Malondialdehyde-deoxyguanosine adduct formation in workers of pathology wards: the role of air formaldehyde exposure

Association of formaldehyde concentration with depression risk in US adults: a population-based epidemiology study

The association of formaldehyde exposure with depression remains unknown. We used the data from National Health and Nutrition Examination Survey (NHANES) 2015-2016 to evaluate the association between formaldehyde exposure and depression. Multivariable logistic regressions and restricted cubic spline (RCS) were implemented to examine the association between formaldehyde exposure and depression. A total of 1336 participants were included in the analysis, of which 110 (8.23%) participants were depressed. After adjusting for confounders, a significant association between formaldehyde exposure and depression (OR = 1.01, 95% CI: 1.00-1.02, P = 0.043) was observed. The RCS plot showed a positive association in a linear manner (PNonlinear = 0.109), and the risk began to rise rapidly with concentrations above 129.37 nmol/g HB. The positive association remained in participants with high-intensity physical activity (OR = 1.08, 95% CI: 1.02-1.13, P = 0.003), but not in participants with other physical activities. Moreover, we constructed a novel nomogram to easily estimate the individual-specific probabilities of depression. In conclusion, formaldehyde exposure was associated with an elevated risk of depression, and the effect exhibited differences in participants with different levels of physical activity.

Oxidative stress is associated with markers of renal dysfunction in children aged 6-9 years old in a South African population

INTRODUCTION

although studies have shown a relationship between albuminuria and oxidative stress in adults, limited information on the subject is available in children. The aim of this study was to assess the relationship between oxidative stress and albuminuria in South African children of African ancestry.

METHODS

a cross-sectional study involving 6-9 years old children in randomly selected rural and urban schools of the Eastern Cape Province of South Africa was conducted. Anthropometric measurements were done and urine samples were collected for the determination of titres of albumin, creatinine, 8-hydroxy-2-deoxy-guanosine (8-OHdG) and thiobarbituric acid reactive substances (TBARS). The urinary albumin to creatinine ratio (ACR) was calculated and used to determine albuminuria.

RESULTS

creatinine and 8-OHdG were significantly higher (p<0.05) in urban children than in rural children while albumin, ACR and TBARS were significantly higher (p<0.05) in rural compared to urban children. The prevalence of albuminuria was 14.05% of which microalbuminuria was 8.83% while macroalbuminuria was 5.22%. Albuminuria was higher in rural children than their urban counterparts and was more prevalent in females. TBARS was positively (p<0.05) associated with creatinine and albumin in the cohort as well as in females and urban children while 8-OHdG was positively associated with albumin in the cohort.

CONCLUSION

findings of this study showed that oxidative stress was associated with markers of renal dysfunction with a 14% prevalence of albuminuria observed in South African children of African ancestry.

Influencing factors of carbonyl compounds and other VOCs in commercial airliner cabins: On-board investigation of 56 flights

Volatile organic compounds (VOCs) as a non-negligible aircraft cabin air quality (CAQ) factor influence the health and comfort of passengers and crew members. On-board measurements of carbonyls (short-chain (C₁ -C₆ )) and other volatile organic compounds (VOCs, long-chain (C₆ -C₁₆ )) with a total of 350 samples were conducted in 56 commercial airliner cabins covering 8 aircraft models in this study. The mean concentration for each individual carbonyl compound was between 0.3 and 8.3 μg/m³ (except for acrolein & acetone, average = 20.7 μg/m³ ) similar to the mean concentrations of other highly detected VOCs (long-chain (C₆ -C₁₆ ), 97% of which ranged in 0-10 μg/m³ ) in aircraft cabins. Formaldehyde concentrations in flights were significantly lower than in residential buildings, where construction materials are known formaldehyde sources. Acetone is a VOC emitted by humans, and its concentration in flights was similar to that in other high-occupant density transportation vehicles. The variation of VOC concentrations in different flight phases of long-haul flights was the same as that of CO₂ concentration except for the meal phase, which indicates the importance of cabin ventilation in diluting the gaseous contaminants, while the sustained and slow growth of the VOC concentrations during the cruising phase in short-haul flights indicated that the ventilation could not adequately dilute the emission of VOCs. For the different categories of VOCs, the mean concentration during the cruising phase of benzene series, aldehydes, alkanes, other VOCs (detection rate > 50%), and carbonyls in long-haul flights was 44.2 µg/m³ , 17.9 µg/m³ , 18.6 µg/m³ , 31.5 µg/m³ , and 20.4 µg/m³  lower than those in short-haul flights, respectively. Carbonyls and d-limonene showed a significant correlation with meal service (p < 0.05). Unlike the newly decorated rooms or new vehicles, the inner materials were not the major emission sources in aircraft cabins. Practical Implications. The on-board measurements of 56 flights enrich the VOC database of cabin environment, especially for carbonyls. The literature review of carbonyls in the past 20 years contributes to the understanding the current status of cabin air quality (CAQ). The analysis of VOC concentration variation for different flight phases, flight duration, and aircraft age lays a foundation for exploring effective control methods, including ventilation and purification for cabin VOC pollution. The enriched VOC data is helpful to explore the key VOCs of aircraft cabin environment and to evaluate the acute/chronic health exposure risk of pollutants for passengers and crew members.

Arterial stiffness and carotid distensibility following acute formaldehyde exposure in female adults

Formaldehyde (FA) is a ubiquitous organic preservative used in several industries and represents an occupational health hazard. Short-term exposure to FA can increase oxidative stress and cause a decrease in conduit vessel function. These decrements in vascular function may extend to the arterial architecture, predisposing individuals to increased risk of cardiovascular disease. The purpose of this study was to investigate the impact of an acute 90-minute FA exposure period (259 ± 95 ppb) on indices of arterial architecture. Arterial stiffness and carotid distensibility as determined by central pressures, augmentation index (AIx), and carotid-femoral pulse wave velocity (cfPWV) (n=13F, 24 ± 1 year) as well as carotid stiffness and intima media thickness (IMT) (n = 9F, 23 ± 1 year) were assessed prior to (Pre-FA) and immediately following (Post-FA) exposure to FA in human cadaver dissection laboratories. Central pressures and cfPWV (Pre-FA: 5.2 ± 0.8 m.s^-1, Post-FA: 5.2 ± 1.1 m s^-1) were unchanged by acute FA exposure (p > 0.05). Carotid stiffness parameters and distension were unchanged by acute FA exposure (p > 0.05), although distensibility (Pre-FA: 33.9 ± 10.5[10-3*kPa^-1], Post-FA: 25.9 ± 5.5[10-3*kPa-1], p < 0.05), and IMT (Pre-FA: 0.42 ± 0.05 mm, Post-FA: 0.51 ± 0.11 mm, p < 0.05) decreased and increased, respectively. Individual Pre- to Post-FA changes in these markers of arterial architecture did not correlate with levels of FA exposure ([FA]: 20-473 ppb) (p > 0.05). Our group previously found vascular function decrements following acute FA exposure in human cadaver laboratories; here we found that carotid distensibility and intima media thickness are altered following FA exposure.

Formaldehyde in Hospitals Induces Oxidative Stress: The Role of GSTT1 and GSTM1 Polymorphisms

Despite the toxicity and health risk characteristics of formaldehyde (FA), it is currently used as a cytological fixative and the definition of safe exposure levels is still a matter of debate. Our aim was to investigate the alterations in both oxidative and inflammatory status in a hospital working population. The 68 workers recruited wore a personal air-FA passive sampler, provided a urine sample to measure 15-F_2t-Isoprostane (15-F_2t-IsoP) and malondialdehyde (MDA) and a blood specimen to measure tumour necrosis factor α (TNFα). Subjects were also genotyped for GSTT1 (Presence/Absence), GSTM1 (Presence/Absence), CYP1A1 exon 7 (A > G), and IL6 (−174, G > C). Workers were ex post split into formalin-employers (57.3 μg/m³) and non-employers (13.5 μg/m³). In the formalin-employers group we assessed significantly higher levels of 15-F_2t-IsoP, MDA and TNFα (<0.001) in comparison to the non-employers group. The air-FA levels turned out to be positively correlated with 15-F_2t-IsoP (p = 0.027) and MDA (p < 0.001). In the formalin-employers group the MDA level was significantly higher in GSTT1 Null (p = 0.038), GSTM1 Null (p = 0.031), and CYP1A1 exon 7 mutation carrier (p = 0.008) workers, compared to the wild type subjects. This study confirms the role of FA in biomolecular profiles alterations, highlighting how low occupational exposure can also result in measurable biological outcomes.

Chemical risk in hospital settings: Overview on monitoring strategies and international regulatory aspects

Chemical risk in hospital settings is a growing concern that health professionals and supervisory authorities must deal with daily. Exposure to chemical risk is quite different depending on the hospital department involved and might origin from multiple sources, such as the use of sterilizing agents, disinfectants, detergents, solvents, heavy metals, dangerous drugs, and anesthetic gases. Improving prevention procedures and constantly monitoring the presence and level of potentially toxic substances, both in workers (biological monitoring) and in working environments (environmental monitoring), might significantly reduce the risk of exposure and contaminations. The purpose of this article is to present an overview on this subject, which includes the current international regulations, the chemical pollutants to which medical and paramedical personnel are mainly exposed, and the strategies developed to improve safety conditions for all healthcare workers.

Oxidative stress induction in woodworkers occupationally exposed to wood dust and formaldehyde

BACKGROUND

Many workers are exposed to wood dust (WD) and formaldehyde (FA), whose carcinogenic activity is supposed to be oxidative stress-mediated. This study aims to assess to what extent the occupational exposure to WD and FA, albeit within regulatory limits, could result in OS induction in a woodworkers' population.

METHODS

The sample population consisted of 127 woodworkers from 4 factories and 111 unexposed controls. Individual exposure was assessed by personal air-samplers. Each participant enrolled in the study filled out a questionnaire and provided a urinary sample to quantify OS biomarkers, namely 15-F2t-IsoProstane (15-F2t-IsoP) and 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dGuo). The main confounding factor for OS, i.e. tobacco smoking exposure, was assessed by measuring cotinine in urine samples.

RESULTS

Woodworkers were exposed to significantly higher amounts of WD and FA as compared to controls (p < 0.001). Among OS biomarkers, 15-F2t-IsoP showed statistically significant higher values in woodworkers compared to controls (p = 0.004). A significant, positive correlation was observed between 15-F2t-IsoP and 8-oxo-dGuo (p = 0.005), cotinine (p = 0.05), FA (p < 0.001) and WD (p = 0.01); 8-oxo-dGuo was significantly correlated with cotinine (p = 0.001) and WD (p = 0.004). In addition, WD and FA were significantly correlated each other (p < 0.001).

CONCLUSIONS

The study confirms that WD and FA may induce OS in woodworkers, and highlights that even the compliance with occupational exposure limits can result in measurable biological outcomes.

Vascular dysfunction and oxidative stress caused by acute formaldehyde exposure in female adults

Formaldehyde (FA) is a common, volatile organic compound used in organic preservation with known health effects of eye, nose, and throat irritation linked to oxidative stress and inflammation. Indeed, long-term FA exposure may provoke skin disorders, cancer, and cardiovascular disease. However, the effects of short-term FA exposure on the vasculature have yet to be investigated. We sought to investigate the impact of an acute FA exposure on 1) macrovascular function in the arm (brachial artery flow-mediated dilation, FMD), 2) microvascular function in the arm (brachial artery reactive hyperemia, RH) and leg (common femoral artery, supine passive limb movement, PLM), and 3) circulating markers of oxidative stress (xanthine oxidase, XO; protein carbonyl, PC; and malondialdehyde, MDA) and inflammation (C-reactive protein, CRP). Ten (n = 10) healthy females (23 ± 1 yr) were studied before and immediately after a 90-min FA exposure [(FA): 197 ± 79 ppb] in cadaver dissection laboratories. Brachial artery FMD% decreased following FA exposure (Pre-FA Exp: 9.41 ± 4.21%, Post-FA Exp: 6.74 ± 2.57%; P = 0.043), and FMD/shear decreased following FA exposure (Pre-FA Exp: 0.13 ± 0.07 AU, Post-FA Exp: 0.07 ± 0.03 AU; P = 0.016). The area under the curve for brachial artery RH (Pre-FA Exp: 481 ± 191 ml, Post-FA Exp: 499 ± 165 ml) and common femoral artery PLM (Pre-FA Exp: 139 ± 95 ml, Post-FA Exp: 129 ± 64 ml) were unchanged by FA exposure (P > 0.05). Circulating MDA increased (Pre-FA Exp: 4.8 ± 1.3 µM, Post-FA Exp: 6.3 ± 2.2 µM; P = 0.047) while XO, PC, and CRP were unchanged by FA exposure (P > 0.05). These initial data suggest a short FA exposure can adversely alter vascular function and oxidative stress, influencing cardiovascular health.NEW & NOTEWORTHY This study was the first to investigate the implications of acute formaldehyde (FA) exposure on adult female vascular function in the arms and legs. The main findings of this study were a decrease in conduit vessel function without any alteration to microvascular function following a 90-min FA exposure. Additionally, the oxidative stress marker malondialdehyde increased after FA exposure. Taken together, these results suggest acute FA exposure have deleterious implications for the vasculature and redox balance.Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/formaldehyde-exposure-decreases-vascular-function/.

Applying Tobacco, Environmental, and Dietary-Related Biomarkers to Understand Cancer Etiology and Evaluate Prevention Strategies

Many human cancers are caused by environmental and lifestyle factors. Biomarkers of exposure and risk developed by our team have provided critical data on internal exposure to toxic and genotoxic chemicals and their connection to cancer in humans. This review highlights our research using biomarkers to identify key factors influencing cancer risk as well as their application to assess the effectiveness of exposure intervention and chemoprevention protocols. The use of these biomarkers to understand individual susceptibility to the harmful effects of tobacco products is a powerful example of the value of this type of research and has provided key data confirming the link between tobacco smoke exposure and cancer risk. Furthermore, this information has led to policy changes that have reduced tobacco use and consequently, the tobacco-related cancer burden. Recent technological advances in mass spectrometry led to the ability to detect DNA damage in human tissues as well as the development of adductomic approaches. These new methods allowed for the detection of DNA adducts in tissues from patients with cancer, providing key evidence that exposure to carcinogens leads to DNA damage in the target tissue. These advances will provide valuable insights into the etiologic causes of cancer that are not tobacco-related.See all articles in this CEBP Focus section, "Environmental Carcinogenesis: Pathways to Prevention."

Proteomic and transcriptomic changes in rat liver following oral feeding of formaldehyde

Formaldehyde (FA), a ubiquitous volatile organic compound present in a wide range of resources, is a hazardous chemical and human carcinogen. Contamination of FA in food, especially perishable commodities like fish and meat, is a major source of exposure, although it is not recommended for use in food and food products owing to its carcinogenicity. Effects of oral feeding of FA have been studied by evaluating general health, haematology and clinical chemistry in rat. Recent studies have shown that FA exposure leads to detrimental cardiovascular effects. It regulates vascular tensions through nitric oxide-cGMP signalling pathway and ion channels in rats. Although FA is an established carcinogen, molecular studies on carcinogenic potential with dose dependency are meagre. In this context, the present study was undertaken to investigate the toxicogenomic and proteomic alterations in liver of rats fed FA through drinking water. By proteomic analysis, 621 proteins/protein-subunits showed differential abundance (proteome data available via ProteomeXchange with identifier PXD010534), whereas 536 differentially-expressed-genes were identified by transcriptome analysis (data available via Sequence Read Archive with identifier SRR7974113). Gene ontology analysis showed that binding, catalysis, signal transduction were affected in formaldehyde-fed rats. Pathway analysis revealed that formaldehyde-exposure activated PI3K-AKT pathway that leads to inhibition of caspase activity thereby assisting cells to survive against apoptosis. Decreased abundance/down-regulation of ANGPT, eNOS, STAT3 proteins/transcripts and increased abundance of EDN1 indicated decrease in angiogenesis and vasodilatation that restricted hepatic cells from becoming tumorigenic; thus, indicating FA could be less toxic and non-tumorigenic at low concentrations.

Formaldehyde, Oxidative Stress, and FeNO in Traffic Police Officers Working in Two Cities of Northern Italy

Personal air formaldehyde (air-FA) was measured as risk factor of airways inflammation and oxidative stress (SO) induction. Overall, 154 police officers were enrolled from two differently urbanised Italian cities, Turin and Pavia. Urinary F2t-isoprostane (15-F2t-IsoP), a prostaglandin-like compound, was quantified as a biomarker of general OS in vivo and fractional exhaled nitric oxide (FeNO) was measured for monitoring local inflammatory processes. Urinary cotinine was quantified as a biomarker of tobacco smoking exposure. Traffic police officers living in Turin showed an increased level of log air-FA (p < 0.001), equal to +53.6% (p < 0.001). Log air-(FA) mean values were 3.38 (C.I. 95% 3.33–3.43) and 2.84 (C.I. 95% 2.77–2.92) in Turin and Pavia, respectively. Log (air-FA) was higher in “outdoor workers” (3.18, C.I. 95% 3.13–3.24, p = 0.035) compared to “indoor workers”, showing an increase of +9.3%, even controlling for sex and city. The analyses on 15-F2t-IsoP and FeNO, both adjusted for log air-FA, highlighted that OS and inflammation were higher (+66.8%, p < 0.001 and +75%, p < 0.001, respectively) in Turin traffic police officers compared to those from Pavia. Our findings suggest that even low exposures to traffic-related emissions and urbanisation may influence both general oxidative stress levels and local inflammation.

Occupational exposure to formaldehyde and early biomarkers of cancer risk, immunotoxicity and susceptibility

Formaldehyde (FA) is a high-volume production chemical manufactured worldwide to which many people are exposed to both environmentally and occupationally. FA was recently reclassified as a human carcinogen. Several epidemiological studies have revealed an increased risk of cancer development among workers exposed to FA. Although FA genotoxicity was confirmed in a variety of experimental systems, data from human studies are conflicting. The aim of the present study was to evaluate the occupational exposure to FA in a multistage approach relating the exposure with different biomarkers (dose and effect) and individual susceptibility. Air monitoring was performed to estimate the level of exposure to FA during shift work. Eighty-five workers from hospital anatomy-pathology laboratories exposed to FA and 87 controls were tested for cytogenetic alterations in lymphocytes (micronucleus, MN; sister-chromatid exchange, SCE) and T-cell receptor (TCR) mutation assay. The frequency of MN in exfoliated buccal cells, a first contact tissue was also assessed. Percentages of different lymphocyte subpopulations were selected as immunotoxicity biomarkers. The level of formic acid in urine was investigated as a potential biomarker of internal dose. The effects of polymorphic genes of xenobiotic metabolising enzymes and DNA repair enzymes on the endpoints studied were determined. The mean level of FA exposure was 0.38 ± 0.03 ppm. MN (in lymphocytes and buccal cells) and SCE were significantly increased in FA-exposed workers compared to controls. MN frequency positively correlated with FA levels of exposure and duration. Significant alterations in the percentage of T cytotoxic lymphocytes, NK cells and B lymphocytes were found between groups. Polymorphisms in CYP2E1, GSTP1 and FANCA genes were associated with increased genetic damage in FA-exposed subjects. The obtained information may provide new important data to be used by health and safety care programs and by governmental agencies responsible for setting the acceptable levels for occupational exposure to FA.

Toward safer thanatopraxy cares: formaldehyde-releasers use

Human cadavers constitute very useful educational tools to teach anatomy in medical scholarship and related disciplines such as physiology, for example. However, as biological material, human body is subjected to decay. Thanatopraxy cares such as embalming have been developed to slow down and inhibit this decay, but the formula used for the preservation fluids are mainly formaldehyde (FA)-based. Very recently, other formulas were developed in order to replace FA, and to avoid its toxicity leading to important environmental and professional exposure concerns. However, these alternative FA-free fluids are still not validated or commercialized, and their efficiency is still under discussion. In this context, the use of FA-releasing substances, already used in the cosmetics industry, may offer interesting alternatives in order to reduce professional exposures to FA. Simultaneously, the preservation of the body is still guaranteed by FA generated over time from FA-releasers. The aim of this review is to revaluate the use of FA in thanatopraxy cares, to present its benefits and disadvantages, and finally to propose an alternative to reduce FA professional exposure during thanatopraxy cares thanks to FA-releasers use.

Bisphenol A, Tobacco Smoke, and Age as Predictors of Oxidative Stress in Children and Adolescents

OBJECTIVES

The purpose of this study was to investigate bisphenol A (BPA) and its role in the induction of oxidative stress and confirm the same for tobacco smoke.

METHODS

A total of 223 young, healthy students (7-19 years old) were recruited in Chivasso, Italy. A spot of urine of each subject was analyzed to quantify BPA, cotinine, and 15F2t-isoprostane.

RESULTS

BPA showed a slight increase of concentration proportional with increasing age, even though the 11-14 years age group had slightly lower results, inducing a V-shape. The same trend was observed for 15F2t-isoprostane and cotinine. The result of piecewise linear robust regression shows a break point of the effect of BPA on 15F2t-isoprostane at 6 ng/mg CREA (p < 0.001). At higher levels, 15F2t-isoprostane shows an exponential increase by more than threefold for each one-log unit of BPA. An increase of oxidative stress due to BPA was observed, but only from 6 ng/mg of CREA up. Passive tobacco smoke is also able to induce an increase in oxidative stress.

CONCLUSION

Prevention against BPA and passive tobacco smoke represents an important tool for promoting the highest health standard.

A Cross-Sectional Study on 3-(2-Deoxy-β-D-Erythro-Pentafuranosyl)Pyrimido[1,2-α]Purin-10(3H)-One Deoxyguanosine Adducts among Woodworkers in Tuscany, Italy

Occupational exposure to wood dust has been estimated to affect 3.6 million workers within the European Union (EU). The most serious health effect caused by wood dust is the nasal and sinonasal cancer (SNC), which has been observed predominantly among woodworkers. Free radicals produced by inflammatory reactions as a consequence of wood dust could play a major role in SNC development. Therefore, we investigated the association between wood dust and oxidative DNA damage in the cells of nasal epithelia, the target site of SNC. We have analyzed oxidative DNA damage by determining the levels of 3-(2-deoxy-β-D-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M₁dG), a major-peroxidation-derived DNA adduct and a biomarker of cancer risk in 136 woodworkers compared to 87 controls in Tuscany, Italy. We then examined the association of M₁dG with co-exposure to volatile organic compounds (VOCs), exposure length, and urinary 15-F_2t isoprostane (15-F_2t-IsoP), a biomarker of oxidant status. Wood dust at the workplace was estimated by the Information System for Recording Occupational Exposures to Carcinogens. M₁dG was measured using ³²P-postlabeling and mass spectrometry. 15-F_2t-IsoP was analyzed using ELISA. Results show a significant excess of M₁dG in the woodworkers exposed to average levels of 1.48 mg/m³ relative to the controls. The overall mean ratio (MR) between the woodworkers and the controls was 1.28 (95% C.I. 1.03-1.58). After stratification for smoking habits and occupational status (exposure to wood dust alone and co-exposure to VOCs), the association of M₁dG with wood dust (alone) was even greater in non-smokers workers, MR of 1.43 (95% C.I. 1.09-1.87). Conversely, not consistent results were found in ex-smokers and current smokers. M₁dG was significantly associated with co-exposure to VOCs, MR of 1.95 (95% C.I. 1.46-2.61), and occupational history, MR of 2.47 (95% C.I. 1.67-3.62). Next, the frequency of M₁dG was significantly correlated to the urinary excretion of 15-F_2t-IsoP, regression coefficient (β) = 0.442 ± 0.172 (SE). Consistent with the hypothesis of a genotoxic mechanism, we observed an enhanced frequency of M₁dG adducts in woodworkers, even at the external levels below the regulatory limit. Our data implement the understanding of SNC and could be useful for the management of the adverse effects caused by this carcinogen.

Wood dust and urinary 15-F2t isoprostane in Italian industry workers

Wood dust is one of the most common occupational exposures, with about 3.6 million of workers in the wood industry in Europe. Wood particles can deposit in the nose and the respiratory tract and cause adverse health effects. Occupational exposure to wood dust has been associated with malignant tumors of the nasal cavity and paranasal sinuses. The induction of oxidative stress and the generation of reactive oxygen species through activation of inflammatory cells could have a role in the carcinogenicity of respirable wood dust. Therefore, we conducted a cross-sectional study to evaluate the prevalence of urinary 15-F_2t isoprostane (15-F_2t-IsoP), a biomarker of oxidative stress and peroxidation of lipids, in 123 wood workers compared to 57 unexposed controls living in Tuscany region, Italy. 15-F_2t-IsoP generation was measured by ELISA. The main result of the present study showed that a statistically significant excess of this biomarker occurred in the workers exposed to 1.48 mg/m³ of airborne wood dust with respect to the unexposed controls. The overall mean ratio (MR) between the workers exposed to wood dust and the controls was 1.36, 95% Confidence Interval (C.I.) 1.18-1.57, after correction for age and smoking habits. A significant increment of 15-F_2t-IsoP (43%) was observed in the smokers as compared to the non-smokers. The urinary excretion of 15-F_2t-IsoP was significantly associated with co-exposure to organic solvents, i.e., MR of 1.41, 95% C.I. 1.17-1.70, after adjustment for age and smoking habits. A 41% excess was observed in long-term wood workers, 95% C.I. 1.14-1.75. Multivariate regression analysis showed that the level of 15-F_2t-IsoP was linearly correlated to the length of exposure, regression coefficient (β) = 0.244 ± 0.002 (SE). The overall increment by exposure group persisted after stratification for smoking habits. For instance, in smokers, a 53% excess was detected in the wood workers as compared to the controls, 95% C.I. 1.23-1.91. Our data support the hypothesis that oxidative stress and lipid peroxidation can have a role in the toxicity of wood dust F₂-IsoP measure can be a tool for the evaluation of the effectiveness of targeted interventions aimed to reduce exposures to environmental carcinogens.

The effect of malondialdehyde is modified by simian virus 40 transformation in human lung fibroblast cells

The effects of malondialdehyde (MDA), a product of oxidative stress, on normal lung fibroblast cells (MRC5) and transformed cells (MRC5 SV2) showed differing responses between the two cell lines. MRC5 cells showed lower viability at low MDA concentrations (<250 μM) but had better viability at higher concentrations than the transformed cells. Both cell lines showed an increase in the number of micronuclei, nuclear size and a relocation of p53 to the nucleus with increasing MDA. The expression of p53 was higher in the MRC5 cells at 24 h; 2-8 fold induction vs 1-2.5 fold in the MRC5 SV2 cells, but reduced to almost zero at 48 h in the MRC5 cells. Mutation sequencing of the PCR products of a 689 bp region (residues 4640-5328) of the TP53 gene revealed MRC5 had more mutations than MRC5 SV2 cells (n = 21 and 11 respectively) and that they were predominantly insertions (MRC5 81%, MRC5 SV2 100%). A common mutation was observed in both cell lines; a G insertion at residue 4724 (n = 7) which could prove to be a mutational hotspot. These results indicate that the transformed cells are slower to respond to oxidative stress and/or mutagenic compounds. The mutation spectrum of predominantly frameshift mutations (insertions) suggests that oxidative stress plays a minimal role in smoking related lung cancer, but could be of greater importance to other lung diseases and cancer caused by exposures such as passive smokers, passive vapers and atmospheric pollutants.

Changes in Work Practices for Safe Use of Formaldehyde in a University-Based Anatomy Teaching and Research Facility

Anatomy teaching and research relies on the use of formaldehyde (FA) as a preservation agent for human and animal tissues. Due to the recent classification of FA as a carcinogen, university hospitals are facing a challenge to (further) reduce exposure to FA. The aim of this study was to reduce exposure to FA in the anatomy teaching and research facility. Workers participated in the development of improved work practices, both technical and organizational solutions. Over a period of 6 years mitigating measures were introduced, including improvement of a down-flow ventilation system, introduction of local exhaust ventilation, collection of drain liquid from displayed specimens in closed containers and leak prevention. Furthermore, some organizational changes were made to reduce the number of FA peak exposures. Stationary and personal air sampling was performed in three different campaigns to assess the effect of these new work practices on inhalation exposure to FA. Samples were collected over 8 h (full shift) and 15 min (task-based) to support mitigation of exposure and improvement of work practices. Air was collected on an adsorbent coated with 2,4-dinitrophenylhydrazine (DNPH) and analyzed by HPLC-UV. Geometric mean (GM) concentrations of FA in the breathing zone over a work-shift were 123 µg/m³ in 2012 and 114 µg/m³ in 2014, exceeding the workplace standard of 150 µg/m³ (8 h time-weighted average, TWA) on 46% of the workdays in 2012 and 38% of the workdays in 2014. This exposure was reduced to an average of 28.8 µg/m³ in 2017 with an estimated probability of exceeding the OEL of 0.6%. Task-based measurements resulted in a mean peak exposures of 291 µg/m³ in 2012 (n = 19) and a mean of 272 µg/m³ in 2014 (n = 21), occasionally exceeding the standard of 500 µg/m³ (15 min TWA), and were reduced to a mean of 88.7 µg/m³ in 2017 (n = 12) with an estimated probability of exceeding the OEL of 1.6%.

Formaldehyde regulates vascular tensions through nitric oxide-cGMP signaling pathway and ion channels

Formaldehyde (FA) has been linked to the detrimental cardiovascular effects. Here, we explored the effects and mechanisms of FA on rat aortas both in vivo and in vitro. The results presented that FA evidently lowered the blood pressures of rats. The expression levels of BK_Ca subunits α and β1 and iNOS of the aortas were up-regulated by FA in vivo. However, FA markedly reduced the levels of Ca_v1.2 and Ca_v1.3, which are the subunits of L-Ca²⁺ channel. Furthermore, the contents of NO, cGMP and iNOS in the aortas were augmented by FA. To further confirm these findings, the mechanisms accredited to these effects were examined in vitro. The data showed that FA contracted the isolated aortic rings at low concentrations (<300 μM), while it relaxed the rings at high concentrations (>500 μM). The FA-induced vasoconstriction at low concentrations was blocked partly by an inhibitor of ACE. The relaxation caused by FA at high concentrations was attenuated by the inhibitors of NO-cGMP pathway, L-Ca²⁺ channel and BK_Ca channel, respectively. Similarly, the expression of iNOS was strongly enhanced by FA in vitro. The effects of FA on the aortic rings with endothelium were significantly greater than those on the rings without endothelium. Our results indicate that the vasoconstriction of FA at low concentrations might be partially pertinent to endothelin, and the FA-caused vasorelaxation at high concentrations is possibly associated with the NO-cGMP pathway, L-Ca²⁺ channel and BK_Ca channel. This study will improve our understanding of the pathogenic mechanisms for FA-related cardiovascular diseases.

Magnetic Hyperthermia and Oxidative Damage to DNA of Human Hepatocarcinoma Cells

Nanotechnology is addressing major urgent needs for cancer treatment. We conducted a study to compare the frequency of 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M₁dG) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) adducts, biomarkers of oxidative stress and/or lipid peroxidation, on human hepatocarcinoma HepG2 cells exposed to increasing levels of Fe₃O₄-nanoparticles (NPs) versus untreated cells at different lengths of incubations, and in the presence of increasing exposures to an alternating magnetic field (AMF) of 186 kHz using ³²P-postlabeling. The levels of oxidative damage tended to increase significantly after ≥24 h of incubations compared to controls. The oxidative DNA damage tended to reach a steady-state after treatment with 60 μg/mL of Fe₃O₄-NPs. Significant dose–response relationships were observed. A greater adduct production was observed after magnetic hyperthermia, with the highest amounts of oxidative lesions after 40 min exposure to AMF. The effects of magnetic hyperthermia were significantly increased with exposure and incubation times. Most important, the levels of oxidative lesions in AMF exposed NP treated cells were up to 20-fold greater relative to those observed in nonexposed NP treated cells. Generation of oxidative lesions may be a mechanism by which magnetic hyperthermia induces cancer cell death.

Bulky DNA Adducts, Tobacco Smoking, Genetic Susceptibility, and Lung Cancer Risk

The generation of bulky DNA adducts consists of conjugates formed between large reactive electrophiles and DNA-binding sites. The term "bulky DNA adducts" comes from early experiments that employed a ³²P-DNA postlabeling approach. This technique has long been used to elucidate the association between adducts and carcinogen exposure in tobacco smoke studies and assess the predictive value of adducts in cancer risk. Molecular data showed increased DNA adducts in respiratory tracts of smokers vs nonsmokers. Experimental studies and meta-analysis demonstrated that the relationship between adducts and carcinogens was linear at low doses, but reached steady state at high exposure, possibly due to metabolic and DNA repair pathway saturation and increased apoptosis. Polymorphisms of metabolic and DNA repair genes can increase the effects of environmental factors and confer greater likelihood of adduct formation. Nevertheless, the central question remains as to whether bulky adducts cause human cancer. If so, lowering them would reduce cancer incidence. Pooled and meta-analysis has shown that smokers with increased adducts have increased risk of lung cancer. Adduct excess in smokers, especially in prospective longitudinal studies, supports their use as biomarkers predictive of lung cancer.

3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine adducts of workers exposed to asbestos fibers

Asbestos is the commercial name for a group of silicate minerals naturally occurring in the environment and widely used in the industry. Asbestos exposure has been associated with pulmonary fibrosis, mesothelioma, and malignancies, which may appear after a period of latency of 20-40 years. Mechanisms involved in the carcinogenic effects of asbestos are still not fully elucidated, although the oxidative stress theory suggests that phagocytic cells produce large amounts of reactive oxygen species, due to their inability to digest asbestos fiber. We have conducted a mechanistic study to evaluate the association between 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M₁dG) adducts, a biomarker of oxidative stress and lipid peroxidation, and asbestos exposure in the peripheral blood of 327 subjects living in Tuscany and Liguria, Italy, stratified by occupational exposure to asbestos. Adduct frequency was significantly greater into exposed subjects with respect to the controls. M₁dG per 10⁸ normal nucleotides were 4.0±0.5 (SE) in 156 asbestos workers, employed in mechanic, naval, petrochemical, building industries, and in pottery and ceramic plants, versus a value of 2.3±0.1 (SE) in 171 controls (p<0.001). After stratification for occupational history, the effects persisted in 54 current asbestos workers, mainly employed in building renovation industry (2.9±0.3 (SE)), and in 102 former asbestos workers (4.5±0.7 (SE)), with p-values of 0.033, and <0.001, respectively. A significant effect of smoking on heavy smokers was found (p=0.005). Our study gives additional support to the oxidative stress theory, where M₁dG may reflect an additional potential mechanism of asbestos-induced toxicity.

Evaluation of oxidative stress markers in the heart and liver of rainbow trout (Oncorhynchus mykiss walbaum) exposed to the formalin

The aim of this study was to examine change in lipid and protein oxidation biomarkers, transamination enzymes and lactate dehydrogenase activities, lactate and pyruvate levels in liver and heart tissue of rainbow trout (Oncorhynchus mykiss Walbaum) that was exposed to formalin baths. Increase of 2-thiobarbituric acid reactive substances and carbonyl derivatives of protein oxidative destruction was noticed only in cardiac tissue of formalin-exposed fish. Activity of lactate dehydrogenase and lactate level in the cardiac tissue were elevated, indicating active glycolysis. Effects of formalin disinfection were different in both tissues. Aldehydic and ketonic derivatives of oxidatively modified proteins in liver were consistently reduced upon exposure to the formalin. In support of this, decrease in alanine and aspartate aminotransferases was noticed. Formalin disinfection of rainbow trout results in metabolic plasticity, predominantly in liver with decreased levels of oxidative stress biomarkers and aminotransferases activity. Formalin-induced oxidative stress in the cardiac tissue was more considerable.

8-Oxo-7,8-dihydro-2'-deoxyguanosine and other lesions along the coding strand of the exon 5 of the tumour suppressor gene P53 in a breast cancer case-control study

The next-generation sequencing studies of breast cancer have reported that the tumour suppressor P53 (TP53) gene is mutated in more than 40% of the tumours. We studied the levels of oxidative lesions, including 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), along the coding strand of the exon 5 in breast cancer patients as well as in a reactive oxygen species (ROS)-attacked breast cancer cell line using the ligation-mediated polymerase chain reaction technique. We detected a significant 'in vitro' generation of 8-oxodG between the codons 163 and 175, corresponding to a TP53 region with high mutation prevalence, after treatment with xanthine plus xanthine oxidase, a ROS-generating system. Then, we evaluated the occurrence of oxidative lesions in the DNA-binding domain of the TP53 in the core needle biopsies of 113 of women undergoing breast investigation for diagnostic purpose. An increment of oxidative damage at the -G- residues into the codons 163 and 175 was found in the cancer cases as compared to the controls. We found significant associations with the pathological stage and the histological grade of tumours. As the major news of this study, this largest analysis of genomic footprinting of oxidative lesions at the TP53 sequence level to date provided a first roadmap describing the signatures of oxidative lesions in human breast cancer. Our results provide evidence that the generation of oxidative lesions at single nucleotide resolution is not an event highly stochastic, but causes a characteristic pattern of DNA lesions at the site of mutations in the TP53, suggesting causal relationship between oxidative DNA adducts and breast cancer.

Formaldehyde-induced toxicity in the nasal epithelia of workers of a plastic laminate plant

Formaldehyde is a ubiquitous volatile organic compound widely used for various industrial purposes. Formaldehyde was reclassified by the International Agency for Research on Cancer as a human carcinogen, based on sufficient evidence for a casual role for nasopharyngeal cancer. However, the mechanisms by which this compound causes nasopharyngeal cancer are not completely understood. Therefore, we have examined the formaldehyde-induced toxicity in the nasal epithelia of the workers of a plastic laminate plant in Bra, Cuneo, Piedmont region, North-Western Italy, hence in the target site for formaldehyde-related nasal carcinogenesis. We have conducted a cross-sectional study aimed at comparing the frequency of 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M1dG) adducts, a biomarker of oxidative stress and lipid peroxidation, in 50 male exposed workers and 45 male controls using 32P-DNA post-labeling. The personal levels of formaldehyde exposure were analysed by gas-chromatography mass-spectrometry. The smoking status was estimated by measuring the concentrations of urinary cotinine by gas-chromatography mass-spectrometry. The air monitoring results showed that the exposure levels of formaldehyde were significantly greater for the plastic laminate plant workers, 211.4 ± 14.8 standard error (SE) μg m-3, than controls, 35.2 ± 3.4 (SE) μg m-3, P < 0.001. The levels of urinary cotinine were 1064 ± 118 ng ml-1 and 14.18 ± 2.5 ng ml-1 in smokers and non-smokers, respectively, P < 0.001. The M1dG adduct frequency per 108 normal nucleotides was significantly higher among the workers of the plastic laminate plant exposed to formaldehyde, 111.6 ± 14.3 (SE), compared to controls, 49.6 ± 3.4 (SE), P < 0.001. This significant association persisted also when personal dosimeters were used to measure the extent of indoor levels of formaldehyde exposure. No influences of smoking and age were observed across the study population. However, after categorization for occupational exposure, a significant effect was found in the controls, P = 0.018, where the levels of DNA damage were significantly correlated with the levels of urinary cotinine, regression coefficient (β) = 0.494 ± 0.000 (SE), P < 0.002. Our findings indicated that M1dG adducts constitute a potential mechanism of formaldehyde-induced toxicity. Persistent DNA damage contributes to the general decline of the physiological mechanisms designed to maintain cellular homeostasis.

Towards a formalin-free hospital. Levels of 15-F2t-isoprostane and malondialdehyde to monitor exposure to formaldehyde in nurses from operating theatres

Purpose: nurses are exposed to formaldehyde when managing surgical samples that are to be later transferred to histopathology. We evaluated the conditions favouring the risk of exposure to this toxic reagent and the effect of measures to prevent it. Methods: we conducted a cross-sectional study where 94 female workers were enrolled as being potentially exposed to formaldehyde. From each nurse were collected: (1) personal air-formaldehyde by a personal dosimeter (8 hours), (2) a standardized questionnaire, (3) a urine sample to test 15-F2t-isoprostane, malondialdehyde, cotinine. Results: the results indicate a marked difference related to the adoption of the under vacuum sealing procedure, as an alternative to formaldehyde for preserving tissues. Nurses using the under vacuum sealing system in the operating rooms are exposed to levels of formaldehyde 75% lower than those who do not use that system. Oxidative stress biomarkers (15-F2t-isoprostane, malondialdehyde) are significantly higher in nurses using formaldehyde (p < 0.001) and in the absence of the under vacuum sealing system (p = 0.027), in particular in those workers who use liquid formaldehyde in the operating theatre (p = 0.012). Conclusions: analysis of the biological biomarkers confirms a direct responsibility of air formaldehyde on the onset of oxidative stress while the use of the under vacuum sealing technique is associated with a significant reduction of the exposure to air-formaldehyde and redox status. Our findings can be useful to characterize the environmental health risk in operating theatres and to plan preventive measures such as the under vacuum sealing procedure.

Alcohol, Aldehydes, Adducts and Airways

Drinking alcohol and smoking cigarettes results in the formation of reactive aldehydes in the lung, which are capable of forming adducts with several proteins and DNA. Acetaldehyde and malondialdehyde are the major aldehydes generated in high levels in the lung of subjects with alcohol use disorder who smoke cigarettes. In addition to the above aldehydes, several other aldehydes like 4-hydroxynonenal, formaldehyde and acrolein are also detected in the lung due to exposure to toxic gases, vapors and chemicals. These aldehydes react with nucleophilic targets in cells such as DNA, lipids and proteins to form both stable and unstable adducts. This adduction may disturb cellular functions as well as damage proteins, nucleic acids and lipids. Among several adducts formed in the lung, malondialdehyde DNA (MDA-DNA) adduct and hybrid malondialdehyde-acetaldehyde (MAA) protein adducts have been shown to initiate several pathological conditions in the lung. MDA-DNA adducts are pre-mutagenic in mammalian cells and induce frame shift and base-pair substitution mutations, whereas MAA protein adducts have been shown to induce inflammation and inhibit wound healing. This review provides an insight into different reactive aldehyde adducts and their role in the pathogenesis of lung disease.

Formation, Accumulation, and Hydrolysis of Endogenous and Exogenous Formaldehyde-Induced DNA Damage

Formaldehyde is not only a widely used chemical with well-known carcinogenicity but is also a normal metabolite of living cells. It thus poses unique challenges for understanding risks associated with exposure. N(2-)hydroxymethyl-dG (N(2)-HOMe-dG) is the main formaldehyde-induced DNA mono-adduct, which together with DNA-protein crosslinks (DPCs) and toxicity-induced cell proliferation, play important roles in a mutagenic mode of action for cancer. In this study, N(2)-HOMe-dG was shown to be an excellent biomarker for direct adduction of formaldehyde to DNA and the hydrolysis of DPCs. The use of inhaled [(13)CD2]-formaldehyde exposures of rats and primates coupled with ultrasensitive nano ultra performance liquid chromatography-tandem mass spectrometry permitted accurate determinations of endogenous and exogenous formaldehyde DNA damage. The results show that inhaled formaldehyde only reached rat and monkey noses, but not tissues distant to the site of initial contact. The amounts of exogenous adducts were remarkably lower than those of endogenous adducts in exposed nasal epithelium. Moreover, exogenous adducts accumulated in rat nasal epithelium over the 28-days exposure to reach steady-state concentrations, followed by elimination with a half-life (t1/2) of 7.1 days. Additionally, we examined artifact formation during DNA preparation to ensure the accuracy of nonlabeled N(2)-HOMe-dG measurements. These novel findings provide critical new data for understanding major issues identified by the National Research Council Review of the 2010 Environmental Protection Agency's Draft Integrated Risk Information System Formaldehyde Risk Assessment. They support a data-driven need for reflection on whether risks have been overestimated for inhaled formaldehyde, whereas underappreciating endogenous formaldehyde as the primary source of exposure that results in bone marrow toxicity and leukemia in susceptible humans and rodents deficient in DNA repair.

Oxidatively damaged DNA in the nasal epithelium of workers occupationally exposed to silica dust in Tuscany region, Italy

Chronic silica exposure has been associated to cancer and silicosis. Furthermore, the induction of oxidative stress and the generation of reactive oxygen species have been indicated to play a main role in the carcinogenicity of respirable silica. Therefore, we conducted a cross-sectional study to evaluate the prevalence of 3-(2-deoxy-β-D-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M1dG) adducts, a biomarker of oxidative stress and peroxidation of lipids, in the nasal epithelium of 135 silica-exposed workers, employed in pottery, ceramic and marble manufacturing plants as well as in a stone quarry, in respect to 118 controls living in Tuscany region, Italy. The M1dG generation was measured by the (32)P-postlabelling assay. Significant higher levels of M1dG adducts per 10(8) normal nucleotides were observed in the nasal epithelium of smokers, 77.9±9.8 (SE), and in those of former smokers, 80.7±9.7 (SE), as compared to non-smokers, 57.1±6.2 (SE), P = 0.001 and P = 0.004, respectively. Significant increments of M1dG adducts were found in the nasal epithelium of workers that handle artificial marble conglomerates, 184±36.4 (SE), and in those of quarry workers, 120±34.7 (SE), with respect to controls, 50.6±2.7 (SE), P = 0.014 and P < 0.001, respectively. Null increments were observed in association with the pottery and the ceramic factories. After stratification for different exposures, silica-exposed workers that were co-exposed to organic solvents, and welding and exhaust fumes have significantly higher M1dG levels, 90.4±13.4 (SE), P = 0.014 vs.

CONTROL

Our data suggested that silica exposure might be associated with genotoxicity in the nasal epithelial cells of silica-exposed workers that handle of artificial marble conglomerates and quarry workers. Importantly, we observed that co-exposures to other respiratory carcinogens may have contributed to enhance the burden of M1dG adducts in the nasal epithelium of silica-exposed workers.

Effect of carnosine supplementation on apoptosis and irisin, total oxidant and antioxidants levels in the serum, liver and lung tissues in rats exposed to formaldehyde inhalation

The main objective of the study has been to show whether carnosine has positive effects on liver and lung tissues of rats exposed to a range of formaldehyde concentrations, and to explore how irisin expression and antioxidant capacity are altered in these tissues by carnosine supplementation. Sprague-Dawley type male rats were divided into 8 groups with 6 animals in each: (I) Control; no chemical supplementation); (II) sham (100mg/kg/day carnosine); (III) low dose formaldehyde (LDFA) for 5 days/week; (IV) LDFA for 5 days/week and carnosine); (V) moderate dose formaldehyde (MDFA) for 5 days/week); (VI) MDFA for 5 days/week and carnosine; (VII) high dose formaldehyde (HDFA) for 5 days/week; (VIII) and HDFA for 5 days/week and carnosine. Sham and control groups were exposed to normal air. Irisin levels of the serum, liver and lung tissue supernatants were analyzed by ELISA, while the REL method was used to determine total oxidant/antioxidant capacity. Irisin production by the tissues was detected immunohistochemically. Increasing doses of FA decreased serum/tissue irisin and total antioxidant levels relative to the controls, as also to increases in TUNEL expressions, total oxidant level, oxidant and apoptosis index. Irisin expression was detected in hepatocyte and sinusoidal cells of the liver and parenchymal cells of the lung. In conclusion, while FA exposure reduces irisin and total oxidant in the serum, liver and lung tissues in a dose-dependent manner and increases the total antioxidant capacity, carnosine supplementation reduces the oxidative stress and restores the histopathological and biochemical signs.

Exocyclic DNA adducts in sheep with skeletal fluorosis resident in the proximity of the Portoscuso-Portovesme industrial estate on Sardinia Island, Italy

The mechanisms by which fluoride produces its toxic effects are still not clear.

Analysis of a malondialdehyde-deoxyguanosine adduct in human leukocyte DNA by liquid chromatography nanoelectrospray-high-resolution tandem mass spectrometry

Malondialdehyde (MDA), an endogenous genotoxic product formed upon lipid peroxidation and prostaglandin biosynthesis, can react with DNA to form stable adducts. These adducts may contribute to the development of such inflammation-mediated diseases as cancer and cardiovascular and neurodegenerative diseases. The predominant MDA-derived DNA adduct formed under physiological conditions is 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M₁dG). In this study, we developed a novel liquid chromatography (LC)–nanoelectrospray ionization (NSI)–high-resolution tandem mass spectrometry (HRMS/MS) method for the analysis of M₁dG in human leukocyte DNA. After enzymatic hydrolysis of DNA, M₁dG and the added internal standard [¹³C₃]M₁dG were reduced to their 5,6-dihydro derivatives by addition of sodium borohydride to the hydrolysate and purified by solid-phase extraction and column chromatography. The 5,6-dihydro derivatives in the purified samples were analyzed by LC–NSI–HRMS/MS using higher-energy collisional dissociation (HCD) fragmentation, isolation widths of 1 Da for both the analyte and internal standard, and a resolution of 50 000. The detection limit of the developed method is 5 amol on-column, and the limit of quantitation is 0.125 fmol/mg DNA starting with 200 μg of DNA. Method accuracy and precision were characterized. The developed method was further applied to the analysis of leukocyte DNA from 50 human subjects. M₁dG was detected in all samples and ranged from 0.132 to 275 fmol/mg DNA, or 0.004 to 9.15 adducts per 10⁸ bases. This unique and highly sensitive HRMS/MS-based method can be used in future studies investigating the pathophysiological role of M₁dG in human diseases.

Recent developments in DNA adduct analysis by mass spectrometry: a tool for exposure biomonitoring and identification of hazard for environmental pollutants

DNA adducts represent an important category of biomarkers for detection and exposure surveillance of potential carcinogenic and genotoxic chemicals in the environment. Sensitive and specific analytical methods are required to detect and differentiate low levels of adducts from native DNA from in vivo exposure. In addition to biomonitoring of environmental pollutants, analytical methods have been developed for structural identification of adducts which provides fundamental information for determining the toxic pathway of hazardous chemicals. In order to achieve the required sensitivity, mass spectrometry has been increasingly utilized to quantify adducts at low levels as well as to obtain structural information. Furthermore, separation techniques such as chromatography and capillary electrophoresis can be coupled to mass spectrometry to increase the selectivity. This review will provide an overview of advances in detection of adducted and modified DNA by mass spectrometry with a focus on the analysis of nucleosides since 2007. Instrument advances, sample and instrument considerations, and recent applications will be summarized in the context of hazard assessment. Finally, advances in biomonitoring applying mass spectrometry will be highlighted. Most importantly, the usefulness of DNA adducts measurement and detection will be comprehensively discussed as a tool for assessment of in vitro and in vivo exposure to environmental pollutants.

Oxidative DNA damage and formalin-fixation procedures

An experimental study on how formaldehyde-fixation is capable of inducing excess oxidative DNA damage in formalin-fixed paraffin-embedded tissues.

Aberrant methylation of hypermethylated-in-cancer-1 and exocyclic DNA adducts in tobacco smokers

Tobacco smoke has been shown to produce both DNA damage and epigenetic alterations. However, the potential role of DNA damage in generating epigenetic changes is largely underinvestigated in human studies. We examined the effects of smoking on the levels of DNA methylation in genes for tumor protein p53, cyclin-dependent kinase inhibitor2A, hypermethylated-in-cancer-1 (HIC1), interleukin-6, Long Interspersed Nuclear Element type1, and Alu retrotransposons in blood of 177 residents in Thailand using bisulfite-PCR andpyrosequencing. Then, we analyzed the relationship of this methylation with the oxidative DNA adduct, M₁dG (a malondialdehyde adduct), measured by ³²P-postlabeling. Multivariate statistical analyses showed that HIC1 methylation levels were significantly increased in smokers compared with nonsmokers (p ≤ .05). A dose response was observed, with the highest HIC1 methylation levels in smokers of ≥ 10 cigarettes/day relative to nonsmokers and intermediate values in smokers of 1-9 cigarettes/day (p for trend ≤ .001). No additional relationships were observed. We also evaluated correlations between M₁dG and the methylation changes at each HIC1 CpG site individually. The levels of this adduct in smokers showed a significant linear correlation with methylation at one of the 3 CpGs evaluated in HIC1: hypermethylation at position 1904864340 was significantly correlated with the adduct M₁dG (covariate-adjusted regression coefficient (β) = .224 ± .101 [SE], p ≤ .05). No other correlations were detected. Our study extends prior work by others associating hypermethylation of HIC1 with smoking; shows that a very specific hypermethylation event can arise from smoking; and encourages future studies that explore a possible role for M₁dG in connecting smoking to this latter hypermethylation.

Exocycilic DNA Adducts in a Murine Model of Non-alcoholic Steatohepatitis

Introduction:

Non-alcoholic fatty liver disease is the most common hepatic disorder in Western countries. The transition from abnormal accumulation of lipids toward non-alcoholic steatohepatitis (NASH) represents a key step in the development of chronic liver pathologies. Oxidative stress and lipid peroxidation have often been proposed as mechanisms in the progression to steatohepatitis.

Methods:

We have examined the hepatic levels of exocyclic DNA adducts, indicated from 3-(2-deoxy-β-D-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M₁dG) adduct, a biomarker of oxidative stress and lipid peroxidation, in a murine model of NASH using the ³²P-DNA postlabeling assay.

Results:

Our findings show that C57BL/6 mice fed with high-fat and cholesterol diet developed signs associated with NASH after eight weeks, whereas there was no evidence of steatosis in control mice. The score for steatohepatitis ranged from grade 2 to 3 for steatosis, inflammation, and fibrosis, showing that the experimental diet was able to induce pathologic alterations of the parenchyma in eight weeks. Higher levels of M₁dG adducts were detected in the livers of C57BL/6 mice which developed experimental NASH after eight weeks of high-fat and cholesterol feed, 5.6 M ₁dG ± 0.4 (SE) per 10⁶ total nucleotides, as compared to control mice, 1.6 M₁dG ± 0.4 (SE). The statistical analysis showed that the increment of oxidatively damaged DNA in mice with NASH raised on high-fat and cholesterol diet was statistically significant as compared to control mice, P=0.006.

Conclusions:

Our report suggests a link between NASH and M₁dG in experimental animals fed with a diet rich in saturated fats and cholesterol. High-fat and cholesterol may act together in inducing a broader spectrum of oxidatively damaged DNA, including exocyclic DNA adducts, that may contribute to the decline of hepatocyte functions, from disturbance of critical pathways, such as transcription and replication, triggering transient or permanent cell-cycle arrest and cell-death, up to chromosomal instability.

Immune response to acetaldehyde-human serum albumin adduct among healthy subjects related to alcohol intake

Acetaldehyde (AA) is the main metabolic product in ethanol metabolism, although it can also derive from sources of airborne pollution. As a typical aldehyde, AA is able to react with a variety of molecular targets, including DNA and protein. This property justifies the hypothesis of a immune reaction against this kind of adduct, to be studied by a seroprevalence screening approach. In this study, the correlation between drinking habits and the amount of circulating AA-human serum albumin adduct (AA-HSA) was evaluated in a group of healthy subjects, non alcohol-addicted. Daily ethanol intake (grams) was inferred for each subject using the information collected through a questionnaire, and AA-HSA antibodies (AA-HSA ab) analyses were performed using the Displacement Assay on whole blood samples. The findings showed a correlation between ethanol intake and immune response to molecular adduct. These results underscore the evaluation of AA-HSA ab amount as a suitable molecular marker for alcohol intake that can be applied in future investigations on a large scale for prevention screening.

Oxidative stress in adolescent passive smokers living in urban and rural environments

Purpose of this study was to study the oxidative stress status through the urinary 15-F(2t)-isoprostane (15-F(2t)-isoP) among a group of 168 adolescents, differently exposed to passive tobacco smoke. Subjects were enrolled, with written informed consent, between two populations of students living and attending school in two areas with different levels of urbanization in Piedmont Region, North-Western Italy. A general linear model (GLM) analysis was performed to evaluate the role of air pollution, dependent from selected degree of urbanization and of passive exposure to tobacco smoke, quantified through cotinine, in the synthesis of 15-F(2t)-isoP, measured with ELISA technique. Formaldehyde (FA) concentration in air was also evaluated as a primary confounding factor in oxidative stress but no significant differences between the two sites were found. Conversely, direct relationship between oxidative stress status and residence of adolescents was found: oxidative stress level was 31% higher for adolescents living in Chivasso (urban site) than for those living in Casalborgone (countryside area). Furthermore, also passive tobacco smoke exposure proved to play another important direct role in the distribution of 15-F(2t)-isoP levels (p<0.0001). Lastly, an inversely proportional relationship was found between the age of adolescents and 15-F(2t)-isoP (p<0.0001). Finally, the detection of such a sensitive biological response as a consequence of limited differences of environmental pollution and exposure to tobacco smoke passively breathed could provide new and useful knowledge for the appraisal of preventive strategies, particularly for young subjects.

Malondialdehyde-deoxyguanosine and bulky DNA adducts in schoolchildren resident in the proximity of the Sarroch industrial estate on Sardinia Island, Italy

Air quality is a primary environmental concern in highly industrialised areas, with potential health effects in children residing nearby. The Sarroch industrial estate in Cagliari province, Sardinia Island, Italy, hosts the world's largest power plant and the second largest European oil refinery and petrochemical park. This industrial estate produces a complex mixture of air pollutants, including benzene, heavy metals and polycyclic aromatic hydrocarbons. Thus, we conducted a cross-sectional study to evaluate the prevalence of malondialdehyde-deoxyguanosine adducts in the nasal epithelium of 75 representative children, aged 6-14 years, attending primary and secondary schools in Sarroch in comparison with 73 rural controls. Additionally, the levels of bulky DNA adducts were analysed in a subset of 62 study children. DNA damage was measured by (32)P-postlabelling methodologies. The air concentrations of benzene and ethyl benzene were measured in the school gardens of Sarroch and a rural village by diffusive samplers. Outdoor measurements were also performed in other Sarroch areas and in the proximity of the industrial estate. The outdoor levels of benzene and ethyl benzene were significantly higher in the school gardens of Sarroch than in the rural village. Higher concentrations were also found in other Sarroch areas and in the vicinity of the industrial park. The mean levels of malondialdehyde-deoxyguanosine adducts per 10(8) normal nucleotides ± standard error (SE) were 74.6±9.1 and 34.1±4.4 in the children from Sarroch and the rural village, respectively. The mean ratio was 2.53, 95% confidence interval (CI): 1.71-2.89, P < 0.001, versus rural controls. Similarly, the levels of bulky DNA adducts per 10(8) normal nucleotides ± SE were 2.9±0.4 and 1.6±0.2 in the schoolchildren from Sarroch and the rural village, respectively. The means ratio was 1.90, 95% CI: 1.25-2.89, P = 0.003 versus rural controls. Our study indicates that children residing near the industrial estate have a significant increment of DNA damage.

DNA and protein adducts in human tissues resulting from exposure to tobacco smoke

Tobacco smoke contains a variety of genotoxic carcinogens that form adducts with DNA and protein in the tissues of smokers. Not only are these biochemical events relevant to the carcinogenic process, but the detection of adducts provides a means of monitoring exposure to tobacco smoke. Characterization of smoking-related adducts has shed light on the mechanisms of smoking-related diseases and many different types of smoking-derived DNA and protein adducts have been identified. Such approaches also reveal the potential harm of environmental tobacco smoke (ETS) to nonsmokers, infants and children. Because the majority of tobacco-smoke carcinogens are not exclusive to this source of exposure, studies comparing smokers and nonsmokers may be confounded by other environmental sources. Nevertheless, certain DNA and protein adducts have been validated as biomarkers of exposure to tobacco smoke, with continuing applications in the study of ETS exposures, cancer prevention and tobacco product legislation. Our article is a review of the literature on smoking-related adducts in human tissues published since 2002.

Evaluation of two commercial and three home-made fixatives for the substitution of formalin: a formaldehyde-free laboratory is possible

BACKGROUND

Formaldehyde (HCHO) is a gas (available as a 37% concentrated solution, stabilized with methanol). The 10% dilution (approximately 4% formaldehyde) has been used as a fixative since the end of the 19th century. Alternative fixatives are also commercially available or may be prepared in-house in laboratories. Statements by the IARC, along with other USA agencies (CalEPA, RoC/NTP) on the carcinogenicity of formaldehyde for humans renders its substitution in Pathology Departments necessary since the annual use of formalin may exceed 3,500 liters for a medium-large laboratory. To achieve a "formalin-free laboratory" we tested straightforward-to-make fixatives along with registered reagents offered as formalin substitutes.

METHODS

More than two hundreds specimens were fixed in parallel with in-laboratory made fixatives PAGA (Polyethylenglycol, ethyl Alcohol, Glycerol, Acetic acid), two zinc-based fixatives (ZBF, Z7), and commercially-available alternatives (RCL2 and CellBlock). Tissue micro arrays were used for morphological and immunohistochemical comparison. Extraction of RNA was carried out to evaluate preservation of nucleic acids.

RESULTS

Differences compared to formalin fixation were evident in alcohol-based fixatives, mainly restricted to higher stain affinity and considerable tissue shrinkage. Conversely, nuclear detail was superior with these alcohol-based formulas compared to formalin or glyoxale-based recipes. RNA extraction was superior for Z7, PAGA and RCL2 with regard to concentration but relatively comparable regarding quality.

CONCLUSIONS

Abolition of the human carcinogen formaldehyde from pathology laboratories is possible even in contexts whereby commercial alternatives to formalin are unavailable or are too expensive for routine use, and aspiration devices are lacking or not adequately serviced. The use of known formulations, possibly with simple and not-noxious ("alimentary grade") constituents, comparable with registered proprietary products, may expand the search for the ideal fixative combining satisfactory morphology with improved preservation of nucleic acids and proteins as well as being easy and safe to dispose of.

Nontargeted nucleotide analysis based on benzoylhistamine labeling-MALDI-TOF/TOF-MS: discovery of putative 6-oxo-thymine in DNA

A method for nontargeted analysis of modified nucleotides in DNA (and RNA) is reported based on labeling with benzoylhistamine (BH) followed by MALDI-MS. The method provides deoxynucleotide-specific detection, accurate measurement of molecular ions, high sensitivity, semiquantitation, and, to the extent studied to date, normalization of response within a factor of <3.

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.

Fruit and vegetable and fried food consumption and 3-(2-deoxy-β-D-erythro-pentafuranosyl)pyrimido[1,2-α] purin-10(3H)-one deoxyguanosine adduct formation

Diet has been shown to modulate M(1)dG adduct, a biomarker of oxidative stress and lipid peroxidation. Thus, we analysed the association between diet and M(1)dG in 120 controls and 67 Map Ta Phut industrial estate workers in Rayong, Thailand, to evaluate the influence of fruit and vegetables, and fried and charcoal-grilled/barbecued food consumption on M(1)dG. M(1)dG was decreased in controls reporting to consume 14-17 servings/week of fruit and vegetables (mean ratio [MR]= 0.35, CI 0.18-0.69, p< 0.05). Conversely, a non-statistically significant M(1)dG increment was detected in controls consuming 9-18 servings/week of fried food (MR = 1.33, CI 0.88-2.00, p = 0.168). No effect of charcoal-grilled/barbecued food was found. No effect of diet was observed in workers. An association with smoking was observed in controls (MR = 1.88, CI 1.14-3.10, p < 0.05), but not in workers. M(1)dG can induce mutations and/or methylation changes within the promoter regions of cancer-related genes, thus promotion of healthy eating practices should be recommended.

Exposure to formaldehyde and its potential human health hazards

A widely used chemical, formaldehyde is normally present in both indoor and outdoor air. The rapid growth of formaldehyde-related industries in the past two decades reflects the result of its increased use in building materials and other commercial sectors. Consequently, formaldehyde is encountered almost every day from large segments of society due to its various sources. Many governments and agencies around the world have thus issued a series of standards to regulate its exposure in homes, office buildings, workshops, public places, and food. In light of the deleterious properties of formaldehyde, this article provides an overview of its market, regulation standards, and human health effects.