Sinonasal cancer and occupational exposure to formaldehyde and other substances

Using Rapid Prototyping to Develop a Cell-Based Platform with Electrical Impedance Sensor Membranes for In Vitro RPMI2650 Nasal Nanotoxicology Monitoring

Due to advances in additive manufacturing and prototyping, affordable and rapid microfluidic sensor-integrated assays can be fabricated using additive manufacturing, xurography and electrode shadow masking to create versatile platform technologies aimed toward qualitative assessment of acute cytotoxic or cytolytic events using stand-alone biochip platforms in the context of environmental risk assessment. In the current study, we established a nasal mucosa biosensing platform using RPMI2650 mucosa cells inside a membrane-integrated impedance-sensing biochip using exclusively rapid prototyping technologies. In a final proof-of-concept, we applied this biosensing platform to create human cell models of nasal mucosa for monitoring the acute cytotoxic effect of zinc oxide reference nanoparticles. Our data generated with the biochip platform successfully monitored the acute toxicity and cytolytic activity of 6 mM zinc oxide nanoparticles, which was non-invasively monitored as a negative impedance slope on nasal epithelial models, demonstrating the feasibility of rapid prototyping technologies such as additive manufacturing and xurography for cell-based platform development.

Large-data contextualizations of social determinant associations in pediatric head and neck cancers

PURPOSE OF REVIEW

Prior investigations in social determinants of health (SDoH) and their impact on pediatric head and neck cancers are limited by the narrow scope of cancer types and SDoH being studied while lacking inquiry on the interrelational contribution of varied SDoH in real-world contexts. The purpose of this review is to discuss the current research tackling these shortcomings of SDoH-based studies in head and neck cancer and to discuss means of applying these findings in prospective initiatives and implementations.

RECENT FINDINGS

Through leveraging contemporary, large-data analyses measuring diverse social vulnerabilities, several studies have identified comprehensive delineations of which social disparities contribute the largest quantifiable impact on the care of head and neck cancer patients. Progressing from prior SDoH-based research of the decade, these studies contextualize the effect of social vulnerabilities and have laid the foundations to begin addressing these issues in the complex, modern-day environment of interrelatedsocial factors.

SUMMARY

Social determinants of health markedly affect pediatric head and neck cancer care and prognosis in complex and surprising ways. Modern-day tools and analyses derived from large-data techniques have unveiled the quantifiable underpinnings of how SDoH impact these pathologies.

Gene Expression Profiles of Methyltransferases and Demethylases Associated with Metastasis, Tumor Invasion, CpG73 Methylation, and HPV Status in Head and Neck Squamous Cell Carcinoma

Epigenetic studies on the role of DNA-modifying enzymes in HNSCC tumorigenesis have focused on a single enzyme or a group of enzymes. To acquire a more comprehensive insight into the expression profile of methyltransferases and demethylases, in the present study, we examined the mRNA expression of the DNA methyltransferases DNMT1, DNMT3A, and DNMT3B, the DNA demethylases TET1, TET2, TET3, and TDG, and the RNA methyltransferase TRDMT1 by RT-qPCR in paired tumor-normal tissue samples from HNSCC patients. We characterized their expression patterns in relation to regional lymph node metastasis, invasion, HPV16 infection, and CpG73 methylation. Here, we show that tumors with regional lymph node metastases (pN+) exhibited decreased expression of DNMT1, 3A and 3B, and TET1 and 3 compared to non-metastatic tumors (pN0), suggesting that metastasis requires a distinct expression profile of DNA methyltransferases/demethylases in solid tumors. Furthermore, we identified the effect of perivascular invasion and HPV16 on DNMT3B expression in HNSCC. Finally, the expression of TET2 and TDG was inversely correlated with the hypermethylation of CpG73, which has previously been associated with poorer survival in HNSCC. Our study further confirms the importance of DNA methyltransferases and demethylases as potential prognostic biomarkers as well as molecular therapeutic targets for HNSCC.

Unravelling the emerging carcinogenic contaminants from industrial waste water for prospective remediation by electrocoagulation - A review

The need of the hour relies on finding new but sustainable ways to curb rising pollution levels. The accelerated levels of urbanization and increase in population deplete the finite resources essential for human sustenance. In this aspect, water is one of the non-renewable sources that is running out very fast and is polluted drastically day by day. One way of tackling the problem is to reduce the pollution levels by decreasing the usage of chemicals in the process, and the other is to find ways to reuse or reduce the contaminants in the effluent by treatment methods. Most of the available water recycling or treatment methods are not sustainable. Some of them even use toxic chemicals in the processing steps. Treatment of organic wastes from industries is a challenging task as they are hard to remove. Electrocoagulation is one of the emerging water treatment technologies that is highly sustainable and has a comparatively cheaper operating cost. Being a broad-spectrum treatment process, it is suitable for treating the most common water pollutants ranging from oils, bacteria, heavy metals, and others. The process is also straightforward, where electrical current is used to coagulate the contaminates. The presence of carcinogens in these waste water increases the need for its treatment towards further use. The present investigation is made as an extensive analysis of the emerging carcinogens and their various sources from process industries, especially in the form of organic waste and their removal by electrocoagulation and its coupled techniques. The paper also aims to ascertain why the electrocoagulation technique may be a better alternative compared with other methods for the removal of carcinogens in organic wastewater, an analysis which has not been explored before.

A comprehensive review on human health effects of chromium: insights on induced toxicity

The growing use of heavy metals in most industrial activities has led to it being considered as the most important environmental pollutant that may cause harm and toxicity to animals and humans. Chromium has been found in the environment in different oxidation states such as Cr⁰, Cr(III), and Cr(VI) and is released from a variety of anthropogenic and natural activities. At among, trivalent and hexavalent chromium are the most stable forms. Considerably, Cr(VI) is frequently more toxic than Cr(III) because of its particular solubility and high mobility. Chronic exposure and bioaccumulation of chromium, as a heavy metal, can cause toxicity and numerous pathophysiological defects, including allergic reactions, anemia, burns, and sores especially in the stomach and small intestine, damage to sperm along with the male reproductive system, and affect various biological systems. Chromium pollution can have severe consequences for water and the soil environment. This article reviews the toxicological effects of Cr(VI) and Cr(III) and their mechanisms of toxicity and carcinogenicity.

Human papillomavirus-related carcinoma with adenoid cystic-like features of the sinonasal tract: Case report and literature review

INTRODUCTION AND IMPORTANCE

HPV-related carcinoma with adenoid cystic carcinoma-like features currently known as HPV-related multiphenotypic sinonasal carcinoma (HMSC) is a rare distinct head and neck high-risk HPV-related carcinoma. The high-risk HPV subtypes implicated are particularly type 33,35 and 56. So far this is the first reported rare case of a variant of sinonasal carcinoma in Tanzania.

CASE PRESENTATION

We present a 59-year old female who presented with a history of right-sided nasal obstruction and intermittent epistaxis for about one year and later on had ipsilateral proptosis. A provisional diagnosis of advanced right-sided malignant sinonasal tumor was made. Trans nasal biopsy revealed HMSC.

CLINICAL DISCUSSION

The patient had a right sided fixed neck mass that measured about 7.5 × 8.2 cm. Magnetic resonance imaging (MRI) of the paranasal sinuses revealed a T1 weighted contrasted images that showed a huge extensive enhancing mass (estimated to measure 4.5 × 4.4) involving the nasal cavity, bilateral ethmoid sinuses, frontal and sphenoid sinuses and also the tumor exhibit intracranial extension (anterior cranial fossa) and tend to compress medial walls of both orbits though more marked on the right side. Histopathology and immunohistochemistry confirmed HPV-related multiphenotypic sinonasal carcinoma. The disease was staged to be T4bN3aM0 and the patient was referred for palliative chemoradiation.

CONCLUSION

Although HMSC presents at advanced stage in close to half of cases and has a high-grade histological appearance it paradoxically exhibits a relatively indolent manner with frequent local recurrences. Prompt histopathological diagnosis is important to prevent metastases and HMSC-related deaths.

Occurrence of Sinonasal Intestinal-Type Adenocarcinoma and Non-Intestinal-Type Adenocarcinoma in Two Countries with Different Patterns of Wood Dust Exposure

Sinonasal intestinal-type adenocarcinoma is strongly associated with hardwood dust exposure. Non-intestinal-type adenocarcinoma is a rarer and less well-known subtype considered not to be related with wood dust exposure. We determined the relative numbers of these two tumor types in 56 sinonasal adenocarcinoma patients in France and Finland, relating them with carefully assessed wood dust exposure histories. Diagnostic workup including immunohistochemistry for the intestinal markers CDX2 and CK20 indicated that the proportions of the two tumors differed significantly between France and Finland. In Finnish samples non-intestinal adenocarcinomas were more common than intestinal-type adenocarcinomas (12 non-intestinal vs. nine intestinal), while in the French samples the reverse was true (six non-intestinal vs. 29 intestinal). Such remarkably dissimilar occurrence of these tumors in France and Finland presumably reflects different pathogenetic circumstances in the two countries, and perhaps their different patterns of wood dust exposure. In France the main source of wood dust is from hardwoods. In Finland it is derived from softwoods. This is the first systematic comparison of the occurrence of intestinal-type adenocarcinoma and non-intestinal-type adenocarcinoma in two countries with different wood usage. It appears to be the first systematic study on differences in wood dust exposure between intestinal-type adenocarcinoma and non-intestinal-type adenocarcinoma.

Occupational exposure to hexavalent chromium. Part II. Hazard assessment of carcinogenic effects

Hexavalent chromium (Cr(VI)) compounds have been studied extensively and several agencies have described their toxicological profile. In the past, personnel of the Dutch Ministry of Defence may have been exposed to Cr(VI) during maintenance activities on NATO equipment. To investigate if this exposure may have caused irreversible adverse health effects, the Dutch National Institute for Public Health and the Environment (RIVM) summarized all available knowledge from previous evaluations. This information was complemented with a scoping review to retrieve new scientific literature. All scientific evidence was evaluated in workshops with external experts to come to an overview of irreversible adverse health effects that could be caused by occupational exposure to Cr(VI) compounds. This review provides the hazard assessment for occupational exposure to Cr(VI) and carcinogenic effects by integrating and weighting evidence provided by international agencies complemented with newly published studies. It was concluded that occupational exposure to Cr(VI) can cause lung cancer, nose and nasal sinus cancer in humans. Cr(VI) is suspected to cause stomach cancer and laryngeal cancer in humans. It is currently insufficiently clear if Cr(VI) can cause cancer of the small intestine, oral cavity, pancreas, prostate or bladder in humans.

Malignant Sinonasal Tumors: Update on Histological and Clinical Management

Tumors of nasal cavity and paranasal sinuses (TuNSs) are rare and heterogeneous malignancies, presenting different histological features and clinical behavior. We reviewed the literature about etiology, biology, and clinical features of TuNSs to define pathologic features and possible treatment strategies. From a diagnostic point of view, it is mandatory to have high expertise and perform an immunohistochemical assessment to distinguish between different histotypes. Due to the extreme rarity of these neoplasms, there are no standard and evidence-based therapeutic strategies, lacking prospective and large clinical trials. In fact, most studies are retrospective analyses. Surgery represents the mainstay of treatment of TuNSs for small and localized tumors allowing complete tumor removal. Locally advanced lesions require more demolitive surgery that should be always followed by adjuvant radio- or chemo-radiotherapy. Recurrent/metastatic disease requires palliative chemo- and/or radiotherapy. Many studies emphasize the role of specific genes mutations in the development of TuNSs like mutations in the exons 4-9 of the TP53 gene, in the exon 9 of the PIK3CA gene and in the promoter of the TERT gene. In the near future, this genetic assessment will have new therapeutic implications. Future improvements in the understanding of the etiology, biology, and clinical features of TuNSs are warranted to improve their management.

Cancer of the head and neck: a set of indicators based on register and administrative data

SUMMARY

Head and neck (H&N) tumours are a heterogeneous group of neoplasms with 5-year relative survival ranging from about 25% for the hypopharynx to 60% for the larynx in Europe. To improve survival rates, along with therapeutic improvements, it is important to standardise and optimise care received by patients with H&N tumours across different healthcare providers. To reach this goal, it is necessary to evaluate adherence to standards of received care at a population level. Published guidelines can serve as the basis to develop indicators, which can be computed from administrative health databases, measuring the adherence to specific recommendations at the individual level in unselected H&N cancer patients, identified from a population cancer register. We developed a set of indicators and calculated them in a cohort of 2007-2012 incident cases of H&N tumours in the cancer register of the Milan province (n = 1441 cases). The study cohort was mainly composed of men (77%) and patients older than 50 years (89%). Surgery was the most frequently employed treatment (66%). Ten percent of patients had no recorded treatment. Timing between cyto-histological assessment and first therapy for those having a recorded microscopic verification procedure was ≤ 60 days for 90.4% of patients undergoing surgery, 86.3% of those undergoing radiotherapy, and 90.7% of patients receiving chemotherapy. Eighty-three percent of patients underwent cyto-histological assessment in the 180 days before the first treatment. Evaluation by a pain therapist, opioid therapy or hospitalisation for palliative therapy in the 90 days before death was performed in 51% of patients who eventually died of cancer. This is the first Italian study defining and calculating quality indicators to monitor adherence to standards of care received by H&N cancer patients at a population level.

Cancer Risks of Hexavalent Chromium in the Respiratory Tract

Hexavalent chromium (Cr(VI)) compounds are recognized as carcinogens in the respiratory tract, giving rise to cancers of the lung, nose and nasal sinuses, especially in certain occupational environments. Inhalation exposure of Cr(VI)-containing particles, dusts and fumes commonly occurs in chromium-related occupational environments, such as chromium production, plating, welding of chromium-containing metals and alloys, electroplating, chromium-containing pigments and paints. Epidemiological surveys of chromium compounds have shown strong associations between exposure to Cr(VI) and mortality due to lung cancer, as well as positive associations with cancers of the nose and nasal cavity. Nasal symptoms, such as nasal irritation, ulceration and perforation of the nasal septum, nasal turbinate engorgement and hypertrophy, are important signs for the early diagnosis of lung cancer and cancers of the nose and nasal cavity in those with an occupational history of Cr(VI) exposure. Cr(VI) exposure in the workplace remains a serious problem as a cause of lung cancer and cancers of nose and nasal cavity, especially in relatively small enterprises that use chromium compounds. Appropriate protection for workers should be considered in occupations that involve exposure to chromium compounds.

Review of carcinogenicity of hexavalent chrome and proposal of revising approval standards for an occupational cancers in Korea

Background

The objective of this study is to suggest revised recognition standards for occupational disease due to chromium (VI) by reflecting recent domestic and international research works and considering domestic exposure status with respect to target organs, exposure period, and cumulative exposure dose in relation to the chromium (VI)-induced occupational disease compensation.

Methods

In this study, the reports published by major international institutions such as World Health Organization (WHO) International Agency for Research on Cancer (IARC) (2012), Occupational Safety and Health Administration (OSHA) (2006), National Institute for Occupational Safety and Health (NIOSH) (2013), American Conference of Governmental Industrial Hygienists (ACGIH) (2004), National Toxicology Program (NTP) (2014), and Agency for Toxic Substances and Disease Registry (ASTDR) (2012) were reviewed and the recent research works searched by PubMed were summarized.

Results

Considering the recent research works and the domestic situation, only lung cancer is conserved in the legislative bill in relation to chromium (VI), and the exposure period is not included in the bill. Nasal and paranasal sinus cancer was excluded from the list of cancers that are compensated as the chromium (VI)- induced occupational disease, while lung cancer remains in the list. In the view of legislative unity, considering the fact that only the cancers having sufficient evidence are included in the conventional list of cancers compensated as occupational disease, nasal and paranasal sinus cancer having limited evidence were excluded from the list.

The exposure period was also removed from the legislative bill due to the insufficient evidence. Recent advices in connection with cumulative exposure dose were proposed, and other considerable points were provided with respect to individual occupational relevance.

Conclusions

It is suggested that the current recognition standard which is “Lung cancer or nasal and paranasal sinus cancer caused by exposure to chromium (VI) or compounds thereof (exposure for two years or longer), or nickel compounds” should be changed to “Lung cancer caused by exposure to chromium (VI) or compounds thereof, and lung cancer or nasal and paranasal sinus cancer caused by exposure to nickel compounds”.

Occupational exposure to wood dust and risk of nasal and nasopharyngeal cancer: A case-control study among men in four nordic countries-With an emphasis on nasal adenocarcinoma

The current study aims to provide stronger evidence to aid in our understanding of the role of cumulative occupational exposure to (softwood-dominated) mixed wood dust in aetiology of nasal cancer. We included broad exposure occurred in a range of wood-processing occupation across varied industries in four Nordic countries. A population-based case-control study was conducted on all male cases with nasal adenocarcinoma (393 cases), other types of nasal cancer (2,446) and nasopharyngeal cancer (1,747) diagnosed in Finland, Sweden, Norway and Iceland between 1961 and 2005. For each case, five male controls, who were alive at the time of diagnosis of the case (index date), were randomly selected, matched by birth-year and country. Cumulative exposures (CE)s to wood dust and formaldehyde before the index date were quantified based on a job-exposure matrix linked to occupational titles derived from population censuses. Hazard ratios (HRs) for the CE of wood dust were estimated by conditional logistic regression, adjusted for CE to formaldehyde and 95% confidence intervals (CIs) were calculated. There was an increasing risk of nasal adenocarcinoma related to wood dust exposure. The HR in the highest CE category of wood dust (≥ 28.82 mg/m³ -years) was 16.5 (95% CI 5.05-54.1). Neither nonadenocarcinoma of the nose nor nasopharyngeal cancer could be linked to wood dust exposure. CE to softwood-dominated mixed wood dusts is strongly linked with elevated risk in nasal adenocarcinoma but not with other types of nasal or nasopharyngeal cancer.

Invasive Sinonasal Lesions: From the Nasal Fossa and Paranasal Sinuses to the Endocranium

The aim of this work is to review the spectrum of sinonasal lesions that extend to the endocranium and to present key points that may narrow the differential diagnosis. The most frequent sinonasal lesions that extend into the endocranium are malignant; however, benign entities are not unusual. Imaging diagnosis is difficult because malignant lesions and benign entities share similar clinical, epidemiologic, and imaging features. Tumor features in relation to bone, intratumor homogeneity and structure, magnetic resonance imaging signal, along with clinical and epidemiologic aspects may allow an appropriate diagnostic focus with important management implications.

Nasal Cavity and Paranasal Sinuses

The nasal cavity and paranasal sinuses occupy the top of the upper respiratory tract and form pneumatic spaces connected with the atmosphere. They are located immediately beneath the base of the cranium, where crucial vital structures are harbored. From this region, very much exposed to airborne agents, arise some of the more complex and rare benign and malignant lesions seen in humans, whose difficulties in interpretation make this remarkable territory one of the most challenging in the practice of surgical pathology.

Contents of this chapter cover inflammations and infections, polyps and pseudotumors, fungal and midfacial destructive granulomatous lesions, as well as benign, borderline, and malignant neoplasms. Among the neoplasms, emphasis is made on those entities characteristic or even unique for the sinonasal region, such as Schneiderian papillomas, glomangiopericytoma, intestinal- and non-intestinal-type adenocarcinomas, olfactory neuroblastoma, nasal-type NK-/T-cell lymphoma, and teratocarcinosarcoma. Moreover, recently recognized entities involving this territory, i.e., HPV-related non-keratinizing carcinoma, NUT carcinoma, and SMARCB1-deficient basaloid carcinoma, are also discussed in the light of their specific molecular findings. Furthermore, the text is accompanied by numerous classical and recent references, several tables, and 100 illustrations.

Activation of aryl hydrocarbon receptor signaling by extracts of teak and other wood dusts

Wood dusts, as a group, are categorized as known human carcinogens, but the risks of exposure to specific types of wood dusts and the carcinogenic chemicals they contain are not well studied. Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is linked to the carcinogenic action of specific classes of chemicals. Here we examined whether chemicals in various wood dusts had the potential to activate AhR signaling as a potential toxic mechanism of action. We found that methanol extracts of teak, walnut, mahogany, and poplar dusts contained a wide range of AhR ligand activity, whereas extracts of oak, pine, and other softwoods did not contain appreciable activity. Teak dust extract, being particularly potent, was subjected to chemical analysis. The 2-methylanthraquinone (2-MAQ) accounted for the AhR ligand activity and was present at an average concentration of 0.27 parts per hundred in teak dust. Pure 2-MAQ potently induced AhR signaling (EC50 115 nM), confirming that this was the active ligand. Aqueous extracts of teak dust made using yeast or mammalian cell culture medium also contained robust AhR activity, suggesting the 2-MAQ ligand is soluble at bioactive concentrations in physiologically relevant fluids. The high concentration and potency of 2-MAQ in teak wood suggest it may mediate toxic effects through activation of AhR signaling in exposed wood workers.

Potential Occupational Exposures and Health Risks Associated with Biomass-Based Power Generation

Biomass is increasingly being used for power generation; however, assessment of potential occupational health and safety (OH&S) concerns related to usage of biomass fuels in combustion-based generation remains limited. We reviewed the available literature on known and potential OH&S issues associated with biomass-based fuel usage for electricity generation at the utility scale. We considered three potential exposure scenarios--pre-combustion exposure to material associated with the fuel, exposure to combustion products, and post-combustion exposure to ash and residues. Testing of dust, fungal and bacterial levels at two power stations was also undertaken. Results indicated that dust concentrations within biomass plants can be extremely variable, with peak levels in some areas exceeding occupational exposure limits for wood dust and general inhalable dust. Fungal spore types, identified as common environmental species, were higher than in outdoor air. Our review suggests that pre-combustion risks, including bioaerosols and biogenic organics, should be considered further. Combustion and post-combustion risks appear similar to current fossil-based combustion. In light of limited available information, additional studies at power plants utilizing a variety of technologies and biomass fuels are recommended.

Occupational safety threats among dental personnel and related risk factors

Occupational diseases are primarily considered to be important health problems for individuals with occupations in heavy industry fields. Although dentists work in very clean and elegant offices, they are frequently exposed to various chemicals and high-intensity, sound-producing instruments, such as compressors and aerators. In our study, we aimed to investigate the risk for occupational hearing loss of dental personnel, by performing pure-tone audiometry in 40 dentists and comparing the results with those of healthy individuals. We also sampled the nasal mucosa to investigate the effects of occupational chemicals on the nasal mucosa of the dentists. The pure-tone audiometric thresholds at 5 different frequencies (1000, 2000, 4000, 6000, and 8000 Hz) and working time were evaluated as potential risk factors. The pure-tone audiometric results (as decibels) at each frequency and the median values for each side (right and left ears) were significantly higher for dentists than for the control group (P < 0.05). The pure-tone audiometric results did not significantly differ between the women and men in the study group (P > 0.05). The findings in the nasal mucosa (goblet cell hyperplasia, neutrophil/eosinophil/basophil distribution, metaplasia, dysplasia, premalignant or malignant cells) were similar in the study and control groups (P > 0.05). In conclusion, our study indicated that high-intensity, sound-producing equipment is an important occupational threat for dentists, whereas chemical agents have minimal hazardous effects.

Occupational irritant and allergic rhinitis

The upper airway (extending from the nares to larynx) fulfills essential physiologic functions, including sensation, air conditioning, filtration, and communication. As the portal of entry for the respiratory tract, the upper airway's sentinel function is performed by the olfactory and trigeminal nerves. Sensory (eye, nose and throat) irritation figures prominently in symptom reporting in so-called "problem buildings," as well as in industrial exposures to irritant gases, vapors, and smokes. Both irritants and allergens can alter function in the upper airway, leading to loss of air conditioning and filtering due to airflow obstruction and hypersecretion. Increasing evidence points to a "unified airway" model of pathogenesis (in which rhinitis may precede the development of asthma). The spectrum of occupational irritant- and allergen-related upper airway health effects-including sensory irritation, olfactory dysfunction, rhinitis, sinusitis, nasal septal perforation, and sinonasal cancer-is reviewed in this article.

Low-dose formaldehyde delays DNA damage recognition and DNA excision repair in human cells

OBJECTIVE

Formaldehyde is still widely employed as a universal crosslinking agent, preservative and disinfectant, despite its proven carcinogenicity in occupationally exposed workers. Therefore, it is of paramount importance to understand the possible impact of low-dose formaldehyde exposures in the general population. Due to the concomitant occurrence of multiple indoor and outdoor toxicants, we tested how formaldehyde, at micromolar concentrations, interferes with general DNA damage recognition and excision processes that remove some of the most frequently inflicted DNA lesions.

METHODOLOGY/PRINCIPAL FINDINGS

The overall mobility of the DNA damage sensors UV-DDB (ultraviolet-damaged DNA-binding) and XPC (xeroderma pigmentosum group C) was analyzed by assessing real-time protein dynamics in the nucleus of cultured human cells exposed to non-cytotoxic (<100 μM) formaldehyde concentrations. The DNA lesion-specific recruitment of these damage sensors was tested by monitoring their accumulation at local irradiation spots. DNA repair activity was determined in host-cell reactivation assays and, more directly, by measuring the excision of DNA lesions from chromosomes. Taken together, these assays demonstrated that formaldehyde obstructs the rapid nuclear trafficking of DNA damage sensors and, consequently, slows down their relocation to DNA damage sites thus delaying the excision repair of target lesions. A concentration-dependent effect relationship established a threshold concentration of as low as 25 micromolar for the inhibition of DNA excision repair.

CONCLUSIONS/SIGNIFICANCE

A main implication of the retarded repair activity is that low-dose formaldehyde may exert an adjuvant role in carcinogenesis by impeding the excision of multiple mutagenic base lesions. In view of this generally disruptive effect on DNA repair, we propose that formaldehyde exposures in the general population should be further decreased to help reducing cancer risks.

Mortality from solid tumors among workers in formaldehyde industries: an update of the NCI cohort

BACKGROUND

Formaldehyde, a widely used chemical, is considered a human carcinogen.

METHODS

We extended follow-up of the largest industrial cohort of workers in formaldehyde industries (n = 25,619) by 10 years through 2004. Standardized mortality ratios (SMRs) and rate ratios (RRs) were calculated for deaths from solid tumors using quantitative formaldehyde exposure estimates.

RESULTS

During 998,239 person-years, 13,951 deaths occurred. With one additional death, previously observed excesses for nasopharyngeal cancer (n = 10) persisted for peak, average intensity and cumulative exposure; RRs in the highest exposure categories were 7.66 (95% CI: 0.94, 62.34), P-trend = 0.005, 11.54 (95% CI: 1.38, 96.81), P-trend = 0.09, and 2.94 (95% CI: 0.65, 13.28), P-trend = 0.06, respectively. For all cancer, solid tumors and lung cancer, SMRs among exposed workers were elevated, but internal analyses revealed no positive associations with formaldehyde exposure.

CONCLUSIONS

Consistent with previous analyses of this cohort, this update continues to suggest a link between formaldehyde exposure and nasopharyngeal cancer.

Occupational rhinitis and other work-related upper respiratory tract conditions

The nose and upper airways form the initial area of impact for air pollutants and allergens. The development of nasal allergies in the workplace (occupational rhinitis) may herald subsequent development of occupational asthma. Exposure controls, periodic surveillance, and early intervention may circumvent work-related airways disease and prevent unnecessary worker impairment and disability.

Human papillomavirus-related carcinomas of the sinonasal tract

High-risk human papillomavirus (HPV) is an established cause of head and neck carcinomas arising in the oropharynx. The presence of HPV has also been reported in some carcinomas arising in the sinonasal tract, but little is known about their overall incidence or their clinicopathologic profile. The surgical pathology archives of The Johns Hopkins Hospital were searched for all carcinomas arising in the sinonasal tract from 1995 to 2011, and tissue microarrays were constructed. p16 immunohistochemical analysis and DNA in situ hybridization for high-risk types of HPV were performed. Demographic and clinical outcome data were extracted from patient medical records. Of 161 sinonasal carcinomas, 34 (21%) were positive for high-risk HPV DNA, including type 16 (82%), type 31/33 (12%), and type 18 (6%). HPV-positive carcinomas consisted of 28 squamous cell carcinomas and variants (15 nonkeratinizing or partially keratinizing, 4 papillary, 5 adenosquamous, 4 basaloid), 1 small cell carcinoma, 1 sinonasal undifferentiated carcinoma, and 4 carcinomas that were difficult to classify but exhibited adenoid cystic carcinoma-like features. Immunohistochemistry for p16 was positive in 59/161 (37%) cases, and p16 expression strongly correlated with the presence of HPV DNA: 33 of 34 (97%) HPV-positive tumors exhibited high p16 expression, whereas only 26 of 127 (20%) HPV-negative tumors were p16 positive (P<0.0001). The HPV-related carcinomas occurred in 19 men and 15 women ranging in age from 33 to 87 years (mean, 54 y). A trend toward improved survival was observed in the HPV-positive group (hazard ratio=0.58, 95% confidence interval [0.26, 1.28]). The presence of high-risk HPV in 21% of sinonasal carcinomas confirms HPV as an important oncologic agent of carcinomas arising in the sinonasal tract. Although nonkeratinizing squamous cell carcinoma is the most common histologic type, there is a wide morphologic spectrum of HPV-related disease that includes a variant that resembles adenoid cystic carcinoma. The distinctiveness of these HPV-related carcinomas of the sinonasal tract with respect to risk factors, clinical behavior, and response to therapy remains to be clarified.

Formaldehyde and epigenetic alterations: microRNA changes in the nasal epithelium of nonhuman primates

BACKGROUND

Formaldehyde is an air pollutant present in both indoor and outdoor atmospheres. Because of its ubiquitous nature, it is imperative to understand the mechanisms underlying formaldehyde-induced toxicity and carcinogenicity. MicroRNAs (miRNAs) can influence disease caused by environmental exposures, yet miRNAs are understudied in relation to formaldehyde. Our previous investigation demonstrated that formaldehyde exposure in human lung cells caused disruptions in miRNA expression profiles in vitro.

OBJECTIVES

Using an in vivo model, we set out to test the hypothesis that formaldehyde inhalation exposure significantly alters miRNA expression profiles within the nasal epithelium of nonhuman primates.

METHODS

Cynomolgus macaques were exposed by inhalation to approximately 0, 2, or 6 ppm formaldehyde for 6 hr/day for 2 consecutive days. Small RNAs were extracted from nasal samples and assessed for genome-wide miRNA expression levels. Transcriptional targets of formaldehyde-altered miRNAs were computationally predicted, analyzed at the systems level, and assessed using real-time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Expression analysis revealed that 3 and 13 miRNAs were dysregulated in response to 2 and 6 ppm formaldehyde, respectively. Transcriptional targets of the miRNA with the greatest increase (miR-125b) and decrease (miR-142-3p) in expression were predicted and analyzed at the systems level. Enrichment was identified for miR-125b targeting genes involved in apoptosis signaling. The apoptosis-related targets were functionally tested using RT-PCR, where all targets showed decreased expression in formaldehyde-exposed samples.

CONCLUSIONS

Formaldehyde exposure significantly disrupts miRNA expression profiles within the nasal epithelium, and these alterations likely influence apoptosis signaling.

[Cancers of the nasal cavity and paranasal sinuses: clinicopathological, etiological and therapeutic aspects]

Sinonasal cancers are rare and are often associated with occupational exposure that should be researched. Their diagnosis is often delayed. Carcinomas are the most common histological variety. The aim of the present report is to review the main scientific literature about sinonasal cancer to identify their clinicopathological features, and their main causes and treatment modalities. The treatment of these tumors is surgical, usually followed by radiotherapy.

Risk factors for nasal malignancies in German men: the South-German Nasal cancer study

BACKGROUND

There are few studies of the effects of nasal snuff and environmental factors on the risk of nasal cancer. This study aimed to investigate the impact of using nasal snuff and of other risk factors on the risk of nasal cancer in German men.

METHODS

A population-based case-control study was conducted in the German Federal States of Bavaria and Baden-Württemberg. Tumor registries and ear, nose and throat departments provided access to patients born in 1926 or later.

RESULTS

Telephone interviews were conducted with 427 cases (mean age 62.1 years) and 2.401 population-based controls (mean age 60.8 years). Ever-use of nasal snuff was associated with an odds ratio (OR) for nasal cancer of 1.45 (95% confidence interval [CI] 0.88-2.38) in the total study population, whereas OR in smokers was 2.01 (95% CI 1.00-4.02) and in never smokers was 1.10 (95% CI 0.43-2.80). The OR in ever-smokers vs. never-smokers was 1.60 (95% CI 1.24-2.07), with an OR of 1.06 (95% CI 1.05-1.07) per pack-year smoked, and the risk was significantly decreased after quitting smoking. Exposure to hardwood dust for at least 1 year resulted in an OR of 2.33 (95% CI 1.40-3.91) in the total population, which was further increased in never-smokers (OR 4.89, 95% CI 1.92-12.49) in analyses stratified by smoking status. The OR for nasal cancer after exposure to organic solvents for at least 1 year was 1.53 (1.17-2.01). Ever-use of nasal sprays/nasal lavage for at least 1 month rendered an OR of 1.59 (1.04-2.44). The OR after use of insecticides in homes was 1.48 (95% CI 1.04-2.11).

CONCLUSIONS

Smoking and exposure to hardwood dust were confirmed as risk factors for nasal carcinoma. There is evidence that exposure to organic solvents, and in-house use of insecticides could represent novel risk factors. Exposure to asbestos and use of nasal snuff were risk factors in smokers only.

Endoscopic skull base surgery for sinonasal malignancy

Management of malignant neoplasms of the sinonasal tract and skull base is hampered by the relative low incidence and pathologic diversity of patient presentations. Many studies have reported successful outcomes in the endoscopic management of malignancy since 1996, and these are summarized in this article. Nonsurgical adjuvant therapies are important for locoregional control because surgery occurs in a restricted anatomic space with close margins to critical structures, and distant disease is an ongoing concern in these disorders. There remains a need for collaborative consistent multicenter reporting, and international registries have been established to assist in such efforts.

Nasenhöhle und Nasennebenhöhlen

Die Gesichtsmitte (der Bezirk zwischen Oberlippe und Stirn) entwickelt sich zwischen der 4. und 8. Schwangerschaftswoche. [ 220] Der Stirnfortsatz bildet sich währen der 4. postovulatorischen Woche, aus ihm gehen die oberen und mittleren Anteile des Gesichts hervor. Die Oberkiefer- und Nasenwülste entwickeln sich unterhalb des Stirnfortsatzes. Am Ende der 4. Woche bilden zwei oberflächliche Verdickungen der Nasenwülste die Riechplakoden, die ektodermaler Herkunft sind und aus denen der Epithelbelag der Nasenhöhle und Nasennebenhöhlen hervorgeht. Die Plakoden stülpen sich ein und bilden die Riechgruben, aus denen die vorderen Choanen (Nasenlöcher) und weniger oberflächlich die primitiven hinteren Choanen entstehen. Die medialen Nasen- und Stirnfortsätze bilden das Nasenseptum, die Stirnknochen, Nasenknochen, die Siebbeinzellen- Komplexe und die oberen Schneidezähne. Die lateralen Nasen- und Oberkieferfortsätze vereinigen sich zur Bildung des Philtrum und der Columella. Das knorpelige Nasenskelet bildet sich während der 7. und 8. postovulatorischen Woche tief unterhalb der Nasen- und Stirnbeinknochen aus dem Chondrocranium. Die Nasennebenhöhlen entwickeln sich in der 6. Fetalwoche aus den lateralen Nasenwänden, und ihr Wachstum setzt sich nach der Geburt während des gesamten Kindes- und Jugendalters fort.

Development of a job exposure matrix (JEM) for the textile industry in Shanghai, China

We developed a job exposure matrix (JEM) for the Shanghai textile industry constructed along three axes: industry sector, textile process, and hazardous agent. We assessed 35 different categories of dust, chemical, and physical agents for 149 textile processes within nine industry sectors: cotton, cotton/synthetic, cotton/other (nonsynthetic), wool, silk, synthetic, mineral, other mixed (e.g., wool and synthetic), and nonproduction. The JEM was constructed from two components: a priori assessment of the textile process by a team of U.S. industrial hygienists, and the prevalence of exposures reported by Chinese industrial hygienists in specific textile processes within the factory. The JEM was applied to an ongoing case-cohort study of cancer in women textile workers. The JEM assessed only dichotomous exposure (ever/never), and could be coupled with cumulative exposure by years of employment. The most common exposures in cotton mills were cotton dust and solvent exposures. Dyeing processes had the highest frequency of exposures, including solvents, acids, bases and caustics, bleaching agents, dyes, dye chemicals and intermediates, and formaldehyde. Only two processes were identified with formaldehyde exposure, beck dyeing and resin finishing. The most prevalent exposures among the subcohort, occurring in more than 60% of the women, were electromagnetic fields, lubricants, and cotton dust. More than one-third of subcohort subjects were also exposed to synthetic fiber dust, and slightly less than one-third of women were exposed to endotoxin. This JEM could be applicable for epidemiologic research in other textile industries.

The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium

The nose is a very complex organ with multiple functions that include not only olfaction, but also the conditioning (e.g., humidifying, warming, and filtering) of inhaled air. The nose is also a "scrubbing tower" that removes inhaled chemicals that may be harmful to the more sensitive tissues in the lower tracheobronchial airways and pulmonary parenchyma. Because the nasal airway may also be a prime target for many inhaled toxicants, it is important to understand the comparative aspects of nasal structure and function among laboratory animals commonly used in inhalation toxicology studies, and how nasal tissues and cells in these mammalian species may respond to inhaled toxicants. The surface epithelium lining the nasal passages is often the first tissue in the nose to be directly injured by inhaled toxicants. Five morphologically and functionally distinct epithelia line the mammalian nasal passages--olfactory, respiratory, squamous, transitional, and lymphoepithelial--and each nasal epithelium may be injured by an inhaled toxicant. Toxicant-induced epithelial lesions in the nasal passages of laboratory animals (and humans) are often site-specific and dependent on the intranasal regional dose of the inhaled chemical and the sensitivity of the nasal epithelial tissue to the specific chemical. In this brief review, we present examples of nonneoplastic epithelial lesions (e.g., cell death, hyperplasia, metaplasia) caused by single or repeated exposure to various inhaled chemical toxicants. In addition, we provide examples of how nasal maps may be used to record the character, magnitude and distribution of toxicant-induced epithelial injury in the nasal airways of laboratory animals. Intranasal mapping of nasal histopathology (or molecular and biochemical alterations to the nasal mucosa) may be used along with innovative dosimetric models to determine dose/response relationships and to understand if site-specific lesions are driven primarily by airflow, by tissue sensitivity, or by another mechanism of toxicity. The present review provides a brief overview of comparative nasal structure, function and toxicologic pathology of the mammalian nasal epithelium and a brief discussion on how data from animal toxicology studies have been used to estimate the risk of inhaled chemicals to human health.

Risk assessment of formaldehyde for the general population in Japan

Formaldehyde is used in the production of resins, molding compounds, photographic film, bactericide, and tissue preservative. The purpose of this study was to provide an up-to-date critical review of the information to the toxicological profile of formaldehyde, and to assess the risk of formaldehyde for the general population in Japan. Inhaled formaldehyde is an effective sensory irritant at a dosage of 0.5 ppm in mice. Following inhalation in laboratory animals, more than 6 ppm formaldehyde causes degenerative non-neoplastic effects in mice and monkeys and nasal tumors in rats. It is considered that formaldehyde induces genotoxic effects directly in vitro and secondarily in vivo. Sensory irritation of the eyes and respiratory tract in response to inhalation exposure to formaldehyde has been reported at 0.08 ppm and above in human study. Formaldehyde is carcinogenic at the site of contact as a consequence of epithelial cell regenerative proliferation resulting from cytotoxicity and mutation, based on studies in both animals and humans. Levels of formaldehyde in atmosphere detected in rural, suburban, and urban areas in Japan were 2.5-3.2 ppb from 1998 to 2003. The majority of the population is exposed to atmosphere concentrations of formaldehyde less than those associated with sensory irritation. The reference concentration of formaldehyde in atmosphere for the Japanese general population is recommended to be 0.01 ppm.

Adenocarcinoma of the nose and paranasal sinuses: a retrospective study of diagnosis, histologic characteristics, and outcomes in 24 patients

BACKGROUND

Adenocarcinomas of the sinonasal cavity are unusual tumors with variable clinical courses.

METHODS

We conducted a retrospective chart review between 1980 and 2001.

RESULTS

Twenty-four patients (17 men) with sinonasal adenocarcinoma were identified. Nasal obstruction was the most common presenting symptom (75%), and the nose was the most common site of involvement (83%). Eleven tumors (46%) were high grade (grade 3 or 4). Twenty-three patients (95%) underwent an attempt at surgical excision with tumor recurrence or residual disease in seven. Age and tumor grade were associated with overall survival, and tumor grade and intracranial extension were associated with death from disease.

CONCLUSIONS

Presentation and treatment for nasal adenocarcinoma varies widely. Some low-grade variants of nasal adenocarcinomas seem to be associated with a more favorable prognosis and, depending on the extent of the tumor, can be treated with less-aggressive therapy.

After the Smoke Clears

Both environmental and occupational exposures are associated with the development of carcinomas of the upper aerodigestive tract, although most squamous cell carcinomas of the upper aerodigestive tract are related to smoking and drinking. This review discusses environmental and occupational risk factors, other than tobacco and alcohol, for carcinoma of the upper aerodigestive tract and the difficulties encountered when attempts are made to study these environmental and occupational exposures. However, this is not an all-inclusive review; rather, it is designed to give the reader an understanding of the topic, to allow for appropriate counseling of patients, and perhaps to advance public health initiatives.

Toxicology of nasal irritants

The upper airway, including nasal cavities, naso-, oro-, and hypopharynx, is the portal of entry for air pollutants. Upper airway (as well as eye) irritation figures prominently in symptom reporting in so-called problem buildings and with exposure to environmental tobacco smoke. Large particles and water-soluble gases and vapors are likely to have their initial irritant effects in the mucous membranes of the upper airway and eyes, giving warning to the exposed individual to minimize further exposure. The spectrum of irritant-related upper airway health effects is reviewed in this article.

Inhaled formaldehyde: exposure estimation, hazard characterization, and exposure-response analysis

Formaldehyde has been assessed as a Priority Substance under the Canadian Environmental Protection Act. Probabilistic estimates of exposure of the general population in Canada to formaldehyde in ambient and indoor air are presented. Critical health effects include sensory irritation and the potential to induce tumors in the upper respiratory tract (the nasal region in rodents and potentially the lungs of humans). The majority of the general population is exposed to airborne concentrations of formaldehyde less than those typically associated with sensory irritation (i.e., 0.1 mg/m3). Based primarily upon data derived from laboratory studies, the inhalation of formaldehyde under conditions that induce cytotoxicity and sustained regenerative proliferation within the respiratory tract is considered to present a carcinogenic hazard to humans. At airborne levels for which the prevalence of sensory irritation is minimal (i.e., 0.1 mg/m3), risks of respiratory-tract cancers for the general population estimated on the basis of a biologically motivated case-specific model are exceedingly low. This biologically motivated case-specific model incorporates two-stage clonal expansion and is supported by dosimetry calculations from computational fluid dynamics analyses of formaldehyde flux in various regions of the nose and single-path modeling for the lower respiratory tract. The degree of confidence in the underlying database and uncertainties in estimates of exposure and in characterization of hazard and dose response are delineated.

Smoking-induced squamous-cell cancer of the nose

Squamous-cell cancer (SCC) isolated to the anterior nose is uncommon. Numerous industrial and environmental contaminants have been implicated as causative factors in nasal carcinoma. The association between nasal cancer and smoking was recognized in the 1980s, but results have not been consistent and no possible mechanisms have been suggested. The case histories of 11 patients with SCC limited to the anterior nasal cavity were reviewed. The authors found no relationship with exposures to chemicals previously implicated in nasal cancer. Nine patients with SCC were exposed to cigarette smoke (mean = 103 pack-years). Cigarette smoke may induce cancer directly, thus affecting the mucosa, or by inducing genetic alterations. The authors favor the former mechanism.

Study of ethmoidal mucosa in a population at occupational high risk of sinonasal adenocarcinoma

The occurrence of nasal adenocarcinomas was first described in 1965. Since 1988 these tumors have been accepted as an occupational disease for woodworkers in Italy. There are several underlying reasons why there is interest in studying the ways in which sinonasal adenocarcinomas occur. Often diagnosed at advanced stages of development because their symptoms are non-specific, these tumors are associated with a high mortality rate. A multidisciplinary study protocol was developed in this investigation. The aim was to identify the factors and conditions that promote sinonasal tumor growth in a population at risk due to occupational exposure to wood dust. Sixty-eight carpenters with a minimum of 10 years exposure to wood dust were studied. The control group comprised 81 volunteers. The patients underwent the following protocol: completion of a case report form, physical examination, evaluation of nasal cavity patency, clinical laboratory tests and histological study of the nasal mucosa. Our study provides significant evidence of the elevated incidence of pavimentous metaplasia in workers occupationally exposed to wood dust. In addition, it underscores a significant deficit of immunoglobulin A in such workers compared to the controls. However, we did not find, as reported elsewhere in the literature, a statistically significant difference between cases and controls as regards nasal symptoms and hyperemia of the nasal mucosa. Our study showed that, even in the absence of evident sinonasal lesions, it is still possible to determine an increased incidence of morphofunctional changes in subjects occupationally exposed to wood dust. Our findings may lead to the identification of occupational groups prone to elevated risk of the disease.

Wood dust exposure and cancer incidence: a retrospective cohort study of furniture workers in Estonia

BACKGROUND

Occupational wood dust exposure is associated with increased risk of sinonasal cancer in men. However, little is known whether it is associated with sinonasal cancer in women or with malignancies of other sites.

METHODS

In a retrospective cohort study of furniture workers, cancer incidence in 3723 men and 3063 women between 1968 and 1995 was compared to the incidence in the general population of Estonia. Cancer risks were analyzed by employment duration and occupation.

RESULTS

The standardized incidence ratio (SIR) for all cancers did not differ significantly from one. Two men and one woman had sinonasal cancer (expected 1.07 and 0.53, respectively). Significantly increased risk of colon cancer was seen in the cohort (SIR 1.65, 95% confidence interval (CI) 1.22-2.17). Subjects employed for 10 years and over had significant excess of colon cancer (SIR 2.29, 95% CI 1.28-3.77) and rectal cancer (SIR 2.10, 95% CI 1.05-3.76) in the analysis by employment duration using exposure with a latency of 20 years. The nonsignificant excess of pharyngeal cancer in men (SIR 1.82) and lung cancer in women (SIR 1.43) was restricted to short-term workers.

CONCLUSIONS

This study found an excess of colon and rectal cancer in furniture workers. There was no increase in total cancer risk.

Preventable risk factors for nasal cancer

PURPOSE

To determine preventable risk factors for cancers of the nasal cavity and paranasal sinuses in the United States, we analyzed data from the population-based, case-control Selected Cancers Study.

METHODS

Cases were men born between 1929 and 1953 who were diagnosed with primary nasal cancer between 1984 and 1988 and identified from population-based cancer registries; we narrowed the cohort to 70 subjects whose diagnosis of nasal cancer was confirmed by pathology review. All living controls interviewed for the Selected Cancers Study were included as the comparison group (n = 1910); they were recruited by random-digit dial telephone and were frequency-matched to the lymphoma cases of the Selected Cancers Study by geographic area and age. Both cases and controls were interviewed by telephone.

RESULTS

Logistic regression analyses showed that cases were 2.5 times more likely than controls to have smoked cigarettes [95% confidence interval (CI) = 1.1-5.3], and 2.2 times more likely to have worked in selected occupations, including lawn care, forestry, and maintenance of highway right-of-way areas (CI = 1.2-3.7). These occupations may cause workers to be exposed to pesticides or herbicides. The population attributable risk (PAR) was 53% for having ever smoked cigarettes.

CONCLUSIONS

The study results suggest that among U.S. men, some nasal cancer may be preventable by avoiding cigarette smoking.

Sinonasal cancer, occupation, and tobacco smoking in European women and men

BACKGROUND

In this analysis of European case-control studies on sinonasal cancer, we examined the risk for occupation and smoking, by gender and histological type.

METHODS

The pooled data included 104 female and 451 male cases, and 241 female and 1,464 male controls. Lifetime smoking and occupational history were recoded following uniform criteria, and job-exposure matrices were applied for wood and leather dust.

RESULTS

Wood dust exposure was associated with an excess risk in men (OR = 2.36, 95% CI 1.75-3.2) but not in women (OR = 1.17, 95% CI 0.31-4.47). Exposure to leather dust was associated with an excess risk in both genders. Both wood and leather dust were associated with adenocarcinomas rather than squamous cell carcinomas. Excess risks for smoking were higher for squamous cell carcinomas and higher in men than in women.

CONCLUSIONS

In these European populations, occupation was associated with about 11% of all sinonasal cancers in women and 39% in men. This difference can, in part, be attributed to variation in exposure patterns between genders.

Carcinogenic response of the nasal cavity to inhaled chemical mixtures

Nasal cancers occur in experimental animals following chronic exposure to a wide range of inhaled chemicals. Although exposure to several of these chemicals is common in industrial as well as domestic environments, epidemiological studies have not provided convincing evidence that exposure to these chemicals individually is associated with nasal cancer in humans. The reverse seems to be true for inhalation of chemical mixtures. The evidence for nasal carcinogenicity of inhaled chemical mixtures in experimental animals is very limited, while there is ample evidence in humans that occupational exposure to certain chemical mixtures is associated with increased risk of nasal cancer. Examples of such (complex) chemical mixtures are wood dust, textile dust, chromium- and nickel-containing materials and leather dust. It is remarkable that these mixtures are aerosols, suggesting that a 'dusty working environment' may increase nasal cancer risk.

An updated meta-analysis of formaldehyde exposure and upper respiratory tract cancers

In this study, we summarize 47 epidemiologic studies related to formaldehyde exposure and use meta-analytic techniques to assess findings for cancers of the lung, nose/nasal sinuses, and nasopharynx. Our analyses indicate that workers with formaldehyde exposure have essentially null findings for lung cancer and a slight deficit of sinonasal cancer. Nasopharyngeal cancer rates were elevated moderately in a minority of studies. Most studies, however, did not find any nasopharyngeal cancers, and many failed to report their findings. After correcting for underreporting, we found a meta relative risk of 1.0 for cohort studies. Case-control studies had a meta relative risk of 1.3. Our review of the exposure literature indicated that the nasopharyngeal cancer case-control studies represented much lower and less certain exposures than the cohort studies. We conclude that the available studies do not support a causal relation between formaldehyde exposure and nasopharyngeal cancer. This conclusion conflicts with conclusions from two previous meta-analyses, primarily because of our consideration of unreported data.