N-Methylenvaline in a group of subjects occupationally exposed to formaldehyde

Ultraperformance Liquid Chromatography Tandem Mass Spectrometry Method To Determine Formaldehyde Hemoglobin Adducts in Humans as Biomarker for Formaldehyde Exposure

Formaldehyde (FA) is an environmental chemical classified as a human carcinogen. It is highly reactive and can bind covalently with hemoglobin (Hb) to produce Hb adducts. Measurement of these Hb adducts provides valuable information about exposure to this chemical. We developed a robust, ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantifying FA-Hb adducts in red blood cells. The method measures the FA-VHLTPEEK peptide after trypic digestion. The peptide is a FA adduct at the N-terminus of the beta chain of human Hb. Method mean (±SD) accuracy, determined by recovery in quality control and blank material was 103.2% ± 8.11. The mean among-day and within-day coefficients of variation determined at three concentration levels (%CV) were 9.2% (range: 7.2-10.2%) and 4.9% (range 3.1-7.3%), respectively. The limit of detection was 3.4 nmol/g Hb. This method was applied to the analysis of 135 human blood samples, and FA-VHLTPEEK was detected in all study samples. FA-VHLTPEEK concentrations were not significantly different between smokers and nonsmokers. This work is the first validated UPLC-MS/MS method in which a FA peptide derived from a FA-Hb adduct could be used to monitor exposure to FA in population studies.

Is it possible to use biomonitoring for the quantitative assessment of formaldehyde occupational exposure?

The European classification, labeling and packaging classified formaldehyde as human carcinogen Group 1B and mutagen 2, fostering the re-evaluation of the exposure risk in occupational settings. Although formaldehyde exposure is traditionally measured in air, many efforts were made to identify specific exposure biomarkers: urinary formaldehyde, formic acid and DNA damage indicators. Though used in combination, none of these seems satisfactory. The influence of the metabolism on exogenous formaldehyde levels, the exposure to other xenobiotics, the difference in genetic background and metabolism efficiency, misled the relationship between genotoxicity and exposure data. Nevertheless, the limitation of adverse effects to the local contact sites hampers biomonitoring. Here we discuss the feasibility of formaldehyde biomonitoring and the use of DNA, DNA-protein cross-links and protein adducts as potential biomarkers.

Environmental and biological monitoring of occupational formaldehyde exposure resulting from the use of products for hair straightening

The evaluation of formaldehyde (FD) exposure in beauty salons, due to the use of hair straightening products, and its relation with genotoxicity biomarkers was performed in this study. Regardless of official recommendations, the inappropriate use of homemade hair creams has became a popular practice in Brazil, and high formaldehyde content in the "progressive straightening" creams can contain mutagens that could increase the incidence of neoplasia in those people who use them. Damage to DNA was assessed by conducting a micronuclei test (MNT) on buccal cells and the comet assay on heparinized venous blood samples. A total of 50 volunteers were recruited at six different beauty salons (labeled A to F). At two salons that used products that did not contain FD (salons D and E), environmental FD concentrations were 0.04 and 0.02 ppm. In contrast, the products used at salons A, B, C, and F contained 5.7, 2.61, 5.9, and 5.79% of FD, and these salons had environmental FD concentrations of 0.07, 0.14, 0.16, and 0.14 ppm, respectively. Comparison of the beauty salon workers from each of the six beauty salons revealed significant differences in urinary formic acid (FA) concentration before exposure (p = 0.016), urinary FA after exposure (p = 0.004), variation in FA concentration before and after exposure (p = 0.018), environmental FD concentration (p < 0.001), cytogenetic damage detected by the comet assay according to both damage index (p < 0.001) and frequency of damage (p < 0.001), and for karyorrhexis only according to the MNT (p = 0.001).

Evaluation of genotoxicity in workers exposed to low levels of formaldehyde in a furniture manufacturing facility

Formaldehyde (FA) is a chemical widely used in the furniture industry and has been classified as a potential human carcinogen. The purpose of this study was to evaluate the occupational exposure of workers to FA at a furniture manufacturing facility and the relationship between environmental concentrations of FA, formic acid concentration in urine, and DNA damage. The sample consisted of 46 workers exposed to FA and a control group of 45 individuals with no history of occupational exposure. Environmental concentrations of FA were determined by high-performance liquid chromatography. Urinary formic acid concentrations were determined by gas chromatography with flame ionization detector. DNA damage was evaluated by the micronucleus (MN) test performed in exfoliated buccal cells and comet assay with venous blood. The 8-h time-weighted average of FA environmental concentration ranged from 0.03 ppm to 0.09 ppm at the plant, and the control group was exposed to a mean concentration of 0.012 ppm. Workers exposed to higher environmental FA concentrations had urinary formic acid concentrations significantly different from those of controls (31.85 mg L(-1) vs. 19.35 mg L(-), p ≤ 0.01 Mann-Whitney test). Significant differences were found between control and exposed groups for the following parameters: damage frequency and damage index in the comet assay, frequency of binucleated cells in the MN test, and formic acid concentration in urine. The frequency of micronuclei, nuclear buds, and karyorrhexis did not differ between groups. There was a positive correlation between environmental concentrations of FA and damage frequency (Spearman's rank correlation coefficient [r s] = 0.24), damage index (r s = 0.21), binucleated cells (r s = 0.34), and urinary formic acid concentration (r s = 0.63). The results indicate that, although workers in the furniture manufacturing facility were exposed to low environmental levels of FA, this agent contributes to the observed increase in cytogenetic damage. In addition, urinary formic acid concentrations correlated strongly with occupational exposure to FA.

Small molecule metabolite biomarker candidates in urine from mice exposed to formaldehyde

Formaldehyde (FA) is a ubiquitous compound used in a wide variety of industries, and is also a major indoor pollutant emitted from building materials, furniture, etc. Because FA is rapidly metabolized and endogenous to many materials, specific biomarkers for exposure have not been identified. In this study, we identified small metabolite biomarkers in urine that might be related FA exposure. Mice were allowed to inhale FA (0, 4, 8 mg/m³) 6 h per day for 7 consecutive days, and urine samples were collected on the 7th day of exposure. Liquid chromatography coupled with time of flight-mass spectrometry and principal component analysis (PCA) was applied to determine alterations of endogenous metabolites in urine. Additionally, immune toxicity studies were conducted to ensure that any resultant toxic effects could be attributed to inhalation of FA. The results showed a significant decrease in the relative rates of T lymphocyte production in the spleen and thymus of mice exposed to FA. Additionally, decreased superoxide dismutase activity and increased reactive oxygen species levels were found in the isolated spleen cells of exposed mice. A total of 12 small molecules were found to be altered in the urine, and PCA analysis showed that urine from the control and FA exposed groups could be distinguished from each other based on the altered molecules. Hippuric acid and cinnamoylglycine were identified in urine using exact mass and fragment ions. Our results suggest that the pattern of metabolites found in urine is significantly changed following FA inhalation, and hippuric acid and cinnamoylglycine might represent potential biomarker candidates for FA exposure.

Inhaled formaldehyde induces DNA-protein crosslinks and oxidative stress in bone marrow and other distant organs of exposed mice

Formaldehyde (FA), a major industrial chemical and ubiquitous environmental pollutant, has been classified as a leukemogen. The causal relationship remains unclear, however, due to limited evidence that FA induces toxicity in bone marrow, the site of leukemia induction, and in other distal organs. Although induction of DNA-protein crosslinks (DPC), a hallmark of FA toxicity, was not previously detected in the bone marrow of FA-exposed rats and monkeys in studies published in the 1980s, our recent studies showed increased DPC in the bone marrow, liver, kidney, and testes of exposed Kunming mice. To confirm these preliminary results, in the current study we exposed BALB/c mice to 0, 0.5, 1.0, and 3.0 mg m(-3) FA (8 hr per day, for 7 consecutive days) by nose-only inhalation and measured DPC levels in bone marrow and other organs of exposed mice. As oxidative stress is a potential mechanism of FA toxicity, we also measured glutathione (GSH), reactive oxygen species (ROS), and malondialdehyde (MDA), in the bone marrow, peripheral blood mononuclear cells, lung, liver, spleen, and testes of exposed mice. Significant dose-dependent increases in DPC, decreases in GSH, and increases in ROS and MDA were observed in all organs examined (except for DPC in lung). Bone marrow was among the organs with the strongest effects for DPC, GSH, and ROS. In conclusion, exposure of mice to FA by inhalation induced genotoxicity and oxidative stress in bone marrow and other organs. These findings strengthen the biological plausibility of FA-induced leukemogenesis and systemic toxicity.

The determination of exogenous formaldehyde in blood of rats during and after inhalation exposure

Formaldehyde (FA) is suspected of being associated with the development of leukemia. An inhalation experiment with FA was performed in rats to study whether FA can enter the blood and could thus cause systemic toxicity in remote tissues such as the bone marrow. Therefore, a sophisticated analytical method was developed to detect blood concentrations of FA during and after single 6-h exposure by inhalation. In order to differentiate between exogenous and endogenous FA the rats were exposed to stable isotope ((13)C) labeled FA by inhalation. During and after exposure of the rats to (13)C-FA their blood was analyzed to determine the ratio between labeled and natural FA in blood and the total blood concentration of FA. With respect to sensitivity, with the applied method exogenous (13)C-FA could have been detected in blood at a concentration approximately 1.5% of the endogenous FA blood concentration. Exogenous (13)C-FA was not detectable in the blood of rats either during or up to 30 min after the exposure. It was concluded that the inhalation of (13)C-FA at 10 ppm for 6h did not result in an increase of the total FA concentration in blood.

Formaldehyde and tobacco smoke as alkylating agents: the formation of N-methylenvaline in pathologists and in plastic laminate workers

OBJECTIVE

Aim of this study was to investigate the relationships between the concentration of formaldehyde in air and the alkylation of hemoglobin to form a terminal N-methylenvaline residue in three occupationally exposed groups: a) technicians of pathology wards, b) workers of the plastic laminates industry, and c) a control group. All subjects recruited in this study were also tested on their smoking habits.

METHODS

Formaldehyde adsorbed on passive air samplers was quantified by HPLC with UV detection (360 nm), cotinine was quantified by GC-MS. Terminal hemoglobin N-methylenvaline was determined by treating globine under reducing conditions with pentafluorophenyl isothiocyanate to yield a derivative, subsequently detected by GC-MS. One-way analysis of variance was performed to compare among the three groups the biomarkers considered in this study.

RESULTS

For air-FA and N-methylenvaline a difference between the three groups was detected (p < 0.0001) and a significant higher concentration in the two professionally exposed groups was proved. Mean values for FA (μg/m(3)): group a) 188.6, group b) 210.1, and group c) 41.4; mean values for N-methylenvaline (nmol/g of globin): group a) 377.9, group b) 342.8, and group c) 144.8. Conversely, the comparison between the two professionally exposed groups, a) vs b), does not show any significant difference highlighting similar exposition to FA and, consequently, similar biological response. Tobacco smoke proves to have a minor impact on the formation of N-methylenvaline molecular adduct.

CONCLUSIONS

A positive correlation was demonstrated between professional exposition to air-formaldehyde and hemoglobin alkylation to form N-methylenvaline molecular adduct in two occupationally exposed groups of subjects considered in the present study. In comparison with occupational exposition, tobacco smoke proved to have a minor impact on the formation of N-methylenvaline molecular adduct.

Reproductive and developmental toxicity of formaldehyde: a systematic review

Formaldehyde, the recently classified carcinogen and ubiquitous environmental contaminant, has long been suspected of causing adverse reproductive and developmental effects, but previous reviews were inconclusive, due in part, to limitations in the design of many of the human population studies. In the current review, we systematically evaluated evidence of an association between formaldehyde exposure and adverse reproductive and developmental effects, in human populations and in vivo animal studies, in the peer-reviewed literature. The mostly retrospective human studies provided evidence of an association of maternal exposure with adverse reproductive and developmental effects. Further assessment of this association by meta-analysis revealed an increased risk of spontaneous abortion (1.76, 95% CI 1.20-2.59, p=0.002) and of all adverse pregnancy outcomes combined (1.54, 95% CI 1.27-1.88, p<0.001), in formaldehyde-exposed women, although differential recall, selection bias, or confounding cannot be ruled out. Evaluation of the animal studies including all routes of exposure, doses and dosing regimens studied, suggested positive associations between formaldehyde exposure and reproductive toxicity, mostly in males. Potential mechanisms underlying formaldehyde-induced reproductive and developmental toxicities, including chromosome and DNA damage (genotoxicity), oxidative stress, altered level and/or function of enzymes, hormones and proteins, apoptosis, toxicogenomic and epigenomic effects (such as DNA methylation), were identified. To clarify these associations, well-designed molecular epidemiologic studies, that include quantitative exposure assessment and diminish confounding factors, should examine both reproductive and developmental outcomes associated with exposure in males and females. Together with mechanistic and animal studies, this will allow us to better understand the systemic effect of formaldehyde exposure.

Formaldehyde adduct to human serum albumin with reference to aspartame intake

A preliminary study was performed to evaluate the role of formaldehyde (F) deriving from aspartame intake in the production of the adduct F-human serum albumin (F-HSA) by mean of a sera-epidemiological investigation. A blood-donors population (68 subjects) was analysed for the presence of anti-F-HSA IgG by an indirect competitive immunoenzymatic assay (displacement assay). Only the 41% of the subjects were aspartame consumer and with a low daily intake (0.96mg/(kgday)). A 50% sera-prevalence of IgG anti-F-HSA was observed in the population, but no association between this biomarker and aspartame intake was pointed out. A significant association was found between the IgG anti-F-HSA presence and exogenous F exposure sources (cigarette active smoke and occupational exposure). Considering the low number of the investigated subjects and the low doses of aspartame consumption, the results of this preliminary study seems to suggest that aspartame low intake does not influence the formation of F adducts.