Exploring the characteristics of Burkholderia gladioli pathovar cocovenenans: Growth, bongkrekic acid production, and potential risks of food contamination in wet rice noodles and vermicelli.

This research investigated the presence of Burkholderia gladioli pathovar cocovenenans (BGC) in wet rice and starch products, Tremella, and Auricularia auricula in Guangzhou, China. It examined BGC growth and bongkrekic acid (BA) production in wet rice noodles and vermicelli with varying rice flour, edible starch ratios, and oil concentrations. A qualitative analysis of 482 samples revealed a detection rate of 0.62%, with three positive for BGC. Rice flour-based wet rice noodles had BA concentrations of 13.67 ± 0.64 mg/kg, 2.92 times higher than 100% corn starch samples (4.68 ± 0.54 mg/kg). Wet rice noodles with 4% soybean oil had a BA concentration of 31.72 ± 9.41 mg/kg, 5.74 times higher than those without soybean oil (5.53 ± 1.23 mg/kg). The BA concentration correlated positively (r = 0.707, P < 0.05) with BGC contamination levels. Low temperatures (4 °C and -18 °C) inhibited BGC growth and BA production, while higher storage temperatures (26 °C and 32 °C) promoted BGC proliferation and increased BA production. Reducing edible oil use and increasing edible starch can mitigate the risk of BGC-related food poisoning in wet rice noodles and vermicelli production. Further research is needed to find alternative oils that do not enhance BA production. Strengthening prevention and control measures is crucial across the entire production chain to address BGC contamination and BA production.

High-rise buildings: A risk factor in the COVID-19 Omicron epidemic period.

Objectives: This study aimed to investigate possible viral transmission scenarios inside a high-rise building during the Omicron phase of the COVID-19 pandemic. Study design: Cross-sectional study design. Methods: In order to determine the pathogenicity of the Omicron variant of SARS-CoV-2, demographic, vaccination and clinical data were collected from COVID-19 positive cases during an outbreak in a high-rise residential building in Shenzhen, China, in early 2022. The pattern of viral transmission inside the building was determined through field investigation and engineering analysis. The results highlight the risk of Omicron infection in high-rise residential buildings. Results: Symptoms of infection with the Omicron variant are predominantly mild. Younger age has a greater impact on the severity of disease than vaccination status. Each floor of the high-rise building investigated contained 7 apartments, numbered 01 to 07, positioned in the same layout on each floor. The drainage system included vertical pipes from the ground to the roof of the building. There were statistically significant differences in infection rates at different time points and incidence ratios between apartment numbers ending in 07 (type 07) and other apartments (P < 0.001). Households with early disease onset were concentrated in apartment type 07 and the severity of their disease was more severe. The incubation period of the outbreak was 5.21-5.31 days and the time-dependent reproduction number (Rt) was 12.08 (95% confidence interval [CI] 7.66, 18.29). Results suggest both non-contact and contact viral transmission may have contributed to the outbreak. The drainage system in the building allows aerosol regurgitation, thus indicating that the structure of the building may have led to spread of the virus from the sewage pipes. Infections in other apartments may have been as result of viral transmission in the elevators and intimate family contact. Conclusions: Results from this study suggest that Omicron transmission was likely to be via the sewage system, supplemented by contact transmission in the stairs and elevators. The environmental spread of Omicron needs to be highlighted and prevented.

Probabilistic risk assessment of dietary exposure to pentachlorophenol in Guangzhou, China.

Pentachlorophenol (PCP) is a ubiquitous environmental contaminant commonly existing as its sodium salt (NaPCP), which enters the human body primarily through long term but low-level dietary exposure. PCP contributes to chemical carcinogenesis and teratogenesis. In this study, the probabilistic risk of dietary exposure to PCP in Guangzhou citizens was investigated. In total, 923 food samples in the categories of pork, livestock (beef and lamb), poultry, offal, eggs, and freshwater fish (considered to be relatively susceptible to PCP contamination) were collected from various markets in Guangzhou and tested for PCP. Probabilistic risk assessment model calculations for PCP dietary exposure and margin of exposure (MOE) values were performed using @RISK software, based on a Monte Carlo simulation with 10,000 iterations. The overall detection rate of PCP (above 1 µg kg-1, the detection limit) was 19.9% (184/923), with an average of 7.9 µg kg-1. The highest rate of PCP detection, 28.2%, was in livestock (beef and lamb). The MOE value for dietary PCP exposure in general Guangzhou residents averaged 400, which was far below 5,000 (the borderline for judging a health risk). The lowest MOE value, 190, was observed in the 3- to-6-year old population and indicates a significant risk. In conclusion, this study suggests that PCP exposure in Guangzhou residents is of considerable health risk, especially for the pre-school young children.

[Lead contamination status and assessment of potential risk to human health of commercial foods in Guangzhou City in 2017-2019].

OBJECTIVE: To investigate lead contamination in commercial foods in Guangzhou City, and to assess the health risk of dietary lead exposure in the residents. METHODS: Food samples were collected in 11 districts in Guangzhou City from 2017 to 2019.The samples were tested for lead by using inductively coupled plasma mass spectrometry. The dietary exposure to lead of residents of different age groups in Guangzhou was calculated in combination with the intake of foods from the food consumption survey of Guangzhou residents in 2011, and the margin of exposure(MOE) method was used to evaluate the health risk of the population. RESULTS: A todal of 3130 food samples of 15 categories were collected. The overall lead detection rate was 82.11%, the exceeding rate was 0.13%, and the average lead content was 0.031 mg/kg. The highest lead levels were found in bivalve, edible fungi and flour and flour products. Excessive levels of lead were found in bivalve, eggs and egg products, and flour and flour products. The average daily dietary intake of lead in people aged 3-6, 7-17, 18-59 and over 60 in Guangzhou were 0.368, 0.377, 0.326 and 0.337 µg/kg, respectively. Daily lead exposure of population with high consumption(P95) in various age groups through foods were 1.091, 1.079, 0.906 and 0.925 µg/kg, respectively. Brassica and leafy vegetables, rice and its products and meat were the main sources of dietary lead exposure, accounting for 53.28% of the total dietary lead exposure. The average MOE of lead in all age groups were greater than 1, but the P95 of MOE value of people aged 3-6 and 7-17 were 0.55 and 0.56, respectively, which presented certain health risks. CONCLUSION: There was a certain amount of lead exceeding the standard in commercial foods in Guangzhou. The average level of dietary lead exposure for residents of all ages posed a low risk to population health, but the dietary lead exposure risk of high-food consumers aged 3-6 and 7-17 posed certain health risks that deserve significant attention.

Probabilistic Risk Assessment of Dietary Exposure to Chloramphenicol in Guangzhou, China.

Chloramphenicol has been used in veterinary medicine, where its residues can remain in food of animal origin, thus potentially causing adverse health effects. This facilitated the ban for its use in food-producing animals globally, but its residues have remained ubiquitous. In this study, food commodities possibly contaminated with chloramphenicol, including livestock meat, poultry, edible viscera, fish, shrimp and crab, molluscs, milk, and eggs, were collected from domestic retail shops in all the 11 districts of Guangzhou and tested for its residue. Probabilistic risk assessment model calculations for its dietary exposure, and the margin of exposure (displayed as mean values and 5th percentile to 95th percentile ranges) were performed by using @RISK software based on a Monte Carlo simulation with 10,000 iterations. The results indicated the detection of chloramphenicol in 248 out of 1454 samples (17.1%), which averaged to a level of 29.1 µg/kg. The highest average value was observed in molluscs (148.2 µg/kg, with the top value as 8196 µg/kg); meanwhile, based on the dietary structure of a typical Cantonese, pond fish, pork, and poultry meat contributed most (about 80%) to the residents' dietary exposure to chloramphenicol. The margin of exposure for dietary chloramphenicol exposure in Guangzhou residents was 2489, which was apparently below 5000 (the borderline for judging a health risk), particularly low in preschool children (2094, suggesting an increased risk). In conclusion, the study suggests that chloramphenicol exposure in Guangzhou residents is considerable, and its relevant health hazard, especially for preschool children, is worthy of further investigation.

Probabilistic risk assessment of dietary exposure to aflatoxin B1 in Guangzhou, China.

Aflatoxin B1 (AFB1) contamination in foods is an important health challenge for low-and middle-income countries in subtropical regions. AFB1 has been detected in a variety of foodsin Guangzhou, while the risk of dietary exposure is unknown. This study aimed to assess the probabilistic risk of dietary exposure to AFB1 contamination in food stuffs in Guangzhou by using margin of exposure (MOE) and quantitative liver cancer risk approaches. A total of1854 AFB1-contaminated foodstuffs were sampled in supermarkets, agricultural markets, retail shops, and family workshops from 11 districts of Guangzhou, and AFB1 content was determined by HPLC-fluorescence detector. In total, 9.9% (184/1854) of the test samples had AFB1 concentrations above the limit of detection. Home-made peanut oil had the highest AFB1 concentration, with a mean value of 38.74 ± 47.45 µg kg-1. The average MOE levels of Guangzhou residents ranged from 100 to 1000. The risk of liver cancer was 0.0264 cancers (100,000 population year)-1. The health risks of suburban people were higher than those of urban people, and home-made peanut oil was the main contributorto dietary exposure to AFB1 among suburban residents in Guangzhou. The production of home-made peanut oil should be supervised to reduce the risk of AFB1 exposure.

Dietary Lead Exposure and Associated Health Risks in Guangzhou, China.

Lead exposure is associated with a wide range of adverse effects on human health. The principal exposure route in the general population is through the diet. In this study, we estimate the dietary lead intake and associated health risks among the residents of Guangzhou, China. Data on lead concentrations were derived from the food safety risk monitoring system, which included 6339 samples from 27 food categories collected in 2014-2017. Food consumption data were taken from a 2011 dietary survey of 2960 Guangzhou residents from 998 households. Dietary lead intake was estimated by age group (3-6, 7-17, 18-59, and ≥60 years), and relevant health risks were assessed using the margin of exposure (MOE) method. The mean and 95th percentiles (P95) of dietary lead intake were respectively 0.7466 and 2.4525 µg/kg body weight per day for preschool children aged 3-6 years; 0.4739 and 1.5522 µg/kg bw/day for school children aged 7-17 years; 0.3759 and 1.1832 µg/kg bw/day for adults aged 18-59 years; and 0.4031 and 1.3589 µg/kg bw/day for adults aged ≥60 years. The MOE value was less than 1 for preschool children at the mean exposure level and for all age groups at the P95 exposure level. Rice and its products, leafy vegetables, and wheat flour and its products were found to be the primary food sources of lead exposure. Our findings suggest that the health risk from dietary lead exposure is low for Guangzhou residents overall, but that young children and consumers of certain foods may be at increased risk. Continued efforts are needed to reduce the dietary lead exposure in Guangzhou.

Epidemiological characteristics of asymptomatic Norovirus infection in a population from oyster (Ostrea rivularis Gould) farms in southern China.

The following paper investigates the prevalence and characteristics of asymptomatic norovirus infection in the population living around oyster farm sites. Two consecutive surveys were conducted from January 2014 to December 2014 and 4549 stool samples were screened during the same time period. The total asymptomatic infection rate was 4.04% (184/4549). Norovirus infection rate was 5.20% in oyster farming population which was significantly higher compared with non-farming population where the infection rate was 3.65% (χ2 = 5.49, P < 0.05). A total of 184 NoV positive samples were identified by real time-quantitative polymerase chain reaction (RT-qPCR) and semi-nested RT-PCR and 136 sequences were obtained. The sequences were clustered into 14 genotypes. GI strains were clustered into six genotypes, including GI.2, GI.3, GI.5, GI.6, GI.8 and GI.9; while GII strains were clustered into GII.2, GII.3, GII.4, GII.5, GII.6, GII.8 and GII.13. GI.9 and GII.17 were the predominant and most prevalent genotypes, respectively. The GII.17 genotype replaced GII.4 becoming the dominant genotype in the oyster farming area in 2014. To sum up, long-term monitoring of asymptomatic infection is crucial for the detection of new variant strains and for identifying outbreaks during the early stage.

[Norovirus infection surveillance in early warning of outbreaks in population in oyster farming areas].

OBJECTIVE: To have an insight into the prevalence tendency caused by Noroviruses( NoVs) in population of oyster farming areas, and evaluate the early warning signification of acute gastroenteritis( AGE) monitoring. METHODS: Between January and December in 2014, a retrospective household survey of AGE during past four weeks was conducted to residents using multi-stage sampling in oyster farming areas. Norovirus capsid genome was detected using real-time RT-PCR and semi-nested PCR, sequenced and phylogenetic analyzed. RESULTS: A total of 75 cases of AGE were reported. The incidence rate was 0. 10 per person-year, the detection rate of norovirus was 20. 0%( 15 /75). The dominant epidemic No Vs strain in oyster farming was still GII. 4 Sydney 2012. Furthermore, a newly GII. 17 variant was detected and early in March 2014. CONCLUSION: The GII. 4 Sydney 2012 genotype is still prevalent strain that caused AGE currently in the community residents of oyster farming areas. NoVs GII. 17 variant was found in sporadic patients of sentinel hospital AGE monitoring in March 2014 that have an early warning effect to the outbreaks of winter in 2014.