Update on chromium speciation analysis in foods: a review of advances in analytical methods and dietary exposure assessment.

Chromium occurs naturally in different oxidation states. Amongst them, hexavalent chromium is classified as both genotoxic and carcinogenic while trivalent chromium can be considered as an essential element. Therefore, speciation analysis is essential when conducting dietary exposure assessment. Several critical reviews have been published on chromium speciation analysis in foodstuffs in the last decade. However, a method that can account for species interconversion during the extraction procedure has not been reported in the reviews. In recent years, an online method using species-specific isotope dilution mass spectrometry has been developed for the simultaneous determination of trivalent and hexavalent chromium in foodstuffs. Apart from that, new methods based on offline analytical techniques, to analyse trivalent and hexavalent chromium separately, are still under development. Therefore, one of the objectives of this paper is to review these recently published analytical methods and assess whether they are fit for chromium speciation analysis in foodstuffs. Additionally, an objective is also to assess whether their limits of detection are sufficiently low for dietary exposure assessment with respect to the neoplastic effects of hexavalent chromium. Moreover, possible future research gaps are identified based on the current knowledge and existing literature.

Chromatographic analysis of dithiocarbamate residues and their metabolites in foods employed in dietary exposure studies-a review.

Dithiocarbamates (DTCs) belong to a group of compounds used as fungicides in food production and can be divided into three major groups. Since DTCs easily oxidise and hydrolyse in alkaline and acidic medium respectively, precautions have to be implemented during preparation/homogenisation and extraction of samples. As such, test samples are commonly prepared individually by cutting into small pieces just before the digestion of DTCs with a hot acid to give carbon disulphide (CS2) and the results are expressed as CS2 without any differentiation of individual DTCs. However, individual DTCs have different toxicological potencies whilst their metabolites are more toxic than the parent compound. Apart from the hot digestion method, chromatographic separation of three major groups of DTCs has been developed by a number of different researchers. This review provides a comprehensive examination of sample preparation, extraction, clean-up and chromatographic methods for the determination of individual DTCs and their more toxic metabolites in foodstuffs. Moreover, this review also studies on how dietary exposure of DTCs can be efficiently and effectively estimated using different methods of analysis.

End stage liver disease etiology & transplantation referral outcomes of major ethnic groups in British Columbia, Canada: A cohort study.

ABSTRACT: Liver disease etiology and transplantation outcomes may vary by ethnicity. We aimed to determine if disparities exist in our province.We reviewed the provincial database for liver transplant referrals. We stratified cohorts by ethnicity and analyzed disease etiology and outcomes.Four thousand nine hundred sixteen referrals included 220 South Asians, 413 Asians, 235 First Nations (Indigenous), and 2725 Caucasians. Predominant etiologies by ethnicity included alcohol (27.4%) and primary sclerosing cholangitis (PSC) (8.8%) in South Asians, hepatitis B (45.5%) and malignancy (13.9%) in Asians, primary biliary cholangitis (PBC) (33.2%) and autoimmune hepatitis (AIH) (10.8%) in First Nations, and hepatitis C (35.9%) in Caucasians. First Nations had lowest rate of transplantation (30.6%, P = .01) and highest rate of waitlist death (10.6%, P = .03). Median time from referral to transplantation (268 days) did not differ between ethnicities (P = .47). Likelihood of transplantation increased with lower body mass index (BMI) (hazard ratio [HR] 0.99, P = .03), higher model for end stage liver disease (MELD) (HR 1.02, P < .01), or fulminant liver failure (HR 9.47, P < .01). Median time from referral to ineligibility status was 170 days, and shorter time was associated with increased MELD (HR 1.01, P < .01), increased age (HR 1.01, P < .01), fulminant liver failure (HR 2.56, P < .01) or South Asian ethnicity (HR 2.54, P < .01). Competing risks analysis revealed no differences in time to transplant (P = .66) or time to ineligibility (P = .91) but confirmed increased waitlist death for First Nations (P = .04).We have noted emerging trends such as alcohol related liver disease and PSC in South Asians. First Nations have increased autoimmune liver disease, lower transplantation rates and higher waitlist deaths. These data have significance for designing ethnicity specific interventions.

Successful Liver Transplantation in a Patient With Acute COVID-19 Infection and Acute Liver Failure: A Case Report.

Current liver transplantation societies recommend recipients with active coronavirus disease 2019 (COVID-19) be deferred from transplantation for at least 2 wks, have symptom resolution and at least 1 negative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test.1 This approach does not address patients who require urgent transplantation and will otherwise die from liver failure. We report a successful orthotopic liver transplant (OLT) in a patient with active COVID-19 infection. This is only the second to be reported worldwide and the first in Canada.

Quantification of permitted synthetic colours in food by liquid chromatographic methods: A review on analytical methods and theirperformance.

Colours, natural and synthetic, are substances which add or restore colour to a food after processing or storage. They are widely used by food manufacturers but may pose a potential risk to human health. Most food safety authorities set up regulations to limit the use of synthetic colours, and monitor their levels and consumption by the general public. Therefore, validated analytical methods are needed to fulfil this requirement. This review presents a comprehensive overview of various liquid chromatographic methods used for quantification of permitted synthetic colours in foods. Available analytical methods have been assessed for their fitness for purpose in terms of extraction, clean-up, liquid chromatographic separation, quantification and method performance. The advantages and disadvantages are given of available analytical methods for analysing 24 synthetic colours, permitted for use by different jurisdictions. Gaps in the knowledge and levels of validation are identified and recommendations made on further research to develop suitable methods for routine monitoring of these permitted synthetic colours.

A critical review of analytical methods for ergot alkaloids in cereals and feed and in particular suitability of method performance for regulatory monitoring and epimer-specific quantification.

Cereals and feed contaminated with ergot alkaloids (EAs) have been of concern for several decades. Nowadays, analysis of EAs is focused on ergometrine, ergotamine, ergosine, ergocristine, ergocryptine (a mixture of α- and ß-isomers) and ergocornine and their related -inine epimers as listed in the European Commission Recommendation 2012/154/EU. Liquid chromatography with fluorescence detection has been used for quantification of EAs for decades whilst LC-MS has become the work-horse for quantification of EAs in the last decade. However, in LC-MS analysis matrix effects of different magnitudes exist for each EA epimer, especially ergometrine/ergometrinine, even after different clean-up procedures. This leads to an underestimation or overestimation of EAs levels. Moreover, isotopic labelled standards for EAs are still not available in the market. This review aims to provide background information on different analytical methods, discuss their advantages and disadvantages and possible advancement. Moreover, the method performance requirements to support forthcoming regulations are also discussed.

The development of isomer-specific analysis of branched 4-nonylphenol in food for dietary exposure - a critical review of analytical methods and occurrence in foodstuffs.

4-Nonylphenol (4-NP) is a para-substituted phenolic compound comprising a straight or branched carbon chain group while branched 4-NP consists of 211 possible structural isomers. NP is recognised as an environmental pollutant and exists ubiquitously in both the environment and in food. 4-NP, especially branched 4-NP, has been shown to have the potential role of endocrine disruptor and xeno-oestrogen. Moreover, different NP isomers also exhibit different oestrogen-like activities. Recently, it was reported that the isomer-specific profile of 4-NP in foodstuffs varies greatly between and within food groups. Hence, risk assessment based on total branched 4-NP cannot reflect dietary risk. This study reviews the analytical methods applicable to conduct an isomer-specific analysis of 4-NP and its occurrence in foodstuffs. Lastly, research gaps are identified for future research.

The role of intraperitoneal chemotherapy in the surgical management of pancreatic ductal adenocarcinoma: a systematic review.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with poor prognosis, particularly for patients with metastatic disease. Treatment for oligometastatic presentation has been reported in recent literature, but the role of intraperitoneal chemotherapy for patients with peritoneal metastases (PM) remains unclear. We performed a systematic literature search of the PubMed, Cochrane and Embase databases in order to identify clinical trials and case-series reporting on the safety and efficacy of intraperitoneal chemotherapy in patients with PDAC-derived PM. Eight publications reporting on 85 patients were identified, using three different therapeutic strategies. First, 37 patients received cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) for PDAC with PM. Grade 3 and 4 complications occurred in 37.8% of patients, without perioperative mortality. Median disease-free survival and overall survival (OS) rates varied from 4 to 36 months and 4 to 62 months, respectively. Secondly, 40 patients with resectable PDAC without PM received prophylactic HIPEC following pancreatic resection, with postoperative morbidity and mortality rates of 30% and 5%, and 5-year OS rates of 23-24%. Finally, eight patients with PDAC-derived peritoneal disease were converted to resectable disease after receiving neoadjuvant intraperitoneal chemotherapy and operated on with curative intent, achieving a median OS of 27.8 months. In conclusion, CRS with HIPEC for PDAC-derived PM appears to be safe, conferring the same postoperative morbidity and mortality as reported on non-pancreatic malignancies. In highly selected patients, it could be considered for short-term disease control. However, long-term survival remains poor. The addition of prophylactic HIPEC for resectable PDAC cannot be recommended.

Occurrence of organotin compounds in seafood from Hong Kong market.

The degree of organotin compounds (OTCs), including dibutyltin, tributyltin, triphenyltin and dioctyltin, contamination in seafood purchased in 2017 and 2018 from Hong Kong market was studied. Edible portions of 341 seafood samples, including fish, crustaceans and molluscs, were used for analysis by gas chromatograph coupled to an inductively coupled plasma mass spectrometry (GC-ICP/MS). The method detection limits and quantification limits of OTCs were below or equal to 0.25 and 1.0 µg Sn kg-1 respectively. Triphenyltin accounted for the majority amongst other OTCs and was detected in 53% of samples. In general, mean total OTCs levels of fish (24 µg Sn kg-1) were higher than crustaceans (14 µg Sn kg-1) and molluscs (15 µg Sn kg-1). The highest detected levels of triphenyltin, tributyltin, dibutyltin and dioctyltin were found to be 480, 24, 4.5 and 0.89 µg Sn kg-1 in a mangrove snapper, noodle fish, coral clam and giant grouper respectively.

Development and validation of an analytical method for the analysis of Sterigmatocystin in roasted coffee beans and black pepper using liquid chromatography-tandem mass spectrometry.

Sterigmatocystin (STC) is a toxic and potentially carcinogenic fungal toxin found in a variety of food commodities. This study describes the development of an analytical method to determine STC in roasted coffee beans and black pepper using ultra performance liquid chromatography (UPLC) coupled with triple quadrupole tandem mass spectrometry (MS/MS). 13C18-STC was used as internal standard. STC was extracted with a mixture of acetonitrile/water, diluted with a buffer, followed by purification with a solid-phase extraction and an immunoaffinity column prior to the UPLC-MS/MS analysis. Two multiple reaction monitoring (MRM) transitions were employed, one for quantification and one for confirmation of STC. The UPLC-MS/MS analytical method was validated with respect to selectivity, linearity, sensitivity, accuracy, precision, recovery, and stability. Calibration curves were linear over a concentration range 25-2,500 pg mL-1 with correlation coefficients (r) > 0.998. The method limit of quantification for STC in roasted coffee beans and black pepper was 0.10 µg kg-1. The accuracy and precision of the analytical method were acceptable within 15% at all quality control levels. This method was suitable to determine STC levels because of its selectivity, precision, and accuracy. The method was successfully applied to roasted coffee beans and black pepper samples.

Minimally invasive hepatectomy is associated with decreased morbidity and resource utilization in the elderly.

BACKGROUND: The aim of this study was to evaluate whether elderly patients undergoing elective hepatectomy experience increased morbidity/mortality and whether these outcomes could be mitigated by minimally invasive hepatectomy (MIH). METHODS: 15,612 patients from 2014 to 2017 were identified in the Hepatectomy Targeted Procedure Participant Use File of the American College of Surgeons National Surgical Quality Improvement Program. Multivariable logistic regression models were constructed to examine the effect of elderly status (age ≥ 75 years, N = 1769) on outcomes with a subgroup analysis of elderly only patients by open (OH) versus MIH (robotic, laparoscopic, and hybrid, N = 4044). Propensity score matching was conducted comparing the effect of MIH to OH in elderly patients to ensure that results are not the artifact of imbalance in baseline characteristics. RESULTS: Overall, elderly patients had increased risk for 30-day mortality, major morbidity, prolonged length of hospital stay, and discharge to destination other than home. In the elderly subgroup, MIH was associated with decreased major morbidity (OR 0.71, P = 0.031), invasive intervention (OR 0.61, P = 0.032), liver failure (OR 0.15, P = 0.011), bleeding (OR 0.46, P < 0.001), and prolonged length of stay (OR 0.46, P < 0.001). Propensity score-matched analyses successfully matched 4021 pairs of patients treated by MIH vs. OH, and logistic regression analyses on this matched sample found that MIH was associated with decreased major complications (OR 0.69, P = 0.023), liver failure (OR 0.14, P = 0.010), bile leak (OR 0.46, P = 0.009), bleeding requiring transfusion (OR 0.46, P < 0.001), prolonged length of stay (OR 0.46, P < 0.001), and discharge to destination other than home (OR 0.691, P = 0.035) compared to OH. CONCLUSION: MIH is associated with decreased risk of major morbidity, liver failure, bile leak, bleeding, prolonged length of stay, and discharge to destination other than home among elderly patients in this retrospective study. However, MIH in elderly patients does not protect against postoperative mortality.

Impact of surgical wait times on oncologic outcomes in resectable pancreas adenocarcinoma.

BACKGROUND: Timely surgical resection in patients with suspected or diagnosed pancreas adenocarcinoma is an essential part of care. We hypothesized that longer surgical wait time was associated with worse oncologic outcomes. METHODS: A retrospective cohort of patients (N = 144) with resectable pancreas adenocarcinoma was divided into four wait time groups (<4, 4-8, 8-12, and >12 weeks), defined from the time of diagnosis on cross-sectional imaging. Overall and recurrence-free survival were analyzed using the Kaplan-Meier method and Cox proportional hazards regression. A higher rate of conversion to palliative bypass in patients waiting over 4 weeks was observed and further analyzed using post-hoc multivariate regression. RESULTS: On multivariable analysis, longer wait time was associated with improved overall (HR 0.49, 95% CI: 0.28-0.85) and recurrence-free survival (HR 0.29, 95% CI: 0.15-0.56) in >12 weeks compared to <4 weeks group. On post-hoc analysis, longer wait time over 8 weeks was positively associated with palliative bypass (OR 5.33, 95% CI: 1.32-27.88). CONCLUSION: Wait time over 8 weeks was associated with a higher rate of palliative bypass. There was an improvement in overall and recurrence-free survival in patients who waited over 12 weeks, likely due to selection bias.

Development of an Analytical Method for Analyzing Pyrrolizidine Alkaloids in Different Groups of Food by UPLC-MS/MS.

Suspected nontargeted pyrrolizidine alkaloids (PAs), without analytical reference standard, were observed and interfered with the determination of targeted PAs in complex food matrices, especially for spices samples. Selectivity and applicability of multiple reaction monitoring (MRM) transitions, multistage fragmentation (MS3), and MRM with differential ion mobility spectrometry (DMS) for eliminating false positive identifications were evaluated. Afterward, a selective and sensitive LC-MS/MS method for the determination of 15 PAs and 13 PA N-oxides in foodstuffs was developed. The sample preparation and cleanup are applicable to a wide range of foodstuffs, including cereal products, dairy products, meat, eggs, honey, tea infusion, and spices. Freezing-out of the raw extract and the water/acetonitrile washing steps in a solid phase extraction was found to efficiently remove complex matrices. The method was validated at 0.05 µg kg-1 for general food and 0.5 µg kg-1 for spices, with reference to the Eurachem Guide. The estimated limit of quantifications of different PAs was in the range of 0.010-0.087 µg kg-1 for general food and 0.04-0.76 µg kg-1 for spices. Isotopically labeled PAs were used as internal standards to correct the variation of PAs/PANs performance in different food commodities. Matrix effects observed in complex food matrices could be reduced by solvent dilution. Recoveries of PAs and PA N-oxides were all seen within 50-120%.

Determination of butyltins, phenyltins and octyltins in foods with preservation of their moieties: A critical review on analytical methods.

Tributyltin and triphenyltin have been extensively applied in anti-fouling paints since the 1960s. Hence, organotin compounds (OTCs), especially butyltins and phenyltins, in seafood has been of concern for decades. Even though the "International Convention on the Control of Harmful Anti-Fouling Systems on Ships, 2001" entered into force internationally in 2008 and prohibited the use of OTCs in anti-fouling paints used on ships, the analysis of OTCs in seafood was not commonly included in routine monitoring programmes. Besides, species of triphenyltin, including triphenyltin hydroxide and acetate, have been used as pesticides and may accumulate in food. Moreover, the European Food Safety Agency established a group tolerable daily intake for tributyltin, dibutyltin, triphenyltin and dioctyltin in 2004 as they exert their immunotoxic effects by similar mode of action and potency. Therefore, suitable methods are needed to analyze butyl-, phenyl- and octyl-tins simultaneously in food without affecting their moieties. This review aims to provide background information in this area.

Investigation of pyrrolizidine alkaloids including their respective N-oxides in selected food products available in Hong Kong by liquid chromatography electrospray ionisation mass spectrometry.

This study determined the levels of pyrrolizidine alkaloids (PAs), including their respective N-oxides, in foodstuffs available in Hong Kong by liquid chromatography-electrospray ionisation tandem mass spectrometry. A total of 234 samples (48 food items) were collected randomly from a local market and analysed. About 50% of samples were found to contain detectable amount of PAs. Amongst the 48 food items, PAs were not detected in 11 food items, including barley flour, beef, cattle liver, pork, pig liver, chicken meat, chicken liver, milk, non-fermented tea, Melissa tea and linden tea. For those found to contain detectable PAs, the summed PA content ranged up to 11,000 µg kg-1. The highest sum of PA content among the 37 food items calculated with lower bound was cumin seed, then followed by oregano, tarragon and herbs de Provence with ranges of 2.5-11,000, 1.5-5100, 8.0-3300 and 18-1300 µg kg-1 respectively. Among the samples, the highest sum of PA content was detected in a cumin seed sample (11,000 µg kg-1), followed by an oregano (5100 µg kg-1), a tarragon (3300 µg kg-1) and a herbs de Provence (1300 µg kg-1). In general, the results of this study agreed well with other published results in peer-reviewed journals, except that the total PAs in honey and specific tea infusion in this study were comparatively lower.

The differential effects of metronomic gemcitabine and antiangiogenic treatment in patient-derived xenografts of pancreatic cancer: treatment effects on metabolism, vascular function, cell proliferation, and tumor growth.

BACKGROUND: Metronomic chemotherapy has shown promising activity against solid tumors and is believed to act in an antiangiogenic manner. The current study describes and quantifies the therapeutic efficacy, and mode of activity, of metronomic gemcitabine and a dedicated antiangiogenic agent (DC101) in patient-derived xenografts of pancreatic cancer. METHODS: Two primary human pancreatic cancer xenograft lines were dosed metronomically with gemcitabine or DC101 weekly. Changes in tumor growth, vascular function, and metabolism over time were measured with magnetic resonance imaging, positron emission tomography, and immunofluorescence microscopy to determine the anti-tumor effects of the respective treatments. RESULTS: Tumors treated with metronomic gemcitabine were 10-fold smaller than those in the control and DC101 groups. Metronomic gemcitabine, but not DC101, reduced the tumors' avidity for glucose, proliferation, and apoptosis. Metronomic gemcitabine-treated tumors had higher perfusion rates and uniformly distributed blood flow within the tumor, whereas perfusion rates in DC101-treated tumors were lower and confined to the periphery. DC101 treatment reduced the tumor's vascular density, but did not change their function. In contrast, metronomic gemcitabine increased vessel density, improved tumor perfusion transiently, and decreased hypoxia. CONCLUSION: The aggregate data suggest that metronomic gemcitabine treatment affects both tumor vasculature and tumor cells continuously, and the overall effect is to significantly slow tumor growth. The observed increase in tumor perfusion induced by metronomic gemcitabine may be used as a therapeutic window for the administration of a second drug or radiation therapy. Non-invasive imaging could be used to detect early changes in tumor physiology before reductions in tumor volume were evident.

The effect of doxorubicin loading on response and toxicity with drug-eluting embolization in resectable hepatoma: a dose escalation study.

AIM: The dose-response relationship between doxorubicin and superabsorbent drug-eluting microspheres has not been established. In this study, we investigated the relationships between dose and delivery parameters as they pertain to toxicity and response in surgically resectable hepatocellular carcinoma (HCC). PATIENTS AND METHODS: Twenty-five patients with resectable HCC were randomly assigned and divided into four groups, each receiving either bland, 25 mg, 50 mg or 75 mg of doxorubicin loaded Super Absorbent Polymer microspheres, with 24 patients undergoing surgical resection. Response Evaluation and Criteria in Solid Tumors (RECIST) 1.0 and European Association for the Study of the Liver (EASL)-based volumetric response was performed at one month and surgical resection of the reference tumor was performed at two months. Adverse events were collected at regular intervals. RESULTS: Fifty-six percent of patients demonstrated complete response according to EASL criteria as opposed to 0% according to RECIST (v1.0) criteria. Residual tumor was identified in all groups (0 mg: 35%±28.5%; 25 mg: 42%±30.4%; 50 mg: 3.6%±3.3%; and 75 mg: 49.29%±32.6%. A total of 112 adverse events of grades 1-3 occurred (average 5.1 per patient), with no grade 4 or 5. No difference was noted between bland embolic and drug-loaded groups. Subset analysis did demonstrate a significantly increased degree of necrosis in the 50 mg-loaded group (p=0.018). Strong correlation existed between arterial phase Computer Tomography EASL-based response and histopathology (r=0.81; p<0.0001). All groups had residual tumor. CONCLUSION: Histology correlates strongly with one-month post-procedural imaging and response optimized at 50 mg of loading per vial. Adverse events were a reflection of embolization, with no relationship between loading dose or administered dose of doxorubicin.

Development of an ultraperformance liquid chromatography-tandem mass spectrometry method for the analysis of perfluorinated compounds in fish and Fatty food.

This paper reports the development of a method for the quantitative analysis of perfluorinated compounds (PFCs), including C6-C14 perfluorinated carboxylic acids (PFCAs) and C4-C12 perfluorinated sulfonates (PFSAs), in fish and fatty foods by ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) in which the UPLC was equipped a PFC Analysis Kit to eliminate background contamination. Rapid baseline separation was achieved for 17 PFCs within 12 min, and PFCs were well-resolved from potential interferences from taurodeoxycholic acid and branched isomers of PFCs. The method was validated according to Commission Regulation 2002/657/EC of the European Commission with matrices including salmon, beef, egg, and butter. Average spiked recoveries, measured at concentration levels of 0.02 (method limit of quantification (MLOQ)), 0.2, and 2 µg/kg, were in the range of 68-117% with relative standard deviations below 20%. Matrix effects were evaluated and found to be correctable by internal standardization, especially for short- and long-chained PFCs. Trueness was verified against two certified reference materials. The method has also been successfully applied to the analysis of more than 200 food samples of a risk assessment study.

A versatile self-assembly approach toward high performance nanoenergetic composite using functionalized graphene.

Exploiting the functionalization chemistry of graphene, long-range electrostatic and short-range covalent interactions were harnessed to produce multifunctional energetic materials through hierarchical self-assembly of nanoscale oxidizer and fuel into highly reactive macrostructures. Specifically, we report a methodology for directing the self-assembly of Al and Bi2O3 nanoparticles on functionalized graphene sheets (FGS) leading to the formation of nanocomposite structures in a colloidal suspension phase that ultimately condense into ultradense macrostructures. The mechanisms driving self-assembly were studied using a host of characterization techniques including zeta potential measurements, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), particle size analysis, micro-Raman spectroscopy, and electron microscopy. A remarkable enhancement in energy release from 739 ± 18 to 1421 ± 12 J/g was experimentally measured for the FGS self-assembled nanocomposites.

Dietary exposure of Hong Kong adults to pesticide residues: results of the first Hong Kong Total Diet Study.

The use of pesticides and other chemicals has become a common practice in modern agriculture to enhance and stabilise crop yield, protect the nutritional integrity of food, facilitate food storage to assure year-round supplies, and provide attractive and appealing food products. With the adoption of strict good agricultural practice (GAP), only minimal amounts of pesticide residues should remain on the crops or in connected foods of animal origin up the food chain. To assess their associated health risk to local people, the dietary exposure of Hong Kong adults to residues of four groups of pesticides or their metabolites - organophosphorus pesticides (OPPs), carbamates, pyrethrins and pyrethroids, and dithiocarbamate (DTC) metabolites - is estimated in the first Hong Kong Total Diet Study (TDS). A total of 150 commonly consumed food items were collected and prepared "as consumed". A total of 600 composite food samples were analysed for 85 pesticides or their metabolites by liquid chromatography-tandem mass spectrometry (LC-MS/MS). These pesticides were primarily found at low levels (highest mean = 350 µg kg⁻¹) in food samples of plant origin such as vegetables and fruits. Dietary exposures to pesticide residues were estimated based on the analytical results and the food consumption data of the local residents. The estimated dietary exposures of Hong Kong adults to all individual pesticides were well below their respective acceptable daily intakes (ADIs). The percentage contributions of the estimated mean and 95th percentile dietary exposures to the ADIs of individual pesticides were <6% and <24% for the OPPs, <1% for the carbamates and pyrethrins and pyrethroids, and <1% and <4% for the DTC metabolites, respectively. The findings indicate that dietary exposures to all the pesticide residues analysed in this study were unlikely to pose unacceptable health risks to the Hong Kong population.