Abstract:Food contaminant standards are an important way to control food contamination and ensure food safety. After more than 30 years of development, our food contaminant standards have been continuously improved, which have played an important role in protecting consumer health and promoting fair trade. The article reviews the process and development of the food contaminant standards in China, analyzes the scientificity and changes in its international status, and proposes the future strategies for China's food contaminants standards system, so as to provide a solid foundation for food contaminant standards to reach the height of developed countries and modernization of food safety risk management capabilities.

Abstract:Human breast milk is recommended by World Health Organization as an ideal matrix for conducting human biological monitoring of persistent organic pollutants (POPs). And it is the main matrix to evaluate the efficacy of performing Stockholm Convention. In order to assess the human body burden of POPs and performance evaluation, national monitoring program of breast milk has begun since 2007. Various POPs, including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), were determined in human breast milk samples. We obtained representative data of levels of main POPs in human breast milk from the general population in China as well as their spatial-temporal distribution, which provided a strong support for the performance evaluation of Stockholm Convention in China.

Abstract:Objective To study the mutation and expression of genes of Salmonella when screened by different concentrations of quinolone and fluoroquinolones during propagation and their relation with antibiotic resistance. MethodsSalmonella strain was cultured in broth medium and screened on nutrition plate with different concentration of quinolone and fluoroquinolones. Antimicrobial susceptibility of the screened subculture was tested by broth microdilution method, mutation of genes in quinolone resistance-determining region (QRDR) was detected using polymerase chain reaction(PCR)and DNA sequencing method, and expression level of the encoding genes of multi-drug associated efflux pump AcrAB-TolC was detected by real-time qPCR. Results Antibiotic resistance level of the subcultures screened from LB plate with quinolone and fluoroquinolones inducement increased in different extents. Mutation of Asp87Tyr in gyrA in QRDR was detected from the fifth to the seventh generation of nalidixic acid screened strains. Mutation of Asp87Asn in gyrA in QRDR was detected from the fourth to the seventh generation of ciprofloxacin screened strains. No amino acid mutation was detected from gyrA in the first to the seventh generation of gatifloxacin, levofloxacin and delafloxacin screened strains. Compared to the expression level of the multi-drug efflux pump AcrAB-TolC encoding genes of the original strain, those of the screened strains had significantly (P<0.05) increased resistance. No significant difference was detected among the expression level of AcrAB-TolC encoding genes in the seventh generation of screened strains. The ratio of the minimal inhibitory concentrations (MICs) of the screened strains and that of Salmonella Typhimurium(ATCC 14028s), gene variation and relative expression level of acrAB-tolC of Salmonella significantly positive correlated with subculture generation and antibiotic concentration. Conclusion Under the selective pressure of antibiotics, Salmonella strain could adapt the stress environment through QRDR mutation and increase the expression level of multi-drug efflux pump AcrAB-TolC. When the next generation fluoroquinolone was used, the mutation frequency of QRDR decreased. After subcultured several times, the expression level of acrAB-tolC of the screened strains increased, however, no significant difference was detected among the expression level, which avoided the antibiotic resistance of Salmonella to be further increased.

Abstract:Objective Understanding of bacterial antibiotic resistance is the basis for guiding clinical anti-infective therapy and monitoring antimicrobial resistance trends. The study was aimed to investigate the antibiotic resistance characteristics of nontyphoidal Salmonella isolates from foodborne disease cases in Jiangxi Province in 2018, study the correlations between resistance phenotypes and genotypes, and evaluate the application prospects of whole genome sequencing (WGS) in antimicrobial resistance surveillance. Methods In this study, 58 nontyphoidal Salmonella strains were isolated from foodborne disease patients in Jiangxi Province in 2018 and were tested for susceptibility to 14 antimicrobials using broth microdilution. The 58 isolates were subjected to WGS, and resistance genes were identified from assembled sequences that compared with ResFinder database. Results 77.59%(45/58)of isolates were resistant to tetracycline, and 72.41%(42/58) were resistant to ampicillin. 100.00% of isolates were susceptible to imipenem. 56.90%(33/58) of isolates displayed resistance to at least 3 classes of antibiotics, and 3.45%(2/58) of isolates had resistance to at least 6 of 8 classes tested. A total of 47 unique resistance genes referred to 11 classes of antibiotics, plus mutations in gyrA, gyrB and parC structural of quinolone resistance-determining region(QRDR), were identified. 100.00%(58/58) of isolates had aminoglycoside resistance genes, and 72.41%(42/58) of isolates harboured tetracycline resistance genes. Macrolide resistance genes were presented in 3.45%(2/58) of isolates. 77.59%(45/58) of isolates were contained at least 3 classes of antibiotics resistance genes, and 1.72%(1/58) of isolates harboured at least 9 classes of resistance genes. The overall resistance genotypes and phenotypes were consistent in 93.43%(611/654) of cases. Except quinolones, the correlations were above 91% for tested antibiotics. Correlations were 100% for some classes of antibiotics. Conclusion The antibiotic resistance phenomenon of these isolates was serious. The resistance phenotypes were in good accordance with genotypes, and WGS can be used as an effective tool to predict the antibiotic resistance of nontyphoidal Salmonella. As more new antibiotic resistance genes were discovered, the consistency of resistance genotypes and phenotypes will be further improved.

Abstract:Objective Laboratory investigation was performed on a suspected case of infant botulism. Methods Thirty samples of stool, left-over food and environment swabs related to the case were collected, Clostridium spp. isolation, identification and toxicity determination by mouse assay were carried out, and toxin production for isolate was conducted. Results Mice injected with the stool culture supernatant showed the typical signs of botulism including irritable, dyspnea, bellows breathing and quadriplegia followed by death. The toxicity of the stool culture supernatant was enhanced after the treatment by trypsinization but ceased after being heated at 100 ℃. The polyvalent antibody against botulinum neurotoxins (BoNTs) and the monovalent antibody against BoNT type E could protect mice from death. One gram-positive Clostridium isolate was cultured from infant stool sample. The morphology of the colony on the Columbia blood agar plate showed characteristics of irregular, translucent and flat with rootlike growth. It was positive for type E BoNT-encoding gene and identified as C.butyricum by 16S rRNA sequencing. Toxin production test illustrated that the C.butyricum isolate could produce type E BoNT. Conclusion This was an infant botulism caused by type E BoNT-producing C.butyricum.

Abstract:Objective To compare the species identification method of Cronobacter spp. in food, in order to establish rapid, high throughout identification method. Methods A total of 19 Cronobacter spp. in foods were identified with three method including biochemical method using VITEK 2.0 Compact, matrix assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF MS)and whole-genome sequencing (WGS). The advantages and disadvantages of the three identification method were analyzed. Results The result indicated that the accuracy of VITEK identification for C.sakazakii and C.malonaticus was 67% and 66% respectively. However, WGS and MALDI-TOF MS obtained the same result for 19 Cronobacter spp.. Three subspecies could not be identified by MALDI-TOF MS due to the limited database. Conclusion Biochemical method could not be used for species identification of Cronobacter spp. MALDI-TOF MS was rapid, high throughout and accurate, but still need to expand the fingerprint database for more Cronobacter spp. isolates.

Abstract:Objective This paper aims to evaluate data reliability of the neurotoxic hazard assessment of glutamate and its salts and provide recommendations, as well as to improve toxicology data reliability assessment method (TRAM) via trial application. Methods TRAM was used to evaluate the reliability of 60 articles which were selected by the method of systematic review documentation retrieval. The evaluation was based on types of toxicological data involved in each paper (laboratory animal data or human data) and they were scored by reliability criteria. The quality percentage was obtained via calculations to judge reliability categories and give recommendations. It’s necessary to note that the evaluation of each paper was independently completed by two persons in related fields. Results After three rounds of evaluation, the reliability of 12 articles were evaluated as “high” and recommended for priority use. The reliability of 43 articles was rated as “moderate” and can be used. The reliability of 5 articles was evaluated as “low” and not recommended to use. Conclusion TRAM takes both reporting quality and methodological quality into consideration, especially including human data reliability evaluation method which is absent in the other toxicology data reliability assessment tools. TRAM is more suitable for food safety risk assessment. It provides a better objective and scientific guarantee for hazard identification and risk assessment.

Abstract:Objective To establish a method for determination of 6 kinds of carbamate pesticides and 3 kinds of chloronicotinyl pesticides in Chinese Kushui rose by ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with QuEChERS. Methods After extracted by acetonitrile, the Chinese Kushui rose was cleaned by QuEChERS. The target compounds were separated by C18 column(2.1 mm×100 mm,1.7 μm) using 10 mmol/L ammonium acetate solution (0.1% formic acid) with acetonrtrile as mobile phase for gradient elution, and analyzed by MS/MS system with electrospray ionization(ESI+) under muti-reaction monitoring mode and quantified by external standard method. Results All the 9 kinds of pesticides showed good linear relationships in range of 0.01-0.50 μg/mL, and the correlation coefficients were above 0.990, the recoveries at different spiked levels for all target compounds in blank matrices were 76.3%-102%,and the relative standard deviation (RSD)were 1.3%-9.0%(n=6). The limits of detection and quantification of the method were 0.001 6-0.003 2 and 0.005 4-0.010 mg/kg. Conclusion The method was suitable for rapid screening and analysis of 9 pesticide residues in Chinese Kushui rose with the advantage of accuracy, rapidity, simplicity and high sensitivity.

Abstract:Objective To establish a method for the determination of norfloxacin, ciprofloxacin, lomefloxacin, enrofloxacin, ofloxacin and pefloxacin in aquatic products by QuEChERS with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods Six fluoroquinolones in aquatic products were extracted by 1% formic acid acetonitrile solution, purified by QuEChERS, separated by C₁₈ column(2.1 mm×100 mm, 1.7 μm) using 0.1% formic acid and methanol-acetonitrile(4∶6,V/V) as mobile phases, then identified and quantified by UPLC-MS/MS. Results Norfloxacin, ciprofloxacin, lomefloxacin, enrofloxacin, ofloxacin and pefloxacin had good linear relationships in a certain concentration range with correlation coefficients(r) above 0.999. The limits of detection of six fluoroquinolones were 0.30-0.80 μg/kg, and limits of quantification were 1.0-2.5 μg/kg. The average recoveries of the method were between 86.6% and 120%, and the relative standard deviations were between 0.59% and 7.6%. Conclusion The method was rapid and accurate, and was suitable for rapid screening and analysis of the six fluoroquinolones in aquatic products.

Abstract:Objective To establish a real-time recombinase-aid amplification(RAA) method for rapid detection of Pseudomonas aeruginosa. Methods Specific primers and exo probes based on ecfX gene of P.aeruginosa were designed in this study, and the validity of the method was evaluated by sensitivity, specificity and suspected strains detection. Results Real-time RAA was performed successfully at 39 ℃ for 20 min. Only the P.aeruginosa strains but not other bacteria were amplified, showing the good specificity. The limit of detection was 3.0×10³fg genomic DNA per reaction, and 1.0×10³ CFU P.aeruginosa pure culture per reaction. The developed real-time RAA was further evaluated on 36 suspected of P.aeruginosa, which were identified successfully to be P.aeruginosa. The detection result were the same with those of a real-time PCR assay and the VITEK 2 Compact. Conclusion The developed real-time RAA assay is a rapid, simple and reliable tool for accurate detection of P.aeruginosa of diverse origins.

Abstract:Objective To detect microbial contamination status of edible raw meat products in catering enterprises of Shanghai and to provide reference for food safety and supervision. Methods According to the national standards a total of 198 batches of edible raw meat products and related products from catering enterprises in Shanghai in 2019 were tested for hygienic indicator organisms and common foodborne pathogenic bacteria. SPSS 16.0 software was used to analyze the test result. Results Judging from the hygienic indicator organisms, 2.06% (2/97) of edible raw meat products, raw and supplementary materials had aerobic plate count ≥ 100 000 CFU/g, 5.15% (5/97) of them had coliforms more than 100 CFU/g, and the detection rate of Escherichia coli was 2.06%(2/97), among which the detection rate of raw beef samples was 11.11% (2/18) and the quantitative value was all 10 CFU/g. In terms of the contact surface samples of ready-to-eat foods, the detection rate of coliform was 12.87%(13/101), among which the positive rate of processing tools and utensils was 20.83% (10/48), higher than the tableware samples 5.66%(3/53) (χ²=12.678,P<0.05). According to the detection of foodborne pathogenic bacteria, the detection rates of Salmonella in raw beef and finished products were 5.56% (1/18) respectively and no foodborne pathogens were detected in the remaining samples. Conclusion According to the result of this survey, the detection of the hygienic indicator organisms and Salmonella of edible raw meat products and the raw materials from catering in Shanghai in 2019 was worthy of attention, and the supervison agency should attach importance to the hygienic supervision of the processing tools and utensils in direct contact with ready-to-eat foods.

Abstract:Objective To establish the basic parameters for exposure assessment of contact materials for nut-seed food in China. Methods The contact area method was used to study the contact materials of nut-seed food in this study. Based on the contact area values, ratio of contact areas and unit mass were obtained. Results Through investigation and analysis, 114 kinds of nut-seed food were sampled, and 3 648 related data were obtained. Food contact materials of nut-seed food on the market mainly included aluminum, polyethylene, polyethylene terephthalate, polypropylene, polystyrene and coating. The average contact area per unit mass or volume(S/V)was 21.29 dm²/kg, the median was 13.40 dm²/kg, P5 was 1.11 dm²/kg, and P95 was 67.46 dm²/kg. Conclusion The basic parameters of nut-seed food contact materials could provide data support for the safety assessment in China.

Abstract:Objective To investigate the infectious status,virulence gene,molecular typing and antibiotic resistance of diarrheogenic Escherichia coli (DEC)in sentinel hospitals of Fujian Province in 2019. Methods Fluorescent polymerase chain reaction(PCR) was used to identify 210 fecal samples of diarrhea patients after isolation of E.coli according to GB 4789.6-2016, and then pulsed field gel electrophoresis(PFGE) molecular traceability and antibiotic resistance test were conducted on the isolated DEC.Results Thirty two strains of bacteria were detected, with a detection rate of 15.2% (32/210). Among them, enteropathogenic E.coli (EPEC) accounted for 37.5% (12/32), enteroaggregative E.coli (EAEC) for 37.5% (12/32), and enterotoxigenic E.coli (ETEC) for 25.0% (8/32). The results of antibiotic resistance test showed that these 32 strains of bacteria were most resistant to ampicillin, with a resistance rate of 78.1% (25/32), followed by tetracycline and trimethoprim/sulfamethoxazole, with resistance rates of 62.5% (20/32) and 59.4% (19/32), respectively. The multiple antibiotic resistance rate was 50.0%(16/32). The results of PFGE showed that 32 strains of bacteria causing diarrhea were divided into 28 PFGE banding patterns. Among them, 12 strains of EPEC and 12 strains of EAEC were divided into 10 PFGE banding patterns, respectively, and 8 strains of ETEC were divided into 8 PFGE banding patterns. The results of cluster analysis showed that two groups of EPEC strains had 100.0% similar banding patterns, one group of EAEC strains had 100.0% similar banding patterns, and ETEC strains did not have completely consistent banding pattern. Conclusion EPEC and EAEC were the main pathogens of diarrhea in surveillance points of Fujian Province in 2019. The genetic diversity of the strains showed that the genetic relationship between them was relatively distant. The antibiotic resistance of DEC was severe, and the rate of multiple antibiotic resistance was high.

Abstract:Objective To analyze the chloropropanol monoesters (MCPD esters) levels in the infant formulas available in Hangzhou market from 2017 to 2019, and to assess the exposure risk of MCPD esters for 0-3 years infants. Methods Concentrations of 3-MCPD esters and 2-MCPD esters in the infant formulas were determined with gas chromatography-mass spectrometry(GC-MS). 3-MCPD esters exposure risk in target population was assessed by the level of 3-MCPD esters in infant formulas and the consumption recommendation from diatery guideline. Results The 3-MCPD esters and 2-MCPD esters contamination existed in all infant formulas samples; the median and P97.5 daily dietary exposure of 3-MCPD esters were 0.46-2.50 and 0.87-4.30 μg/kg BW, account for 23.0%-125.0% and 43.5%-215.0% of the tolerable daily intake (TDI, 2 μg/kg BW per day) respectively. For infants aged 0-6 months, the high intake levels(P97.5) of 3-MCPD esters were above TDI. Conclusion The levels of 3-MCPD esters in infant formulas sold in Hangzhou may pose a potential risk. Infants aged 0-6 months had higher exposure level than other age groups.

Abstract:People in the real world are exposed to multiple chemicals via multiple routes and co-exposure to multiple agents may induce joint effects, which draws extensive attention from the international community. Regulations of many countries oblige risk assessors to conduct cumulative risk assessments based on their own guidelines, findings of which provide the basis for scientific decision-making. By analyzing the method and frameworks of international risk assessment models of multiple chemicals, this paper explores the establishment of a risk assessment framework of multiple chemicals combined exposure to in food in China.

Abstract:Objective To investigate sugar intake from carbonated beverages of Chinese residents. Methods Multi-stage stratified random cluster and probability proportionate sampling method was used, and 27 485 residents aged 3 and above were included from one urban and one rural district of 14 provinces(cities) in China. Data was collected by non-continuous 3-day and 24-hour-dietary retrospective method. The added sugar content in 132 carbonated beverages was obtained through the investigation of added sugar content in beverages, the energy provided by added sugar in carbonated beverages was calculated and compared with the total dietary energy from the nutrition and health monitoring diet of Chinese residents, and energy supply ratio of added sugar in carbonated drinks was calculated. Results In 2014, the daily intake of added sugar from carbonated beverages was 0.5 g, and the energy supply ratio was 0.11%. The mean daily intake of added sugar was 13.4 g, the median was 12.3 g, and the energy supply ratio was 2.69%. The median daily intake of carbonated beverages for males (15.3 g) was higher than that for females (10.1 g), it was higher for the urban areas(13.8 g) than that for rural areas (10.7 g), the differences were statistically significant(P＜0.05). However, there was no significant difference in the daily energy supply of carbonated beverages between the sexes(P＞0.05). In addition, the consumption of carbonated beverages in urban areas (3.02%) was higher than that in rural areas (2.01%), the difference was statistically significant(P＜0.05). The energy supply ratio of carbonated beverage in 13-17 age group was 3.41%. Conclusion Adolescents are the high consumption group of carbonated drinks, so we should strengthen health education to guide reasonable consumption.

Abstract:Objective Summarize and analyze the common issues on new food additive applications, and make suggestions on both processes of submission and evaluation of applications for new food additives, and facilitate scientific, reasonable and standardized evaluation. Methods Use the “health administrative authorization management system” to obtain the statistics of new food additives applied in the year of 2010-2019, analyze the common problems, and put forward suggestions from technical aspects for new food additives. Results By analyzing final decisions of 769 new food additives applied in 2010-2019, common problems in both reception and safety evaluation stage were pointed out. On this basis, suggestions were put forward to further improve dossier requirements and safety data requirements from the management perspective. Conclusion The existing new food additive regulations and requirements can basically meet the needs of the safety evaluation. It is suggested to further refine the application requirements, formulate the application guidelines, and reinforce the safety evaluation requirements of new food additives.

Abstract:Objective Analyzing on-site disposal process of a mushroom poisoning in Wuhan. Identifying the toxin in the mushrooms and providing references for similar poisoning incidents. Methods Epidemiological investigation, clinical treatment data and suspicious poisonous mushroom sample were collected. Mushroom sample was identified by molecular analysis. Results All patients ate different quantity of fried mushroom. The early clinical symptom were mainly gastrointestinal symptoms, and the liver, kidney and coagulopathy were damaged in the later stage. The mushroom samples were identified as Amanita rimosa. Conclusion According to epidemiological,clinical,morphological and molecular biological evidence,this incident was confirmed to be a mushroom poisoning incident caused by Amanita rimosa.

Abstract:Objective To find out the suspicious food, pathogenic factors and risk factors of a foodborne disease outbreak in a factory, and to discuss the problems exposed in the investigation of the incident, so as to provide reference for the prevention, control and investigation of similar incidents in the future. Methods A case was defined as the onset of abdominal pain or diarrhea(≥3 times/24 hours)or vomiting in a person who worked in M factory from March 3 to March 4 in 2019. Case interviews and retrospective research was carried out using descriptive and analytical epidemics pathological method. Stool specimens of the cases,leftover food and related environmental samples were gathered for pathogen isolation and toxin gene detection using polymerase chain reaction(PCR). Results 106 cases were identified with a attack rate of 73.6% (106/144). The symptoms were diarrhea (78.3%,83/106), abdominal cramps (78.3%,83/106), abdominal gas pains(9.4%,10/106),and no fever. The epidemic curve showed a point source exposure pattern. The median incubation time was 10 hours (range:2-22 h). Illness were associated with three food items of the lunch on March 3 in 2019 by univariate analysis and Logistic regression analysis:braised fish pieces [relative risk (RR)=1.55,95% confidence interval (95%CI):1.29-1.85], pork stir-fried with garlic sprouts (RR=1.26,95%CI:1.01-1.57) and duck blood stir-fried with pickles (RR=1.47,95%CI:1.16-1.87). Alpha toxin and enterotoxin CPE genes were positive and beta toxin genes was negative in the Clostridium perfringens strain isolated in anal swabs of three patients, three environmental samples and two leftover food samples. There were possible bacterial contamination and reproduction in the processing and preparation of enterprise D, which delivered food. Conclusion This incident was caused by the food poisoning of Clostridium perfringens caused by the consumption of a meal provided by a catering company. After the meal was delivered, it should be cooled quickly and stored at low temperature. If it cannot be eaten immediately, it should be heated sufficiently before eating.

Abstract:Non-typhoidal Salmonella enterica is one of most important foodborne pathogens in the world. It infects humans through contaminated poultry and livestock meats. Published literature were reviewed to better understand quantitative microbiological risk assessment (QMRA) of non-typhoidal Salmonella enterica in pork products, especially the models commonly used. The challenges of QMRA of non-typhoidal Salmonella enterica in pork in China were analyzed, which could be the reference for the researches to be conducted in the future.

Abstract:The current study, using a systematic-literature-search approach, was intended to conduct hazard identification for dehydroacetic acid (DHA) and sodium dehydroacetate (DHA-S) which are currently used as food additives in China. DHA and DHA-S belong to the category of low toxic chemicals in terms of acute toxicity, mainly causing adverse effects in the central nervous system. Its subacute, subchronic and chronic toxicity mainly include significant reduction of body weight and food intake as well as anticoagulant effect. Reproductive development toxicity result show they can decrease body weight and inhibit bone development in offspring. According to the hazard identification result, oral intake of dehydroacetic acid and its sodium salt can produce a variety of toxic effects above certain doses. Further study is needed to determine the acceptable daily intake of DHA and its sodium salt and provide scientific evidence for safely use of these compounds as food additives.