Micron-size tire tread particles leach organic compounds at higher rates than centimeter-size particles: Compound identification and profile comparison

Tire tread particles (TTP) are environmentally prevalent microplastics and generate toxic aqueous leachate. We determined the total carbon and nitrogen leachate concentrations and chemical profiles from micron (∼32 μm) and centimeter (∼1 cm) TTP leachate over 12 days. Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were used to measure the concentration of leached compounds. Nontargeted chemical analysis by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS) was used to compare the chemical profiles of leachates. After leaching for 12 days, DOC was 4.0 times higher in the micron TTP leachate than in the centimeter TTP leachate, and TDN was 2.6 times higher. The total GC×GC/TOF-MS chromatographic feature peak area was 2.9 times greater in the micron TTP leachate than the centimeter TTP leachate, and similarly, the total relative abundance of 54 tentatively identified compounds was 3.3 times greater. We identified frequently measured tire-related chemicals, such as 6PPD, N-cyclohexyl-N'-phenylurea (CPU), and hexa(methoxymethyl)melamine (HMMM), but nearly 50% of detected chemicals were not previously reported in tire literature or lacked toxicity information. Overall, the results demonstrate that smaller TTP have a greater potential to leach chemicals into aquatic systems, but a significant portion of these chemicals are not well-studied and require further risk assessment.

Assessing Marine Endocrine-Disrupting Chemicals in the Critically Endangered California Condor: Implications for Reintroduction to Coastal Environments

Coastal reintroduction sites for California condors (Gymnogyps californianus) can lead to elevated halogenated organic compound (HOC) exposure and potential health impacts due to the consumption of scavenged marine mammals. Using nontargeted analysis based on comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS), we compared HOC profiles of plasma from inland and coastal scavenging California condors from the state of California (CA), and marine mammal blubber from CA and the Gulf of California off Baja California (BC), Mexico. We detected more HOCs in coastal condors (32 ± 5, mean number of HOCs ± SD, n = 7) than in inland condors (8 ± 1, n = 10) and in CA marine mammals (136 ± 87, n = 25) than in BC marine mammals (55 ± 46, n = 8). ∑DDT-related compounds, ∑PCBs, and total tris(chlorophenyl)methane (∑TCPM) were, respectively, ∼7, ∼3.5, and ∼148 times more abundant in CA than in BC marine mammals. The endocrine-disrupting potential of selected polychlorinated biphenyls (PCB) congeners, TCPM, and TCPMOH was determined by in vitro California condor estrogen receptor (ER) activation. The higher levels of HOCs in coastal condors compared to those in inland condors and lower levels of HOC contamination in Baja California marine mammals compared to those from the state of California are factors to consider in condor reintroduction efforts.

Study of the Reproducibility Characteristics of a Liquid Chromatographic Method for the Determination of Fumonisins B1 and B2 in Corn: IUPAC Collaborative Study

An interlaboratory study of the reproducibility characteristics of a liquid chromatographic method for the determination of fumonisins B1 and B2 in corn was conducted in 11 laboratories in the United States, South Africa, Italy, Japan, United Kingdom, and The Netherlands. Each laboratory was supplied with 12 coded, blind duplicates of 6 samples of naturally contaminated corn containing different amounts of fumonisins B1 and B2 . Samples are extracted with methanol-water (3 + 1), extracts are centrifuged, and supernatants are cleaned up on strong-anion-exchange cartridges, which were supplied to participants. Solutions are derivatized with o-phthaldialdehyde, and individual fumonisins are determined by reversed-phase liquid chromatography with fluorescence detection. Quantitation is by comparison with the supplied fumonisin standards. The within-laboratory repeatability was determined by statistical analysis of data after exclusion of outliers. Relative standard deviations for within-laboratory repeatability varied from 7.7 to 25.5% for fumonisin B1 at concentrations between 200 and 2000 ng/g and from 12.5 to 36.8% for fumonisin B2 at concentrations between 70 and 740 ng/g. Relative standard deviations for betweenlaboratory reproducibility varied from 18.0 to 26.7% for fumonisin B1 and from 28.0 to 45.6% for fumonisin B2 at the concentrations mentioned above. These measures of variability indicate that the method is suitable for adoption as an official method provided that the accuracy characteristics are verified collaboratively.

Liquid Chromatographic Determination of Fumonisins B1, B2, and B3 in Corn: AOAC–IUPAC Collaborative Study

A liquid chromatographic (LC) method for simultaneous determination of fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) in corn was subjected to a collaborative study involving 12 participants from 10 countries, in which the accuracy and reproducibility characteristics of the method were established. Mean analyte recoveries from corn ranged from 81.1 to 84.2% for FB1 (at a spiking range of 500 to 8000 ng/g), from 75.9 to 81.9% for FB2 (at a spiking range of 200 to 3200 ng/g), and from 75.8 to 86.8% for FB3 (at a spiking range of 100 to 1600 ng/g). The valid data were statistically evaluated after exclusion of outliers. Relative standard deviations for within-laboratory repeatability ranged from 5.8 to 13.2% for FB1, from 7.2 to 17.5% for FB2, and from 8.0 to 17.2% for FB3. Relative standard deviations for between-laboratory reproducibility varied from 13.9 to 22.2% for FB1, from 15.8 to 26.7% for FB2, and from 19.5 to 24.9% for FB3. HORRAT ratios, calculated for the individual toxin analogues, ranged from 0.75 to 1.73. The LC method for determination of fumonisins B1, B2, and B3 in corn (at concentrations of 800–12800 ng total fumonisins/g) has been adopted by AOAC INTERNATIONAL.

Microplastic fiber uptake, ingestion, and egestion rates in the blue mussel (Mytilus edulis)

Microplastic fibers (MPF) are a ubiquitous marine contaminant, making up to 90% of global microplastic concentrations. Imaging flow cytometry was used to measure uptake and ingestion rates of MPF by blue mussels (Mytilus edulis). Mussels were fed a diet of Rhodomonas salina and MPF concentrations up to 30 MPF mL^-1, or 0.374% of available seston. Filtration rates were greatly reduced in mussels exposed to MPF. Uptake of MPF followed a Holling's Type II functional response with 95% of the maximum rate (5227 MPF h^-1) occurring at 13 MPF mL^-1. An average of 39 MPF (SE ± 15, n = 4) was found in feces (maximum of 70 MPF). Most MPF (71%) were quickly rejected as pseudofeces, with approximately 9% ingested and <1% excreted in feces. Mussels may act as microplastic sinks in Gulf of Maine coastal waters, where MPF concentrations are near the order of magnitude as the experimental treatments herein.

Species- and sex-specific renal cytotoxicity of ochratoxin A and B in vitro

Four different cell models were chosen for comparison of OTA and OTB toxicity: primary porcine (PKC), rat (RPTC) and human renal proximal epithelial cells (HKC) from both sexes and a porcine renal cell line: LLC-PK1. Culture conditions were tested and optimized for each respective cell type (species/sex and origin). All cell types were characterized for epithelial origin and growth patterns and following optimization of dosing strategies and assay procedures, a strict study design was implemented to avoid systemic variations. Due to possible sensitivity differences, three simple endpoints were chosen to provide basic data for interspecies comparison: neutral red uptake, MTT reduction and cell number. Of the endpoints tested neutral red appeared the most sensitive, although all three parameters yielded comparable EC50's. Sex-differences were observed between male and female HKC cells following 96 h exposure to OTA, with HKC(m) being more sensitive than HKC(f). No sex-difference was observed in PKC cells, however, the PKC were approximately 3 and 10 times more sensitive than HKC(m) and HKC(f), respectively, to OTA and OTB. Interestingly, the CI95 of the EC50 values obtained for OTA (15.5-16.5 microM) and OTB (17.0-2 1.0 microM) were comparable in the PKC cells. In contrast, OTB had lower cytotoxicity than OTA in HKC and LLC-PK1 (approx. 2-fold) and no effects in RPTC. Overall, HKC(m) were nearly as sensitive as PKC towards OTA, followed by RPTC, LLC-PK1 and HKC(f), thus suggesting a sex specific sensitivity in humans towards OTA induced cytotoxicity.

Fumonisin b1 carcinogenicity in a two-year feeding study using F344 rats and B6C3F1 mice

Fumonisin B1 (FB1) is a mycotoxin isolated from Fusarium fungi that contaminate crops worldwide. A previous study demonstrated that FB1 promoted preneoplastic foci in initiated rats and induced hepatocellular carcinomas in BD IX rats at 50 parts per million (ppm), but fundamental dose-response data were not available to assist in setting regulatory guidelines for this mycotoxin. To provide this information, female and male F344/N/Nctr BR rats and B6C3F1 Nctr BR mice were fed for two years a powdered NIH-31 diet containing the following concentrations of FB1: female rats, 0, 5, 15, 50, and 100 ppm; male rats, 0, 5, 15, 50, and 150 ppm; female mice, 0, 5, 15, 50, and 80 ppm; male mice, 0, 5, 15, 80, and 150 ppm. FB1 was not tumorigenic in female F344 rats with doses as high as 100 ppm. Including FB1 in the diets of male rats induced renal tubule adenomas and carcinomas in 0/48, 0/40, 9/48, and 15/48 rats at 0, 5, 15, 50, and 150 ppm, respectively. Including up to 150 ppm FB1 in the diet of male mice did not affect tumor incidence. Hepatocellular adenomas and carcinomas were induced by FB1 in the female mice, occurring in 5/47, 3/48, 1/48, 19/47, and 39/45 female mice that consumed diets containing 0, 5, 15, 50, and 80 ppm FB1, respectively. This study demonstrates that FB1 is a rodent carcinogen that induces renal tubule tumors in male F344 rats and hepatic tumors in female B6C3F1 mice.

Production of alternariol and alternariol methyl ether by Alternaria alternata grown on fruits at various temperatures

Two toxigenic strains of the fungus Alternaria alternata (ATCC 56836 and ATCC 66868) were grown on surface-disinfected, fresh, ripe fruits and tested for the production of alternariol (AOH) and alternariol methyl ether (AME). Examined fruits included strawberries; red and green seedless grapes; concord grapes; red delicious, golden delicious, and gala apples; and blueberries. After inoculation, fruits were incubated at 4, 10 degrees C, or room temperature (approximately 21 degrees C) for up to 3 weeks. At weekly intervals, duplicate samples were analyzed for AOH and AME by using liquid chromatography. Results indicated that A. alternata and its metabolites were not a major problem in strawberries due to the presence of fast-growing molds like Rhizopus and Botrytis that outgrew and possibly inhibited Alternaria. Both Alternaria strains showed limited growth on apples, although fast-growing molds were not present after surface disinfection; AOH and AME were produced only by the ATCC 56836 strain on the golden delicious and gala varieties, (ranging from <0.1 to 5 microg/g and <0.1 to 14 microg/g for AOH and AME, respectively). Restricted growth of both strains without toxin production occurred in blueberries, whereas moderate growth and AOH (<0.1 to 3,336 microg/g) and AME (<0.1 to 1,716 microg/g) production took place in grapes.

Analysis of fumonisin B1 and its hydrolysis product in tortillas

Fumonisins are toxic metabolites of Fusarium moniliforme, a fungus that occurs widely in corn. Fumonisins causes leukoencephalomalacia in horses and pulmonary edema in swine and have been suggested as a possible cause of an increased incidence of neural tube defects among people living along the Texas-Mexico border. As part of an effort to determine levels of fumonisins in human food, a liquid chromatographic (LC) method was devised for determining fumonisin B1 (FB1) and the total hydrolysis product of FB1 (HB1) in tortillas. The method uses acetonitrile-0.1M phosphate buffer (pH 3; 1 + 1) extraction, solid-phase C18 cleanup, o-phthalaldehyde and 2-mercaptoethanol derivatization, and reversed-phase LC. Average recoveries from tortillas spiked with FB1 and HB1 at 250, 500, and 1000 ng/g were 86.5% for FB1 and 82.6% for HB1. Tortillas (54) and masa (8) from the Texas-Mexico border were analyzed for FB1 and HB1. Average amounts of FB1 and HB1 in tortillas were 187 and 82 ng/g, respectively. Average amounts of FB1 and HB1 in masas were 262 and 64 ng/g, respectively. The results show that fumonisin B1 and its hydrolysis product are present in tortillas consumed by a population experiencing an increased incidence of neural tube defects.

Assessment of the embryotoxic potential of the total hydrolysis product of fumonisin B1 using cultured organogenesis-staged rat embryos

Aminopentol (AP1) is the total hydrolysis product of fumonisin B1 (FB1), the major and best characterized of the fumonisins, which are mycotoxins that are common contaminants of corn and corn meal. Some human populations expected to have significant exposure to AP1 have a high incidence of babies born with neural tube defects (NTD). The embryotoxicity of AP1 was evaluated in cultured rat embryos. Gestation day 9.5 embryos were exposed to 0, 3, 10, 30, 100 or 300 microM AP1 throughout the entire 45-hr culture period. At 100 microM AP1, growth and overall development were reduced significantly. There was also a significant increase in the incidence of abnormal embryos. 29% of the embryos had NTD, and 36% of the embryos had other abnormalities. At 300 microM AP1, the incidence of NTD was 15%, and 85% of the embryos had other abnormalities. These findings suggest that AP1, at concentrations of 100 microM and above, can induce NTD in organogenesis-stage cultured rat embryos. However, these NTD are in conjunction with significant overall retardation of growth and development as well as significant increases in the incidence of other defects. These studies also showed, when compared with previous findings, that AP1 is over 100-fold less toxic than FB1 to cultured rat embryos.

Fumonisin levels in Uruguayan corn products

A survey was conducted to evaluate fumonisins FB1 and FB2 in Uruguayan corn products. Sixty-four samples of different local brands were purchased from retail stores during a 15-month period and analyzed for FB1 and FB2 by methanol-water extraction, cleanup with a 1 mL. strong-anion-exchange solid-phase extraction column, and liquid chromatography with o-pthaldialdehyde-2-mercaptoethanol derivatization and fluorescence detection. Contamination levels for FB1 varied from 50 ng/g (detection limit) to 6342 ng/g. Values were highest in feed samples (up to 6342 ng/g), unprocessed corn kernel (up to 3688 ng/g), and milled products, which included polenta (up to 427 ng/g). They were lowest in processed corn kernel (up to 155 ng/g) and snacks (up to 314 ng/g). FB2 was determined in one-fourth of the total samples and detected at trace levels in only one feed sample. The data demonstrated the natural occurrence of fumonisins in corn products in Uruguay. Feed and polenta that contain fumonisins could be of concern because they are consumed in large amounts and are often the main nutrient source in Uruguay.

Immunoaffinity column coupled with liquid chromatography for determination of fumonisin B1 in canned and frozen sweet corn

A modified liquid chromatographic (LC) method for determining fumonisin B1 (FB1) in corn was applied to canned and frozen sweet corn. The corn is extracted with methanol-water (8 + 2), and the extract is filtered. The filtrate is diluted with water and passed through an immunoaffinity column. After the column is washed with water, FB1 is eluted with methanol-water (8 + 2). The eluate is evaporated to dryness by using a vacuum concentrator, and the residue is dissolved in acetonitrile-water (1 + 1). FB1 is derivatized with o-phthaldialdehyde. The derivative is separated on a reversed-phase C18 LC column using acetonitrile-water-acetic acid (50 + 50 + 1) and quantitated with a fluorescence detector. Recoveries of FB1 from canned and frozen corn spiked over the range of 50-200 ng/g were 76-88%. The limit of determination was about 25 ng/g, and the limit of detection was about 4 ng/g. The method was applied to 97 commercial canned and frozen sweet corn samples collected from different areas of the United States. Sixty samples contained no FB1. Low levels (trace-82 ng FB1/g corn) were found in 35 samples; 235 ng FB1/g was found in 1 canned corn sample, and 350 ng FB1/g was found in 1 frozen corn sample.

Survey of deoxynivalenol in U.S. 1993 wheat and barley crops by enzyme-linked immunosorbent assay

Wheat and barley from the 1993 crop year were analyzed for deoxynivalenol (DON). A total of 630 samples were collected by the Federal Grain Inspection Service in 25 states and analyzed using a commercially available, direct competitive, enzyme-linked immunosorbent assay. The limit of determination was about 0.5 micrograms/g. DON contamination in the 483 wheat samples averaged 2.0 micrograms/g and ranged from < 0.5 to 18 micrograms/g. DON contamination in the 147 barley samples averaged 4.2 micrograms/g and ranged from < 0.5 to 26 micrograms/g. About 40% fo the wheat samples and 57% of the barley samples contained DON levels that were greater than the U.S. Food and Drug Administration 1982 advisory level of 2 micrograms/g for DON in wheat designated for milling (human consumption).

Multifunctional column coupled with liquid chromatography for determination of aflatoxins B1, B2, G1, and G2 in corn, almonds, brazil nuts, peanuts, and pistachio nuts: collaborative study

An AOAC/IUPAC collaborative study was conducted to evaluate the effectiveness of a multifunctional column for the determination of aflatoxins. The test portion is extracted with acetonitrile-water (9 + 1), the extract is filtered, and the filtrate is passed through the column. The aflatoxins in the eluate are determined by reversed-phase liquid chromatography after derivatization with trifluoroacetic acid. Naturally contaminated corn, almonds, Brazil nuts, peanuts, and pistachio nuts spiked with total aflatoxins at 5, 10, 20, and 30 ng/g were sent to 12 collaborators in the United States, Denmark, France, Japan, and Switzerland. Eleven collaborators completed the study. Average recoveries of total aflatoxins for each spike level for the various commodities (excluding Brazil nuts at 5 ng/g) were 93, 97, 95, and 95%, respectively; the repeatability relative standard deviation (RSDr) ranged from 6.0 to 23.2% and the reproducibility relative standard deviation (RSDR) ranged from 12.0 to 69.4%. The multifunctional column coupled with a liquid chromatographic method for determination of aflatoxins in corn, almonds, Brazil nuts, peanuts, and pistachio nuts has been adopted first action by AOAC INTERNATIONAL.

Evaluation of alternariol and alternariol methyl ether for mutagenic activity in Salmonella typhimurium

Alternariol and alternariol methyl ether were tested in the Ames Salmonella typhimurium assay, and both were shown, with and without metabolic activation, to be nonmutagenic to strains TA98 and TA100. The finding of other investigators that alternariol methyl ether is weakly mutagenic to TA98 without metabolic activation could have resulted from the presence of a small amount of one of the highly mutagenic altertoxins in the alternariol methyl ether originally tested.

Determination of deoxynivalenol in 1991 U.S. winter and spring wheat by high-performance thin-layer chromatography

A thin-layer chromatographic (TLC) method was modified for determination of deoxynivalenol (DON) in 1991 U.S. winter and spring wheat. After extraction with acetonitrile-water (84 + 16) and cleanup on a charcoal-alumina-Celite (7 + 5 + 3) column, acetonitrile was used instead of ethyl acetate to transfer the concentrated extract containing DON. After the extract was evaporated to dryness, the residue was dissolved in methanol and an aliquot was spotted on a high-performance TLC plate. After development with chloroform-acetone-2-propanol (8 + 1 + 1), the plates were sprayed with aluminum chloride solution and heated; DON was quantitated by fluorodensitometry. Average recoveries of DON added to duplicate test portions of wheat at 200, 400, and 800 ng/g were 83, 82, and 72%, respectively. The detection limit was 40 ng/g. The method was applied to 81 test samples of spring and winter wheat. The wheat contained DON levels that ranged from nondetectable to 9330 ng/g (average 1570 ng/g). The results indicate that DON levels were higher in wheat from Missouri, North Dakota, and Tennessee than in wheat from 7 other states. The identity of DON, which was isolated from 21 of the extracts by preparatory TLC, was confirmed by gas chromatography/mass spectrometry in all 21 test samples.

Enzyme-linked immunosorbent assay of total aflatoxins B1, B2, and G1 in corn: follow-up collaborative study

A direct competitive enzyme-linked immunosorbent assay screening method for aflatoxins at 20 ng/g in corn was studied by 15 collaborating laboratories. Test samples of corn were extracted by blending with methanol-water (8 + 2). The extracts were filtered and the filtrates were diluted with buffer to a final methanol concentration of < 30%. Each diluted filtrate was applied to a test device containing a filter with immobilized polyclonal antibodies specific to aflatoxins B1, B2, and G1. Aflatoxin B1-peroxidase conjugate was added, the test device was washed with water, and a mixture of hydrogen peroxide and tetramethylbenzidine was added. A test sample was judged to contain > or = 20 ng aflatoxins/g when, after exactly 1 min, no color was observed on the filter; if a blue or gray color developed, the test sample was judged to contain < 20 ng aflatoxins/g. All laboratories correctly identified naturally contaminated corn test samples. Only one false positive was found for controls containing no aflatoxins. The correct responses for positive test samples spiked at levels of 10, 20, and 30 ng aflatoxins/g (the ratio of B1:B2:G1 was 15:1:3) were 67, 97, and 100%, respectively. This method was adopted first action by AOAC INTERNATIONAL as a change in method for 990.34 for screening for aflatoxins B1, B2, and G1 in corn at total aflatoxin concentrations of > or = 20 ng/g.

Mutagenicity of stemphyltoxin III, a metabolite of Alternaria alternata

Some common decay organisms of vegetables and ripened fruits are Alternaria species. Even fruits and vegetables kept under refrigeration can be spoiled by Alternaria species because the mold grows at low temperatures. Alternaria alternata is commonly found in grain in areas with a high incidence of esophageal cancer. Three metabolites, altertoxins I, II, and III, have been isolated from A. alternata and have hydroxyperylenequinone structures. Although other perylenequinone metabolites such as stemphyperylenol and stemphyltoxins I, II, III, and IV, have been isolated from Stemphylium botryosum var. lactucum, a plant pathogen and mold, we isolated and identified stemphyltoxin III from A. alternata. This metabolite was tested for mutagenicity in the Ames Salmonella typhimurium plate incorporation assay with and without Aroclor 1254-induced rat S-9 metabolic activation. A positive response was noted with and without metabolic activation in S. typhimurium TA98 and TA1537, and there was a marginal response in strain TA100.

Liquid chromatographic method for determination of aflatoxins B1, B2, G1, and G2 in corn and peanut products: collaborative study

A collaborative study of a liquid chromatographic method for the determination of aflatoxins B1, B2, G1, and G2 was conducted in laboratories located in the United States, Canada, South Africa, and Switzerland. Twenty-one artificially contaminated raw peanuts, peanut butter, and corn samples containing varying amounts of aflatoxins B1, B2, G1, and G2 were distributed to participating laboratories. The test portion was extracted with methanol-0.1N HCl (4 + 1), filtered, defatted with hexane, and then partitioned with methylene chloride. The concentrated extract was passed through a silica gel column. Aflatoxins B1 and G1 were derivatized with trifluoroacetic acid, and the individual aflatoxins were determined by reverse-phase liquid chromatography with fluorescence detection. Statistical analysis of the data was performed to determine or confirm outliers, and to compute repeatability and reproducibility of the method. For corn, relative standard deviations for repeatability (RSDr) for aflatoxin B1 ranged from 27.2 to 8.3% for contamination levels from 5 through 50 ng/g. For raw peanuts and peanut butter, RSDr values for aflatoxin B1 were 35.0 to 41.2% and 11.2 to 19.1%, respectively, for contamination levels from 5 through 25 ng/g. RSDr values for aflatoxins B2, G1, and G2 were similar. Relative standard deviations for reproducibility (RSDr) for aflatoxin B1 ranged from 15.8 to 38.4%, 24.4 to 33.4%, and 43.9 to 54.0% for corn, peanut butter, and raw peanuts, respectively. The method has been adopted official first action for the determination of aflatoxins B1, B2, G1, and G2 in peanut butter and corn at concentrations greater than or equal to 13 ng total aflatoxins/g.

Enzyme-linked immunosorbent assay of aflatoxins B1, B2, and G1 in corn, cottonseed, peanuts, peanut butter, and poultry feed: collaborative study

A direct competitive enzyme-linked immunosorbent assay (ELISA) screening method for aflatoxins at 20 ng/g was studied by 12 collaborators. Test samples of peanut butter were extracted by blending with methanol-water-hexane (55 + 45 + 100) and heating the test extracts on a steam bath; test samples of the other commodities were extracted by blending with methanol-water (80 + 20). All test extracts were filtered and the filtrates were diluted with buffer to a final methanol concentration of less than 30%. Each diluted filtrate was applied to a cup containing a filter with immobilized polyclonal antibodies specific to aflatoxins B1, B2, and G1. Aflatoxin B1-peroxidase conjugate was added, the cup was washed with water, and a mixture of hydrogen peroxide and tetramethylbenzidine was added. The test sample was judged to contain greater than or equal to 20 ng aflatoxins/g when, after exactly 1 min, no color was observed on the filter; when a blue or gray color developed, the test sample was judged to contain less than 20 ng aflatoxins/g. All collaborators correctly identified naturally contaminated corn and raw peanut positive test samples. No false positives were found for controls containing less than 2 ng aflatoxins/g. The correct responses for positive test samples spiked at levels of 10, 20, and greater than or equal to 30 ng aflatoxins/g (the ratio of B1:B2:G1 was 10:1:3) were 52, 86, and 96%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Photodynamic Production of Superoxide In Vitro by Altertoxins in the Presence of Reducing Agents

Superoxide production by the three 4,9-dihydroxyperylene-3,10-quinone fungal toxins, altertoxins I, II, and III, was stimulated on illumination with broad-spectrum light. As determined previously for cercosporin, superoxide production by illuminated altertoxins was increased by the addition of the reducing substances ergothioneine or urate; ascorbate also effectively increased superoxide production. Illuminated urate alone engendered some superoxide production.

Mutagenicity of the Alternaria metabolites altertoxins I, II, and III

The Ames Salmonella typhimurium assay was used to demonstrate that an extract of the mold Alternaria alternata was mutagenic. The mutagenic extract was fractionated, and the Ames test was used to determine which fractions were mutagenic. Subsequently, altertoxins I and II and a new compound referred to as altertoxin III were isolated by liquid chromatography and shown to be hydroxyperylenequinone compounds by mass spectrometry and infrared, ultraviolet, and proton magnetic resonance spectroscopy. Altertoxins I, II, and III were mutagenic to S. typhimurium TA98, TA100, and TA1537 with and without metabolic activation.

Liquid chromatographic determination of tenuazonic acid and alternariol methyl ether in tomatoes and tomato products

A liquid chromatographic (LC) method for determining tenuazonic acid (TA) and alternariol methyl ether (AME) in tomatoes and tomato products is described. The Alternaria metabolites are extracted from a water slurry of the sample with CHCl3, the mixture is centrifuged, and the extract is fractionated on a silica gel column. Reverse phase LC with an ultraviolet detector (for TA) and a fluorescence detector (for AME) connected in series is used for final separation and determination. The limit of determination for TA and AME is 25 and 3 ng/g, respectively, with average recoveries from catsup of 83 and 68%, respectively. The LC method also detects alternariol, but interfering peaks in some samples prevent accurate quantitation. Chemical ionization mass spectrometry (CIMS) is used to confirm TA. Samples (142) of tomatoes collected from commercial processing lines were analyzed; TA was found in 73 samples (0.4-70 micrograms/g).

Isolation and identification of dihydrocitrinone, a urinary metabolite of citrinin in rats

Dihydrocitrinone, 3,4-dihydro-6,8-dihydroxy-3,4,5-trimethylisocoumarin-7-carboxylic acid, was isolated and identified as a urinary metabolite after oral administration of citrinin to rats. Male and female Osborne-Mendel rats received 30 mg citrinin/kg body weight by oral intubation. The metabolite dihydrocitrinone was present in urine collected at 0-2, 2-4, 4-6, 6-8, and 8-24 h after treatment. Only unchanged citrinin was found in blood collected 24 h after administration of the compound. The metabolite had a blue fluorescence and the same Rf on thin-layer chromatography, the same retention time on reverse-phase high-pressure liquid chromatography, and the same mass spectrum as an authentic sample of dihydrocitrinone.

High pressure liquid chromatographic determination of satratoxins G and H in cereal grains

A high pressure liquid chromatographic (HPLC) method is described for the detection and quantitative determination of satratoxins G and H in cereal grains. The toxins are extracted from the sample by blending with methanol--water (55 + 45) in the presence of hexane, followed by partitioning into chloroform. The chloroform extract is further purified on a 10 g silica gel column. A high pressure liquid chromatograph, equipped with a microparticle silica gel column and a 254 nm absorbance detector, is used for the determination. Additional confirmation of identity is obtained by mass spectrometry or by a brine shrimp bioassay of the HPLC eluates corresponding to the retention times of satratoxins G and H. The recoveries of added satratoxins G and H from wheat samples averaged 65% for G and 71% for H (200--1000 mg/kg). The coefficients of variation (CV) were 15% for G and 14% for H. The lower limit of detection was 200 microgram/kg for wheat. Analysis of corn, oats, and barley samples (400 microgram/kg of each toxin added) gave comparable recoveries. Only the corn extract exhibited HPLC interferences at the retention time for satratoxin H. The method was also used to analyze samples of corn, oats, wheat, barley, and rice on which Stachybotrys atra had been cultured.

Hepatocarcinogenicity of sterigmatocystin and versicolorin A to rainbow trout (Salmo gairdneri) embryos

Versicolorin A (VA) and sterigmatocystin (ST) are biosynthetic precursors of aflatoxin B1 (AFB1). The carcinogenicity of these compounds relative to AFB1 was determined with the use of rainbow trout (Salmo gairdneri) embryo exposure. Exposure of 14-day rainbow trout embryos to a 0.5-ppm aqueous suspension of ST for 1 hour produced a 13% incidence of hepatocellular carcinomas among survivors 1 year later. Similar exposure of trout eggs to a 0.5-ppm solution of AFB1 produced a 53% incidence among survivors. Subsequent exposure of 21-day rainbow trout embryos to 5- and 25-ppm solutions of VA resulted in hepatocellular carcinoma incidences among survivors of 42 and 68%, respectively, at 12 months. A 0.5-ppm AFB1 positive control group had a 68% incidence among survivors of hepatocellular carcinomas at 1 year. These results established the carcinogenicity of VA for the first time and confirmed previous reports of ST carcinogenicity. Both compounds were of sufficient potencies to warrant caution as possible human health hazards.

Production of xanthomegnin and viomellein by isolates of Aspergillus ochraceus, Penicillium cyclopium, and Penicillium viridicatum

Fungal isolates from legumes were cultured on rice and examined for production of the toxic mold metabolites xanthomegnin and viomellein. Six of 14 Aspergillus ochraceus isolates produced from 0.3 to 1.3 mg of xanthomegnin per g and 0.1 to 1.0 mg of viomellein per g. One of nine isolates of Penicillium cyclopium produced 0.1 mg of xanthomegnin per g and 0.06 mg of viomellein per g. Three of nine P. viridicatum isolates produced from 0.4 to 1.6 mg of xanthomegnin per g and 0.2 to 0.4 mg of viomellein per g. This is the first report of xanthomegnin and viomellein production by A. ochraeus and P. cyclopium.

High pressure liquid chromatographic determination of xanthomegnin in corn

A method is described for the detection and quantitative analysis of xanthomegnin in corn samples. Initial extraction with CHCl3 in the presence of 0.5M H3PO4 is followed by additional purification using silica gel column chromatography. A high pressure liquid chromatograph equipped with a microparticle silica gel column and a 405 nm absorbance detector is used for detection and quantitation of the xanthomegnin. The identity of xanthomegnin is confirmed by thin layer chromatography on silica gel plates developed with benzene-methanol-acetic acid (90 + 5 + 5). The recovery of xanthomegnin added to corn samples at levels of 0.75--9.6 mg/kg averaged 41% with a coefficient of variation of 25%.

Isolation and identification of xanthomegnin, viomellein, rubrosulphin, and viopurpurin as metabolites of penicillium viridicatum

Four of the metabolites of Penicillium viridicatum 66-68-2 grown on rice cultures were isolated and identified as xanthomegnin, viomellein, rubrosulphin, and viopurpurin. Melting points, elemental analysis, and infrared, ultraviolet, and field desorption and electron impact mass spectra of the isolated compounds were consistent with values reported in the literature for these compounds. In addition, diacetate and triacetate derivatives were prepared, and the chemical and physical analyses of the derivatives were also consistent with literature data. Proton magnetic resonance spectroscopy and thin-layer chromatography were also used for the additional identification of selected compounds.

Determination of sterigmatocystin in corn and oats by gel permeation and high-pressure liquid chromatography

Corn and oats samples are extracted with acetonitrile-water, followed by partition of the extract against hexane, transfer to chloroform, and elution from a silica gel column. The extract is purified by gel permeation chromatography on an automatic instrument. Reverse phase high-pressure liquid chromatography, using a 254 nm ultraviolet detector and 0.1 M KH2PO4-acetonitrile (7+5) as the mobile phase, is used for quantitation. The average recovery from 6 samples of corn to which 0, 25, 50, and 100 mug sterigmatocystin/kg had been added was 59%, with a coefficient of variation of 8.4%. The average recovery from oats fortified at the same levels was 74%, with a coefficient of variation of 12%. A confirmation procedure based on hemiacetal derivative formation on a thin layer chromatographic plate is also described.

Collaborative study of a method for chemical confirmation of the identity of aflatoxin

The chemical method for confirmation of the identity of aflatoxin by derivative formation directly on the TLC plate was studied collaboratively by 8 participants. The results show that aflatoxin B-1 was confirmed in 17 of 17 sample extracts representing 15 mu-g aflatoxin B-1/kg peanut butter, in 13 of 16 extracts representing 5 mu-g/kg, and in none of the 7 aflatoxin-free extracts. Collaborators commented that the method was easily performed and gave good results. The method has been adopted as official first action.

Derivative Method for Chemical Confirmation of Identity of Aflatoxin M1

A very sensitive chemical confirmatory test for aflatoxin M1, involving the formation of 2 derivatives, has been developed. One derivative is the acetate of M1 formed in a solution of acetic anhydride and pyridine. The other derivative is formed from the acetate, using water a n d HCl, and is probably the hemiacetal. The derivatives are detected as fluorescent spots on TLC. The derivatives have been formed and detected from 1 ng aflatoxin M1 and from M1 isolated from milk, urine, and mold culture