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1.
ABSTRACT

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants whose use has contaminated foods and caused subsequent human exposures. To address the issue of possible human exposure, samples from a 2012–13 US meat and poultry (beef, pork, chicken, turkey) study were analysed for seven PBDEs. The mean summed concentrations of the seven BDE congeners (ΣPBDE) from beef, pork, chicken and turkey were 0.40, 0.36, 0.19, and 0.76 ng g–1 lipid weight (lw). The range of ΣPBDEs for all meat classes was 0.01–15.78 ng g–1 lw. A comparison of this study with a 2007–08 study revealed a decline in the median ΣPBDEs for all four meat classes, a reduction of 25.9% to 70.0%, with pork, chicken and turkey PBDE residues being statistically lower relative to the 2007–08 study. BDEs 47 and 99 contributed the most to the ΣPBDE concentrations, indicating likely animal exposures to the penta-BDE formulation. Based on the reported data an estimate of US consumer daily intake of PBDEs from meat and poultry was 6.42 ng day–1.  相似文献   

2.
ABSTRACT

Meat and meat products are included in a great number of human diets. However, the great consumption of meat needs to be controlled for the presence of traces of contaminants. The European Commission has not stated maximum limits for some environmental pollutants such as the perfluoroalkyl substances (PFASs) and polybrominated diphenyl ether (PBDE); the European Food Safety Authority (EFSA) Scientific Panel has recommended that more occurrence data for PFASs in food should be collected to improve the accuracy of future exposure calculations. Therefore, the distribution of PFASs and PBDEs trace contaminants from eight EU Member States were investigated through liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) and Gas Chromatography-Mass Spectrometry (GC-MS/MS). No PFASs were detected, except perfluorooctanoic acid, in only one Austrian sample at the concentration of 0.531 ng g?1. PBDEs were detected in 3 out of 77 samples: one from Germany showed the presence of all congeners analysed in the concentration range 0.53–0.77 ng g?1, the others, from Netherland and Italy, respectively contained PBDE 153 (0.53 ng g?1) and PBDE 100 (0.62 ng g?1). The results show that the analysed samples do not pose a risk for human beings in regard to PFASs and PBDEs. Further studies are needed to keep monitoring their presence in foodstuff, as it has been suggested by European Commission.  相似文献   

3.
A survey on 73 milk samples from different animal breeds and 24 dairy products samples from Sicily, Italy, was carried out for the presence of aflatoxin M1 (AFM1) by LC-fluorescence detection after immunoaffinity cleanup. AFM1 was detected in 48% and 42% of the milk and dairy samples at concentration ranges between <5.0–16.0 and <5.0–18.0 ng L?1, respectively. Within the raw milk samples, 92% had an AFM1 content below 5.0 ng L?1, in 7% of the cases it was in the range 5.0–10.0 ng L?1 and 1% was contaminated between 10.0 and 20.0 ng L?1. For the dairy products, ultra-high-temperature treated (UHT) milk, milk cream and cheese, the incidence was 42%, of which 83% contained less than 5.0 ng L?1 and 17% contained 10.0–20.0 ng L?1 AFM1. The levels of contamination found justify continuous monitoring for public health and to reduce consumer exposure.  相似文献   

4.
Aflatoxin M1 contamination in dairy products is a risk when feedstuff contaminated with aflatoxin B1 produced by moulds is consumed by milk-producing animals. Milk can be screened for aflatoxin M1 at the European Union maximum limit of 50 ng l?1 by a lateral flow test, the MRLAFMQ (Aflatoxin M1) Test. The method takes 15 min with no milk dilution or a sample preparation step. The lateral flow assay was validated at the Technology and Food Science Unit of the Institute for Agricultural and Fisheries Research (ILVO-T&V) according to European Union guidelines using fortified raw milk samples. A detection capability of 50 ng l?1 was demonstrated with a false negative rate lower than 2% at 50 ng l?1 and a false positive rate of less than 0.3%. Quantitative readings had a mean bias of +2 to 6 ng l?1 at 50 ng l?1 with a standard deviation of 5–8 ng l?1. Based on the validation results, the test could be considered appropriate for milk screening prior to milk unload at dairies.  相似文献   

5.
The presence of aflatoxin M1 (AFM1) in milk was assessed in Italy in the framework of designing a monitoring plan actuated by the milk industry in the period 2005–10. Overall, 21 969 samples were taken from tankers collecting milk from 690 dairy farms. The milk samples were representative of the consignments of co-mingled milk received from multiple (two to six) farms. Systematic, biweekly sampling of consignments involved each of the 121 districts (70 in the North, 17 in the Central and 34 in the South regions of Italy). AFM1 concentration was measured using an enzyme-linked immunoassay method (validated within the range of 5–100 ng kg?1) whereas an HPLC method was used for the quantification of levels in the samples that had concentrations higher than 100 ng kg?1. Process control charts using data collected in three processing plants illustrate, as an example, the seasonal variation of the contamination. The mean concentration of AFM1 was in the range between 11 and 19 ng kg?1. The 90th and 99th percentile values were 19–34 and 41–91 ng kg?1, respectively, and values as high as 280 ng kg?1 were reached in 2008. The number of non-compliant consignments (those with an AFM1 concentration above the statutory limit of 50 ng kg?1) varied between 0.3% and 3.1% per year, with peaks in September, after the maize harvest season. The variability between different regions was not significant. The results show that controlling the aflatoxins in feed at farm level was inadequate, consequently screening of raw milk prior to processing was needed. The evaluation of the AFM1 contamination level observed during a long-term period can provide useful data for defining the frequency of sampling.  相似文献   

6.
ABSTRACT

Hens’ eggs collected in home-producing farms located in different areas of the Campania region of southern Italy were analysed for six NDL-polychlorobiphenyls (PCB indicators), 17 polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs), and 12 congeners of dioxin-like PCBs (DL-PCBs). In the investigated area, waste from civil, industrial and hospital activities was illegally dumped and in many cases burned, so the area is called the ‘Land of fire’. This illicit practice has been considered the main source of pollution in this territory and the cause of the persistent organic pollutants’ (POPs) contamination in the neighbouring lands intended for agricultural use and livestock. The results, which were obtained from the analysis of 56 samples of eggs, showed levels of contamination by dioxins and PCBs that have often exceeded the action levels set by European Union Recommendation 711/2013 and sometimes even exceeded the maximum levels set by Commission Regulation (EU) 1259/2011. The median PCDD/Fs was 0.41 pg TEQ g?1 fat (range = 0.01–6.18 pg TEQ g?1 fat) and the median concentration of DL-PCBs was 0.70 pg TEQ g?1 fat (range = 0.01–14.60 pg TEQ g?1 fat), whereas NDL-PCBs median was 7.35 ng g?1 fat (range = 0.48–67.55 ng g?1 fat). Nevertheless, the estimated weekly intake (EWI) calculated for consumers of eggs home produced in Campania is lower than the tolerable weekly intake (TWI) established by the European Union Scientific Committee on Food (SCF).  相似文献   

7.
Maize silage has become the major forage component in the ration of dairy cows over the last few decades. This review provides information on the mean content and variability in chemical composition, fatty acid (FA) profile and ensiling quality of maize silages, and discusses the major factors which cause these variations. In addition, the effect of the broad range in chemical composition of maize silages on the total tract digestibility of dietary nutrients, milk production and milk composition of dairy cows is quantified and discussed. Finally, the optimum inclusion level of maize silage in the ration of dairy cows for milk production and composition is reviewed. The data showed that the nutritive value of maize silages is highly variable and that most of this variation is caused by large differences in maturity at harvest. Maize silages ensiled at a very early stage (dry matter (DM) < 250 g kg?1) were particularly low in starch content and starch/neutral detergent fibre (NDF) ratio, and resulted in a lower DM intake (DMI), milk yield and milk protein content. The DMI, milk yield and milk protein content increased with advancing maturity, reaching an optimum level for maize silages ensiled at DM contents of 300–350 g kg?1, and then declined slightly at further maturity beyond 350 g kg?1. The increases in milk (R2 = 0.599) and protein (R2 = 0.605) yields with maturity of maize silages were positively related to the increase in starch/NDF ratio of the maize silages. On average, the inclusion of maize silage in grass silage‐based diets improved the forage DMI by 2 kg d?1, milk yield by 1.9 kg d?1 and milk protein content by 1.2 g kg?1. Further comparisons showed that, in terms of milk and milk constituent yields, the optimum grass/maize silage ratio depends on the quality of both the grass and maize silages. Replacement of grass silage with maize silage in the ration, as well as an increasing maturity of the maize silages, altered the milk FA profile of the dairy cows, notably, the concentration of the cis‐unsaturated FAs, C18:3n‐3 and n‐3/n‐6 ratio decreased in milk fat. Despite variation in nutritive value, maize silage is rich in metabolizable energy and supports higher DMI and milk yield. Harvesting maize silages at a DM content between 300 and 350 g kg?1 and feeding in combination with grass silage results in a higher milk yield of dairy cows. © 2014 Society of Chemical Industry  相似文献   

8.
A total of 225 maize kernel samples were collected from Shandong Province in China from 2012 to 2014 and analysed for contamination with Fusarium spp. and fumonisins (FBs) using molecular methods and high-performance liquid chromatography with fluorescence detection. The results showed that the average incidences of Fusarium spp. in 2012, 2013 and 2014 were 23.3%, 37.1% and 36.5%, respectively, Fusarium verticillioides being the predominant species. In 2012, the average contamination level of FBs was 3071 ng g?1, which was higher than that in 2014 (2913 ng g?1) and 2013 (2072 ng g?1). Of all samples, 13% and 19% had FB contamination levels higher than 2000 and 4000 ng g?1, which are the maximum limits as set by the Food and Drug Administration of the United States and the European Commission, respectively. Therefore, efforts should be taken to minimise the potential risk of FBs to the health of humans and animals.  相似文献   

9.
During 2016–2017, 156 samples of fresh milk samples were collected from local markets of Karachi, Pakistan and analysed for aflatoxin M1 (AFM1) contamination using ELISA technique. AFM1 was detected in 143 (91.7%) samples, ranged from 20 to 3090 ng L?1 with a mean level of 346.2 ng L?1. In 125 (80.1%) samples, the AFM1 contamination was greater than the maximum limit (ML = 50 ng L?1) set by EU. However, in 51 (32.7%) samples, the AFM1 level was higher than the ML of 500 ng L?1 as assigned by the USA. Statistical analysis showed that the AFM1 level in milk samples from summer was significantly (p < 0.05) higher than that obtained in winter. It was concluded that the AFM1 levels in the tested samples appear to be a serious public health problem. Therefore, immediate measures should be taken and re-evaluation done for the procedures for farming, transportation, refrigeration, and storage for the control of AFM1 level in milk samples.  相似文献   

10.
The study reports the results of testing the sensitivity of an early warning sampling plan for detecting milk batches with high aflatoxin AFM1 concentration. The effectiveness of the method was investigated by the analysis of 9017 milk samples collected in Italian milk processing plants that applied control plans with different action limits (AL). For those milk processing plants where 30 ng kg?1 AL has been applied, the AFM1 contamination was significantly lower at or above the 95th percentile of the milk samples when compared with plants that used 40 ng kg?1 AL. The results show that the control plan can be used effectively for early warning of occurrence of high AFM1 contamination of milk and to carry out pro-active measures to limit the level of contamination. Estimation of dietary exposure was also carried out, based on the aflatoxin M1 content of the milk samples and on Italian food consumption data. Estimated Daily Intakes (EDI) and Hazard Indices (HI) were calculated for different age groups of the population. HIs show that no adverse effects are expected for the adult population, but in the case of children under age three, the approximate HI values were considerably higher. This underlines the importance of the careful monitoring and control of aflatoxin M1 in milk and dairy products.  相似文献   

11.
Aflatoxin M1 (AFM1) contamination in raw milk from household cows fed with sunflower seedcakes or sunflower-based seedcake feeds was determined in 37 milk samples collected randomly from different locations in Singida region, Tanzania. Aflatoxin B1 (AFB1) contamination in sunflower-based seedcake feed was determined in 20 feed samples collected from the same household dairy farmers. The samples were analysed by RP-HPLC using fluorescent detection after immunoaffinity column clean-up. Recoveries were 88.0% and 94.5%, while the limits of detection (LOD) were 0.026 ng mL?1 and 0.364 ng g?1 for AFM1 and AFB1, respectively. Of the analysed cow’s milk samples, 83.8% (31/37) contained AFM1, with levels ranging from LOD to 2.007 ng mL?1, exceeding both the European Commission (EC) and Tanzania Food and Drug Authority (TFDA) limit of 0.05 ng mL?1. Of the contaminated samples, 16.1% exceeded the Codex Alimentarius limit of 0.5 ng mL?1. AFB1 was present in 65% (13/20) of the feed samples with levels ranging from LOD to 20.47 ng g?1, 61.53% exceeding the TFDA and EC maximum limits of 5 ng g?1 for complete dairy animal feed. The observed AFM1 and AFB1 contamination necessitates the need to raise awareness to dairy farmers in Tanzania to safeguard the health of the end-users.  相似文献   

12.
This study summarises the results of the levels of 21 perfluoroalkyl substances (PFASs) in 50 selected pooled samples representing 15 food commodities with the special focus on those of animal origin, as meat, seafood, fish, milk, dairy products and hen eggs, which are commonly consumed in various European markets, e.g. Czech, Italian, Belgian and Norwegian. A new, rapid sample preparation approach based on the QuEChERS extraction procedure was applied. Ultra-performance liquid chromatography (UHPLC) coupled to tandem mass spectrometry (MS/MS) employing electrospray ionisation (ESI) in negative mode was used for the quantification of target analytes. Method quantification limits (MQLs) were in the range of 1–10 ng kg?1 (ng l?1) for fish, meat, hen eggs, cheese and milk, and in the range of 2.5–125 ng kg?1 for butter. Only 16 of the group of 21 PFASs were found in at least one analysed sample. From 16 PFASs, perfluorooctane sulfonate (PFOS) was the most frequently detected analyte present in approximately 50% of samples (in the range of 0.98–2600 ng kg?1). PFCAs with C8–C14 carbon chain were presented in approximately 20% of samples. The concentration ranges of individual compounds in the respective groups of PFASs were: 2.33–76.3 ng kg?1 for PFSAs (without PFOS), 4.99–961 ng kg?1 for PFCAs, 10.6–95.4 ng kg?1 for PFPAs, and 1.61–519 ng kg?1 for FOSA. The contamination level in the analysed food commodities decreased in the following order: seafood > pig/bovine liver >> freshwater/marine fish > hen egg > meat >> butter. When comparing the total contamination and profiles of PFASs in food commodities that originated from various sampling countries, differences were identified, and the contents decreased as follows: Belgium >> Norway, Italy > Czech Republic.  相似文献   

13.
The aim of this study was to evaluate the seasonal variation/geographical distribution of environmental concentration of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) across Poland using butter fat as an indicator of the contaminants. The average concentration of six indicator PCBs determined in the studied samples was 1500?pg?g–1 fat. The average concentration of 12 dioxin-like PCBs expressed as lower-bound dioxin-equivalent toxicity was 0.684 pg TEQ g?1 fat. The average total concentration of 14 investigated PBDE congeners was 105?pg?g?1 fat. Statistically significant concentration differences between summer and winter samples were found. The results of this study indicate also a significant geographical diversification of butter contamination reflecting regional differences in environmental contamination. The seasonal variation of PBDE profiles evidences transformation of PBDE within the environment.  相似文献   

14.
Nitrofurazone is an antibiotic with carcinogenic properties. Efforts by regulatory authorities to control nitrofurazone from agricultural foods are an important public health measure that have, to some extent, been undermined by widespread use amongst laboratories of the unreliable marker metabolite semicarbazide. This work confirms what has long been suspected, namely that powdered dairy products that are initially free of semicarbazide develop semicarbazide under storage conditions such as occur normally across commercial supply chains. The low ng g?1 levels of semicarbazide formed in this way are insufficient to present any food safety hazard. That such development of a marker metabolite is demonstrated to occur by innocent means effectively invalidates the use of semicarbazide as a marker metabolite for powdered dairy products, and exacerbates the regulatory need for a more suitable analytical methodology. In milk, unlike meat, nitrofurazone is known to remain stable and thus available for analysis in the intact form, rather than necessitating any use of a metabolite or fragment. However, no previous methodology that was capable of achieving the stringent European minimum required performance limit of 1 ng g?1 when using intact nitrofurazone had been described for milk. This work describes a specific methodology using LC-MS/MS for milk and milk powder; it achieves detection of intact nitrofurazone (as well as furazolidone, furaltadone and nitrofurantoin) to levels well below 1 ng g?1. Laboratories will no longer need to use semicarbazide as an unreliable marker metabolite for the analysis of nitrofurazone in dairy products, paving the way for regulatory authorities to better control nitrofurazone abuse with greater confidence.  相似文献   

15.
Brominated flame retardants – polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), hexabromocyclododecane (HBCD) and others – have been measured in 11 pooled breast milk samples from 109 first-time mothers in Ireland. Additionally, the study has measured levels of polybrominated dibenzo-p-dioxins and furans (PBDD/Fs), mixed halogenated dioxins (PXCC/Fs) and biphenyls (PXBs), polychlorinated naphthalenes (PCNs) and perfluoroalkylated substances (PFAS) in these samples. The mean sum of 19 PBDEs including BDE-209 was 4.85 ng g?1 fat, which is comparable with that found in other European countries. BDE-47, BDE-153, BDE-209, BDE-99 and BDE-100 were found at the highest concentrations. The only PBBs detected consistently were BB-77, BB-126 and BB-153, with highest concentrations being found for BB-153 (mean = 0.13 ng g?1 fat). The mean sum of HBCD enantiomers was 3.52 ng g?1 fat, with α-HBCD representing over 70% of the total. Of the other brominated flame retardants – tetrabromobisphenol-A (TBBP-A), hexabromobenzene (HBB), decabromodiphenylethane (DBDPE) and bis(2,4,6-tribromophenoxyethane) (BTBPE) – examined, only TBBP-A was detected above the limit of detection (LOD), in two of the 11 pools analysed. All measured PBDF congeners were observed (at 0.02–0.91 pg g?1 fat), but 2,3,7,8-tetrabromo-dibenzodioxin (TeBDD) was the only PBDD detected, with a mean concentration of 0.09 pg g?1 fat. The occurrence of the mixed chlorinated/brominated dibenzodioxins, dibenzofurans and biphenyls, 2-B-3,7,8-CDD, 2,3-B-7,8-CDF, 4-B-2,3,7,8-CDF, PXB 105, PXB 118, PXB 126 and PCB 156 in breast milk in the current study may indicate that levels of these contaminants are increasing in the environment. Polychlorinated naphthalenes were detected in all samples, but not perfluorooctane sulfonate (PFOS) and other PFAS. The pattern of occurrence of these brominated and fluorinated persistent organic pollutants (POPs) in Irish breast milk shows a general relationship to their occurrence in food, as reported in a number of surveillance studies carried out by the Food Safety Authority of Ireland.  相似文献   

16.
Brominated dioxins (PBDD/Fs) and 17 polybrominated diphenylether (PBDE) congeners including BDE-209 were analysed in 100 composite samples of commonly consumed foods of animal origin, prepared from ten to 40 individual subsamples of each type. These included 30 samples of milk from farms; eggs from chickens; fat from cows, pigs, sheep, and poultry; and liver from cows, pigs, sheep, horses, and poultry. The ISO 17025-accredited analytical methodology used, follows similar guidelines as given for chlorinated dioxins and polychlorinated biphenyls (PCBs) in European Commission Directive 2002/69/EC. Apart from some samples of milk, PBDD/Fs and PBDEs were detected in all food types. Concentrations ranged from 0.31 µg kg?1 Σ17 PBDEs for a sample of milk to 37.5 µg kg?1 Σ17 PBDEs for a sample of liver. The corresponding range for the PBDD/F toxicity (computed using analogous PCDD/F toxic equivalency factors (TEFs)) was 0.09 ng TEQ kg?1 to approximately 3.5 ng TEQ kg?1. The detection of these compounds, in particular PBDD/Fs, is consistent with the increased use and disposal of brominated organic compounds.  相似文献   

17.
This paper reports levels of polybrominated diphenyl ethers (PBDEs) in a wide range of foods of animal origin and estimates their dietary exposure for secondary school students in Hong Kong, China. Dietary exposure to PBDEs was estimated using local food consumption data obtained from secondary school students in 2000 and the concentrations of PBDEs in food samples taken from local market in 2008. The PBDE levels on a fresh weight basis for fish ranged from 13 to 6600 pg g?1, for seafood and seafood products ranged from 15 to 1200 pg g?1, for meat and meat products ranged from 23 to 3500 pg g?1, for poultry ranged from 68 to 670 pg g?1, for eggs ranged from 280 to 800 pg g?1, and for dairy products ranged from 12 to 480 pg g?1. The dietary exposures of secondary school students for the average and high consumers were estimated to be 2.6 and 6.4 ng kg?1 body weight day?1, respectively. According to the Joint FAO/WHO Expert Committee on Food Additives (JECFA), for the more toxic PBDE congeners, adverse effects would be unlikely to occur in laboratory animals at doses of less than approximately 100 µg kg?1 body weight day?1. The resulting margins of exposures (38,000 for average consumers and 16,000 for high consumers) showed that the estimated dietary exposures of secondary school students were far below any adverse effect dose observed in laboratory animals and were therefore of low concern for human health.  相似文献   

18.
Bisphenol A (BPA) is a high-production-volume chemical that is widely used in polycarbonate plastics and epoxy food-can coatings. Following several studies that have reported adverse effects of BPA over the past decade, other bisphenol analogues, such as bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF), and bisphenol B (BPB), have been gradually developed as substitutes for BPA in several applications. Nevertheless, few studies have reported on the occurrence of compounds other than BPA in foodstuffs. In this study, 289 food samples (13 categories: cereals and cereal products, meat and meat products, fish and seafood, eggs, milk and milk products, bean products, fruits, vegetables, cookies/snacks, beverages, cooking oils, condiments, and others), collected from nine cities in China, were analysed for eight bisphenol analogues using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). BPA and BPF were found widely in foodstuffs at concentrations ranging from below the limit of quantitation (LOQ) to 299 ng g–1 (mean = 4.94 ng g–1) and from below the LOQ to 623 ng g–1 (mean = 2.50 ng g–1), fresh weight, respectively. The highest total concentrations of bisphenols (∑BPs: sum of eight bisphenols) were found in the category of vegetables that included canned products (mean = 27.0 ng g–1), followed by fish and seafood (16.5 ng g–1) and beverages (15.6 ng g–1). ∑BP concentrations (mean = 2–3 ng g–1) in milk and milk products, cooking oils, and eggs were low. Food samples sold in metallic cans contained higher mean ∑BP concentrations (56.9 ng g–1) in comparison with those packaged in glass (0.43 ng g–1), paper (11.9 ng g–1), or plastic (6.40 ng g–1). The daily dietary intakes of bisphenols were estimated, based on the mean concentrations measured and daily consumption rates of foods, to be 646 and 664 ng kg–1 bw day–1 for men and women, respectively.  相似文献   

19.
This paper reported on selective Raman spectroscopic and mass spectrometric determination of functionalized aflatoxins. Performance parameter methods encompassed six component mixtures of AFs, B1, G1, M1 and B2A, G2A, and M2A at concentration range of ∈ 0.096–21.581?ng g?1. Limits of detection (LODs) and limits of quantitation (LOQ) are 0.135 and 0.45 ng g?1, respectively. The matrix effect of AFB2A, AFG2A, and AFM2A in multicomponent mixtures is evaluated. The LODs of 0.11–0.09 ng g?1 is achieved. Raman spectroscopic method performance parameters at concentration range of ∈ 0.10–5,000 μg kg?1 for six component mixtures (r 2?=?0.97651) are LOD?=?10.13 μg kg?1 and LOQ?=?33.76?μg kg?1. The designed experimental schedule and sampling model is tested on contaminated grain samples. As far as the biochemistry and genetic engineering of aflatoxins and their major metabolites involved the high regioselectivity and binding affinity to N7 guanine residue at DNA, causing carcinogenic and mutagenic effects, the data reported are of emergency on the frontier fields of analytical chemistry, environmental bioengineering, monitoring, and assessment of human health risk from aflatoxins contamination. Aflatoxins are considered as biochemical weapons. Therefore, the essence of the study is on the instrumental methodology, which would be of interest and encompassed public security research and related scientific elaborations of more effective methods for (1) prevention, (2) reducing of the damages, and/or (3) acquisition of the outgrowths from biological (chemical) terrorist attacks.  相似文献   

20.
A sensitive and selective GC-MS method was developed and used to analyse human milk samples for both free and total bisphenol A (BPA). Total BPA was detected in 72 of the 278 human milk samples (25.9%) at concentrations from < 0.036 to 2.5 ng g–1 with a geometric mean (GM) of 0.13 ng g–1 and median of 0.11 ng g–1, while free BPA was detected in fewer samples, 46 of the 278 samples (16.5%) at concentrations ranging from < 0.036 to 2.3 ng g–1 with a GM of 0.11 ng g–1 and median of 0.10 ng g–1. Ratios of [free BPA]/[total BPA] for the positive samples ranged from 7.9% to 100% with a GM of 57.2% and median of 70.3%. Concentrations of free and total BPA in most samples were low with 0.39 and 0.65 ng g–1 at the 95th percentile for free and total BPA, respectively, and they are also lower than those reported in other countries. Based on the low frequency of detection of free BPA in human milk samples, in general, dietary exposure to BPA for Canadian breast-fed infants is expected to be somewhat lower compared with exposure among formula-fed infants.  相似文献   

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