Effect of pressure cooking on aflatoxin B1 in rice

The effect of pressure cooking on aflatoxin residues in polished rice was conducted to determine reduction of aflatoxin and mutagenic potentials. Three rice lots consisting of naturally contaminated, A. parasiticus-infested, and aflatoxin-spiked rice were steamed by ordinary and pressure cookers after they were washed with water. They were chemically analyzed for aflatoxins using a silica solid phase extraction tube and high-performance liquid chromatography (HPLC)-fluorescence detection (FD), and the presence of aflatoxin residues was confirmed using HPLC-electrospray ionization (ESI)-mass spectrometry (MS). An in vitro mutagenicity test with Salmonella typhimurium TA100 was employed to verify the results based on chemical analyses. The aflatoxin loss (78-88%) was notable after pressure cooking, and the reduction of aflatoxin-induced mutagenic potential (68-78%) was in good agreement with the HPLC results. It can be concluded that Koreans are safe from the aflatoxin-related risk if a pressure cooker is employed for cooking rice. The average Korean daily intake of aflatoxin through the consumption of staple rice would fall to 0.15 ng/kg bw/day, which would not exceed the established tolerable daily intake (0.40 ng/kg bw/day).     

Survey of aflatoxins, ochratoxin A, zearalenone, and sterigmatocystin in some Brazilian foods by using multi-toxin thin-layer chromatographic method

A previously published method for ochratoxin A was evaluated and proved appropriate for simultaneous determination of aflatoxins, ochratoxin A, sterigmatocystin, and zearalenone, with considerable savings in time and reagent costs. The detection limits were 2, 5, 15, and 55 micrograms/kg, respectively. The recoveries and coefficients of variation obtained with artificially contaminated samples were 91-101% and 0-16% for aflatoxin B1, 98-117% and 0-17% for sterigmatocystin, and 96-107% and 0-17% for zearalenone, respectively. The coefficients of variation for naturally contaminated samples (aflatoxins in rice and ochratoxin A in beans) ranged from 0 to 8%. The method was used to survey 296 samples that included 10 cultivars of dried beans, 8 types of corn products, 3 types of cassava flour, and both polished and parboiled rice between May 1985 and June 1986 in Campinas, Brazil. Only aflatoxin B1 (9 samples, 20-52 micrograms/kg), aflatoxin G1 (4 samples, 18-31 micrograms/kg), and ochratoxin A (5 samples, 32-160 micrograms/kg) were found. The average contamination percentage was 4.7%; beans showed the highest (6.6%) and rice showed the lowest (3.3%) incidence rates. Zearalenone and sterigmatocystin were not detected. Positive samples were confirmed by chemical derivatization, corroborated by development in 3 solvent systems.     

Screening and quantitation of ochratoxin A in corn, peanuts, beans, rice, and cassava

To answer the need for simple, economical, rapid methods for mycotoxins, a procedure for screening and quantitation of ochratoxin A was developed. A methanol-aqueous KCl extraction is used, followed by cleanup with clarifying agents and partition into chloroform. Part of the chloroform extract is used for screening and the other part for quantitation by thin layer chromatography (TLC). The screening procedure takes 40 min, using a silica gel/aluminum oxide minicolumn developed for this purpose. The limits of detection are 80 and 10 micrograms/kg, respectively, for minicolumn screening and TLC quantitation. Ammonium sulfate is efficient in cleaning samples of corn and cassava; cupric sulfate is better with peanuts, beans, and rice. Tests were conducted on triplicate spiked samples of yellow corn meal, raw peanuts, dried black beans, polished rice, and cassava flour at different levels (400, 200, 80, 40, and 10 micrograms/kg). Recoveries ranged from 86 to 160% and the coefficients of variation ranged from 0 to 26%.     

Dietary acrylamide exposure estimates for the United Kingdom and Ireland: comparison between semiprobabilistic and probabilistic exposure models

Since the discovery of acrylamide in foods, there have been many calculations of dietary exposure. Total diet studies have been commonly used to estimate consumer exposure of acrylamide; however, these often fall short in evaluating true exposure levels because of limitations in small occurrence data sets. Dietary exposure to acrylamide can also be estimated by use of modeling packages. The U.K. Food Standards Agency and the Food Safety Authority of Ireland have prepared estimates for dietary acrylamide exposure using semiprobabilistic and probabilistic modeling. Occurrence data were obtained from the European Union acrylamide monitoring database, whereas consumption data were obtained from the relevant U.K. and Irish National Diet and Nutrition Surveys. The mean adult U.K. consumer exposure was estimated as 0.61 microg/kg of body weight (bw)/day and high-level adult consumer exposure (P97.5) as 1.29 microg/kg of bw/day. The mean adult Irish consumer exposure was estimated as 0.59 microg/kg of bw/day and the high-level adult consumer exposure (P97.5) as 1.75 microg/kg of bw/day. Owing to the wide range of acrylamide levels in foods, semiprobabilistic modeling does not always provide an accurate picture of dietary exposure levels and patterns. Therefore, a comparison of semiprobabilistic assessments to probabilistic assessments of U.K. and Irish dietary exposure estimates of certain food groups is provided.     

Perfluorinated compounds in human blood, water, edible freshwater fish, and seafood in China: daily intake and regional differences in human exposures

Despite the growing public interest in perfluorinated compounds (PFCs), very few studies have reported the sources and pathways of human exposure to these compounds in China. In this study, concentrations of 10 PFCs were measured in human blood, water (tap water and surface water), freshwater fish, and seafood samples collected from China. On the basis of the data, we calculated daily intakes of PFCs, regional differences in human exposures, and potential risks associated with ingestion of PFCs from diet, drinking water, and indoor dust for the Chinese population. Perfluorooctane sulfonate (PFOS) was the most predominant PFC found with a mean concentration of 12.5 ng/mL in human blood from Tianjin and 0.92 ng/g wet wt in freshwater fish and seafood; perfluorooctanoic acid (PFOA) was the major PFC found in drinking water at a concentration range of 0.10 to 0.92 ng/L. The estimated daily intake of PFOS and PFOA via fish and seafood consumption (EDI(fish&seafood)) ranged from 0.10 to 2.51 and 0.13 to 0.38 ng/kg bw/day, respectively, for different age groups (i.e., toddlers, adolescents and children, and adults) from selected locations (i.e., Tianjin, Nanchang, Wuhan, and Shenyang). The EDI(fish&seafood) of PFCs decreased (p < 0.05) with age. The estimated daily intake of PFOS and PFOA via drinking water consumption (EDI(drinking water)) ranged from 0.006 to 0.014 and 0.010 to 0.159 ng/kg bw/day, respectively. Comparison of EDI(fish&seafood) and EDI(drinking water) values with those of the modeled total dietary intake (TDI) of PFCs by adults from Tianjin, Nanchang, Wuhan, and Shenyang showed that contributions of fish and seafood to TDI of PFOS varied depending on the location. Fish and seafood accounted for 7%, 24%, 80%, and 84% of PFOS intake in Nanchang, Shenyang, Wuhan, and Tianjin, respectively, suggesting regional differences in human exposure to PFOS. Drinking water was a minor source of PFOS (<1%) exposure in adults from all the study locations.     

Simultaneous extraction and fractionation and thin layer chromatographic determination of 14 mycotoxins in grains.

A simple, systematic analytical method for multiple mycotoxins was developed for detecting 14 mycotoxins; aflatoxins B1, B2, G1, and G2, sterigmatocystin, T-2 toxin, diacetoxyscirpenol, neosolaniol, fusarenon X, zearalenone, ochratoxin A, citrinin, luteoskyrin, and rugulosin. These mycotoxins were extracted with 20% H2SO4-4% KCl-acetonitrile (2 + 20 + 178), defatted with isooctane, and transferred to chloroform. The chloroform extract was cleaned up by silica gel column chromatography; the first 10 toxins were eluted with chloroform-methanol (97 + 3) and the remaining 4 toxins with benzene-acetone-acetic acid (75 + 20 + 5). Each fraction was analyzed by thin layer chromatography for the final determination. The method has been applied to polished rice, rough rice, corn, wheat, and peanuts as an analytical screening procedure. The detection limits in these commodities ranged from 10.00 to 800.0 microgram/kg, depending on the mycotoxin, but all limits were superior to those obtained for the individual mycotoxins by using other methods.     

Levels of perfluorinated compounds in food and dietary intake of PFOS and PFOA in the Netherlands

This study presents concentrations of perfluorinated compounds in food and the dietary intake of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in The Netherlands. The concentrations of perfluorinated compounds in food were analyzed in pooled samples of foodstuffs randomly purchased in several Dutch retail store chains with nation-wide coverage. The concentrations analyzed for PFOS and PFOA were used to assess the exposure to these compounds in The Netherlands. As concentrations in drinking water in The Netherlands were missing for these compounds, conservative default concentrations of 7 pg/g for PFOS and 9 pg/g for PFOA, as reported by European Food Safety Authority, were used in the exposure assessment. In food, 6 out of 14 analyzed perfluorinated compounds could be quantified in the majority of the food categories (perfluoroheptanoic acid (PFHpA), PFOA, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoro-1-hexanesulfonate (PFHxS), and PFOS). The highest concentration of the sum of these six compounds was found in crustaceans (825 pg/g product, PFOS: 582 pg/g product) and in lean fish (481 pg/g product, PFOS: 308 pg/g product). Lower concentrations were found in beef, fatty fish, flour, butter, eggs, and cheese (concentrations between 20 and 100 pg/g product; PFOS, 29-82 pg/g product) and milk, pork, bakery products, chicken, vegetable, and industrial oils (concentration lower than 10 pg/g product; PFOS not detected). The median long-term intake for PFOS was 0.3 ng/kg bw/day and for PFOA 0.2 ng/kg bw/day. The corresponding high level intakes (99th percentile) were 0.6 and 0.5 ng/kg bw/day, respectively. These intakes were well below the tolerable daily intake values of both compounds (PFOS, 150 ng/kg bw/day; PFOA, 1500 ng/kg bw/day). The intake calculations quantified the contribution of drinking water to the PFOS and PFOA intake in The Netherlands. Important contributors of PFOA intake were vegetables/fruit and flour. Milk, beef, and lean fish were important contributors of PFOS intake.     

Ochratoxin a contamination in italian wine samples and evaluation of the exposure in the italian population

The scope of this study was to evaluate the exposure of the Italian population to ochratoxin A (OTA) attributable to wine consumption. With this aim 1166 wine samples (773 red wines, 290 white, 75 rose, and 28 dessert wines), collected in 19 different Italian regions and mostly produced between 1988 and 2004, were analyzed for OTA content. The obtained results are reported by year of harvest, geographical area of production, and type of wine. Red wine showed the highest maximum level of contamination (7.50 ng/mL), even though rose wines were characterized by a higher mean value (0.01 ng/mL). A gradually increasing mean concentration was also observed from the north (0.05 ng/mL) to south of Italy (0.54 ng/mL). Exposure calculations, performed using two different consumption databases, indicate a daily intake for consumer only of 0.59 up to 1.24 ng/(kg of b.w.)/day and of 0.33 up to 0.90 ng/(kg of b.w.)/day for the total population. Even in the worst case, corresponding to the calculation of the intake for consumers only in southern Italy and Islands and considering the mean consumption data increased by 1 standard deviation, a quite low exposure (1.68 ng/(kg of b.w.)/day, accounting for 9.8% of TDI) was obtained. Considering the overall OTA dietary exposure, obtained exposure rates indicate that wine did not pose a risk to the Italian population health.     

Analysis of Ferulic and p‐Coumaric Acids in Japanese Rice for Sake Brewing

Ferulic and p‐coumaric acids were analyzed in 50 rice (Oryza sativa L.) samples from 32 cultivars harvested in Japan. In brown rice, ferulic and p‐coumaric acid levels ranged from 309 to 607 mg/kg and from 49 to 100 mg/kg, respectively. In 70% polished rice, ferulic and p‐coumaric acid levels ranged from 27 to 103 mg/kg and from 0.4 to 3.5 mg/kg, respectively. Ratios of average phenolic acid levels in the 70% polished rice to the brown rice were 13.9% for ferulic acid and 1.9% for p‐coumaric acid. The ferulic acid level was highly correlated between brown and 70% polished rice (R = 0.815; P < 0.01), but there was no clear correlation for p‐coumaric acid. Phenolic acid levels in the 70% polished rice did not show any clear correlations between the analytical index measurements for sake brewing suitability (weight of 1,000 grains, water absorption, digestibility, crude protein, and potassium content). Phenolic acid levels in the 70% polished rice directly affected levels in the rice koji enzyme digest. The results indicated that phenolic acid levels in sake were affected by the levels in ingredient rice grains, which may then influence the sensory quality of sake.     

Polybrominated diphenyl ethers (PBDEs) in foodstuffs: human exposure through the diet

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in a variety of materials, including synthetic polymers and textiles. Although these chemicals have been detected in environmental samples and human tissues, there is little information about human exposure to PBDEs through the diet. In the present study, we determined the concentrations of PBDEs in a number of food samples acquired in Catalonia (Spain) during 2000. The dietary intake of PBDEs was estimated for the general population living in this Spanish region. The highest PBDE concentrations were found in oils and fats, fish and shellfish, meat and meat products, and eggs, while the lowest levels corresponded to fruits, vegetables, and tubers. The dietary intake of PBDEs for an adult male was 97.3 ng/day (assuming not detected (ND) = (1)/(2) limit of detection (LOD)) or 81.9 ng/day (assuming ND = 0) The greatest contribution to these values corresponded to fish and shellfish, with approximately one-third of the total intake. TetraBDEs and pentaBDEs were the homologues showing the highest percentages of contribution to the sum of total PBDEs. The comparison of the current dietary intake with the suggested lowest observed adverse effect level value of 1 mg/kg/day for the most sensitive endpoints for toxic effects of PBDEs results in a safety factor over 5 orders of magnitude in relation to PBDE exposure from food.     

Human exposure to perfluorinated chemicals through the diet: intake of perfluorinated compounds in foods from the Catalan (Spain) market

The aim of this study was to determine the dietary intake of perfluorinated chemicals (PFCs) by the population of Tarragona County (Catalonia, Spain). PFC levels were determined in 36 composite samples of foodstuffs randomly purchased in various locations. Exposure to PFCs through the diet was estimated for various age/gender groups. Perfluorooctane sulfonate (PFOS), perfluorocarboxylate perfluorooctanoate (PFOA), and perfluoroheptanoic acid (PFHpA) were the only detected PFCs in foodstuffs. On average, for a standard adult man (70 kg of body weight), the dietary intake of PFOS was estimated to be 62.5 or 74.2 ng/day (assuming ND=0 or ND=1/2 LOD, respectively). Fish, followed by dairy products and meats, were the main contributors to PFOS intake. For an adult man, the intake of PFOS (1.07 ng/kg/day) and those of PFOA and PFHpA were lower than that recently reported for Canada (4.0 ng/kg/day), and considerably lower than that previously found in the United Kingdom, the only two countries where, to date, results concerning this issue have been reported. A correlation between dietary intake and blood levels of PFOS is suggested. However, the current results do not justify dietary intake as the main route of exposure governing blood concentrations of other PFCs.     

Distribution of total aflatoxins in milled fractions of hulled rice

Two varieties of hulled rice artificially contaminated with aflatoxins at five different levels were processed by dehulling and polishing methods. Contamination levels ranged from 356 to 818 microg/kg and from 244 to 645 microg/kg in medium and long grain rice, respectively. After physical processing, four different milled fractions were obtained (hull, bran, polished broken grains, and polished whole kernels). The fractions were analyzed for total aflatoxins (B1, B2, G1, and G2) by enzyme-linked immunosorbent assay (ELISA). Aflatoxins were removed in fractions intended for human consumption (polished broken grains and polished whole kernels) at rates up to 97%. They were found throughout all fractions, but higher contamination levels were detected in hull and bran fractions than in unprocessed kernels and polished fractions. Regardless of the rice variety, the aflatoxin distribution pattern depended on the initial contamination level and type of milled fraction but not on the duration of polishing.     

Mycotoxins in grain dust: method for analysis of aflatoxins, ochratoxin A, zearalenone, vomitoxin, and secalonic acid D

A multimycotoxin method is presented to quantitate aflatoxins, ochratoxin A, zearalenone, secalonic acid D, and vomitoxin in grain dust. Dust spiked with these mycotoxins was extracted sequentially with methylene chloride followed by acetonitrile-water (86 + 14). Vomitoxin was recovered in the latter extract and all other mycotoxins were recovered in the methylene chloride. Aflatoxins and ochratoxin were quantitated by fluorescence measurement on silica thin layer chromatographic plates. The other mycotoxins were quantitated after cleanup by reverse phase liquid chromatography and ultraviolet detection. Recoveries from dust spiked in the parts per billion (ng/g) range were approximately 80% (SD = 15-29%) for all mycotoxins. Minimum detectable amounts ranged from less than 0.5 ng/g for aflatoxins to 20 ng/g for zearalenone.     

硒对镉胁迫下寒地水稻镉含量与分配的影响

【目的】研究施硒对不同镉污染土壤上镉在水稻各器官中的分配及稻米中镉含量的影响,探讨通过施硒降低水稻镉吸收量及在稻米中分配的可行性。【方法】采用盆栽试验,以垦鉴稻6号为材料,研究添加不同浓度镉(0、2、4和8 mg/kg土壤)的条件下,施硒(0、0.07和0.14 mg/kg土壤)对水稻不同器官镉含量和镉分配的影响。成熟期整盆收获,分别测定叶片、叶鞘、茎秆、根系和糙米、精米镉含量、硒含量和干物重,计算镉积累量和分配比例。【结果】1)当土壤镉浓度在0 4 mg/kg时,水稻各营养器官和糙米、精米中镉含量随土壤镉浓度增高而显著增加,但当土壤中镉浓度4 mg/kg时,糙米和精米中镉含量增加不显著。未施硒(Se0)时,Cd2(4 mg/kg)和Cd3(8mg/kg)处理糙米中镉含量分别为0.221 mg/kg和0.234 mg/kg,分别是Cd0处理的15.8和16.7倍,均超过我国国家食品安全标准中稻米镉的限量(0.2 mg/kg),精米镉含量未超过国家食品安全规定的限量,Cd3处理精米中镉含量最高,为0.174 mg/kg。2)相同镉浓度下,随着硒浓度的增加,水稻各营养器官和糙米、精米的镉含量和镉积累量均显著下降,糙米和精米的镉含量均低于我国国家食品安全规定的稻米镉限量,且Se2(0.14 mg/kg)处理优于Se1(0.07 mg/kg)处理。其中Cd1(2 mg/kg)浓度时,Se2处理的精米镉含量下降幅度最大,比Se0降低31.5%(P0.01)。3)镉在各器官中的分配比例为根系茎鞘稻谷叶片。随着硒浓度的增加,镉在根系中的分配比例增加,在地上部的分配比例减少,在稻壳中的分配比例增加,在精米中的分配比例下降。在Cd1浓度时,根系镉分配比例范围为60.9%67.8%,稻谷镉分配比例为12.6%13.8%;Se2处理稻壳中镉分配比例比Se0增加5.2个百分点,而精米中镉分配比例则下降了6.2个百分点。4)相同镉浓度下,随着硒浓度的增加,植株各营养器官干物重均增加,Se2处理对干物重的影响优于Se1处理。Cd1、Cd2和Cd3浓度下,Se2处理比Se0处理稻谷干物重分别增加了6.4%(P0.01)、5.2%(P0.05)和11.3%(P0.01)。【结论】施硒可降低镉污染土壤上水稻各营养器官和糙米、精米的镉含量,并能显著降低精米中镉的分配比例,保证稻米的食用安全性,尤其在Cd加入量为2mg/kg土浓度下,施硒效果最显著,以施Se量为0.07 mg/kg处理的效果最好。     

Natural occurrence of ochratoxin A and antioxidant activities of green and roasted coffees and corresponding byproducts

Ochratoxin A is an important mycotoxin that can enter the human food chain in cereals, wine, coffee, spices, beer, cocoa, dried fruits, and pork meats. Coffee is one of the most common beverages and, consequently, it has a potential risk factor for human health related to ochratoxin A exposure. In this study, coffee and corresponding byproducts from seven different geographic regions were investigated for ochratoxin A natural occurrence by HPLC-FLD, nutritional characterization, and antioxidant activities by spectrophotometric assay. The research focused on composition changes in coffee during the processing step "from field to cup". Costa Rica and Indian green coffees were the most contaminated samples, with 13 and 11 microg/kg, respectively, while the Ethiopian coffee was the least contaminated, with 3.8 microg/kg of ochratoxin A. The reduction of ochratoxin A contamination during the roasting step was comparable for any samples that were considered under the recommended level of 4 microg/kg. Total dietary fibers ranged from 58.7% for Vietnam and 48.6% for Ivory Coast in green coffees and ranged from 58.6% for Costa Rica to 61.2% for India in roasted coffee. Coffee silverskin byproduct obtained from Ivory Coast was the highest, with 69.2 and 64.2% of insoluble dietary fibers, respectively.     

Effects of chronic ingestion of ochratoxin a on blood levels and excretion of the mycotoxin in sheep

Ruminants are relatively resistant to the acutely toxic effects of ochratoxin A, due to extensive degradation of ochratoxin A to its less toxic metabolite ochratoxin alpha by rumen microorganisms. However, most estimates of the degradation capacity for ochratoxin A in ruminants are based on in vitro studies. In the current study, the metabolism of ochratoxin A was investigated over a period of 29 days, feeding various doses of the mycotoxin (0, 9.5, 19.0, and 28.5 mug ochratoxin A/kg body weight) to sheep. Animals were fed diets consisting of 70% concentrates and 30% grass silage. Significant concentrations of undegraded ochratoxin A were detected in serum of sheep at all levels of ochratoxin A tested. Serum concentrations of ochratoxin A slightly accumulated with time of exposure and were linearly dependent on the administered dose of ochratoxin A. Furthermore, a constant proportion (6-8%) of the dose was excreted in the urine. The results of this study indicate that even at moderate to low levels of ochratoxin A in the diet, considerable amounts of the mycotoxin are absorbed by ruminants and may accumulate in tissues. Therefore, feeding of ochratoxin A-contaminated feedstuffs to ruminants does not seem to be a reliable means for using these feedstuffs.     

Exposure to mercury in Canada: A multimedia analysis

A thorough assessment of Canadian exposure to mercury (Hg) has not been undertaken since 1970. A multimedia approach was used to update estimates of Hg exposure to members of the general population in Canada, based on currently available information. Adult Canadians have an estimated intake of all Hg species via all routes of 7.7μg/day (0.11μg/kg body weight/day), which equated to an absorbed dose of 5.3μg/day (0.076μg/kg bw/day). Fish consumption accounts for much of this exposure (27% of intake, 40% of absorbed dose), in the form of methylmercury. However, dental amalgam appears to account for a greater proportion of total Hg exposure than fish consumption. Exposure from amalgam was estimated for intake and absorbed doses (of Hg⁰) at 2.81 and 2.25μg/day, respectively. This represents 36% of total Hg intake and 42% of absorbed dose. Hg²⁺ arises principally from foods other than fish. Intake of Hg²⁺ by adults was determined to be 1.82μg/day and absorbed dose only 0.18μg/day. Exposures for four other age groups of the population were also evaluated.     

Application of manual and automated systems for purification of ochratoxin a and zearalenone in cereals with immunoaffinity columns.

A manual vacuum manifold and an automated solid phase extraction (ASPEC) system were applied for purification of ochratoxin A and zearalenone in wheat, rye, barley, and oat samples with immunoaffinity columns followed by separation with a high-performance liquid chromatograph and fluorescence detection. The immunoaffinity columns for manual sample purification were purchased from a different manufacturer than were those for the automated system. The limit of detection (LOD) for the method for ochratoxin A with a vacuum manifold and ASPEC was 0.1 microg/kg. For the method for zearalenone, the LODs were 1.5 microg/kg with a vacuum manifold and 3 microg/kg with ASPEC. For the methods for ochratoxin A at spiking levels of 0.6 and 2.5 microg/kg, mean recoveries for different cereals varied from 68 to 106%. For the methods for zearalenone, mean recoveries varied from 78 to 117% at spiking levels of 9 and 25 microg/kg. The relative standard deviations of repeatability with various cereals employing both methods were 2-15 and 2-19% for ochratoxin A and zearalenone, respectively.     

南方6省稻米总汞含量调查及其膳食暴露评估

为评价中国南方6省稻米中总汞污染现状,于2009年在江西、湖北、湖南、广东、广西和四川6省抽样检测了1 321份稻米样品,结合中国居民20个性别年龄组人群的稻米消费量和体重信息,采用非参数概率方法对稻米中总汞的膳食暴露量进行了评估。总汞含量采用电感耦合等离子体质谱仪（ICP-MS）测定,检出限（LOD）为0.000 8 mg.kg-1。结果表明,稻米的总汞含量在地区间存在着差异,虽然有76.2%的样本总汞含量（0.000 8～0.063 4 mg.kg-1）高于检出限,但仅有2.3%的样本超出了最高限量（ML 0.02mg.kg-1）。将评估结果比照JECFA推荐的总汞暂定每周耐受摄入量（PTWI）5μg.（kg bw）-1,我国居民食用这6省稻米产生的汞暴露风险较小。但在P99.9的高百分位水平下,14岁以下人群的摄入量相对较高,占PTWI的41.5%～62.9%,其中2～4岁儿童和4～7岁男童的摄入量占PTWI的60%以上,潜在风险较大。建议应对稻米中重金属汞的含量进行追踪监测。     

Co-occurrence of ochratoxin A and citrinin in cereals from Bulgarian villages with a history of Balkan endemic nephropathy

Cereal samples were collected in 1998 from Bulgarian villages without [control village (C), n = 20] or with [endemic villages (E); E1, n = 21; E2, n = 30; E3, n = 23] a history of Balkan endemic nephropathy (BEN). Sampling included foods (wheat, corn) and feeds (barley, oats, wheat bran). Analysis of ochratoxin A and citrinin was done by enzyme immunoassays (EIA), with detection limits of 0.5 and 5 ng/g, respectively. Ochratoxin A-positive results were confirmed by HPLC after immunoaffinity chromatography. Highest toxin levels were found in wheat, wheat bran, and oats. For ochratoxin A, the percentages of positives were 35% (C), 29% (E1), 30% (E2), and 47% (E3), the mean/median values of positives were 1.5/1.3 ng/g (C), 11/1.6 ng/g (E1), 18/1.6 ng/g (E2), and 3.5/1.5 ng/g (E3). For citrinin, 5.0% (C), 14% (E1), 3.3% (E2), and 13% (E3) were positive, and the mean/median values were 6.1/6.1 ng/g (C), 180/83 ng/g (E1), 10/10 ng/g (E2), and 84/20 ng/g (E3). Highest concentrations of ochratoxin (maximum = 140 ng/g) and citrinin (maximum = 420 ng/g) were found in samples from endemic villages. Co-contamination with ochratoxin A and citrinin was found for one sample (14% of positives) from village C and for six samples (22% of positives) from villages E1-E3. Citrinin levels in these samples were 2-200 times higher than those of ochratoxin A.