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3-Monochloropropane-1,2-diol (3-MCPD) is a chiral molecule naturally existing as a racemic mixture of (R)- and (S)-enantiomers. It was thoroughly investigated during the 1970s as a male antifertility drug until research was abandoned because of the side effects observed in toxicity studies. More than 20 years later, 3-MCPD, both in the free form and esterified to the fatty acids, was detected in vegetable oil and discovered to be a widespread contaminant in different processed foods. This review summarises the main toxicological studies on 3-MCPD and its esters. Current knowledge shows that the kidney and reproductive system are the primary targets of 3-MCPD toxicity, followed by neurological and immune systems. Despite uncertainties, in vivo studies suggest that renal and reproductive toxicity is mediated by toxic metabolites, leading to inhibition of glycolysis and energy depletion. Few acute, short-term, and subchronic toxicity studies have investigated the 3-MCPD esters. The pattern of toxicity was similar to that of free 3-MCPD. Some evidence suggests that the toxicity of 3-MCPD diesters may be milder than 3-MCPD, likely because of an incomplete enzymatic hydrolysis in the equivalent free form in the gastrointestinal tract. Further research to clarify absorption, metabolism, and long-term toxicity of 3-MCPD esters would be pivotal to improve the risk assessment of these compounds via food.

3-chloro-1,2-propanediol (3-MCPD) is a member of the group of pollutants known as chloropropanols and is considered a genotoxic carcinogen. Due to the occurrence of 3-MCPD, which cannot be avoided in multiplexed food processes, it is necessary to explore novel agents to reduce or prevent the toxicity of 3-MCPD. Many recent studies on boron compounds reveal their superior biological roles such as antioxidant, anticancer, and antigenotoxic properties. In the current investigation, we have evaluated in vitro cytotoxic, oxidative, and genotoxic damage potential of 3-MCPD on human whole blood cultures and the alleviating effect of boric acid (BA) and borax (BX) for 72 h. In our in vitro experiments, we have treated blood cells with BA and BX (2.5, 5, and 10 mg/L) and 3-MCPD (at IC 50 of 11.12 mg/l) for 72 h to determine the cytotoxic damage potential by using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and lactate dehydrogenase (LDH) release assays. Oxidative damage was assessed using total antioxidant capacity (TAC) and malondialdehyde (MDA) levels. Genotoxicity evaluations were performed using chromosome aberrations (CAs) and 8-hydroxy deoxyguanosine (8-OHdG) assays. The result of our experiments showed that the 3-MCPD compound induced cytotoxicity, oxidative stress, and genotoxicity in a clear concentration-dependent manner. BA and BX reduced cytotoxicity, oxidative stress, and genotoxicity induced by 3-MCPD. In conclusion, BA and BX are safe and non-genotoxic under the in vitro conditions and can alleviate cytotoxic, oxidative, and genetic damage induced by 3-MCPD in the human blood cells. Our findings suggest that dietary boron supplements may offer a novel strategy for mitigating hematotoxicity induced by xenobiotics, including 3-MCPD.

The toxic actions of 2-monochloropropane-1,3-diol (2-MCPD) are still less well understood than those of 3-monochloropropane-1,2-diol (3-MCPD). The toxic effects of 2-MCPD on the heart, especially at the proteomic level, were recently investigated by researchers in a subacute (28 days, in 2017) and in a subchronic (90 days, in 2024) oral toxicity rat study. Here, we set out to perform an updated analysis and re-evaluation of these proteomic in vivo data in a comparative manner and in the context of 2-MCPD metabolism, focusing in particular on mitochondrial energy metabolism and the maintenance of the structural integrity and function of the heart. The aim of our project was to develop further reasonable, toxicologically relevant research hypotheses for future studies addressing this topic in order to shed more light on the—so far—rather limited knowledge of the toxicological properties and modes of action of 2-MCPD. Our updated data analysis and comparative re-evaluation revealed strong indications of cytoskeletal protein deregulation, indicative of cardiomyocyte degeneration, and the deregulation of enzyme proteoforms linked to carbohydrate utilization and mitochondrial functions. This led us to hypothesize that reactive metabolites of 2-MCPD, other than those formed from 3-MCPD, could impair mitochondrial pyruvate utilization and mitochondrial energy production, potentially resulting in cardiac functional heart failure in rats at doses slightly higher than 10 mg 2-MCPD per kg bw/day. Thus, we postulate the intermediate formation of some putative aldehydic and acidic metabolites following oral 2-MCPD exposure that might be causative of cardiotoxicity in rats.

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.

    3-Monochloropropane-1,2-diol (3-MCPD) is a food contaminant formed during acid hydrolysis of vegetable proteins. The toxicological evaluation of smaller doses of 3-MCPD is essential for safety evaluation of this compound. The present study investigates the toxicologic potential of 3-MCPD on male genital organs of rats, applies a correlation between the induced infertility and developed lesions in testes, epididymis, and accessory glands and study the possible mechanisms of 3-MCPD-induced male infertility. Forty rats were randomly divided into four main groups of ten animals each: the control untreated group and three treated groups that were orally administered 3-MCPD at different doses (3, 7.5 and 15 mg/kg b.w) daily via stomach intubation for five successive days per week. Five rats from each group were euthanized after 30 days. The remaining rats were euthanized after 90 days to establish subacute and chronic toxicity studies. Oxidative stress markers, Nrf2 gene expression, semen analysis, and histopathological examination were performed at the end of each experimental period. Results indicated that 3-MCPD induces infertility in male rat via disruption of Nrf2 expression in the testicular tissue with subsequent increased oxidative stress indicators in the testis that affect spermatogenesis and induced testicular degeneration, in addition, induction of epididymal lesions that affect sperm motility and concentration and finally possible development of hyperplastic tissue reactions in accessory glands of intoxicated rats predicting the carcinogenic potential of this compound.

1,3-Dichloro-2-propanol (1,3-DCP), a food contaminant, exerts carcinogenic effects in multiple organs, including the liver and kidneys, in rats. However, the underlying mechanisms of 1,3-DCP-induced carcinogenesis remain unclear. Here, the in vivo mutagenicity and tumor-promoting activity of 1,3-DCP in the liver and kidneys were evaluated using medium-term gpt delta rat models previously established in our laboratory (GPG and GNP models). Six-week-old male F344 gpt delta rats were treated with 0 or 50 mg/kg body weight/day 1,3-DCP by gavage for 4 weeks. After 2 weeks of cessation, partial hepatectomy or unilateral nephrectomy was performed to collect samples for in vivo mutation assays, followed by single administration of diethylnitrosamine (DEN) for tumor initiation. One week after DEN injection, 1,3-DCP treatment was resumed, and tumor-promoting activity was evaluated in the residual liver or kidneys by histopathological analysis of preneoplastic lesions. gpt mutant frequencies increased in excised liver and kidney tissues following 1,3-DCP treatment. 1,3-DCP did not affect the development of glutathione S-transferase placental form-positive foci in residual liver tissues, but enhanced atypical tubule hyperplasia in residual kidney tissues. Detailed histopathological analyses revealed glomerular injury and increased cell proliferation of renal tubular cells in residual kidney tissues of rats treated with 1,3-DCP. These results suggested possible involvement of genotoxic mechanisms in 1,3-DCP-induced carcinogenesis in the liver and kidneys. In addition, we found that 1,3-DCP exhibited limited tumor-promoting activity in the liver, but enhanced clonal expansion in renal carcinogenesis via proliferation of renal tubular cells following glomerular injury.

Chloropropanols are chemical contaminants that can be formed during industrial processing of foods, such as lipids used in commercially available infant and toddler formula in the USA. Many researchers have studied the most common chloropropanol contaminant, 3-monochloropropane-1,2-diol (3-MCPD), as well as its lipid ester derivatives. A plethora of toxicological outcomes have been described in vivo, including effects on the heart, nervous system, reproductive organs, and kidneys. To better understand the concordance of some of these effects to in vitro outcomes, we focused our research on using an in vitro cellular model to investigate whether the proximal tubule cells of the kidney would be vulnerable to the effects of free 3-MCPD and nine of its common esters in commercial formula. Using the established human kidney proximal tubule cell line, HK-2, we performed 24-h treatments using 3-MCPD and nine mono- or di-esters derived from palmitate, oleate, and linoleate. By directly exposing HK-2 cells at treatment doses ranging from 0 to 100 μM, we could evaluate their effects on cell viability, mitochondrial health, reactive oxygen species (ROS) production, and other endpoints of toxicity. Since chloropropanols reportedly inhibit cellular metabolism through interference with glycolysis, we also tested the extent of this mechanism. Overall, we found mild but statistically significant evidence of cytotoxicity at the highest tested treatment concentrations, which were also associated with mitochondrial dysfunction and transient perturbations in cellular metabolism. Based on these findings, further studies will be required to better understand the effects of these compounds under conditions that are more physiologically relevant to human infant and toddler proximal tubules in order to mimic their exposure to chloropropanol-containing foods.

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/kg B.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 13 weeks 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 15 mg/kg B.W./day, respectively.

The chlorinated propanols 2- and 3-monochloropropanediol (MCPD), and their fatty acid esters have gained public attention due to their frequent occurrence as heat-induced food contaminants. Toxic properties of 3-MCPD in kidney and testis have extensively been characterized. Other 3-MCPD target organs include heart and liver, while 2-MCPD toxicity has been observed in striated muscle, heart, kidney, and liver. Inhibition of glycolysis appears to be important in 3-MCPD toxicity, whereas mechanisms of 2-MCPD toxicity are still unknown. It is thus not clear whether toxicity by the two isomeric compounds is dependent on similar or dissimilar modes of action. A 28-day oral feeding study in rats was conducted using daily non-toxic doses of 2-MCPD or 3-MCPD [10 mg/kg body weight], or an equimolar (53 mg/kg body weight) or a lower (13.3 mg/kg body weight) dose of 2-MCPD dipalmitate. Comprehensive comparative proteomic analyses of substance-induced alterations in the common target organ heart revealed striking similarities between effects induced by 2-MCPD and its dipalmitate ester, whereas the degree of effect overlap between 2-MCPD and 3-MCPD was much less. The present data demonstrate that even if exerting effects in the same organ and targeting similar metabolic networks, profound differences between molecular effects of 2-MCPD and 3-MCPD exist thus warranting the necessity of separate risk assessment for the two substances. This study for the first time provides molecular insight into molecular details of 2-MCPD toxicity. Furthermore, for the first time, molecular data on 3-MCPD toxicity in the heart are presented.

Many foods including edible oils contain 2-monochloropropane-1,3-diol (2-MCPD), a processing-induced chemical contaminant. Cardiotoxic effects have been shown to result from oral 2-MCPD exposure in rodents, but the underlying mechanisms of action remain poorly understood. We undertook a comprehensive multi-omics approach to assess changes at the transcriptomic, proteomic, and oxylipin levels in heart tissues from male F344 rats that were exposed to 0 or 40 mg/kg BW/day of 2-MCPD in the diet for 90 days, in a regulatory compliant rodent bioassay. Heart tissues were collected for RNA sequencing, quantitative PCR analysis, proteomic analysis via two-dimensional gel electrophoresis and mass spectrometry, and targeted lipidomic profiling by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). Transcriptomic and proteomic data analyses revealed upregulation of immune/inflammatory response processes and downregulation of energy metabolism and cardiac structure and functions. Among differentially expressed gene–protein pairs, coronin-1A, a key leukocyte-regulating protein, emerged as markedly up-regulated. Oxylipin profiling highlighted a selective suppression of docosahexaenoic acid-derived metabolites, suggesting a disruption in cardioprotective lipid pathways. These findings suggest that 2-MCPD disrupts homeostasis through inflammatory activation and suppression of metabolic and cardiac function. This research provides insights into 2-MCPD's cardiotoxicity, emphasizing the need for further studies to support hazard characterization.