Lead and its compounds can have cumulative harmful effects on the nervous, cardiovascular, and other systems, and especially affect the brain development of children. We collected 4918 samples from 15 food categories in 11 districts of Guangzhou, China, from 2017 to 2022, to investigate the extent of lead contamination in commercial foods and assess the health risk from dietary lead intake of the residents. Lead was measured in the samples using inductively coupled plasma mass spectrometry. Dietary exposure to lead was calculated based on the food consumption survey of Guangzhou residents in 2011, and the health risk of the population was evaluated using the margin of exposure (MOE) method. Lead was detected in 76.5% of the overall samples, with an average lead content of 29.4 mu g kg-1. The highest lead level was found in bivalves. The mean daily dietary lead intakes were as follows: 0.44, 0.34, 0.25, and 0.28 mu g kg-1 body weight (bw) day-1 for groups aged 3-6, 7-17, 18-59, and >= 60 years, respectively. Rice and rice products, leafy vegetables, and wheat flour and wheat products were identified as the primary sources of dietary lead exposure, accounting for 73.1%. The MOE values demonstrated the following tendency: younger age groups had lower MOEs, and 95% confidence ranges for the groups aged 3-6 and 7-17 began at 0.6 and 0.7, respectively, indicating the potential health risk of children, while those for other age groups were all above 1.0. Continued efforts are needed to reduce dietary lead exposure in Guangzhou.

Cadmium (Cd) and its compounds are hazardous environmental pollutants with renal toxicity and human carcinogenicity, with ingestion of contaminated foods representing the major mode of exposure. There have been a number of reports evaluating the Cd content in various foods; however, regarding the actual risk posed by dietary cadmium exposure, only a few reports are available in which single point evaluation (less accurate than multiple point evaluation) was employed. In this study, we used a margin of exposure (MOE) model and @RISK software (for multiple evaluation) to evaluate Cd-related health risk in the local Guangzhou residents at varying ages, through a comparison between the estimated monthly exposures and the provisional tolerable monthly intake (0.025 mg/kg body weight (b.w.)), based on the Cd contents in various food categories available locally (a total of 3964 food samples were collected from each of the 13 districts of Guangzhou between 2015 and 2019), which were determined by using inductively coupled plasma mass spectrometry. In this study, Cd was detected in 69.6% of the samples (averaged 0.120 mg/kg), and rice and its products, leafy vegetables, bivalves, and shrimp and crabs contributed most to Cd exposure (8.63, 3.18, 2.79, and 1.48 ng/kg b.w./day, respectively). The MOE values demonstrated the following tendency: the younger age group, the lower MOE, and its 95% confidence range for the (youngest) 3~6 year old group started from 0.92, indicating a health risk of young children, while that for the other age groups were all above 1.0. Our preliminary findings warrant further clarification using biomarker assays in the relevant population.

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.

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.

目的 了解广州市市售主要食品中镉含量,对广州市3～17岁儿童青少年膳食镉暴露风险进行初步评估.方法 2016-2018年监测广州市共16类2 882份食品镉含量,结合2011年广州市食物消费量调查数据,应用点评估方法,初步评估广州市3～17岁儿童青少年主要膳食的镉暴露风险.结果 广州市市售主要食品中镉平均含量为0.000 4～1.397 5 mg/kg,总检出率为81.37％,其中双壳贝类的镉含量平均值最高,为1.397 5 mg/kg.3～6岁学龄前儿童、7～17岁学龄期儿童青少年主要膳食镉的月平均暴露量分别为17.129 5、13.970 9 μg/kg·BW,安全限值(MOS)均＞1;根据食品化学物高端暴露模型计算,高端暴露量(P95消费量)分别为43.018 2、39.812 7μg/kg·BW,MOS均＜1.3～6岁、7～17岁儿童青少年膳食平均消费水平下镉暴露的主要来源依次为米及米制品、叶菜类和双壳贝类,3类食品累加贡献率分别为72.39％、75.09％;高消费水平下镉暴露的主要来源依次为双壳贝类、米及米制品和叶菜类,3类食品累加贡献率分别达89.01％、91.27％.结论 广州市3～17岁儿童青少年通过日常膳食摄入的镉对健康造成的风险较低,但食物高消费水平下尤其是双壳贝类高摄入人群存在一定的健康风险.应加强重点食品的镉含量监测,倡导平衡膳食和食物摄入的多样性.

Aflatoxin B 1 (AFB 1 ) contamination in foods is an important health challenge for low-and middle-income countries in subtropical regions. AFB 1 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 AFB 1 contamination in food stuffs in Guangzhou by using margin of exposure (MOE) and quantitative liver cancer risk approaches. A total of1854 AFB 1 -contaminated foodstuffs were sampled in supermarkets, agricultural markets, retail shops, and family workshops from 11 districts of Guangzhou, and AFB 1 content was determined by HPLC-fluorescence detector. In total, 9.9% (184/1854) of the test samples had AFB 1 concentrations above the limit of detection. Home-made peanut oil had the highest AFB 1 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 AFB 1 among suburban residents in Guangzhou. The production of home-made peanut oil should be supervised to reduce the risk of AFB 1 exposure.

Background: SARS-CoV-2 has been identified in the feces of COVID-19 patients. However, fecal transmission has never been shown epidemiologically. In April 2020, a COVID-19 outbreak occurred in a low-income community in Guangzhou, China. We investigated this outbreak to identify the mode of transmission. Methods: A home quarantined order was issued in the community. We collected throat swab samples from the residents and environmental samples from the surfaces inside and around the houses, and conducted RT-PCR testing and genome sequencing. We defined a case as a resident in this community with a positive RT-PCR test. We conducted a retrospective cohort study among the residents living in the same building as the cases to identify transmission risk factors. Findings: We found eight cases (four couples) in this community of 2888 residents (attack rate=2.8/1000), with onset from April 5 to 21, 2020. During their incubation periods, Cases 1 and 2 frequented a Market T, where an outbreak was ongoing. Cases 3-8 never visited Market T during incubation periods, lived in separate buildings from, and never interacted with, Cases 1 and 2. Retrospective cohort study showed that working as cleaners or street scavengers (RR=13, 95% CI: 1.8-99), not changing to clean shoes after returning home (RR=7.4, 95% CI: 1.7-33), collating and cleaning dirty shoes after returning home (RR=6.3, 95% CI: 1.4-28) were significant exposure risk factors. Of 63 samples collected from street sewage puddles and sewage pipes, 19% tested positive for SARS-CoV-2. Of 50 samples taken from the cases' apartments, 24% tested positive. RNA sequencing showed that the viruses identified from the squat toilet and the shoe-bottom dirt from the apartments of Cases 1 and 2 are homologous with those from Cases 3-8 and those identified from the sewage samples. The sewage pipe leading from the apartment of Cases 1 and 2 down to the drainage had a large crack above the ground. Rainfalls after the onset of Cases 1 and 2 flooded the streets. Interpretation: Our investigation has for the first time provided epidemiologic evidence that SARS-CoV-2 can be spread by sewage. This finding highlighted the importance of sewage management, especially in densely-populated places with poor hygiene and sanitation measures, such as urban slums and other low-income communities in developing countries. Funding: No.Declaration of Interests: The authors declare no competing interests.Ethics Approval Statement: This study was approved by the ethics committees of GZCDC (approval number GZCDC-ECHR-2020A0004).

目的 了解广州市市售大米镉污染情况,评估镉暴露对居民的健康风险,为确定镉污染监测重点和保障居民膳食安全提供依据.方法 采取分层随机抽样方法,于2014-2019年采集广州市11个区3～4个乡镇(街道)的农贸市场、超市、专卖店和种植户销售的大米.根据GB/T5009.15-2014《食品安全国家标准食品中镉的测定》,采用石墨炉原子吸收光谱测定法检测大米样品中的镉含量,采用单因子污染指数(Pi)评估大米镉污染状况,采用化学致癌物健康风险模型评估镉暴露的健康风险.结果 共采集市售大米600份,检出镉594份,检出率为99.00％.镉含量的中位数为0.093 mg/kg,镉含量超标20份,超标率为3.33％.大米中镉的Pi为0.367～ 0.545,平均值为0.478,污染等级均为优良.2014-2019年广州市居民经食用大米产生的镉暴露个人致癌年风险均值为(2.299～ 3.829)×10-5a-1,平均值为3.221×10-5a-1.结论 2014-2019年广州市市售大米镉含量基本符合国家标准,污染等级均为优良,广州市居民经食用大米摄入镉的健康风险较低.

目的 了解2019年广州市本地种植大米的镉含量,评估本地大米来源的镉暴露风险.方法 2019年采集广州市3个区农户种植的大米,共90份样品.依据GB/T 5009.15-2014《食品中镉的测定》方法检测大米样品镉含量.采用单因子污染指数评价广州市本地种植大米镉污染状况,并采用化学致癌物健康风险模型评估广州市当地居民大米来源的镉暴露风险.结果 90份大米样品中镉的检出率为97.78％,超标率为6.67％,镉含量中位数为0.074 mg/kg;2019年广州市本地种植大米单因子污染指数为0.367,属于优良等级;当地居民经大米摄入镉的健康风险值为3.006×10-5/a,低于国际辐射防护委员会推荐的最大可接受值(5×10-5/a)和美国环境保护署推荐的最大可接受值(1×10-4/a).结论 2019年广州市本地种植大米大部分镉含量处于安全值范围内,但存在个别样品超标;单因子污染指数显示广州市本地种植大米处于优良水平,当地居民通过大米来源的镉暴露风险较低.

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.

Cadmium and its compounds are human carcinogens with severe organ toxicity, and their contamination of agricultural soil in China has been frequently reported; however, the dietary exposure to cadmium in residents and the relevant health risk have seldom been reported. In this study, the concentration of cadmium in various types of food collected from 2013 to 2015 were analyzed using graphite furnace atomic absorption spectrometry, and the dietary exposure to cadmium assessed based on a dietary survey in 2976 Guangzhou residents. In total, 3074 out of 4039 food samples had cadmium levels above the limit of detection. The mean ± standard deviation (50th, 95th percentile) cadmium content in all samples was 159.0 ± 112.7 (8.6, 392.4) μg/kg, with levels ranging from 1.0 to 7830 μg/kg. Using the mean cadmium concentrations, the average monthly dietary exposure of Guangzhou residents to cadmium was 14.4 (μg/kg body weight (BW), accounting for 57.6% of the provisional tolerable monthly intake (PTMI). Rice, laver, vegetables, and live aquatic products were the main sources of cadmium intake, on average accounting for 89% of the total value. The dietary cadmium exposure in high consumers (95th percentile food consumption) was 41.0 μg/kg·BW/month, accounting for 163% of the PTMI. Additionally, dietary cadmium exposure at mean consumption but high cadmium food concentration (95th percentile) was 32.3 μg/kg·BW/month, corresponding to 129% of the PTMI. The level of dietary exposure to cadmium in most Guangzhou residents was within the safety limit, thus increased health risk from dietary cadmium exposure is low at present. However, continued efforts by local governments to monitor the levels of cadmium in the four main food categories contributing to exposure are necessary.

Objective To learn the food consumption and trends of urban and rural residents in Guangzhou for nutrition improvement.Methods The statistics yearbook data of Guangzhou city statistical bureau of urban and rural residents' food consumption were analyzed.We converted data into consumption per person a day,and analyzed the overall change of consumption trend and the differences between town and country.Results The dietary pattern of Guangzhou urban and rural residents had changed during 2000-2013.The results showed that the daily consumption of cereals,vegetative food and fruits were declining obviously while the consumption of meat,fishery products and eggs were increasing in the rural residents.In the urban residents,consumption of vegetative and milk especially cereals and fishery products were declining while the consumption of meat and oil were increasing.Conclusion In recent years,dietary pattern of urban and rural residents in Guangzhou showed the trend of ‘high energy density’ diet.Deviation from a balanced diet especially in rural residents,is likely to increase the further risk of related disease.Publicity and education and nutritional interventions should be carried out.

目的 调查广州市活禽档口H7N9禽流感防控设施现况,探讨活禽市场设施和管理中人感染H7N9禽流感病例发生的危险因素.方法 按各区进行分层随机抽样,抽取72个活禽市场,每个市场根据档口结构调查1～3个活禽档口,共抽取127个档口,均为非病例暴露市场.另选取病例暴露市场16个,调查其活禽档口30个.观察记录活禽档口通风设施、内部分隔及防控措施落实情况.结果 非中心城区档口在将禽类“运离市场”比例(25.86％)高于中心城区档口(7.25％) (x=8.230,P=0.004).在通风设备使用方面,病例暴露市场档口(93.33％)使用搅拌型通风器械比例多于非病例暴露市场档口(68.50％)(x2=6.420,P=0.011);病例暴露市场档口将禽类“留在市场存栏”比例(56.67％)高于非病例暴露市场档口(28.35％) (x2=8.704,P=0.003).结论 搅拌型通风器械和活禽留在市场存栏是人感染H7N9禽流感病例发生的危险因素.广州市活禽市场档口存在较多不利于禽流感防控的因素,政府须继续加强对于活禽档口设施和禽流感防控管理.

目的 分析一例跨省流动H5N1人禽流感病例应急监测结果,为人禽流感疫情的应急监测工作提供参考.方法 对病例密切接触者、可疑暴露市场的禽类从业人员实施症状和危险因素监测,设立应急监测医院进行流感样(In-fluenza Like Illness,ILI)病例监测.采集密切接触者、可疑市场禽类从业人员和应急监测搜索的ILI病例的咽因拭子、血清标本进行禽流感病毒(H5、H7和H9亚型)核酸与抗体检测;采集可疑市场外环境标本检测禽流感病毒(H5、H7、H9亚型)核酸.结果 23名密切接触者、34名禽类从业人员和应急监测搜索8名ILI的人禽流感H5亚型核酸和抗体检测结果均为阴性.病例发病期间,100％ (23/23)的密接者曾在距病例1米范围内工作,其中73.68％(14/19).医护人员密接者仅戴一次性纺纱口罩和手套,100％ (4/4)家属密接者无防护措施.销售或宰杀禽类时,23.53％ (8/34)的禽类从业人员穿戴一次性纺纱口罩与工作衣,32.35％ (11/34)的戴手套.应急监测医院ILI病例就诊百分比低于同期哨点监测医院(3.87％ VS 6.99％,x2=525.03,P＜0.05).禽类从业人员禽流感病毒H9亚型血清阳性率为6.06％ (2/33);市场外环境标本禽流感病毒H5亚型核酸阳性率为4.42％ (5/113),H9亚型阳性率为0.88％(1/113).结论 本起疫情未发现新发或续发病例.密接者与市场禽类从业人员的防护意识欠缺.禽类从业人员中未检出禽流感病毒H5亚型感染,但存在H9亚型感染;市场外环境存在H5和H9亚型感染.

OBJECTIVE:To investigate the molecular epidemiological characteristics of norovirus in Guangzhou from 2009 to 2011.METHODS:A total of 183 water samples, 1162 seafood samples and 1066 diarrhea stool specimens were collected from January 2010 to May 2011, June 2009 to June 2011 and July 2009 to December 2010 respectively in Guangzhou. Norovirus was detected by real time reverse transcript-PCR (qRT-PCR). The partial polymerase gene was amplified from norovirus positive samples, then sequenced and compared with the sequences of norovirus in GenBank. The phylogenetic tree was created.RESULTS:The positive rate was 19.67% (36/183), 8.26% (96/1162) and 37.05% (395/1066) in water samples, seafood and diarrhea patients respectively. Noroviruses from positive samples could be divided into 10 representative strains, in which 7 representative strains of genotype of 208 samples was type G2-4. The sequences from water, seafood and stool specimens were highly homologous with the similarity of 94% - 100%.CONCLUSION:In Guangzhou, the predominant Norovirus genotype was G2-4 and the positive rate of samples was high.

OBJECTIVE:To evaluate the risk of human infection after the outbreak of avian influenza H5N1 in animals, and probe the possibility for virus transmission.METHODS:By means of field epidemiological study, molecular epidemiology, serology and emergency surveillance, persons who had ever closely contacted with sick or dead poultry were observed. While, the RT-PCR and gene sequencing method were used to detect H5 nucleic acid from environmental swabs from 4 epidemic spots, and hemagglutination inhibition assay was also used to detect H5 antibody.RESULTS:Of 22 environmental swabs detected from 4 epidemic spots, one was positive for H5 nucleic acid, and the homogeneity was 95.9% as compared with H5N1 virus A/China/GD01/2006 (H5N1) found in Guangzhou in 2006 by gene sequence analysis. 62 environmental swabs from live poultry stalls of food markets near epidemic spot were detected negative. Six of 68 blood samples of contacts were positive for H9 antibody, and all were negative for H5 antibody. 68 throat swabs of contacts were detected negative for H5 nucleic acid. No close contact was found abnormal after 7 days medical observation. 337 influenza-like cases were reported in emergency surveillance, and no suspicious case was found.CONCLUSION:The current outbreak of H5N1 avian influenza in water fowls has not yet caused further transmission, and human avian influenza case has not been observed. It indicates that the ability of H5N1 virus to transmit to human is not strong yet, and the risk of human infection for H5N1 is still low.

An asymptomatic case of severe acute respiratory syndrome ( SARS) occurred early in 2004, during a community outbreak of SARS in Guangzhou, China. This was the first time that a case of asymptomatic SARS was noted in an individual with antigenemia and seroconversion. The asymptomatic case patient and the second index case patient with SARS in the 2003-2004 outbreak both worked in the same restaurant, where they served palm civets, which were found to carry SARS-associated coronaviruses. Epidemiological information and laboratory findings suggested that the findings for the patient with asymptomatic infection, together with the findings from previously reported serological analyses of handlers of wild animals and the 4 index case patients from the 2004 community outbreak, reflected a likely intermediate phase of animal-to-human transmission of infection, rather than a case of human-to-human transmission. This intermediate phase may be a critical stage for virus evolution and disease prevention.

A patient may have been infected with highly pathogenic avian influenza virus H5N1 in Guangzhou, People's Republic of China, at a food market that had live birds. Virus genes were detected in 1 of 79 wire cages for birds at 9 markets. One of 110 persons in the poultry business at markets had neutralizing antibody against H5N1.

Epidemiologic investigations showed that 2 of 4 patients with severe acute respiratory syndrome (SARS) identified in the winter of 2003–2004 were a waitress at a restaurant in Guangzhou, China, that served palm civets as food and a customer who ate in the restaurant a short distance from animal cages. All 6 palm civets at the restaurant were positive for SARS-associated coronavirus (SARS-CoV). Partial spike (S) gene sequences of SARS-CoV from the 2 patients were identical to 4 of 5 S gene viral sequences from palm civets. Phylogenetic analysis showed that SARS-CoV from palm civets in the restaurant was most closely related to animal isolates. SARS cases at the restaurant were the result of recent interspecies transfer from the putative palm civet reservoir, and not the result of continued circulation of SARS-CoV in the human population.

The genomic sequences of severe acute respiratory syndrome coronaviruses from human and palm civet of the 2003/2004 outbreak in the city of Guangzhou, China, were nearly identical. Phylogenetic analysis suggested an independent viral invasion from animal to human in this new episode. Combining all existing data but excluding singletons, we identified 202 single-nucleotide variations. Among them, 17 are polymorphic in palm civets only. The ratio of nonsynonymous/synonymous nucleotide substitution in palm civets collected 1 yr apart from different geographic locations is very high, suggesting a rapid evolving process of viral proteins in civet as well, much like their adaptation in the human host in the early 2002-2003 epidemic. Major genetic variations in some critical genes, particularly the Spike gene, seemed essential for the transition from animal-to-human transmission to human-to-human transmission, which eventually caused the first severe acute respiratory syndrome outbreak of 2002/2003.