ABSTRACT Background and Aims Melanoma can be effectively treated with immune checkpoint inhibitors (ICIs), but information regarding the risks of treatment‐related adverse events (trAEs), immune‐related adverse events (irAEs), and real‐world adverse events (AEs) is scarce. Methods We searched PubMed, Embase, Medline, and Cochrane CENTRAL databases for randomized controlled trials (RCTs) comparing ICIs for melanoma therapy up to February 16, 2025. Bayesian network meta‐analysis (NMA) was conducted, and odds ratios (ORs) with 95% credible intervals (95%CrI) were calculated. A pharmacovigilance analysis was performed using the Food and Drug Administration Adverse Event Reporting System (FAERS) database. ICI‐associated AEs in patients with melanoma were obtained for the period from the first quarter (Q1) of 2004 to Q1 of 2023. Results The NMA included 31 RCTs, comprising 11,937 patients with melanoma. Ipilimumab (Ipi), nivolumab (Nivo), and pembrolizumab (Pem) were ranked as having the lowest risk of any grade as well as grade 3–5 trAEs. Chemotherapy (Chemo) was associated with the lowest risk of any grade or grade 3–5 irAEs. Compared to other ICIs, Chemo, Ipi, and Ipi‐Chemo were associated with the lowest risk of any irAEs. Based on the results of the FAERS pharmacovigilance analysis, we identified 5974 AEs in 4599 melanoma patients treated with ICIs. ICIs were associated with statistically significant indications involving 236 preferred terms (PTs). Thoroughly examined and pinpointed AEs were strongly correlated with ICIs. Pem treatment was associated with 166 significant PTs. Apart from malignant neoplasm progression and death, the most common PT was an immune‐mediated adverse reaction. Conclusion The results of this study indicated that ICI safety profiles vary. These findings provide comparative safety signals that may help inform AE monitoring and risk assessment in patients with melanoma receiving ICIs, but they should not be interpreted as definitive prescribing guidance.

To define age-related ranges for normal urethral length in different pediatric age groups and to demonstrate the clinical impact of using these reference ranges during hypospadias repair. cohort of 501 male children and adolescents (aged 0-18 years) requiring indwelling catheters during hospitalization was enrolled. Urethral and penile lengths were measured, and participants were stratified into eight age groups. Additionally, 47 hypospadias patients undergoing urethroplasty were randomly divided into two groups: Group A (empirical catheter depth: 13-15 cm) and Group B (the 95th percentile of measurement-based catheterization depth). Postoperative symptoms were compared between groups. Mean urethral length was 12.8 cm (SD = 3.3), showing strong positive correlations with age, height, weight, and BMI (Spearman's ρ = 0.66-0.88, p < 0.001). Group B exhibited fewer postoperative symptoms (hematuria, pain, urinary overflow) than Group A (χ2 = 23.44, p < 0.05 and χ²=23.17, p < 0.0001). Our center cross-sectional study systematically established, for the first time, age-related reference ranges for normal urethral length in pediatric populations, filling a gap in the standardization of developmental anatomy. The application of these reference values in hypospadias repair surgery demonstrated that individualized urethral reconstruction catheterization based on age groups partly reduced postoperative complication rates.

Neonicotinoids (neonics) are a dominant class of insecticides; however, their dietary intake and associated risks in Guangzhou remain poorly characterized. Twelve neonic residues in 225 market-basket rice, vegetable, and fruit samples from Guangzhou were analyzed and the estimated daily intake (EDI) and health risk were assessed. Total neonics were calculated as imidacloprid-equivalent concentrations (IMIRPF) using relative potency factors, with hazard indices (HI) based on acceptable dietary intake (ADI) from GB 2763. Among the analyzed samples, 34.2 % contained at least 1 neonic, whereas 12.9 % contained 2-4 neonics. Vegetables (650 mu g center dot kg-1) and fruits (116 mu g center dot kg-1) had significantly higher IMIRPF than rice (42.34 mu g center dot kg-1). The average EDI of IMIRPF for children, teens, adults, and the elderly was 4.20, 3.32, 2.62, and 2.86 mu g center dot kg-1 body weight (bw)/day, respectively, which was below the chronic reference dose (cRfD) (57 mu g center dot kg-1 bw/day). Vegetables contributed to 89.1 %-92.7 % of the cumulative IMIRPF intake. Leafy vegetables mainly contributed to thiamethoxam (64.3 %-67.9 %) and acetamiprid (89.3 %-90.4 %) intake, whereas root and tuber vegetables accounted for 69.0 %-76.4 % of imidacloprid intake. Rice mainly contributed to clothianidin and dinotefuran exposure (45 %-52 %). Although none of the HIs for individual neonics exceeded 1, evidence for low-dose neurotoxicity and widespread use necessitates continued surveillance and downward revision of the cRfD.

Globally, the high consumption levels of sugar-sweetened beverages (SSBs) and their effect on health have drawn significant attention. This study aimed to identify the consumption patterns of SSBs among children in rural areas of Guangzhou, China, and explore their association with undernutrition. A total of 1864 children aged 9–17 years old were included in this study. Demographics, lifestyle behaviors, and anthropometric and dietary information were collected. Factor analysis was used to identify patterns of SSBs, while nutritional status was assessed using Body Mass Index (BMI). Latent class analysis was used to establish dietary preference models. Log-binomial regression analysis was used to analyze the association between SSBs consumption patterns and undernutrition. The undernutrition prevalence in children was 14.54–19.94% in boys and 9.07% in girls. Three SSB consumption patterns were identified, including the plant protein pattern, dairy-containing pattern, and coffee pattern. Both medium-high (Q3) and the highest (Q4) scores in the dairy-containing pattern were positively associated with the risk of undernutrition, especially in boys. Furthermore, the highest scores in the plant protein pattern and coffee pattern were positively associated with the risk of undernutrition in children aged 9–10 years old. The dairy-containing pattern was a risk factor for undernutrition in children, especially for boys; the plant protein patterns and coffee patterns were risk factors for undernutrition in children aged 9–10 years old. The findings of the study can provide scientific evidence and policy recommendations for improving children’s health conditions.

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.

IntroductionWith the economic recession and pandemic fatigue, milder viral variants and higher vaccine coverage along the time lay the basis for lifting anti-COVID policies to restore COVID-19 normalcy. However, when and how to adjust the anti-COVID policies remain under debate in many countries.MethodsIn this study, four countries (Singapore, South Korea, Australia, and New Zealand) and one region (Hong Kong SAR), that have shifted from the zero-COVID (ZC) policy to or close to the living-with-COVID (LWC) during or after the Omicron outbreak, were selected as research objects. All-cause mortality data were collected for these objects from 2009 to 2019. The expected mortality was estimated by a simple linear regression method. Excess mortality over time was calculated as the difference between the expected mortality and the observed mortality. Finally, percent excess mortality (PEM) was calculated as the excess mortality divided by the expected mortality.ResultsIn the examined four countries, PEM fluctuated around 0% and was lower than 10% most of the time under the ZC policy before 2022. After shifting to the LWC policy, all the examined countries increased the PEM. Briefly, countries with high population density (Singapore and South Korea) experienced an average PEM of 20–40% during the first half of 2022, and followed by a lower average PEM of 15–18% during the second half of 2022. For countries with low population density under the LWC policy, Australia experienced an average PEM of 39.85% during the first half of 2022, while New Zealand was the only country in our analysis that achieved no more than 10% in average PEM all the time. On the contrary, Hong Kong SAR under their ZC policy attained an average PEM of 71.14% during the first half of 2022, while its average PEM decreased to 9.19% in the second half of 2022 with LWC-like policy.ConclusionPEM under different policies within each country/region overtime demonstrated that the mortality burden caused by COVID-19 had been reduced overtime. Moreover, anti-COVID policies are suggested to control the excess mortality to achieve as low as 10% in PEM.

BACKGROUND:Various nonpharmaceutical interventions (NPIs) against COVID-19 continue to have an impact on socioeconomic and population behaviour patterns. However, the effect of NPIs on notifiable infectious diseases remains inconclusive due to the variability of the disease spectrum, high-incidence endemic diseases and environmental factors across different geographical regions. Thus, it is of public health interest to explore the influence of NPIs on notifiable infectious diseases in Yinchuan, Northwest China.METHODS:Based on data on notifiable infectious diseases (NIDs), air pollutants, meteorological data, and the number of health institutional personnel in Yinchuan, we first fitted dynamic regression time series models to the incidence of NIDs from 2013 to 2019 and then estimated the incidence for 2020. Then, we compared the projected time series data with the observed incidence of NIDs in 2020. We calculated the relative reduction in NIDs at different emergency response levels in 2020 to identify the impacts of NIPs on NIDs in Yinchuan.RESULTS:A total of 15,711 cases of NIDs were reported in Yinchuan in 2020, which was 42.59% lower than the average annual number of cases from 2013 to 2019. Natural focal diseases and vector-borne infectious diseases showed an increasing trend, as the observed incidence in 2020 was 46.86% higher than the estimated cases. The observed number of cases changed in respiratory infectious diseases, intestinal infectious diseases and sexually transmitted or bloodborne diseases were 65.27%, 58.45% and 35.01% higher than the expected number, respectively. The NIDs with the highest reductions in each subgroup were hand, foot, and mouth disease (5854 cases), infectious diarrhoea (2157 cases) and scarlet fever (832 cases), respectively. In addition, it was also found that the expected relative reduction in NIDs in 2020 showed a decline across different emergency response levels, as the relative reduction dropped from 65.65% (95% CI: -65.86%, 80.84%) during the level 1 response to 52.72% (95% CI: 20.84%, 66.30%) during the level 3 response.CONCLUSIONS:The widespread implementation of NPIs in 2020 may have had significant inhibitory effects on the incidence of respiratory infectious diseases, intestinal infectious diseases and sexually transmitted or bloodborne diseases. The relative reduction in NIDs during different emergency response levels in 2020 showed a declining trend as the response level changed from level 1 to level 3. These results can serve as essential guidance for policy-makers and stakeholders to take specific actions to control infectious diseases and protect vulnerable populations in the future.

Background: From January 2020 to June 2022, strict public health interventions against COVID-19 were implemented in Guangdong Province, China. Objectives: This study aims to investigate the evolution of within- and between-city COVID-19 dynamics in Guangdong Province in this period. Methods: Data of COVID-19 cases and synchronous interventions from January 2020 to June 2022 in Guangdong Province were collected. The epidemiological characteristics were described, and the effective reproduction number (Rt) was estimated using a sequential Bayesian method. Endemic-epidemic multivariate time-series model was employed to quantitatively analyze the spatiotemporal component values and variations, to identify the evolution of within- and between-city COVID-19 dynamics. Results: The incidence of COVID-19 in Guangdong Province was 12.6/100,000 population (15,989 cases) from January 2020 to June 2022. The Rt predominantly remained below 1 and increased to a peak of 1.68 in Stage 5. Results from the endemic-epidemic multivariate time-series model revealed a strong follow-up impact from previous infections in Dongguan, Guangzhou and Zhanjiang, with autoregressive components of 0.48, 0.45 and 0.36, respectively. Local risk was relative high in Yunfu, Shanwei and Shenzhen, with endemic components of 1.17, 1.04 and 0.71, respectively. The impact of the epidemic on the neighboring regions was significant in Zhanjiang, Shenzhen and Zhuhai, with epidemic components of 2.14, 1.92, and 1.89, respectively. In addition, the endemic-epidemic components have been dynamic transformation during the study period. Conclusion: The findings indicate the presence of spatiotemporal variation of COVID-19 in Guangdong Province, even with the implementation of strict interventions. These results underscore the need for specific interventions and coordinated interventions to control the epidemic of COVID-19.

Background: In this study, we applied a six sigma model to examine cerebrospinal fluid (CSF) biochemical analytes for the first time. Our goal was to evaluate the analytical performance of various CSF biochemical analytes, design an optimized internal quality control (IQC) strategy, and formulate scientific and reasonable improvement plans.Methods: The sigma values of CSF total protein (CSF-TP), albumin (CSF-ALB), chloride (CSF-Cl), and glucose (CSF-GLU) were calculated using the following formula: sigma = [TEa(%)-|bias(%)|]/CV(%). The analytical performance of each analyte was shown using a normalized sigma method decision chart. Individualized IQC schemes and improvement protocols for CSF biochemical analytes were formulated using the Westgard sigma rule flow chart with batch size and quality goal index (QGI).Results: The distribution of sigma values for CSF biochemical analytes ranged from 5.0 to 9.9, and the sigma values varied for different concentrations of the same analyte. The analytical performance of the CSF assays at the two QC levels is displayed visually in normalized sigma method decision charts. Individualized IQC strategies for CSF biochemical analytes were as follows: for CSF-ALB, CSF-TP and CSF-Cl, use 13s with N = 2 and R = 1000; for CSF-GLU, use 13s/22s/R4s with N = 2 and R = 450. In addition, priority improvement measures for analytes with sigma values less than 6 (CSF-GLU) were formulated based on the QGI, and their analytical performance was improved after the corresponding improvement measures were taken.Conclusions: The six sigma model has significant advantages in practical applications involving CSF biochemical analytes and is highly useful for quality assurance and quality improvement.

PurposeColorectal cancer (CRC) is one of the most common malignancies worldwide, with dramatically increasing incidence and mortality for decades. However, current therapeutic strategies for CRC, including chemotherapies and immunotherapies, have only demonstrated limited efficacy. Here, we report a novel immune molecule, CD43, that can regulate the tumor immune microenvironment (TIME) and serves as a promising target for CRC immunotherapy.MethodsThe correlation of CD43 expression with CRC patient prognosis was revealed by public data analysis. CD43 knockout (KO) CRC cell lines were generated by CRISPR-Cas9 technology, and a syngenetic murine CRC model was established to investigate the in vivo function of CD43. The TIME was analyzed via immunohistochemical staining, flow cytometry and RNA-seq. Immune functions were investigated by depletion of immune subsets in vivo and T-cell functional assays in vitro, including T-cell priming, cytotoxicity, and chemotaxis experiments.ResultsIn this study, we found that high expression of CD43 was correlated with poor survival of CRC patients and the limited infiltration of CD8(+) T cells in human CRC tissues. Importantly, CD43 expressed on tumor cells, rather than host cells, promoted tumor progression in a syngeneic tumor model. Loss of CD43 facilitated the infiltration of immune cells and immunological memory in the TIME of CRC tumors. Mechanistically, the protumor effect of CD43 depends on T cells, thereby attenuating T-cell-mediated cytotoxicity and cDC1-mediated antigen-specific T-cell activation. Moreover, targeting CD43 synergistically improved PD-L1 blockade immunotherapy for CRC.ConclusionOur findings revealed that targeting tumor-intrinsic CD43 could activate the antitumor immune response and provide particular value for optimized cancer immunotherapy by regulating the TIME in CRC patients.

BackgroundIt has been observed that cancer and venous thromboembolism (VTE) are associated, but anticancer therapy may violate the causality. Therefore, this study aimed to elucidate the causal relationship of various cancers to VTE using Mendelian randomization (MR).MethodsThree MR methods were used to estimate causal effects: Inverse variance weighted (IVW), MR‐Egger and weighted median. Sensitivity analyses included Cochran's Q‐test, MR‐Egger intercept test and MR‐PRESSO. Gene ontology enrichment analysis was performed to elucidate the underlying mechanisms of VTE development in cancer patients.ResultsThe primary IVW approach showed that non‐Hodgkin's lymphoma (NHL) might increase the risk of VTE (odds ratio [OR]: 1.20, 95% confidence interval [95% CI]: 1.00–1.44, p = 0.045), while melanoma possibly reduced the risk of VTE (OR: 0.89, 95% CI: 0.82–0.97, p = 0.006), although there was no significance after adjustment for multiple testing. No association was observed between VTE risk and other site‐specific cancers. Gene ontology enrichment analysis revealed that vitamin D played an important role in the development of VTE in cancer patients.ConclusionsOur findings suggested that genetically predicted NHL was associated with higher VTE risk, whereas melanoma had lower VTE risk compared with other site‐specific cancers. Moreover, this study suggested that anticancer therapy and increased extensive examination might play a more important role in VTE development than the nature of cancer.

目的 了解广州市中小学生营养不良现状并分析影响因素,为改善学生营养状况提供依据.方法 采用多阶段分层整群随机抽样的方法,抽取广州市增城区(农村)和荔湾区(城区)中小学生共1 403名.收集一般情况、生活方式、饮食行为和体格检查数据,并判断营养状况.采用x2检验比较营养不良率或构成比的差异,采用多因素logistic回归模型分析学生营养不良的影响因素.结果 学生营养不良检出率为8.70％,以消瘦为主(7.84％).其中,男生营养不良检出率高于女生(P = 0.027),城区学生生长迟缓检出率高于农村学生(P =0.020),中重度消瘦检出率随着年龄的增大降低(P= 0.029).多因素logistic回归分析显示男生(OR = 1.893,95％CI:1.270～2.820)是营养不良的危险因素,甜食摄入频次为 1～3 次/周(OR=0.277,95％CI:0.084～0.909)和 4～6 次/周(OR = 0.275,95％CI:0.079～0.954)是营养不良的保护因素.结论 广州市中小学生营养不良情况有所改善,但男生检出率仍较高.提示应重视中小学生营养不良,及时开展均衡膳食、饮食行为等干预,避免不良健康结局.

The emerging targeted therapies have revolutionized the treatment of advanced clear cell renal cell carcinoma (ccRCC) over the past 15 years. Nevertheless, lack of personalized treatment limits the development of effective clinical guidelines and improvement of patient prognosis. In this study, large-scale genomic profiles from ccRCC cohorts were explored for integrative analysis. A credible method was developed to identify synthetic lethality (SL) pairs and a list of 72 candidate pairs was determined, which might be utilized to selectively eliminate tumors with genetic aberrations using SL partners of specific mutations. Further analysis identified BRD4 and PRKDC as novel medical targets for patients with BAP1 mutations. After mapping these target genes to the comprehensive drug datasets, two agents (BI-2536 and PI-103) were found to have considerable therapeutic potentials in the BAP1 mutant tumors. Overall, our findings provided insight into the overview of ccRCC mutation patterns and offered novel opportunities for improving individualized cancer treatment.

Pre-exposure prophylaxis (PrEP) is a promising HIV prevention method. However, the rollout of PrEP among men who have sex with men (MSM) is facing challenges. This study sought to understand PrEP acceptability and service use challenges among MSM in China. The study was conducted in 2018 in Guangdong Province using a mixed-methods approach. Among 489 HIV-negative MSM who completed an online survey, 374 (76.5%) had heard of PrEP before. The most common PrEP information sources were internet/social media (32.1%) and community-based organizations (30.4%). Two-thirds (n=328) of the MSM would accept PrEP even the protective efficacy is less than 100%, 60.1% (n=294) expressed willingness to use PrEP once it is approved in China, and 59.3% (n=290) were willing to pay out of pocket. Employment, disclosure of MSM status, and mental health issues were associated with PrEP acceptability. In-depth interviews with 30 MSM revealed that high cost, low accessibility, and stigma in clinic settings were barriers to PrEP using. Primary care-based PrEP services were acceptable, but patients' confidentiality was a concern. PrEP promotion efforts should address social and mental health challenges among MSM and mobilize primary care systems and community-based organizations to achieve the best result.

AbstractBackgroundThe uptake of colonoscopy is low in individuals at risk of colorectal cancer (CRC). We constructed a risk-prediction score (RPS) in a large community-based sample at high risk of CRC to enable more accurate risk stratification and to motivate and increase the uptake rate of colonoscopy.MethodsA total of 12,628 participants classified as high-risk according to positivity of immunochemical fecal occult blood tests or High-Risk Factor Questionnaire underwent colonoscopy. Logistic regression was used to derive a RPS and analysed the associations of the RPS with colorectal lesions, giving odds ratios (ORs) and 95% confidence intervals (CIs).ResultsOf the participants, men (OR = 1.73, 95% CI = 1.58–1.90), older age (≥65 years; 1.41, 1.31–1.53), higher body mass index (≥28 kg/m2; 1.22, 1.07–1.39), ever smoking (1.47, 1.31–1.65), and weekly alcohol use (1.28, 1.09–1.52) were associated with a higher risk of colorectal lesions. We assigned 1 point to each of the above five risk factors and derived a RPS ranging from 0 to 5, with a higher score indicating a higher risk. Compared with a RPS of 0, a RPS of 1, 2, 3, and 4–5 showed a higher risk of colorectal lesions, with the OR (95% CI) being 1.50 (1.37–1.63), 2.34 (2.12–2.59), 3.58 (3.13–4.10), and 3.91 (3.00–5.10), respectively. The area under the receiver-operating characteristic curve of RPS in predicting colorectal lesions was 0.62.ConclusionsParticipants with an increase in the RPS of ≥1 point had a significantly higher risk of colorectal lesions, suggesting the urgency for measuring colonoscopy in this very high-risk group. High-risk strategies incorporating RPS may be employed to achieve a higher colonoscopy-uptake rate.

A 7-day-old male neonate was admitted due to testing positive for SARS-CoV-2. The neonate was born through cesarian section at 40 weeks and 2 days of gestation. His mother was diagnosed with coronavirus disease 2019 (COVID-19) caused by Omicron variant infection 1 day before delivery. The neonate was separated from his mother after birth and was taken care of by his father. Three days after the neonate was born, his father was also diagnosed with COVID-19. The neonate was diagnosed with COVID-19 on day 7 of life. The neonate presented with hyperpyrexia, dyspnea, hypoxia, and feeding difficulties, and the chest CT showed the coexistence of consolidation and ground glass-like changes mainly located below the posterior pleura. He was given symptomatic support treatment such as low flow oxygen therapy and posture management after admission. He was cured and discharged after 10 days of hospitalization. This is the first reported case of neonatal severe COVID-19 caused by Omicron variant infection in China. It is necessary to take appropriate protective measures for the neonate to prevent infection when the mother or caregiver of the neonate is a suspected or confirmed cases of COVID-19.

Objectives To evaluate the cost-effectiveness of four different primary screening strategies: high-risk factor questionnaire (HRFQ) alone, single immunochemical faecal occult blood test (iFOBT), double iFOBT and HRFQ+double iFOBT for colorectal cancer (CRC) screening compared with no screening using the Markov model. Methods Treeage Pro V.2011 software was used to simulate the Markov model. The incremental cost-effectiveness ratio, which was compared with the willingness-to-pay (WTP) threshold, was used to reflect the cost-effectiveness of the CRC screening method. One-way sensitivity analysis and probabilistic sensitivity analysis were used for parameter uncertainty. Results All strategies had greater effectiveness because they had more quality-adjusted life years (QALYs) than no screening. When the WTP was ¥435 762/QALY, all screening strategies were cost-effective compared with no screening. The double iFOBT strategy was the best-buy option compared with all other strategies because it had the most QALYs and the least cost. One-way sensitivity analysis showed that the sensitivity of low-risk adenoma, compliance with colonoscopy and primary screening cost were the main influencing factors comparing single iFOBT, double iFOBT and HRFQ+double iFOBT with no screening. However, within the scope of this study, there was no fundamental impact on cost-effectiveness. Probabilistic sensitivity analysis showed that when the WTP was ¥435 762/QALY, the probabilities of the cost-effectiveness acceptability curve with HRFQ alone, single iFOBT, double iFOBT and HRFQ+double iFOBT were 0.0%, 5.3%, 69.3% and 25.4%, respectively. Conclusions All screening strategies for CRC were cost-effective compared with no screening strategy. Double iFOBT was the best-buy option compared with all other strategies. The significant influencing factors were the sensitivity of low-risk polyps, compliance with colonoscopy and cost of primary screening.

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.