Abstract:To study the associations between bone mineral density (BMD) and urinary cadmium as well as urinary lead on farmers lived in a non-polluted area of Kaiping, Guangdong Province, China. Methods 283 local healthy residents were investigated who lived in rural Kaiping for more than 15 years, aged 30-80, and mainly lived on local rice and vegetables. Blood and urine specimens were collected for detection of urinary cadmium, lead, phosphorus and calcium by ICP-MS and corrected by urinary creatinine. Furthermore, the bone mineral density (BMD) of far end of the left forearm was determined by Dual Energy X-ray Absorptionmetry (DTX-200), the values of BMD were Z scored. One-way ANOVA, chi-square and the multivariate regression analysis were used to investigate the relationship between BMD and urinary cadmium as well as urinary lead. Results Spearman correlation analysis showed that there was a positive correlation between BMD and U-Cd in both males and females, and the correlation coefficients were -0.21 and -0.22 respectively. No correlation was observed between BMD and U-Pb in both males and females. For males, the BMDs were different under five different U-Cd levels, however, the proportion of each T-SD levels were similar. For females, the BMDs under different U-Cd levels were the same, otherwise, the proportion of each T-SD levels were distinct. With increment of U-Cd level, the proportion of osteopenia and osteoprosis increased, the correlation coefficient was 0.22. Multivariate regression analysis implied that the BMD was associated with age and weight for females and with age and BMI for males. Conclusion There were simple correlations between BMD and U-Cd, however, no linear relationship was observed. Further study is needed to understand the effects of cadmium and lead exposure to bone mineral density for population lived in non-polluted area.

Abstract:To investigate the effect of transgenic Bt rice (TT51) exposure on immune system of parental female rats. Methods Wistar rats were divided into Bt rice group, parent rice group and market rice group. All groups were fed on mixture containing 60% rice. Female and male rats were fed for 10 weeks before copulation, and the parental female rats were carried on the immunotoxicity assessment after being weaned. The parental female rats were sacrificed for blood routine, blood lymphocyte typing, NK activity assay, conA induced lymphocyte transformation test, antibody-producing cell assay as well as lymph node lymphocyte typing. Results Statistical significances were observed on spleen lymphocyte typing and cervical lymph node lymphocyte typing between TT51 rice and market rice , and the proportion of B and T cell between parent rice and market rice. There was no significant difference of other functional experiment among various groups. Conclusion Transgenic Bt rice (TT51) did not have adverse effect on the immune system of parental female rats.

Abstract:To study the pulse-field gel electrophoresis(PFGE)type of Salmonella strains isolated from poultry slaughterhouses in four provinces. Methods DNA collected from 167 Salmonella strains were digested by XbaI according to the standard PFGE protocol of US CDC. The PFGE patterns were analyzed with BioNumerics software. Results167 Salmonella strains were clustered into 18 groups with 75 different patterns, and the same serotype had the similar PFGE pulse types which could be classified to one group. 65 S.Indiana were clustered into 38 patterns. 54 S.Enteritidis were clustered into 16 patterns. 16 S.Albany were clustered into 1 pattern. Conclusion The distribution of pulse types of Salmonella isolates was different between regions, but some pulse types were cross-distributed. Cross-contamination was serious in slaughterhouses. Monitoring and intervention of critical control point during processing should be strengthened in order to decrease salmonella contamination in poultry products, and that was the basic measure of source control.

Abstract:To establish a real time RT-PCR method to detect VBNC Vibrio Parahaemolyticus and study the expression of virulence gene. Methods V.parahaemolyticus strain AS079 was induced into VBNC state by culturing in artificial seawater at 4 ℃. Real-time RT-PCR primers were designed for the toxR, pvuA and tdh2 gene. Various PCR protocol and primer concentration combinations were tested to optimize the PCR procedures for VBNC V.parahaemolyticus as well as virulence analysis. V. parahaemolyticus AS079 samples collected after various periods of incubation were analyzed using real-time RT-PCR method established in this study. Results The result indicated that the expression levels of virulence gene tdh2 and identification gene toxR decreased over incubation in artificial seawater. However, both genes were clearly detectable even after the bacteria had entered VBNC state, suggesting that the method could be used for detection and virulence analysis of V.parahaemolyticus under VBNC state. The sensitivity test showed that the detection limit for identification gene toxR was 48 cfu/ml; whereas evaluating the expression of virulence gene tdh2 required 4.8×10² cfu/ml at least. Meanwhile, no cross-reaction with other closely related food-borne pathogens had been found. Conclusion The real-time RT PCR method established in this study had advantages of fast detection, high specificity and sensitivity, and was suitable for detection and virulence analysis of VBNC V. parahaemolyticus.

Abstract:To investigate the antimicrobial resistance and molecular characterization of Salmonella isolates from food in Taizhou, establish the molecular characteristics background of foodborne Salmonella, and provide science basis for foodborne diseases prevention and control. Methods 22 Salmonella strains isolated from food in recent years were tested for 12 kinds of antibiotics susceptibility and were screened for 10 potential virulence factors by polymerase chain reaction. All strains were genotyped by PFGE and analyzed with BioNumerics 5.0 software. Results The general resistant rate of 22 Salmonella strains was 59.1%. The strains were most resistant to co-trimoxazole (36%), tetracycline (27%) and nalidixic acid (27%). All strains were detected more than 6 kinds of virulence factors. One strain of S.enteritidis was found harboring virulence islands, plasmid and phages. 21 bands were separated by PFGE, which could be divided into five genotypes including 18 kinds of fingerprints. The homology between genotypes was less than 70%. Conclusion Foodborne Salmonella could be a food risk, and the fingerprint databases could provide technical supports for foodborne disease prevention and control.

Abstract:To investigate antibiotic resistance of Cronobacter sakazakii isolated from imported dairy products. Methods100strains of Cronobacter sakazakii were tested for antibiotic susceptibility by disk diffusion recommended by the National Committee of Clinical laboratory Standard. Results All strains were sensitive to Mezlocillin, Imipenem, Meropenem, Gentamicin, Amikacin, Kanamycin, Tobramycin, Chloramphenicol, Cefepime, Cefoperazone, Cefotaxime Sodium, Ceftazidime, Pentahydrate, Ciprofloxacin and Norfloxacin, while resistant to Proctaphlin Sodium. The ratio of resistant strains to Ampicillin, Cefalotin, Cefazolin Sodium, Sodium and Tetracycline was 65%, 17%, 3% and 2%, respectively. The ratio of intermediate resistant strains to Ampicillin, Cefazolin Sodium, Cefalotin Sodium, Ceftriaxone Sodium, Tetracycline was 25%, 23%, 6%, 2% and 1% respectively. 13strains were multiresistant to 3kinds of antibiotics and 4strain was multiresistant. ConclusionCronobacter sakazakii strains isolated from imported dairy products were susceptible to most of the tested antibiotics, but resistance were increasing. In this study, All drug resistant strains to oxacillin. Hereby, the issue of Cronobacter sakazakii multiresistance should arouse abroad attention worldwide.

Abstract:In order to understand the effects of cold storage on the nitrite and nitrate contents of four kinds of green vegetables and evaluate the safety of cold storage processing.Methods Diazotization-coupling reaction spectro-photometer and tnymol spectrophotometer method were used to analysis the nitrite and nitrate contents in four kinds of green vegetables including lettuce, spinach, leaf lettuce and endive in four days stored at 4 ℃. Results The results indicated that nitrite content in lettuce and endive rose up through storage time. The nitrite content in spinach and leaf lettuce reached the maximum on the second and third day, respectively. Then the content began to decrease. However, it rose again on the fourth day in spinach. The peak value of nitrite in the vegetables in four days was 0.419 4 mg/kg (in cucumber) which was far less than the limit of 4 mg/kg. Nitrate content in endive and leaf lettuce was gradually increasing through four days. The nitrate content in spinach reached 418.48 mg/kg on the second day, but decreased to 20.83 mg/kg a few days later. The nitrate content in lettuce reached 317.26 mg/kg on the third day and decreased later. The contents of nitrate in four vegetables were within the safety range (432 mg/kg). Conclusion Compared with nitrite, four vegetables had more nitrates in four days. Meanwhile, contents of nitrate were all in the safety range. Cold storage could effectively slow down the increase of nitrite and nitrate contents in vegetables.

Abstract:To simultaneously determine the three-component system of isobutanol, isoamyl alcohol and n-propanol with overlapping spectra.Methods Experimental conditions were optimized according to the characteristics of color reaction of alcohols with paradimethylaminobenzaldehyde, and partial least squares (PLS) was use to simultaneously determine isobutanol, isoamyl alcohol and n-propanol with serious spectrum overlapping. Results The recoveries of simulative mixed samples were 99.8%, 99.6% and 99.9% with RPEs 0.88%, 1.81% and 0.90%, respectively. Recoveries and RPEs were within the allowable range. Conclusion Partial least squares method for the determination of three-component system of isobutanol, isoamyl alcohol and n-propanol was stable and reliable.

Abstract:To establish a HPLC-MS/MS method for simultaneous determination of eight artificial sweeteners in flavorings. Methods The artificial sweeteners, including acesulfame-K, cyclamate, saccharin, aspartame, alitame, neotame, sucralose and neohesperidine dihydrochalcone were extracted with water and the water-soluble macromolecular compounds in flavorings were precipitated with methanol. The supernatant was cleaned-up using aluminum-N cartridges and separated on a C18 column using 10 mmol/L ammonium formic acid/acetonitrile as mobile phase and then detected by HPLC-MS/MS using multiple reaction monitoring (MRM) in negative ionization mode. Results The calibration curves showed a good linearity with correlation coefficients＞0.990. The linear range for saccharin was 0.05-5 μg/ml, 0.1-10 μg/ml for sucralose, and the other sweeteners was 0.01-1 μg/ml. The average recoveries were from 82.7% to 117.9%, and the relative standard deviations (RSD) were from 0.6% to 10.6%. The detection limits for liquid and semi-solid sweeteners were from 0.01 to 0.1 mg/kg and 0.1 to 1 mg/kg for solid sweeteners. Conclusion The method was specific, sensitive, easy, fast and suitable for the confirmation and quantification of 8 artificial sweeteners in flavorings.

Abstract:To establish a method based on alkaline hydrolysis for determination of L-hydroxyproline(L-Hyp) in hydrolyzed animal protein, in which NaOH solution and polytetrafluoroethylene(PTEF) hydrolysis tube with cover were used. Method The sample was hydrolysed by 6 ml 2.5 mol/L NaOH soultion in 10 ml hydrolysis tube and heated in the oven at 110 ℃ for 2 h. The hydrolysate of L-Hyp was oxidized by chloramine-T and then reacted with paradime thylaminobenzaldehyde to generate red complex. The absorbency was determined at (558±2) nm. ResultsUnder the optimal conditions, the calibration curve was linear in the range of 0-10 μg/ml with detection limit of 1.35 μg/g, and the relative standard deviation(RSD) was 1.0%-2.3%. It was effective in the determination of L-Hyp in milk and dairy products with recoveries of 88.7%-96%. Conclusion Compared with acidolysis, the alkaline hydrolysis had more simple experimental procedure, fewer measurement time, highly sensitive and reproducible with consistency.

Abstract:The method for determination of metabolites of four nitrofuran antibiotics, nitrofurantoin (AMOZ), furaltadone (SEM), nitrofurazone (AHD) and furazolidone (AOZ) in aquatic products was developed by solid-phase extraction coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). Methods Samples with isotope internal standard solutions were hydrolyzed by HCl and derivatized with 2-nitrobenzaldehyde. The analytes were cleaned up on HLB solid-phase column and eluted with ethyl acetate, then evaporated and dried with nitrogen gas. The extract components were separated and gradient eluted on a XTerra C₁₈ column with acetonitrile-5 mmol/L ammonium acetate of 0.1% formic acid solutions ion, and simultaneously quantified by the isotope internal standard operating in positive ion under multiple reactions monitoring mode. Results The limits of quantification ranged from 0.10 μg/kg to 0.30 μg/kg for four nitrofuran metabolites. The standard curves were linear in the range of 0.5-25 μg/kg,with the correlation coefficients＞0.995. The average recoveries for nitrofuran metabolites were 81.0%-104.8%, 91.0%-110.3%, 85.0%-111.4%, 88.0%-108.2% respectively, and their relative standard deviation varied between 2.7% and 14.5%. The method was applied to analyze 180 fish samples from Guangdong region, four of which were confirmed to contain AOZ ranging from 1.3 to 3.6 μg/kg. Conclusion The method developed was selective, sensitive and accurate, completely suitable for nitrofuran metabolites trace analysis in aquatic products.

Abstract:To establish a method of gas chromatography-mass spectrometry with microwave digestion and solid phase extraction to determine bisphenol A in styrofoam fast food boxes. Methods 0.2 g styrofoam fast food boxes was digested in microwave tank, then cleaned by the cartridge (C₁₈, 500 mg,6 ml) and derivated by 100 μl BSTFA-TMCS (99∶1, V/V). Finally, 1 μl solution was injected into GC-MS instrument. Results The linearity range was 0.305 to 3.05 mg/L, r²=0.991. The average recoveries ranged from 90% to 101%, and the coefficient of variation varied between 2.6% to 5.0%. Detection limit for bisphenol A was 15 μg/kg in 0.2 gram sample. Conclusion The method could be used in determination of bisphenol A in styrofoam fast food boxes for its good precision of qualification and quantification.

Abstract:To investigate the illegal use of red 2G in sausage product and provide scientific basis for hazard analysis. Methods Stratified sampling was used to collect 156 sausage samples from supermarket, country fair and boutique in Wuhan urban area. The content of red 2G was determined by high performance liquid chromatography(HPLC), Chromatographic column for Eclipse XDB-C₁₈(4.6 mm×250 mm, 5μm)column by using methyl alcohol and ammonium acetate(0.02 mol/L)as mobile phase with a flow rate of 1.0 ml/min at 35 ℃.The detector at 530 nm with a injection volume of 10 μl. Results Red 2G were detected in 23 sausage products and the contamination ratio was 14.74%. In positive samples, it ranged from 0.20 to 5.21 mg/kg. Conclusion The illegal use of red 2G in sausage was serious and we should bring it into the routine food safety monitoring project.

Abstract:To establish a method for nitrite-UV spectrometry determination of free chlorine in drinking water. Methods 1.0 ml sodium nitrite solution (ρ=5 g/L) was added into water sample containing free chlorinerole, reacted for 30 min, and added 1.0 ml sulfamic acid solution (ρ=10 g/L) and 1.0 ml hydrochloric acid (C=1.0 mol/L). Samples were detected for absorbance value at 220 nm wavelength with nitrate nitrogen as standard, and free chlorine content was calculated. Results Sodium nitrite was quantitatively oxidized by free chlorine into nitrate which showed an equimolar relationship (r=0.999 8). Sulfamic acid eliminated the influence of excessive nitrite. This method could be applied for direct determination of water sample at room temperature.The limit of quantification was 0.05 mg/L with RSD 1.43%～10.00%, the recovery was 94.23%～103.20%. Conclusion This method could be used for the determination of free chlorine in drinking water.

Abstract:To understand the situation of 18 kinds of phthalic acid esters in plastic food packaging. Methods The contents of phthalic acid esters in 280 plastic food packaging of different materials were analyzed by gas chromatography-mass spectrometry (GC-MS) following standard GB/T 21928-2008. The samples were extracted ultrasonically with n-hexane, then separated by HP-5MS capillary column and detected by single quadrupole mass spectrometry. Retention time and characteristic ions were used as qualitative evidence, and external standard was used for quantification.Results The content of 18 kinds of phthalate in 95% of the 62 batches of PVC materials were qualified, all 82 batches of composite materials and 136 batches of other materials were qualified. Diethylhexylphthalate residues were detected, and seriously exceeded the standard limit in 3 polyvinyl chloride materials. Conclusion The phthalic acid esters exposure from plastic food packaging was low, while polyvinyl chloride materials put a potential health risk to human. Regulation and monitoring on phthalic acid esters in plastic food packaging should be strengthened.

Abstract:To investigate the presence and contamination levels of Norovirus ( NoV) in commercial oysters in Guangdong Province from 2011 to 2012, provide suggestions on reducing NoV contamination in oysters, and to prevent and control gastroenteritis outbreaks caused by NoV.Methods Between March 2011 and October 2012, oyster samples collected from several coastal cities in Guangdong Province were examined for NoV by real-time RT-PCR. The contamination levels and genotype of different cities,seasons and sampling sites were compared.Results The overall detection rate of NoV was 14.9%(41/275). In addition, the detection rate was 4.4%, 15.7%, 18.2% and 36.7% in spring, summer, autumn, and winter, respectively. Among 275 samples, 4.0% belonged to GI, 6.2% GII, and 4.7% both GI and GII.Conclusion No significant differences were found in NoV contamination levels and genotye among markets, restaurants, and various cities from 2011 to 2012. However, there were obvious differences in different seasons, especially in winter whick had the highest NoV contamination level in oyster.

Abstract:Objective To study the serotype distribution of Vibrio parahaemolyticus clinical isolates and aquatic products isolates during 2009-2012 in Shanghai. Methods Using slide serum agglutination test to detect the serotypes of Vibrio parahaemolyticus from 622 clinical and 176 aquatic samples. Results Among 622 clinical isolates, 27 serotypes were identified. The predominant serotype was O3∶K6 (61.7%). It was shown that 176 aquatic strains could divide into 9 serum groups. The predominant serotype O3∶K6 among clinical isolates was detected in two aquatic products. Conclusion The serotypes among clinical isolates and aquatic products showed high diversity. The predominant serotype O3∶K6 among clinical isolates appeared in aquatic product representing a public health risk and requiring epidemiological and ecological monitoring to ensure safety.

Abstract:Objective The diarrhetic shellfish poison (DSP) was investigated in shellfish samples collected from Feb 2011 to Jan 2012 in Tianjin seafood market. Methods Mouse bioassay and LC/MS-MS method were used to determine toxin content and its component. Results DSP was detected only in samples of scapharca subcrenata collected on May and august from TangShan, and both were over the limit. DTX-1 and YTX were confirmed in the positive samples by LC/MS-MS. Conclusion The overall DSP detection rate in shellfish from Tianjin market was low, but still essential to prevent the risk in spring and enhance monitoring and public education in summer.

Abstract:objective To understand the presence, contamination and cross contamination of foodborne bacterial pathogens in Ningbo city, provide basis for foodborne disease control, and trace the source of foodborne disease.MethodsStrains were detected directly or after enrichment with biochemistry and API method, and subtyped with serum agglutination method. Antibiotic resistance and relative genes were detected with K-B method and PCR method respectively. Results 2 331(7 species and 12 types)strains were detected from 6 812 food samples and the detection rate is 34.22%(2 331/6 812).The prevalent pathogens were Vibrio parahaemolyticus, and the detection rate was significantly different from the other types(P<0.005).Vibrio parahaemolyticus could be classified into 10 sero-groups, and O6 and O5 were proved as the prevalent sero-groups. Most of the pathogens were sensitive to antibiotics. Three strains of Aeromonas were found multi-resistant with aacc resistance gene. Conclusion Various distribution was proved in foodborne bacteria in Ningbo. Contamination of foodborne pathogens was a major factor of foodborne diseases. Vibrio parahaemolyticus was the prevalent pathogenic bacteria. Most of the pathogens were sensitive to antibiotics. Bacteria with aacc resistance gene were found, which should raise concerns to control the spread of the resistant strains through rational administration of antibiotics and resistance surveillance.

Abstract:To investigate and identify the contamination of main foodborne pathogens in Shanxi province.Methods According to the standard operation procedures in the handbook of 2010 National Surveillance on Foodborne Pathogens. Results Among 1 576 food samples tested, 149 (9.45%) pathogenic strains were isolated. The positive rate for L.monocytogenes was the highest (9.50%), followed by V.parahemolyticus (8.22%), S.aureus (3.02%), E.sakazakii (1.11%) and Salmonella (0.87%). A high prevalence of foodborne pathogens was shown in meat (49.33%), the main contaminating bacteria were Salmonella and L.monocytogenes, followed by salad (17.39%), the main contaminating bacteria were L.monocytogenes and S.aureus; raw aquatic (16.94%), the main contaminating bacteria were L.monocytogenes and V.parahemolyticus; cooked meat (9.84%), the main contaminating bacteria were L.monocytogenes, S.aureus and Salmonella; Chinese salad (8.89%), the main contaminating bacteria was S.aureus; fresh juice (6.67%), the main contaminating bacteria was S.aureus; fresh and frozen aquatic products (5.00%), the main contaminating bacteria was V.parahemolyticus. The detection rate was 1.11% for E.sakazaki in baby formula milk powder/rice noodles/valley powder/soy.Conclusion Foodborne pathogens were frequently found in retail foods in Shanxi, it was necessary to strengthen the monitoring of food.

Abstract:To analysis lead contamination of eggs and egg products in Guangzhou during 2006—2011 through surveillance data. Methods Stratified sampling was used to collect egg samples from 12 districts of Guangzhou city in six types of sampling points, such as meat markets, supermarkets, catering business, retail stores and street vendors. Results Among 518 samples collected, 479 were qualified, accounting for 92.47%. The qualified rate of preserved eggs was 93.85% (168/179), and the detection rate was 62.57% (112/179). The qualified rate of fresh eggs was 93.13% (217/233), and the detection rate was 63.52% (148/233). The qualified rate of salted eggs was 88.68% (94/106), and the detection rate was 58.49% (162/106). Conclusion Lead contamination existed in eggs and egg products in Guangzhou, the violation rate was 7.53%, and the detection rate was 62.16%. More attention should be paid to the supervision and surveillance authorities. We should reduce the lead contamination in eggs and egg products.

Abstract:To identify the cause and process of the food poisoning incident and take effective measures to deal with.Methods The dinners, associated personnel and risk factors were investigated. Samples of suspicious poisoning food were analyzed and identified.Results 11 men were all poisoned by plant medicinal liquor with alcohol consumption ranged from 0.1 to 0.2 kg. The incubation period was 10-20 min, and the attack rate was 100%. Five cases died, and the death rate was 45.46%. Cases without drinking were unaffected. The more alcohol consumption would lead to a shorter incubation period and more serious symptom. The plant steeped in wine was identified as Graceful Jesamine. Conclusion This case of food poisoning was caused by poisonous plant Graceful Jesamine. In order to avoid similar accidents emerging in the future, the local government should put poisonous plant into the food safety education to enhance the consciousness.

Abstract:Because of the extreme similarity in external form between some poisonous mushroom and wild large edible fungi, the phenomenon of eating the poisonous mushroom by mistake was of common occurrence every year in our country. The variety of toxins, the mechanism of poisoning, the type of poisoning and recognition methods of the poisonous mushrooms were summarized in this paper, and some limitations of these methods were pointed out; The research about poisonous mushroom recognition begins gradually from the individual level to the molecular level, and the near infrared technology has development potential in recognizing poisonous mushroom.

Abstract:To understand the species of foodborne parasitic diseases and the relationship with zoonosis and natural focal disease, and provide a scientific basis for prevention and treatment of foodborne parasitic diseases. Methods Human parasite species data found in the province over the years were collected for classification statistics. Results A total of 56 species of human parasite species were found in Guangxi province , accounting for 23.43% Chinese human parasites species (56/239). Among the 56 species, 47 species were foodborne parasites which accounted for 83.93% (47/56). Among the 47 foodborne parasites, 85.11% (40/47) were zoonotic and 74.47% (35/47) were both foodborne, zoonotic and natural focal parasites. There were 28 species of common foodborne parasitic diseases still endemic in Guangxi. Conclusion Guangxi province was one of provinces which had many human parasite species and foodborne parasite species, the task of prevention of foodborne parasitic disease was arduous.