3-MCPD Fatty Acid Esters Research Articles

Exposure to Dietary Glycidyl and 3-MCPD Fatty Acid Esters and Associated Burden of Cancer in Selected Asian and European Countries: A Review and Data Synthesis.

This study evaluated the health implications and oncological impact of consuming glycidyl esters (GE) and 3-monochloro-1,2-propanediol esters (3-MCPDE) in selected Asian and European populations. Data on dietary GE and 3-MCPDE were compiled from 10 studies conducted in China, Taiwan, Poland, and Spain, identified through a systematic search in PubMed and ScienceDirect databases from 2012 to 2022. Studies on food supplements and analytical methods were excluded from the analysis. Health metrics for these nations, spanning 2015 to 2019, were sourced from the Institute of Health Metrics and Evaluation, among others. A Monte Carlo Simulation was employed for data analysis. The results showed that "grains and grain products" was the most consumed food category (260.45-395.35 g/day), whereas "food for infants and children" was the least consumed (0.01-0.09 g/day). Additionally, "fats from animal or plant origin" had the highest contamination levels. While 3-MCPDE exposures remained within safe limits, median GE exposure correlated with an incidence of colon cancer ranging from 3.66 × 10-8 to 0.744%, lung cancer from 0.00256 to 0.287%, and breast cancer from 0.0262 to 2.42% within the study areas. This translated to a total cancer burden of 6.69 to 1020 Disability-Adjusted Life Years (DALYs) per 100 000 individuals. The population in China recorded the highest DALY rate (1,020), followed by Spain (30.2), Poland (19.7), and Taiwan (6.69). Projections suggest an uptick in GE-related cancer cases and associated burdens in the coming decades attributed to demographic shifts, ageing populations, and dietary changes. The study underscores the urgency of mitigating GE and 3-MCPDE food contamination, bolstering public health awareness, and establishing safety guidelines.

Development of Indirect Quantitative Methods for 3-MCPD Fatty Acid Esters (3-MCPDEs) and Glycidyl Fatty Acid Esters (GEs) in Thermally Processed Foodstuffs.

For indirect determination of 3-chloro-1,2-propanediol fatty acid esters (3-MCPDEs) and glycidyl fatty acid esters (GEs) in thermally processed foodstuffs distributed in Japan, we modified two published methods, an enzymatic method (later approved as JOCS Standard Method for the Analysis of Fats, Oils, and Related Materials 2.4.14-2016 and Joint JOCS/AOCS Official Method Cd 29d-19) and EFSA method developed by the Joint Research Centre of the European Commission. The performance of these methods was demonstrated to be satisfactory. The partially modified enzymatic method showed mean recoveries of 93.7-98.5% for 3-MCPDEs, 94.4-98.4% for GEs, and HorRat(r) values of 0.06-0.78 in analyses of 6 types of foods including Japanese specific foods (fried rice cracker, fried instant noodle, biscuit, karinto, vegetable tempura, and frozen deep-fried chicken) spiked with 3-MCPD dioleate and glycidyl oleate at 0.02-0.04 mg/kg or 0.2-0.4 mg/kg. The partially modified EFSA method showed mean recoveries of 96.6-99.4% for 3-MCPDEs, 95.7-100.1% for GEs, and HorRat(r) values of 0.14-1.05 in analyses of 5 types of foods (not including karinto) spiked simultaneously with 3-MCPD dioleate and glycidyl oleate at either 0.02-0.04 mg/kg or 0.2-0.4 mg/kg. The results of analyses of 9 samples (fried rice cracker, biscuit, 2 potato crisps, fried potato snack, baked cracker, cracker dough, seafood tempura, and frozen deep-fried chicken) using these 2 methods were comparable. The 95% confidence intervals determined with weighted Deming regression analysis between the results of 3-MCPDEs or GEs in the same samples analyzed by the 2 methods showed: the slope around 1 (3-MCPDEs, 0.982-1.025; GEs, 0.887-1.078); and intercept close to 0 (3-MCPDEs, －0.002-0.003; GEs, －0.011-0.015). These data confirmed that the concentrations of 3-MCPDEs and GEs in food samples determined by 2 independent analytical methods were equivalent.

Occurrence of 3-monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters in infant formulas from Germany

ABSTRACT Fatty acid esters of 3-monochloropropane-1,2-diol (3-MCPD), 2-monochloropropanediol-1,3-diol (2-MCPD), and glycidol are heat-induced processing contaminants formed during the deodorisation step of edible oil refining. Because these compounds are potentially carcinogenic and/or genotoxic, their presence in refined oils and fats and foods containing these oils/fats poses possible health concerns. In particular, formula-fed infants may be exposed to these compounds due to their presence in commercial infant formulas. For this reason, in 2018, the European Union established maximum limits for glycidyl esters in oils/fats and infant formulas and recently, as of January 2021, implemented regulations for the sum of free 3-MCPD and 3-MCPD fatty acid esters as well. This work involved the analysis of 3-MCPD and glycidyl ester contents in 45 infant formula products purchased from German supermarkets in 2019. The data produced in this study showed that average contaminant concentrations across all manufacturers were exceptionally low, with 100% of the products analysed falling below the current EU regulation for glycidyl esters in powdered formulas and 96% of the products analysed meeting the recently implemented regulation for the sum of free and bound 3-MCPD. In addition, a comparison of the 2019 data set to occurrence data collected for German formulas purchased in 2015 showed that average bound 3-MCPD and glycidol concentrations have decreased (from 0.094 to 0.054 µg g−1 and from 0.010 to 0.006 µg g−1, respectively), likely indicating that additional/improved mitigation measures for reducing contaminant concentrations in infant formulas have been implemented over the 4-year period. The data collected in this occurrence study are suitable for estimating levels of exposure to these compounds for German infants. Abbreviations: 2-MCPD: 2-monochloropropane-1,3-diol; 3-MCPD: 3-monochloropropane-1,2-diol; ARA: arachidonic acid; CE: collision energy; CXP: collision cell exit potential; DHA: docosahexaenoic acid; DP: declustering potential; EP: entrance potential; EPA: eicosapentaenoic acid; EtOAc: ethyl acetate; IPA: isopropanol; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MeOH: methanol; MTBE: methyl tert-butyl ether; SPE: solid-phase extraction.

Dietary exposure of general Chinese population to fatty acid esters of 3-monochloropropane-1, 2-diol (3-MCPD) from edible oils and oil-containing foods

ABSTRACT Edible oils and oil-containing foods have been regarded as the main source of 3-monochloropropane-1, 2-diol (3-MCPD) esters. A total of 3,847 individual food samples were collected in China to carry out 3-MCPD fatty acid esters analysis. The samples comprising edible oils, fried foods and bakery foods from 31 Chinese provinces, municipalities and autonomous regions were obtained from the national food contaminant information system during 2015–2017. The dietary exposure and potential risks associated with the consumption of 3-MPCD esters from edible oils and oil-containing foods were estimated using a semi-probabilistic assessment model. Concentrations of 3-MCPD fatty acid esters in food samples were detected by gas chromatography-mass spectrometry (GC-MS). The mean levels of 3-MCPD fatty acid esters in edible oils, fried foods and bakery foods were 0.862, 0.249 and 0.145 mg/kg, respectively. The range of mean dietary intakes of 3-MCPD esters in different subpopulation groups (classified by gender and age) was from 0.586 to 1.539 μg/kg bw/day, which were all lower than 2 μg/kg bw/day – the tolerable daily intake (TDI) established by the European Food Safety Authority (EFSA). The range of dietary intake of 3-MCPD esters in high consumers (95th percentile) in each group was from 1.511 to 4.027 μg/kg bw/day, which accounted for 75.6% to 201.4% of the TDI. The 3-MCPD esters exposure level of 3.5% of the total Chinese population exceeded the TDI. The findings indicate that the potential health risks caused by dietary 3-MCPD esters from edible oils and oil-containing foods were of low concern for most of the Chinese population. However, the exposure risk of the consumers with excessive edible oil consumption calls for attention.

Absorption and metabolism of 3-MCPD in hepatic and renal cell lines

3-Monochloropropane-1,2-diol (3-MCPD) fatty acid esters are process contaminants mainly formed during the refinement of vegetable oils. Gastrointestinal hydrolysis yields free 3-MCPD, which is resorbed into the body. In long-term rat studies, 3-MCPD caused renal and testicular neoplasms. 3-MCPD metabolism via β-chlorolactic acid has been postulated to underlie the toxic effects of 3-MCPD. Various efforts are ongoing to characterize the toxicological mode of action of 3-MCPD using in vitro systems. Published results suggest a very low sensitivity of cell cultures in vitro, as compared to 3-MCPD levels causing toxic effects in vivo. The insensitivity of in vitro systems raises the question to which extent 3-MCPD is absorbed and metabolized in vitro. We therefore analyzed cytotoxicity, absorption and metabolism of 3-MCPD and its metabolite β-chlorolactic acid in renal and hepatic cells. Cytotoxicity tests using up to 100 mM 3-MCPD confirmed the low sensitivity of human and rat cell lines towards 3-MCPD toxicity. Furthermore, absorption and metabolism of 3-MCPD examined via GC–MS and LC-MS/MS were only observed to a minor degree, and 3-MCPD was also not converted by a metabolizing system (S9 fraction). In conclusion, our data indicate that current in vitro models are not well suited for studying 3-MCPD metabolism and toxicity.

Simultaneous determination of fatty acid esters 2-chloro-1, 3-propandiol(2-mcpd), 3-chloro-1,2- propandiol(3-mcpd) and glycidol in vegetable oils by gas chromatography mass spectrometry GC-MS/MS

The food contaminants including 3-chloro-1,2-propanediol (3-MCPD) and 3-MCPD fatty acid esters have been a matter of great concern in the past few years due to their toxicity and their occurrence in numerous foods. Recently, significant amounts of the isomeric compounds 2-chloro-1,3-propanediol (2-MCPD) fatty acid esters have been detected in refined oil samples. Gas Chromatography (GC) coupled with mass spectroscopy (MS) was used for the quantification of fatty acid esters of 2-Chloro-1,3-propandiol (2-MCPD), 3-Chloro-1,2- propandiol (3-MCPD) and glycidol in oil. Internal standards including 3-MCPD-ester-d5 (rac 1,2-bis-palmitoyl-3-chloropropanediol-d5), 2-MCPD-ester-d5 (1,3-Distearoyl-2- chloropropanediol-d5) and Glycidyl sterate-d5 were added to samples. Spiked samples were, then, incubated in NaBr/H2SO4 and H2SO4/MeOH solutions. They were, eventually, extracted with ethyl acetate and n-hexane solvents in order to convert Glycidyl esters to free MCPD and glycidol in samples before using phenylboronic acid derivative. The limit of quantitation was of 0.1 ppm (mg/kg). The recoveries at the concentration of 0.1 mg/kg ranged from 80 to 120% and the repeatability and reproducibility were less than 10%.

Determination of Fatty Acid Profile and 3-Monochloropropane-1,2-diol (3-MCPD) Levels in Bakery Products

Thermally processed foods and refined oils are the most significant sources of 3-monochloropropane-1,2-diol (3-MCPD) fatty acid esters. The International Agency for Research on Cancer (IARC) classified 3-MCPD as a “possible human carcinogen (group 2B)” and the UK Food Advisory Committee has recommended reducing its level to minimum in foods. In this study, firstly the fatty acid contents of many foods such as cakes, biscuits, waffles, chocolates, cookies products consumed frequently in daily life were determined by GC-MS. Then, 3-MCPD esters formation was examined. The main fatty acids were determined as palmitic acid and stearic acid. The amounts of 3-MCPD esters were found to be between 0.06 and 0.60 mg kg-1, and the amounts of glycidyl esters were found to be between 0.07 and 8.80 mg kg-1.

Elimination of 3-MCPD fatty acid esters and glycidyl esters during palm oil hydrogenation and wet fractionation

Palm oil is the vegetable oil refined and modified in the largest amount. In this study, we present the effect of wet fractionation and hydrogenation of RBD palm oil on the removal of 3-MCPD and glycidyl esters. Fractionated palmstearins had significantly decreased contents of 3-MCPD esters (71–74%) and glycidyl esters (21–26%), whereas top olein contained the highest levels of processing-induced contaminants accompanied by polar compounds. Exhaustive hydrogenation conditions caused rapid degradation of 3-MCPD esters (51–70%) in high melting palm oil products. Reduction of glycidyl esters (1–42%) was dependent on the type of nickel catalyst. The effect of iodine value drop on the contaminant degradation was shown to be linear. The combined action of dry-reduced, supported, 22% Ni and Raney nickel catalysts was found to be an optimal. Adsorptive bleaching and deodorization of hydrogenated palm stearin impacted particularly repeated formation of glycidyl esters up to 1.01–1.76 mg/kg, while 3-MCPD esters remained under the input RBD palm oil level. The mechanism of the catalyst action was investigated with glycidyl-d5 palmitate, 3-MCPD-d5-1,2-dipalmitate. They were transformed into non-carcinogenic and non-genotoxic products by hydrogenolysis and deoxygenation reactions.

Suppression of T lymphocyte activation by 3-chloro-1,2-propanediol mono- and di-palmitate esters in vitro

This study investigated whether and how 3-chloro-1,2-propanediol (3-MCPD) fatty acid esters, a group of food contaminants formed during processing, might inhibit the immune system through suppressing T lymphocyte activation for the first time. Three 3-MCPD esters including 1-palmitoyl-3-chloropropanediol (1-pal), 2-palmitoyl-3-chloropropanediol (2-pal), and1,2-dipalmitoyl-3-chloropropanediol (dipal) were selected as the probe compounds to test the possible effects of fatty acid structure on their potential immune inhibitory effect. The results showed that 1-pal and 2-pal, but not dipal, significantly suppressed ConA-induced T lymphocyte proliferation, cell cycle activity, Th1 and Th2 cytokine secretion, CD4+ T cell populations, and the ratio of CD4+/CD8+ T cells under the experimental conditions. Moreover, Western blotting and immunofluorescence analyses revealed that 1-pal and 2-pal could inhibit the activation of ConA-stimulated mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways. In addition, 1-pal significantly suppressed DNFB-induced delayed-type hyper sensitivity (DTH) reaction characterized by the increased ear thickness and IFN-γ production in mice. These observations indicated that 3-MCPD esters exerted a negative effect on T lymphocyte-mediated immunity, and the immunosuppressive activities of 3-MCPD monopalmitates were stronger than 3-MCPD dipalmitate.

Formation of 3-MCPD Fatty Acid Esters from Monostearoyl Glycerol and the Thermal Stability of 3-MCPD Monoesters.

Formation of 3-monochloropropanediol (3-MCPD) esters from monostearoyl glycerol (MSG) was investigated under high temperature and low moisture conditions. Different organic and inorganic chlorides, including lindane, KCl, CaCl2, NaCl, MgCl2, AlCl3, CuCl2, MnCl2, SnCl2, ZnCl2, and FeCl3, were evaluated for their potential to react with MSG to form 3-MCPD and glycidyl esters at 120 and 240 °C using a UPLC-Q-TOF MS analysis. The results indicated that different chlorine compounds differed in their capacity to react with MSG and formed different products including 3-MCPD mono- and diesters, distearoylglycerol, and glycidyl esters. According to electron spin resonance (ESR) and Fourier transform infrared (FT-IR) spectroscopies, free radical mediated formation mechanisms involving either five-membered or six-membered cyclic acyloxonium free radicals (CAFR) from monoacylglycerol (MAG) were proposed. Tandem quadrupole-time-of-flight (Q-TOF) MS and MS/MS analyses confirmed the free radical mechanisms. In addition, the results from the present study showed that 3-MCPD monoester could be degraded upon thermal treatment and suggested a possible catalytic role of Fe3+ under the experimental conditions.

Indirect Determination of MCPD Fatty Acid Esters in Lipid Fractions of Commercially Available Infant Formulas for the Assessment of Infants’ Health Risk

MCPD esters are intensively investigated food lipid contaminants for over a decade. Concern related to their presence in various types of food products is related to the fact that possible free MCPD release from its esterified form during digestion may lead to elevated daily intake of these toxicants. Special attention should be devoted into powdered infant formulas, which contain significant amounts of refined vegetable oils, likely to contain high amounts of both 3-MCPD and 2-MCPD esters. Infants being fed with this type of food products only may intake risky amounts of these contaminants, which is a matter of great concern. This paper presents the quality assessment of commercially available powdered infant formulas with regard to MCPD esters presence. For estimating the levels of 3-MCPD and 2-MCPD fatty acid esters in lipid fractions of baby foods, methodology involving accelerated solvent extraction (optimized by response surface methodology) followed by SGS “3-in-1” procedure was applied. MCPD esters were detected in 23 per 24 investigated various types of powdered formulas (basic types, anticolic, antireflux, hypoalergic, lactose free, enriched with DHA, for prematures) offered by several suppliers. Detected levels of MCPD esters varied in the range of 0.13–4.80 mg kg−1.

3-MCPD 1-Palmitate Induced Tubular Cell Apoptosis In Vivo via JNK/p53 Pathways.

Fatty acid esters of 3-chloro-1, 2-propanediol (3-MCPD esters) are a group of processing induced food contaminants with nephrotoxicity but the molecular mechanism(s) remains unclear. This study investigated whether and how the JNK/p53 pathway may play a role in the nephrotoxic effect of 3-MCPD esters using 3-MCPD 1-palmitate (MPE) as a probe compound in Sprague Dawley rats. Microarray analysis of the kidney from the Sprague Dawley rats treated with MPE, using Gene Ontology categories and KEGG pathways, revealed that MPE altered mRNA expressions of the genes involved in the mitogen-activated protein kinase (JNK and ERK), p53, and apoptotic signal transduction pathways. The changes in the mRNA expressions were confirmed by qRT-PCR and Western blot analyses and were consistent with the induction of tubular cell apoptosis as determined by histopathological, TUNEL, and immunohistochemistry analyses in the kidneys of the Sprague Dawley rats. Additionally, p53 knockout attenuated the apoptosis, and the apoptosis-related protein bax expression and cleaved caspase-3 activation induced by MPE in the p53 knockout C57BL/6 mice, whereas JNK inhibitor SP600125 but not ERK inhibitor U0126 inhibited MPE-induced apoptosis, supporting the conclusion that JNK/p53 might play a critical role in the tubular cell apoptosis induced by MPE and other 3-MCPD fatty acid esters.

Analysis of 3-MCPD- and 3-MCPD dipalmitate-induced proteomic changes in rat liver

3-Monochloropropane-1,2-diol (3-MCPD) and 3-MCPD fatty acid esters are process contaminants in foodstuff which are generated during thermal treatment. Long-term exposure to 3-MCPD or 3-MCPD esters causes toxicity especially in kidney and testis. 3-MCPD esters are efficiently hydrolyzed in the gastrointestinal tract, suggesting that their toxicity is mediated by free 3-MCPD. Combined exposure to free 3-MCPD and 3-MCPD released from 3-MCPD esters might lead to dietary consumption above the tolerable daily intake of 2 μg/kg body weight/day. Suspected mechanisms of 3-MCPD toxicity include the inhibition of glycolysis and oxidative stress. Here, a comparative proteomic approach was followed to analyze the effects of 3-MCPD or 3-MCPD dipalmitate in livers from rats exposed to 10 mg/kg body weight 3-MCPD, an equimolar dose of 3-MCPD dipalmitate, or a 4-fold lower dose of the ester during a 28-day repeated-dose feeding study. Early cellular changes were monitored in the absence of overt toxicity. A comprehensive view of 3-MCPD- or 3-MCPD dipalmitate-triggered proteomic changes in rat liver links to previously proposed mechanisms of toxicity and substantially extends our knowledge on molecular hepatic effects of 3-MCPD. Organ-independent marker proteins altered upon 3-MCPD exposure, for example DJ-1/PARK7, were identified by comparison of the proteomic patterns of kidney, testis and liver.

Orally administered glycidol and its fatty acid esters as well as 3-MCPD fatty acid esters are metabolized to 3-MCPD in the F344 rat

IARC has classified glycidol and 3-monochloropropane-1,2-diol (3-MCPD) as group 2A and 2B, respectively. Their esters are generated in foodstuffs during processing and there are concerns that they may be hydrolyzed to the carcinogenic forms in vivo. Thus, we conducted two studies. In the first, we administered glycidol and 3-MCPD and associated esters (glycidol oleate: GO, glycidol linoleate: GL, 3-MCPD dipalmitate: CDP, 3-MCPD monopalmitate: CMP, 3-MCPD dioleate: CDO) to male F344 rats by single oral gavage. After 30 min, 3-MCPD was detected in serum from all groups. Glycidol was detected in serum from the rats given glycidol or GL and CDP and CDO in serum from rats given these compounds. In the second, we examined if metabolism occurs on simple reaction with rat intestinal contents (gastric, duodenal and cecal contents) from male F344 gpt delta rats. Newly produced 3-MCPD was detected in all gut contents incubated with the three 3-MCPD fatty acid esters and in gastric and duodenal contents incubated with glycidol and in duodenal and cecal contents incubated with GO. Although our observation was performed at 1 time point, the results showed that not only 3-MCPD esters but also glycidol and glycidol esters are metabolized into 3-MCPD in the rat.

3-Monochloropropane-1,2-diol fatty acid esters in commercial deep-fat fried foods

Levels of 3-monochloropropane-1,2-diol (3-MCPD) fatty acid esters were evaluated in commercial deep-fat fried foods from the Brazilian market using a GC-MS method preceded by acid-catalysed methanolysis. A limit of detection of 0.04 mg kg−1, a limit of quantitation of 0.08 mg kg−1, mean recoveries varying from 82% to 92%, and coefficients of variation ranging from 2.5% to 5.0% for repeatability and from 3.6% to 6.5% for within-laboratory reproducibility were obtained during in-house validation. The levels of the compounds in the evaluated samples, expressed as free 3-MCPD equivalent, ranged from not detected to 0.99 mg kg−1, and the highest concentrations were observed in samples of chopped onion and garlic. A preliminary estimation of 3-MCPD intake using these occurrence data suggested low risks to human health, but a potential concern may arise in particular cases of consumers of fried food.

2-Chloro-1,3-propanediol (2-MCPD) and its fatty acid esters: cytotoxicity, metabolism, and transport by human intestinal Caco-2 cells.

The food contaminants 3-chloro-1,2-propanediol (3-MCPD) and 3-MCPD fatty acid esters have attracted considerable attention in the past few years due to their toxic properties and their occurrence in numerous foods. Recently, significant amounts of the isomeric compounds 2-chloro-1,3-propanediol (2-MCPD) fatty acid esters have been detected in refined oils. Beside the interrogation which toxic effects might be related to the core compound 2-MCPD, the key question from the risk assessment perspective is again-as it was discussed for 3-MCPD fatty acid esters before-to which degree these esters are hydrolyzed in the gut, thereby releasing free 2-MCPD. Here, we show that free 2-MCPD but not 2-MCPD fatty acid esters were able to cross a monolayer of differentiated Caco-2 cells as an in vitro model for the human intestinal barrier. Instead, the esters were hydrolyzed by the cells, thereby releasing free 2-MCPD which was neither absorbed nor metabolized by the cells. Cytotoxicity assays revealed that free 2-MCPD as well as free 3-MCPD was not toxic to Caco-2 cells up to a level of 1 mM, whereas cellular viability was slightly decreased in the presence of a few 2-MCPD and 3-MCPD fatty acid esters at concentrations above 10 µM. The observed cytotoxic effects correlated well with the induction of caspase activity and might be attributed to the induction of apoptosis by free fatty acids which were released from the esters in the presence of Caco-2 cells.

Absence of in vivo genotoxicity of 3-monochloropropane-1,2-diol and associated fatty acid esters in a 4-week comprehensive toxicity study using F344 gpt delta rats.

3-Monochloropropane-1,2-diol (3-MCPD) is regarded as a rat renal and testicular carcinogen and has been classified as a possible human carcinogen (group 2B) by International Agency for Research on Cancer. This is potentially of great importance given that esters of this compound have recently found to be generated in many foods and food ingredients as a result of food processing. There have been a few reports about their toxicity, although we have recently found that the toxicity profile of 3-MCPD esters was similar to that of 3-MCPD in a rat 13-week repeated dose study, except for the acute renal toxicity seen in 3-MCPD-treated females. In the present study, to examine in vivo genotoxicity we administered equimolar doses of 3-MCPD or 3-MCPD fatty acid esters (palmitate diester, palmitate monoester and oleate diester) to 6-week-old male F344 gpt delta rats carrying a reporter transgene for 4 weeks by intragastric administration. In vivo micronucleus, Pig-a mutation and gpt assays were performed, as well as investigations of major toxicological parameters including histopathological features. As one result, the relative kidney weights of the 3-MCPD and all three ester groups were significantly increased compared with the vehicle control group. However, the frequency of micronucleated reticulocytes and Pig-a mutant red blood cells did not differ among groups. Moreover, no changes were observed in mutant frequencies of gpt and red/gam (Spi(-)) genes in the kidney and the testis of 3-MCPD and 3-MCPD-fatty-acid-esters-treated rats. In histopathological analyses, no treatment related changes were observed, except for decrease of eosinophilic bodies in the kidneys of all treated groups. These results suggest that 3-MCPD and its fatty acid esters are not in vivo genotoxins, although they may exert renal toxicity.

A 13-week repeated dose study of three 3-monochloropropane-1,2-diol fatty acid esters in F344 rats

3-monochloropropane-1,2-diol (3-MCPD), a rat renal and testicular carcinogen, has been reported to occur in various foods and food ingredients as free or esterified forms. Since reports about toxicity of 3-MCPD esters are limited, we conducted a 13-week rat subchronic toxicity study of 3-MCPD esters (palmitate diester: CDP, palmitate monoester: CMP, oleate diester: CDO). We administered a carcinogenic dose (3.6×10(-4)mol/kgB.W./day) of 3-MCPD or these esters at equimolar concentrations and two 1/4 lower doses by gavage with olive oil as a vehicle five times a week for 13weeks to F344 male and female rats. As a result, five out of ten 3-MCPD-treated females died from acute renal tubular necrosis, but none of the ester-treated rats. Decreased HGB was observed in all high-dose 3-MCPD fatty acid ester-treated rats, except CDO-treated males. The absolute and relative kidney weights were significantly increased in the ester-treated rats at medium and high doses. Relative liver weights were significantly increased in the esters-treated rat at high dose, except for CMP females. Significant increase in apoptotic epithelial cells in the initial segment of the epididymis of high-dose ester-treated males was also observed. The results suggested that although acute renal toxicity was lower than 3-MCPD, these three 3-MCPD fatty acid esters have the potential to exert subchronic toxicity to the rat kidneys and epididymis, to a similar degree as 3-MCPD under the present conditions. NOAELs (no-observed-adverse-effect levels) of CDP, CMP and CDO were suggested to be 14, 8 and 15mg/kgB.W./day, respectively.

The toxicity of 3-chloropropane-1,2-dipalmitate in Wistar rats and a metabonomics analysis of rat urine by ultra-performance liquid chromatography–mass spectrometry

3-Monochloropropane-1,2-diol(3-MCPD) fatty acid esters can release free 3-MCPD in a certain condition. Free 3-MCPD is a well-known food contaminant and is toxicological well characterized, however, in contrast to free 3-MCPD, the toxicological characterization of 3-MCPD fatty acid esters is puzzling. In this study, toxicological and metabonomics studies of 3-chloropropane-1,2-dipalmitate(3-MCPD dipalmitate) were carried out based on an acute oral toxicity test, a 90-day feeding test and ultra-performance liquid chromatography–mass spectrometry (UPLC–MS) analysis. The LD50 value of 3-MCPD dipalmitate was determined to be 1780mg/kg body weight (bw) for Wistar rats. The results of the 90-day feeding test in male Wistar rats showed that 3-MCPD dipalmitate caused a significant increase in blood urea nitrogen and creatinine in the high-dose group (267mg/kgbw/day) compared to control rats. Renal tubular epithelium cell degeneration and renal tubular hyaline cast accumulation were the major histopathological changes in rats administered 3-MCPD dipalmitate. Urine samples obtained after the 90-day feeding test and analyzed by UPLC–MS showed that the differences in metabolic profiles between control and treated rats were clearly distinguished by partial least squares-discriminant analysis (PLS-DA) of the chromatographic data. Five metabolite biomarkers which had earlier and significant variations had been identified, they were first considered to be the early, sensitive biomarkers in evaluating the effect of 3-MCPD dipalmitate exposure, and the possible mechanism of these biomarkers variation was elucidated. The combination of histopathological examination, clinical chemistry and metabolomics analyses in rats resulted in a systematic and comprehensive assessment of the long-term toxicity of 3-MCPD dipalmitate.

Dietary exposure of Hong Kong adults to fatty acid esters of 3-monochloropropane-1,2-diol

A total of 290 individual food samples were collected in Hong Kong, China, for 3-monochloropropane-1,2-diol (3-MCPD) fatty acid esters analysis. Most samples were processed food and in ready-to-eat form. The results show that the levels of 3-MCPD fatty acid esters were high in biscuits, fats and oils, snacks and Chinese pastry with mean bound 3-MCPD levels of 440, 390, 270 and 270 μg kg−1, respectively. The dietary exposures to bound 3-MCPD of average and high adult consumers were estimated to be 0.20 and 0.53 μg kg bw−1 day−1, respectively. The primary toxicological concern of 3-MCPD fatty acid esters is its potential to release 3-MCPD in vivo during digestion in the gastrointestinal tract. 3-MCPD would affect the kidney, the central nervous system and the male reproductive system of rats. Assuming that 100% of the 3-MCPD was released from 3-MCPD fatty acid esters by hydrolysis in the digestive system, the dietary exposures to 3-MCPD for average and high adult consumers were only 10% and 26% of the provisional maximum tolerable daily intake (PMTDI) of 3-MCPD established by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) (2 μg kg bw−1 day−1), respectively. The results suggest that both average and high adult consumers are unlikely to experience major toxicological effects of 3-MCPD.