination of fumonisins in corn flake samples at the intermediate and final steps of processing. About 60 to 70% of the initial amount of fumonisins were lost during the entire cycle of corn flake processing, with less than 30% losses occurring during the intermediate extrusion step (70 to 170 degrees C for 2 to 5 min). The effect of different additives commonly present in commercial products (sodium chloride, sucrose, and ferrous sulfate heptahydrate) on the reliability of fumonisin analysis has also been investigated. The presence of sodium chloride strongly reduced fumonisin recovery when strong anion-exchange (SAX) columns were used for the clean-up step, whereas the other additives appeared to have little or no effect on the accuracy of fumonisin analysis. The use of reliable analytical methods that are effective for both raw materials and processed products is of paramount relevance for studying the effect of food processing on mycotoxin-contaminated commodities. Despite the fact that some effective fumonisin decontamination occurring during corn flake processing has been shown, more work is needed to identify the thermal breakdown products of fumonisins and their relevant toxicity.

Determination of fumonisins B1 and B2 in cornflakes by high performance liquid chromatography and immunoaffinity clean-up.

The determination of fumonisins in cornflakes is a challenging matter as the actually available methods for the analysis of corn do not perform well when applied to this more complex matrix. After testing several factors that may affect the analytical performance, an accurate method for the determination of fumonisin B1 (FB1) and B2 (FB2) in cornflakes has been developed. The method uses immunoaffinity chromatography for clean-up and high performance liquid chromatography (HPLC) for quantification of the toxins. Samples were extracted twice with acetonitrile-methanol-water (25:25:50) and the combined extracts were diluted with phosphate buffered saline (PBS) and applied to a FumoniTest immunoaffinity column. After washing with PBS, fumonisins were eluted from the column with methanol and reacted with o-phthaldialdehyde/2-mercaptoethanol to form fluorescent derivatives. Fumonisin derivatives were analysed by reversed phase HPLC with fluorometric detection using methanol-0.1 M phosphate buffer (77:23; pH adjusted at 3.35) as mobile phase. The average recoveries for FB1 and FB2 spiked in the ranges of 0.33 2.80 microg/g and 0.17-1.40 microg/g were 102.6% and 95.1%, respectively, with average relative standard deviations of 9% and 8%. The limit of quantification for FB1 and FB2 was 0.005 microg/g based on a signal-to-noise ratio of 6.1 by using a sensitive fluorescence detector. The method was used to analyse 18 cornflakes and cornflake cereals samples/for FB1 and FB2 contamination. All but one sample were found to be contaminated, with maximum FB1 and FB2 concentrations of 1.092 microg/g and 0.235 microg/g, respectively. Mean FB1 and FB2 concentrations were 0.157 microg/(g and 0.036 microg/g, respectively.

Comparison of different extraction and clean-up procedures for the determination of fumonisins in maize and maize-based food products.

In order to optimize the analytical method for the determination of fumonisin B1 (FB1) and fumonisin B2 (FB2) in different maize products, five materials (maize flour, corn flakes, extruded maize, muffins and infant formula) were investigated under a variety of experimental conditions organized in a ruggedness test according to a factorial design. The influence of five factors (extraction solvent, extraction mode, volume of extraction solvent, test sample size and clean-up) on method performances was tested by four laboratories using spiked materials (0.5 microgram/g and 1.5 micrograms/g FB1 + FB2) and naturally contaminated materials (ca 1.5 micrograms/g with FB1 + FB2). The end determination step was performed by high-performance liquid chromatography analysis of the o-phthaldialdehyde derivatized extracts. The ruggedness test permitted identification of two critical factors in the analysis of fumonisins in the above products, namely 'extraction solvent' and 'clean-up procedure'. In particular, the use of acetonitrile (ACN)-water (1 + 1, v + v) as extraction solvent and immunoaffinity column for clean-up provided better recovery of fumonisins and chromatographic resolution as compared with methanol (MeOH)-water (3 + 1, v + v) and strong anion exchange (SAX), respectively. However, phase separation occurring after extraction with ACN-water may have given incorrect results. Based on the information obtained with the present study it was possible to develop a new method horizontally applicable to all the above mentioned maize-based food matrices.

Determination of fumonisins B1 and B2 in corn and corn flakes by liquid chromatography with immunoaffinity column cleanup: collaborative study.

A liquid chromatographic (LC) method for the determination of fumonisins B1 (FB1) and B2 (FB2) in corn and corn flakes was collaboratively studied by 23 laboratories, which analyzed 5 blind duplicate pairs of each matrix to establish the accuracy, repeatability, and reproducibility characteristics of the method. Fumonisin levels in the corn ranged from <0.05 (blank) to 1.41 microg/g for FB1 and from <0.05 to 0.56 microg/g for FB2, whereas in the corn flakes they ranged from <0.05 to 1.05 microg/g for FB1 and from <0.05 to 0.46 microg/g for FB2. The method involved double extraction with acetonitrile-methanol-water (25 + 25 + 50), cleanup through an immunoaffinity column, and LC determination of the fumonisins after derivatization with o-phthaldialdehyde. Relative standard deviations for the within-laboratory repeatability (RSDr) of the corn analyses ranged from 19 to 24% for FB1 and from 19 to 27% for FB2; for the corn flakes analyses, RSDr ranged from 9 to 21 % for FB1 and from 8 to 22% for FB2. Relative standard deviations for the between-laboratories reproducibility (RSDR) of the corn analyses ranged from 22 to 28% for FB1 and from 22 to 30% for the FB2; for corn flakes analyses, RSDR ranged from 27 to 32% for FB1 and from 26 to 35% for FB2. Mean recoveries of FB1 and FB2 from corn spiked with FB1 at 0.80 microg/g and with FB2 at 0.40 microg/g were 76 and 72%, respectively; for corn flakes spiked at the same levels recoveries were 110 and 97% for FB1 and FB2, respectively. HORRAT ratios for the analyses of corn ranged from 1.44 to 1.53 for FB1 and from 0.96 to 1.48 for FB2, whereas for corn flakes they ranged from 1.60 to 1.82 for FB1 and from 1.39 to 1.68 for FB2.