Role of urinary biomarkers of N,N-dimethylformamide in the early detection of hepatic injury among occupational exposed workers

Development of an LC-HRMS non-targeted method for comprehensive profiling of the exposome of nicotine and tobacco product users - A showcase for cigarette smokers

The global prevalence of electronic cigarettes, heated tobacco products, and other smokeless alternatives has grown significantly in the last ten years. These products have been suggested as combustion-free alternatives for conventional tobacco products like cigarettes, aiming to reduce the negative health impacts associated with smoking. However, the impact of those products on the health and safety of the general population are still unclear, as the absolute exposure from those products has not been thoroughly studied, yet. In this project, a non-targeted LC-HRMS method was developed comprising four different analytical modes for the investigation of the exposure profile in urine of the product users. The method is characterized by its high sensitivity and reproducibility, as shown during method validation. As a proof of concept, we first applied this method to detect significant differences in biomarkers of exposure (BoEs) between smokers and non-smokers. We observed a total of 171 BoEs significantly elevated in smokers, including several well-known biomarkers of smoke exposure like nicotine and its metabolites, mercapturic acid derivatives, and phenolic compounds. Some of the detected biomarkers are present at low ng/mL concentrations in urine, proving the high sensitivity needed for a holistic exploration of the exposome. Moreover, we were able to identify BoEs that have not been reported previously for smoking, such as 2,6-dimethoxyphenol and 7-methyl-1-naphthol glucuronide.

Human biomonitoring guidance values (HBM-GVs) for priority substances under the HBM4EU initiative - New values derivation for deltamethrin and cyfluthrin and overall results

The European Initiative HBM4EU aimed to further establish human biomonitoring across Europe as an important tool for determining population exposure to chemicals and as part of health-related risk assessments, thus making it applicable for policy advice. Not only should analytical methods and survey design be harmonized and quality assured, but also the evaluation of human biomonitoring data. For the health-related interpretation of the data within HBM4EU, a strategy for deriving health-based human biomonitoring guidance values (HBM-GVs) for both the general population and workers was agreed on. On this basis, HBM-GVs for exposure biomarkers of 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), phthalates (diethyl hexyl phthalate (DEHP), di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), butyl benzyl phthalate (BBzP), and bis-(2-propylheptyl) phthalate (DPHP)), bisphenols A and S, pyrethroids (deltamethrin and cyfluthrin), solvents (1-methyl-2-pyrrolidone (NMP), 1-ethylpyrrolidin-2-one (NEP), N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC)), the heavy metal cadmium and the mycotoxin deoxynivalenol (DON) were developed and assigned a level of confidence. The approach to HBM-GV derivations, results, and limitations in data interpretation with special focus on the pyrethroids are presented in this paper.

Human Biomonitoring Initiative (HBM4EU): Human Biomonitoring Guidance Values Derived for Dimethylformamide

Within the European Joint Program on Human Biomonitoring HBM4EU, human biomonitoring guidance values (HBM-GVs) for the general population (HBM-GV_GenPop) or for occupationally exposed adults (HBM-GV_Worker) are derived for prioritized substances including dimethylformamide (DMF). The methodology to derive these values that was agreed upon within the HBM4EU project was applied. A large database on DMF exposure from studies conducted at workplaces provided dose–response relationships between biomarker concentrations and health effects. The hepatotoxicity of DMF has been identified as having the most sensitive effect, with increased liver enzyme concentrations serving as biomarkers of the effect. Out of the available biomarkers of DMF exposure studied in this paper, the following were selected to derive HBM-GV_Worker: total N-methylformamide (tNMF) (sum of N-hydroxymethyl-N-methylformamide and NMF) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in urine. The proposed HBM-GV_Worker is 10 mg·L⁻¹ or 10 mg·g⁻¹ creatinine for both biomarkers. Due to their different half-lives, tNMF (representative of the exposure of the day) and AMCC (representative of the preceding days’ exposure) are complementary for the biological monitoring of workers exposed to DMF. The levels of confidence for these HBM-GV_Worker are set to “high” for tNMF and “medium-low” for AMCC. Therefore, further investigations are required for the consolidation of the health-based HBM-GV for AMCC in urine.

Relationships among N,N-dimethylformamide exposure, CYP2E1 and TM6SF2 genes, and non-alcoholic fatty liver disease

OBJECTIVE

This study aimed to examine the relationships among N, N-dimethylformamide (DMF) exposure, cytochrome P4502E1 (CYP2E1) single nucleotide polymorphisms (SNPs) (rs2031920, rs3813867, rs6413432), transmembrane 6 superfamily member 2 (TM6SF2) SNP rs58542926 and non-alcoholic fatty liver disease (NAFLD).

METHODS

Baseline data were collected from participants who were then followed for 5 years in a prospective cohort study. The cohort initially consisted of 802 workers and ultimately included 660 people, all of whom underwent annual occupational health examinations from 2010 to 2015.

RESULTS

The above-threshold group (≥7.3 mg/m³ adjusted relative risk (RR)= 3.620, 95%CI 2.072-6.325) was significantly more likely to develop NAFLD than the below-threshold group (<7.3 mg/m³). The TM6SF2 SNP rs58542926 CT (adjusted RR=3.921, 95% CI 2.329-6.600, P = 0.000) and CT+TT (adjusted RR=4.385, 95% CI 2.639-7.287, P = 0.000) genotypes were risk factors for NAFLD, as compared with the TM6SF2 rs58542926 CC genotype. Each dose group (below-threshold group and above-threshold group) interacting with the genotype of TM6SF2 SNP rs58542926 had an adjusted RR from 7.764 (95% CI 3.272-18.420, P = 0.000) to 24.022 (95% CI 8.971-64.328, P = 0.000). The T allele of rs58542926 in the TM6SF2 gene may be a risk factor for susceptibility to DMF-induced NAFLD.

CONCLUSION

Polymorphisms of TM6SF2 SNP rs58542926 may play an important role in susceptibility to NAFLD after exposure to DMF.

Aberrant expression of SNHG12 contributes to N, N-dimethylformamide-induced hepatic apoptosis both in short-term and long-term DMF exposure

N, N-Dimethylformamide (DMF) can cause liver damage in occupationally exposed workers, but the molecular mechanism of DMF-induced liver damage has not been fully elucidated. Researches have proved that lncRNA plays a major function in chemical-induced liver toxicity and can be used as a biomarker and therapeutic target for liver injury. In order to verify that lncRNA also participates in DMF-induced liver damage, we treated HL-7702 cells with 75 or 150 mM DMF, and obtained lncRNA expression profiles through high-throughput sequencing. Among the differentially expressed lncRNAs, lncRNA SNHG12 was proved to be significantly downregulated in DMF-treated HL-7702 cells and participate in DMF-mediated apoptosis, even under long-term low-dose DMF exposure (5-10 mM, 8 weeks). In addition, according to bioinformatics analysis, miR-218-5p is expected to be a potential target of SNHG12, which was verified by the dual luciferase reporter assay in HEK293FT cells. MiR-218-5p mimic can induce apoptosis in HL-7702 cells. Among the predicted targets of miR-218-5p, protein kinase C epsilon (PRKCE) was reported to be involved in apoptosis, and was indeed downregulated by miR-218-5p mimic in our study. Further experiments showed that changes of the expression of SNHG12 can affect the expression of PRKCE. In the epidemiological study of occupational population, we also found that SNHG12 was downregulated in the serum exosomes of workers exposed to DMF. These results indicated that SNHG12 can mediate DMF-induced apoptosis of HL-7702 cells through miR-218-5p/PRKCE pathway.

Characterization of US population levels of urinary methylcarbamoyl mercapturic acid, a metabolite of N,N-dimethylformamide and methyl isocyanate, in the National Health and Nutrition Examination Survey (NHANES) 2005-2006 and 2011-2016

Methylcarbamoyl mercapturic acid (MCAMA, N-acetyl-S-(N-methylcarbamoyl)-L-cysteine) is a urinary metabolite of N,N-dimethylformamide and methyl isocyanate, which are volatile organic compounds that are harmful to humans. N,N-dimethylformamide exposure causes liver damage, and methyl isocyanate inhalation damages the lining of the respiratory tract, which can increase risk of chronic obstructive pulmonary disease and asthma. This study characterizes urinary MCAMA levels in the US population and explores associations of MCAMA concentrations with select demographic and environmental factors. We used liquid chromatography tandem mass spectrometry to measure MCAMA in urine collected from study participants ≥ 12 years old (N = 8272) as part of the National Health and Nutrition Examination Survey 2005-2006 and 2011-2016. We produced multiple regression models with MCAMA concentrations as the dependent variable and sex, age, fasting time, race/ethnicity, diet, and cigarette smoking as independent variables. Cigarette smokers and nonsmokers had median urinary MCAMA concentrations of 517 μg/g creatinine and 127 μg/g creatinine, respectively. Sample-weighted multiple regression analysis showed that MCAMA was positively associated with serum cotinine (p < 0.0001). Compared to non-exposed participants (serum cotinine ≤ 0.015 ng/mL), presumptive exposure to second-hand tobacco smoke (serum cotinine > 0.015-≤ 10 ng/mL and 0 cigarettes smoked per day) was associated with 20% higher MCAMA (p < 0.0001). Additionally, smoking 1-10 cigarettes per day was associated with 261% higher MCAMA (p < 0.0001), smoking 11-20 cigarettes per day was associated with 357% higher MCAMA (p < 0.0001), and smoking > 20 cigarettes per day was associated with 416% higher MCAMA (p < 0.0001). These findings underscore the strong association of tobacco smoke exposure with urinary MCAMA biomarker levels.

The influence of airborne N,N-dimethylformamide on liver toxicity measured in industry workers: A systematic review and meta-analysis

Background:

Modern industry is developing and so is the consumption of N, N-dimethylformamide (DMF) and the occupational population exposed to DMF. However, chronic occupational and experimental exposure to DMF has been especially linked to liver and gastrointestinal disturbances.

Aims:

This study aims to systematically review and evaluate with a meta-analysis the influence of DMF exposure on human liver toxicity.

Methods:

The PubMed/Medline, the ECHA restriction dossier and the Web of Science were searched. Midpoint DMF exposure levels were calculated, and the association between DMF exposure and liver toxicity was investigated. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

Results:

Of 92 screened articles, 19 articles were included in the review and of them, 10 articles were included in the meta-analysis. No association was observed when the midpoint DMF exposure was less than 20 mg/m3 (OR: 1.58, 95% CIs: 0.68–3.65). A positive association between DMF exposure and liver toxicity was observed when the midpoint DMF exposure was between 21 mg/m3 and 25 mg/m3 (OR: 3.26, 95% CIs: 1.38–7.73).

Conclusions:

Higher exposure DMF levels are associated with liver toxicity. However, these results tend to overestimate potential risks because the use of midpoint exposures includes and gives weight to populations at the upper end of the exposure distributions and because liver toxicity was defined as a statistical significant difference in liver enzyme levels compared to control groups, which is not identical to biologically relevant effects and adverse health effects.

Preparation and Characterization of Self-Colored Waterborne Polyurethane and Its Application in Eco-Friendly Manufacturing of Microfiber Synthetic Leather Base

A novel self-colored waterborne polyurethane (SCPU) was synthesized and used in the preparation of a microfiber synthetic leather (MS-Leather) base in order to reduce the pollution caused by N,N-dimethylformamide (DMF) and dyes. The SCPU was prepared using the reaction of a reactive brilliant red K-2G with a waterborne polyurethane which was then extended via a first generation of hyperbranched poly(amine-ester). With the introduction of the dye, new absorption peaks at 1118 cm⁻¹ [S=O], 1413 cm⁻¹ [N=N], and 1635 cm⁻¹ [C=N] appeared in the Fourier transform infrared (FTIR) spectrum of SCPU, and SCPU mean particle size increased to 162 nm. The X-ray diffraction (XRD) peak intensity of SCPU at 19.27° was 1310 cts. The thermal stability of SCPU at 200–280 °C was inferior to that of the control sample; however, it improved at temperatures above 360 °C. Finally, a free-dyeing MS-Leather base prepared by using SCPU without DMF was manufactured. It was found that the dyes were distributed mainly in the polyurethane matrix rather than in the microfibers. Moreover, the color changes of the base before and after being washed in both a water and a soap solution were 0.93 and 4.21, respectively. This indicated that the base’s washing color fastness to water was better than to a soap solution.

N,N-dimethylformamide-induced acute hepatic failure: A case report and literature review

N,N-dimethylformamide (DMF) is a major solvent predominantly used in the chemical industry. The main toxic effects following exposure to DMF are gastric irritation, skin eruption and hepatotoxicity. However, hepatic failure induced by DMF is rare. In this report, we present a case of acute hepatic failure following exposure to a toxic dose of DMF via respiratory tract inhalation and skin absorption with detailed abdominal computed tomography scan, sequential laboratory data and polymorphisms. The patient recovered satisfactorily following artificial liver support therapy and pharmacological agents to protect the liver in addition to plasma, blood platelet and albumin transfusions. In view of the high mortality rate and rare occurrence rate of acute hepatic failure, the clinical characteristics, polymorphisms and therapeutic strategy of DMF poisoning are discussed.

Hyaluronic acid as a non-invasive biomarker of liver fibrosis

Chronic liver diseases may cause inflammation and progressive scarring, over time leading to irreversible hepatic damage (cirrhosis). As a result, the need to assess and closely monitor individuals for risk factors of components of matrix deposition and degradation, as well as the severity of the fibrosis using biomarkers, has been increasingly recognized.

AIM

Our aim is to review the use of biomarker for diagnosing and defining the severity of liver fibrosis.

METHODS

A systematic literature review was done using the terms "hyaluronic acid" and "liver fibrosis" as well as the name of each biomarker or algorithm known to be employed. PubMed and Google Scholar were searched, and English language articles indexed between January 2010 and October 2014 in which HA was used as a marker of liver fibrosis were retrieved, regardless of the underlying liver disease. Each author read the publications separately and the results were analyzed and discussed.

RESULTS

Biomarkers offer a potential prognostic or diagnostic indicator for disease manifestation, progression, or both. Serum biomarkers, including HA, have been used for many years. Emerging biomarkers such as metalloproteinases have been proposed as tools that provide valuable complementary information to that obtained from traditional biomarkers. Moreover, markers of extracellular matrix degradation provide powerful predictions of risk. In order for biomarkers to be clinically useful in accurately diagnosing and treating disorders, age-specific reference intervals that account for differences in gender and ethnic origin are a necessity.

CONCLUSIONS

This review attempts to provide a comprehensive analysis of the emerging risk biomarkers of liver fibrosis and to describe the clinical significance and analytical considerations of each biomarker pointing out sentinel features of disease progression.

Short-term exposure to dimethylformamide and the impact on digestive system disease: an outdoor study for volatile organic compound

Occupational and experimental studies have revealed the organs most affected by dimethylformamide (DMF) are liver and gastrointestinal tract. However, few studies have focused on the potential effect of outdoor pollution of DMF. This study examined the health risk of hospitalization due to digestive system disease by time series studies in a case city Longwan, China. The urine metabolite of DMF was correlated well with DMF exposure concentration (EC). A 101.0-μg/m(3) (interquartile range) increase in the two-day moving average of DMF EC was associated with a 1.10 (1.01 ˜ 1.20), 1.22 (1.10 ˜ 1.35), and 1.05 (0.90 ˜ 1.22) increase in hospitalization for total digestive system diseases, liver disease, and gastrointestinal tract disease, respectively. The exposure-dose response between DMF and the relative risk of liver disease was linear only below 350 μg/m(3). These findings highlight a previously unrecognized health problem related to VOCs released into the outdoor environment.

Seasonal difference in percutaneous absorption of N,N-dimethylformamide as determined using two urinary metabolites

OBJECTIVE

We evaluated the percutaneous absorption of N,N-dimethylformamide (DMF) in DMF-exposed workers in the summer and winter by assessing their urinary levels of DMF metabolites.

METHODS

Breathing-zone concentrations of DMF and workers' urinary levels of N-methylformamide (NMF) and N-acetyl-S-(N-methylcarbamoyl)-cysteine (AMCC) were simultaneously measured in the summer and winter in 193 male workers wearing a respirator and chemical protective gloves.

RESULTS

The mean breathing-zone concentrations of DMF in both seasons were below the occupational exposure limit of 10 ppm. Although there was no significant seasonal difference in the breathing-zone concentrations of DMF, workers' urinary levels of NMF and AMCC were significantly higher in the summer than in the winter. Log-transformed urinary levels of the metabolites were significantly correlated with log-transformed breathing-zone concentrations of DMF in the summer, whereas no significant correlation between AMCC and DMF was found in the winter. The urinary levels of AMCC were dispersed more widely than those of NMF, suggesting that urinary AMCC reflected the cumulative exposure to DMF over a workweek.

CONCLUSIONS

Percutaneous absorption was the principal route of exposure to DMF for the respirator-wearing workers. Increased urinary levels of NMF and AMCC in the summer were attributed to increased percutaneous absorption of DMF resulting from the increased amount of water-soluble DMF absorbed by sweaty skin caused by the increased summertime room temperature and humidity.