Blood nickel and chromium levels in association with smoking and occupational exposure among head and neck cancer patients in Tunisia

The preventive and carcinogenic effect of metals on cancer: a systematic review

BACKGROUND

Many studies have investigated the role of metals in various types of malignancies. Considering the wide range of studies conducted in this field and the achievement of different results, the presented systematic review was performed to obtain the results of investigations on the prevention and occurrence of various types of cancer associated with metal exposures.

METHODS

In this review, research was conducted in the three databases: Scopus, PubMed, and Web of Science without historical restrictions until May 31, 2024. Animal studies, books, review articles, conference papers, and letters to the editors were omitted. The special checklist of Joanna Briggs Institute (JBI) was used for the quality assessment of the articles. Finally, the findings were classified according to the effect of the metal as preventive or carcinogenic.

RESULTS

The total number of retrieved articles was 4695, and 71 eligible results were used for further investigation. In most studies, the concentration of toxic metals such as lead (Pb), chromium (Cr (VI)), arsenic (As), cadmium (Cd), and nickel (Ni) in the biological and clinical samples of cancer patients was higher than that of healthy people. In addition, the presence of essential elements, such as selenium (Se), zinc (Zn), iron (Fe), and manganese (Mn) in tolerable low concentrations was revealed to have anti-cancer properties, while exposure to high concentrations has detrimental health effects.

CONCLUSIONS

Metals have carcinogenic effects at high levels of exposure. Taking preventive measures, implementing timely screening, and reducing the emission of metal-associated pollutants can play an effective role in reducing cancer rates around the world.

Waterpipe Tobacco Smoking and Risk of Cancer Mortality

Importance

There has been an increasing trend of using noncigarette products, including waterpipe tobacco (WTP), worldwide. While cigarette smoking is a well-established risk factor for numerous cancers, little is known about the association between WTP smoking and cancer mortality.

Objective

To assess the association between WTP smoking and risk of cancer mortality in Vietnam.

Design, Setting, and Participants

This cohort study was based on data from the Hanoi Prospective Cohort Study, an ongoing study with a median (range) follow-up of 11.0 (0.1-11.6) years for participants aged 15 years or older in Northern Vietnam from 2007 through 2019. Data were analyzed from June 1 to September 1, 2023.

Exposures

Tobacco smoking and WTP smoking statuses.

Main Outcomes and Measures

Overall and site-specific cancer mortality. Cox proportional regression models were used to calculate the hazard ratio (HR) and 95% CIs for the associations between WTP smoking alone, cigarette smoking alone, and dual WTP and cigarette smoking and the risk of cancer death.

Results

A total of 554 cancer deaths were identified among the 39 401 study participants (mean [SD] age, 40.4 [18.8] years; 20 616 females [52.3%]). In multivariable models, compared with never smokers, ever smokers had a significantly increased risk of cancer mortality (HR, 1.87; 95% CI, 1.48-2.35). Exclusive WTP smokers had the highest risk of cancer mortality compared with never smokers (HR, 2.66; 95% CI, 2.07-3.43). Risk of cancer mortality was higher for dual smokers of WTP and cigarettes (HR, 2.06; 95% CI, 1.53-2.76) than for exclusive cigarette smokers (HR, 1.86; 95% CI, 1.41-2.45). As most smokers (95.6% [8897 of 9312]) were male, these patterns were more apparent in male participants. Compared with never smokers, exclusive WTP smoking among males was associated with an elevated risk of death from liver cancer (HR, 3.92; 95% CI, 2.25-6.85), lung cancer (HR, 3.49; 95% CI, 2.08-5.88), nasopharyngeal carcinoma (HR, 2.79; 95% CI, 1.27-6.12), and stomach cancer (HR, 4.11; 95% CI, 2.04-8.27). For exclusive WTP smokers, the risk of cancer mortality was highest among those who smoked 11 to 15 sessions per day (HR, 3.42; 95% CI, 2.03-5.75), started smoking at age 26 to 30 years (HR, 4.01; 95% CI, 2.63-6.11), smoked for 9 to 20 years (HR, 4.04; 95% CI, 2.16-7.56), and smoked 61 to 160 sessions annually (HR, 3.68; 95% CI, 2.38-5.71). For males, the risk of cancer death was lower for those who had quit smoking for more than 10 years, compared with those who quit smoking within 1 year (HR, 0.27; 95% CI, 0.11-0.66; P for trend < .001).

Conclusion and Relevance

In this cohort study in Vietnam, WTP smoking alone or in combination with cigarette smoking was associated with an increased risk of cancer death due to liver cancer, lung cancer, nasopharyngeal carcinoma, and stomach cancer. A tailored program to control WTP smoking is warranted in Vietnam and low- and middle-income countries with a high prevalence of smoking and modest resources to address smoking-related issues.

Modifiable risk factors for cancer in the middle East and North Africa: a scoping review

PURPOSE

This scoping review examines controllable predisposing factors attributable to cancer in the Middle East and North Africa (MENA) region's adult population, highlighting opportunities to enhance cancer prevention programs.

DESIGN

We systematically searched the PubMed, Science Direct, and CINAHL, EMBASE, and Cochrane Library databases from 1997 to 2022 for articles reporting on the impact of modifiable risk factors on adult patients with cancer in the MENA region.

RESULTS

The review identified 42 relevant articles, revealing that tobacco consumption, obesity, physical inactivity, and diet are significant modifiable risk factors for cancer in the region. Tobacco smoking is a leading cause of lung, bladder, squamous cell carcinoma, and colorectal cancer. A shift towards a westernized, calorie-dense diet has been observed, with some evidence suggesting that a Mediterranean diet may be protective against cancer. Obesity is a known risk factor for cancer, particularly breast malignancy, but further research is needed to determine its impact in the MENA region. Physical inactivity has been linked to colorectal cancer, but more studies are required to establish this relationship conclusively. Alcohol consumption, infections, and exposure to environmental carcinogens are additional risk factors, although the literature on these topics is limited.

CONCLUSION

The review emphasizes the need for further research and the development of targeted cancer prevention strategies in the MENA region.

Trace elements in hair or fingernail and gastroesophageal cancers: results from a population-based case-control study

BACKGROUND

Growing evidence suggests that environmental factors probably play important roles in the development of gastroesophageal cancers (GOC), however, the effects of trace elements on GOC remain unclear.

OBJECTIVE

To assess the effect of trace elements on GOC and the effect modification by other factors.

METHODS

Hair and fingernail samples were collected from GOC cases and controls in a population-based case-control study in Taixing, China, and were used to detect the concentrations of 12 trace elements using inductively coupled plasma mass spectrometry. Unconditional logistic regression models were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for concentrations of 12 trace elements in association with GOC after adjusting the other factors.

RESULTS

A total of 830 hair samples (581 controls and 249 cases) and 895 fingernail samples (559 controls and 336 cases) were included. Compared to the lowest-tertile concentration, the higher tertiles of Ca, Zn, Fe, Al, Cr, Pb, Se, and V were positively associated with GOC, while the higher tertiles of Mg, Mn, Sr, and As were inversely associated with GOC. Significant interactions between the hair level of Cr and two other risk factors, including smoking (P for interaction = 0.044) and alcohol drinking (P for interaction = 0.028), were observed in association with GOC.

SIGNIFICANCE

The current study reveals that these 12 trace elements in hair and fingernails are associated with GOC to varying degrees. Further studies and animal experiments are needed to clarify the associations and explore potential mechanisms.

IMPACT STATEMENT

The role of trace elements in the development or inhibition of gastroesophageal cancers (GOC) remains unclear. In this study, we further explored the associations between 12 trace elements and GOC based on a population-based case-control study conducted in Taixing, China. Higher levels of Ca, Zn, Fe, Al, Cr, Pb, Se, and V were positively associated with increased GOC, while inverse associations between higher levels of Mg, Mn, Sr, As, and GOC were observed. Observed associations were consistent in hair and fingernail samples. Moreover, interaction effects between hair level of Cr and smoking or alcohol drinking were identified.

Individual, sociodemographic, and lifestyle influence on blood chromium, cobalt, and nickel levels in healthy population living in Belgrade, Serbia

The rapid trend of industrialization and urbanization can lead to greater exposure of the general population to chromium, cobalt, and nickel. Their total body burden from all routes of recent exposure, as well as interindividual variability in exposure levels, metabolism, and excretion rates, are reflected in the blood metal concentrations. The main goals in this study were as follows: observing the reference levels of chromium, cobalt, and nickel in the blood of the population living in Belgrade, identification of individual and sociodemographic factors that most affect their blood levels, and comprehension of recent exposure to chromium, cobalt, and nickel. Blood was sampled from 984 participants, voluntary blood donors, who agreed to participate in this study. Individual and sociodemographic data were collected using questionnaire adapted for different subpopulations. Blood metal analyses were measured using ICP-MS method (7700×, Agilent, USA). Our study provided reference values of chromium, cobalt, and nickel in blood for adult population (18-65 years) and confirmed that blood cobalt and nickel levels were mostly influenced by age and gender, and age, respectively. Furthermore, weight status affected blood chromium and cobalt levels, while national origin affected blood chromium levels. The present study highlighted the importance of human biomonitoring studies to monitor exposure status and identify subpopulations with increased exposure to chromium, cobalt, and nickel.

Nickel nanoparticles exert cytotoxic effects on trophoblast HTR-8/SVneo cells possibly via Nrf2/MAPK/caspase 3 pathway

Nickel nanoparticles are widely used in the industry and may affect the reproductive system. The potential molecular mechanism of exposing the first-trimester trophoblast cell line (HTR-8/SVneo) to nickel nanoparticles remains unclear. Hence, the aim of this study was to investigate the in vitro cytotoxicity of Ni NPs on HTR-8/SVneo cells. HTR-8/SVneo cells were subjected to various concentrations (0, 2.5, 5, 7.5, 10, and 12.5 μg/cm²) of Ni NPs. The toxicity of the Ni NPs was evaluated in HTR-8/SVneo cells by measuring cell viability. The underlying mechanism of nickel nanoparticles toxicity to HTR-8/SVneo cells was determined by measuring the content of intracellular reactive oxygen species, mitochondrial membrane potential, and the rate of cell apoptosis and cell cycle, by measuring adenosine triphosphate levels, intracellular lipid peroxidation malondialdehyde, total superoxide dismutase, and CuZn/Mn-SOD activities, and by determining proteins related to Nrf2, MAPK, and Cytochrome c. Our results showed that the nickel nanoparticles treatment reduced the viability of HTR-8/SVneo cells, while it increased their oxidative stress and lowered their mitochondrial respiratory capacity. Additionally, the nickel nanoparticles treatment induced cell S-phase arrest and apoptosis. These molecular events may be linked to the oxidative stress-Nrf2 pathway/MAPK/Caspase 3 cascade. Thus, nickel nanoparticles exert cytotoxic effects on HTR-8/SVneo cells, which could affect the function of the placenta in human.

Effects of smoking shisha, cancer risk, and strategies for prevention of shisha habit

Smoking tobacco through a water pipe, also referred to as Shisha, is prevalent in Middle Eastern countries but has gained popularity worldwide, especially among youth. The increasing global trend of shisha use is mainly led by misleading information about it being safe. The shisha smoke has potentially harmful chemicals, including several human carcinogens and other toxic products. There are recognised adverse effects on passive smokers exposed to second-hand smoke. It is a potential risk factor for several cancers and risks pregnant women and the foetus. A session of shisha smoking for 40 minutes is equivalent to smoking 100 or more cigarettes. There should be awareness about Shisha's harmful effects to reduce the risk to health through a coordinated global effort.

Smoking is associated with altered serum and hair essential metal and metalloid levels in women

The objective of the study was to evaluate the association between smoking and essential metal (Co, Cr, Cu, Fe, Mn, V, Zn) and metalloid (Se) levels in hair and serum of adult women using inductively coupled plasma-mass spectrometry (ICP-MS). In this cross-sectional study, a total of 344 women 20-70 years old including 199 smokers and 145 non-smoking women were enrolled. Serum Cu, Fe, and Zn levels in smoking women were found to be 6%, 8%, and 3% lower of levels in non-smokers, respectively. In contrast, circulating Mn, V, and especially Cr concentrations in smoking women exceeded the respective values in non-smoking women by 5%, 14%, and 54%. Hair Fe and Se levels in smoking women were 17% and 23% lower as compared to non-smoking controls, respectively. In multiple regression models, smoking severity was inversely associated with serum and hair Se concentrations, whereas the relationship to serum and hair Cr was positive. In addition, serum Zn and hair Fe levels were found to be inversely associated with the number of cigarettes per day. These findings hypothesize that health hazards of smoking may be at least in part be mediated by alteration in essential metal and metalloid metabolism.

Biochemical and reproductive biomarker analysis to study the consequences of heavy metal burden on health profile of male brick kiln workers

The present study aims to assess the effect of a heavy metal burden on general health, biochemical parameters, an antioxidant enzyme, and reproductive hormone parameters in adult male brick kiln workers from Pakistan. The study participants (n = 546) provided demographic data including general health as well as body mass index. Blood was collected to quantitatively assess hematological, biochemical, and reproductive hormone parameters as well as heavy metal concentrations using both atomic absorption spectroscopy (AAS) and particle-induced X-ray emission (PIXE). The data showed that 10% of the brick kiln workers were underweight and 10% obese (P = 0.059), with workers also reporting multiple health issues. Heavy metal concentrations utilizing AAS revealed significantly (p = 0.000) higher levels of cadmium, chromium, and nickel, while PIXE detected more than permissible levels of Si, P, S, Cl, K, Ca, Zn, Ti (p = 0.052), Mn (p = 0.017), Fe (p = 0.055), Co (p = 0.011), Ni (p = 0.045), and Cu (p = 0.003), in the blood of kiln workers. Moreover, a significant increase in platelet count (P = 0.010), a decrease in sodium dismutase levels (p = 0.006), a major increase in reactive oxygen species (p = 0.001), and a reduction in protein content (p = 0.013) were evident. A significant increase in cortisol levels (p = 0.000) among the workers group was also observed. The concentration of LH and FSH increased significantly (p = 0.000), while that of testosterone decreased (p = 0.000) in the worker group compared with controls. A significant inverse relationship was found between cortisol, LH (r =  - 0.380), and FSH (r =  - 0.946), while a positive correlation between cortisol and testosterone was also evident (r = 0.164). The study concludes that increased heavy metal burden in the blood of brick kiln workers exposes them to the development of general and reproductive health problems due to compromised antioxidant enzyme levels, increased oxidative stress conditions, and a disturbing reproductive axis.

Assessing reference levels of nickel and chromium in cord blood, maternal blood and placenta specimens from Ankara, Turkey

Objective:

Placenta is a temporary organ that connects the developing fetus and the mother. However, it cannot protect the embryo against chromium (Cr) and nickel (Ni) exposure. Quantification of Cr and Ni in biological and ecological subjects is challenging. Thus, the first goal of this study was to provide a validated Graphite Furnace Atomic Absorption Spectrometry (GFAAS) method to determine Cr and Ni in mother-newborn specimens. The second goal was to assess the reference Ni and Cr contents in cord blood, maternal blood, and placenta samples in a population from Ankara.

Material and Methods:

Biological samples were collected from 100 healthy mother-newborn pairs. Metal levels were quantified by GFAAS. Method validation of this toxicological analysis was performed by the use of certified reference materials, and assessed through accuracy, precision, specificity, range, quantitation, and detection limits.

Results:

Mean Cr levels of maternal blood, placentas, and cord blood were 0.337±0.222 μg/L, 0.221±0.160 μg/kg, 0.121±0.096 μg/L, respectively while mean Ni concentrations were 0.128±0.093 μg/L, 0.124±0.067 μg/kg, 0.099±0.067 μg/L, respectively. The method showed linearity with excellent correlation coefficients (r²) for Cr (0.9994) and Ni (0.9999). Satisfactory recovery and coefficient of variation for Cr and Ni were 102.85% and 102.35%; 1.75% and 2.91%, respectively. Relative error did not exceed 3%, demonstrating the accuracy of the method. Control charts were drawn to assess inter-day stability. The predicted reference ranges for Cr and Ni concentrations in maternal blood, placenta and cord blood were: Cr 0.033-0.75 μg/L; 0.032-0.526 μg/kg; 0.031-0.309 μg/L and for Ni were 0.011-0.308 μg/L; 0.024-0.251 μg/kg; 0.066-0.209 μg/L, respectively.

Conclusion:

The reported reference values of biological specimens in this paper will provide complementary aid to health professionals in terms of assessment of environmental and occupational exposure.

Elemental characterization of oral cavity squamous cell carcinoma and its relationship with smoking, prognosis and survival

Oral cancer squamous cell carcinoma (OCSCC) mainly affects individuals aged between 50 and 70 years who consume tobacco and alcohol. Tobacco smoke contains hundreds of known toxic and carcinogenic molecules, and a few studies have sought to verify the relationship of such trace elements as risk or prognostic factors for head and neck cancer. We obtained 78 samples of tumor tissues from patients with OCSCC, and performed a qualitative elemental characterization using the micro X-Ray Fluorescence technique based on synchrotron radiation. We found the presence of magnesium, phosphorus, sulfur, chlorine, potassium, calcium, chromium, manganese, iron, zinc, cobalt, nickel, copper, arsenic and bromine in OCSCC samples. Magnesium, chlorine, chromium, manganese, nickel, arsenic and bromine are associated with smoking. We observed a significant association between relapse and chlorine and chromium. The presence of chlorine in the samples was an independent protective factor against relapse (OR = 0.105, CI = 0.01-0.63) and for best disease-free survival (HR = 0.194, CI = 0.04-0.87). Reporting for the first time in oral cancer, these results suggest a key relationship between smoking and the presence of certain elements. In addition, chlorine proved to be important in the context of patient prognosis and survival.

Mortality from Selected Cancers among Brazilian Mechanics

Introduction:

Mechanics are exposed to known human carcinogens. This study aimed to compare mortality from selected cancers between male mechanics and the general population of the South and Southeast regions of Brazil.

Methods:

Data on deaths, occurred between 2006-2017, among male mechanics and the general population, were obtained from the Mortality Information System. Occupations were classified using the Brazilian Classification of Occupations. Mortality Odds Ratio (MOR) and confidence intervals (95%) for selected cancers among mechanics, stratified by age (30-49, 50-69 years), race, and education compared to the general population, were estimated using logistic regression models.

Results:

In general, mechanics showed higher mortality from oropharynx, hypopharynx, larynx, lung and bladder cancers, but lower mortality for all leukemias. Oropharynx and larynx cancer mortality risk was slightly higher among older mechanics, while hypopharynx cancer mortality was more noticeable among the youngest. Lower mortality from all leukemias was observed only among younger mechanics. Mortality by oropharynx and larynx cancers were higher among white mechanics. They were also the only ones to experience higher mortality by hypopharynx cancer, while lung cancer mortality were increased only among non-white ones. Mechanics of all educational levels were more likely to die by the oropharynx cancer. Those with 1-7 and 8 or more years of schooling also showed excess of death by the cancers of larynx and all leukemias. Significantly higher mortality by pancreas cancer was only observed among mechanics with no education, while those with 1-7 years of schooling showed higher risk to die by lung and bladder cancers. Those with 8 or more years of schooling show increased mortality risk for hypopharynx cancer. Increased mortality risk for myeloid leukemia was only observed when stratified by region of residence.

Conclusion:

Results of our study suggest a positive association between mechanic occupation and some specific cancers.

MOFs-carbon hybrid nanocomposites in environmental protection applications

The demand for green engineering environmentally friendly nanomaterials had made carbon nanotube a suitable material to keep metal-organic frameworks (MOFs) in the application of wastewater treatment and air pollution monitoring systems. This review summarizes many of the recent research accomplishments in the synthesis of MOFs and MOFs-carbon hybrid nanocomposites for various applications such as wastewater treatment and removal of hazardous gases (CO, SO₂, H₂S and NH₃) with emphasis on MOF/CNTs composites. This review focuses on the efficient removal of pollutants from the environment using adsorption techniques. Another important application of MOFs composite discussed in this review is sensor materials for environmental pollution.

Environmental Health Research in Africa: Important Progress and Promising Opportunities

The World Health Organization in 2016 estimated that over 20% of the global disease burden and deaths were attributed to modifiable environmental factors. However, data clearly characterizing the impact of environmental exposures and health endpoints in African populations is limited. To describe recent progress and identify important research gaps, we reviewed literature on environmental health research in African populations over the last decade, as well as research incorporating both genomic and environmental factors. We queried PubMed for peer-reviewed research articles, reviews, or books examining environmental exposures and health outcomes in human populations in Africa. Searches utilized medical subheading (MeSH) terms for environmental exposure categories listed in the March 2018 US National Report on Human Exposure to Environmental Chemicals, which includes chemicals with worldwide distributions. Our search strategy retrieved 540 relevant publications, with studies evaluating health impacts of ambient air pollution (n=105), indoor air pollution (n = 166), heavy metals (n = 130), pesticides (n = 95), dietary mold (n = 61), indoor mold (n = 9), per- and polyfluoroalkyl substances (PFASs, n = 0), electronic waste (n = 9), environmental phenols (n = 4), flame retardants (n = 8), and phthalates (n = 3), where publications could belong to more than one exposure category. Only 23 publications characterized both environmental and genomic risk factors. Cardiovascular and respiratory health endpoints impacted by air pollution were comparable to observations in other countries. Air pollution exposures unique to Africa and some other resource limited settings were dust and specific occupational exposures. Literature describing harmful health effects of metals, pesticides, and dietary mold represented a context unique to Africa. Studies of exposures to phthalates, PFASs, phenols, and flame retardants were very limited. These results underscore the need for further focus on current and emerging environmental and chemical health risks as well as better integration of genomic and environmental factors in African research studies. Environmental exposures with distinct routes of exposure, unique co-exposures and co-morbidities, combined with the extensive genomic diversity in Africa may lead to the identification of novel mechanisms underlying complex disease and promising potential for translation to global public health.

Household Smoking Status and Heavy Metal Concentrations in Toenails of Children

There is limited evidence on the distribution of heavy metals and its association with secondhand smoking (SHS) within Pacific Island children living in New Zealand. Certain heavy metals such as cadmium (Cd), lead (Pb), and aluminum (Al) bioaccumulates in the body and can deteriorate health in both children and adults. Others, such as chromium (Cr) and nickel (Ni) in trace amounts are necessary but become toxic at high levels. Exposure routes of these elements include food, water, and air. The purpose of this study was to identify the distribution of toxic metal concentrations and its possible correlation with SHS within the Pacific Island children. A sub-sample of children within Pacific Island families longitudinal study, at the nine-year phase, who were living in the New Zealand city of Auckland were invited to participate, (n = 278). Toenails were used as a biomarker to determine Cr, Pb, Cd, Cu, Ni, and Al concentration using inductively coupled plasma mass spectrometry. Reliable and validated questionnaires were used for demographics, lifestyle, and health outcome variables. Significant differences between household smoking status and ethnicity, as well as parents' marital status, were observed (p < 0.05). There was no statistical difference in heavy metal concentrations in smoking versus non-smoking households. However, Cr, Pb, Cd, Cu, and Ni concentrations were all higher than the required optimal health value in both groups. A high concentration of heavy metals was observed in these children that exceeded the value required for optimal health, although no significant difference in heavy metals with regards to secondhand smoking was observed. SHS was associated with children's ethnicity and parental marital status, but not with household income levels or maternal education.

Indoor vs. outdoor airborne element array: A novel approach using moss bags to explore possible pollution sources

This study investigated by the moss-bag approach the pattern of air dispersed elements in 12 coupled indoor/outdoor exposure sites, all located in urban and rural residential areas. The aims were to discriminate indoor vs. outdoor element composition in coupled exposure sites and find possible relation between moss elemental profile and specific characteristics of each exposure site. Elements were considered enriched when in 60% of the sites, post-exposure concentration exceeded pre-exposure concentration plus two folds the standard deviation. Of the 53 analyzed elements, 15 (As, B, Ca, Co, Cr, Cu, Mn, Mo, Ni, Sb, Se, Sn, Sr, V, Zn) were enriched in moss exposed outdoor, whereas a subset of 7 elements (As, B, Cr, Mo, Ni, Se, V) were enriched also in indoor moss samples. The cluster analysis of the sites based on all elements, clearly separated samples in two groups corresponding to mosses exposed indoor and outdoor, with the latter generally exceeding the first. Among outdoor sites, urban were most impacted than rural; whereas other factors (e.g., heating and cooking systems, building material, residence time and family life style) could affect element profile of indoor environments. Based on the indoor/outdoor ratio, As derived from outdoor and indoor sources, B, Mo and Se were enriched mostly in outdoor sites; Ni, Cr and V were specifically enriched in most indoor samples, supporting the presence of indoor emitting sources for these elements. A PCA of all indoor sites based on enriched elements and site characteristics showed that traffic affected indoor pollution in urban areas. The moss bag approach provided useful information for a global assessment of human exposure.

The crosstalk between trace elements with DNA damage response, repair, and oxidative stress in cancer

DNA damage response (DDR) is a regulatory system responsible for maintaining genome integrity and stability, which can sense and transduce DNA damage signals. The severity of damage appears to determine DDRs, which can include damage repair, cell-cycle arrest, and apoptosis. Furthermore, defective components in DNA damage and repair machinery are an underlying cause for the development and progression of various types of cancers. Increasing evidence indicates that there is an association between trace elements and DDR/repair mechanisms. In fact, trace elements seem to affect mediators of DDR. Besides, it has been revealed that oxidative stress (OS) and trace elements are associated with cancer development. In this review, we discuss the role of some critical trace elements in the risk of cancer. In addition, we provide a brief introduction on DDR and OS in cancer. Finally, we will further review the interactions between some important trace elements including selenium, zinc, chromium, cadmium, and arsenic, and DDR, and OS in cancer.

Tobacco influence in heavy metals levels in head and neck cancer cases

Heavy metals intoxication is known to be risk factors for various diseases, including cancer. These metals may be presented in food and soil as well as in leaf and tobacco smoke. The aim of this study was to correlate the exposure to heavy metals stemming from tobacco and head and neck squamous cell carcinoma carcinogenesis. Analysis of lead, copper, manganese, arsenic, chromium, and cadmium by atomic absorption spectrophotometry was performed in whole blood samples from 91 patients: 68 smokers with oral cavity, pharynx, or laryngeal cancer; 8 non-smokers with oral or larynx cancer; and 15 non-cancer smokers with tobacco-related diseases (control group). No differences were found in metals quantifications, except a significant difference was observed (p = 0.0223) with higher mean in copper levels for non-smokers with cancer. The present study concluded, for the groups evaluated, it was not possible to prove the relationship between the studied metals in the development of the neoplasm. On the other hand, the results of copper demonstrated a correlation with smokers with cancer and lower levels of circulating copper.

Risk assessment of occupational exposure to heavy metal mixtures: a study protocol

Background

Sfax is a very industrialized city located in the southern region of Tunisia where heavy metals (HMs) pollution is now an established matter of fact. The health of its residents mainly those engaged in industrial metals-based activities is under threat. Indeed, such workers are being exposed to a variety of HMs mixtures, and this exposure has cumulative properties. Whereas current HMs exposure assessment is mainly carried out using direct air monitoring approaches, the present study aims to assess health risks associated with chronic occupational exposure to HMs in industry, using a modeling approach that will be validated later on.

Methods

To this end, two questionnaires were used. The first was an identification/descriptive questionnaire aimed at identifying, for each company: the specific activities, materials used, manufactured products and number of employees exposed. The second related to the job-task of the exposed persons, workplace characteristics (dimensions, ventilation, etc.), type of metals and emission configuration in space and time.

Indoor air HMs concentrations were predicted, based on the mathematical models generally used to estimate occupational exposure to volatile substances (such as solvents).

Later on, and in order to validate the adopted model, air monitoring will be carried out, as well as some biological monitoring aimed at assessing HMs excretion in the urine of workers volunteering to participate.

Lastly, an interaction-based hazard index HI_int and a decision support tool will be used to predict the cumulative risk assessment for HMs mixtures.

Discussion

One hundred sixty-one persons working in the 5 participating companies have been identified. Of these, 110 are directly engaged with HMs in the course of the manufacturing process. This model-based prediction of occupational exposure represents an alternative tool that is both time-saving and cost-effective in comparison with direct air monitoring approaches. Following validation of the different models according to job processes, via comparison with direct measurements and exploration of correlations with biological monitoring, these estimates will allow a cumulative risk characterization.

Toxicological impact of waterpipe smoking and flavorings in the oral cavity and respiratory system

Waterpipe smoking (WS), an emerging trend has major health concerns. It is prevalent worldwide as a recreational activity both indoors and outdoors. The aim of this review was to assess the impact of waterpipe smoke on the oral and respiratory system (oral cavity and pulmonary tissues). A number of studies have shown that periodontal health status is compromised in waterpipe smokers when compared with nonsmokers. Some studies have associated WS with oral premalignant and malignant lesions; however, due to the poor quality of these studies, the presented outcomes should be interpreted with caution. Although cigarette smoking has been considered as a potential risk factor for dental caries; there are no studies in indexed literature that have shown an association to exist between dental caries and WS. Inhaled waterpipe smoke imposes oxidative stress and inflammatory responses and compromises the ventilatory capacity of the lungs and may lead to an increased risk of decline in lung function. WS may cause oral and pulmonary diseases, such as periodontal disease and chronic obstructive airway disease, respectively. The association between WS and development of dental caries and oral pre-cancer and their relationships with chronic airways disease requires investigations. This review discusses the current evidence of waterpipe smoke effects on the oral health and respiratory system based on basic and clinical science and provides future directions for research and regulatory science on how WS can affect the oral cavity and the respiratory/pulmonary system.

Evaluating levels and health risk of heavy metals in exposed workers from surgical instrument manufacturing industries of Sialkot, Pakistan

The study aimed to monitor heavy metal (chromium, Cr; cadmium, Cd; nickel, Ni; copper, Cu; lead, Pb; iron, Fe; manganese, Mn; and zinc, Zn) footprints in biological matrices (urine, whole blood, saliva, and hair), as well as in indoor industrial dust samples, and their toxic effects on oxidative stress and health risks in exposed workers. Overall, blood, urine, and saliva samples exhibited significantly higher concentrations of toxic metals in exposed workers (Cr; blood 16.30 μg/L, urine 58.15 μg/L, saliva 5.28 μg/L) than the control samples (Cr; blood 5.48 μg/L, urine 4.47 μg/L, saliva 2.46 μg/L). Indoor industrial dust samples also reported to have elevated heavy metal concentrations, as an example, Cr quantified with concentration of 299 mg/kg of dust, i.e., more than twice the level of Cr in household dust (136 mg/kg). Superoxide dismutase (SOD) level presented significant positive correlation (p ≤ 0.01) with Cr, Zn, and Cd (Cr > Zn > Cd) which is an indication of heavy metal's associated raised oxidative stress in exposed workers. Elevated average daily intake (ADI) of heavy metals resulted in cumulative hazard quotient (HQ) range of 2.97-18.88 in workers of different surgical units; this is an alarming situation of health risk implications. Principal component analysis-multiple linear regression (PCA-MLR)-based pie charts represent that polishing and cutting sections exhibited highest metal inputs to the biological and environmental matrices than other sources. Heavy metal concentrations in biological matrices and dust samples showed a significant positive correlation between Cr in dust, urine, and saliva samples. Current study will help to generate comprehensive base line data of heavy metal status in biomatrices and dust from scientifically ignored industrial sector. Our findings can play vital role for health departments and industrial environmental management system (EMS) authorities in policy making and implementation.

Genotoxic effects of cadmium in human head and neck cell line SQ20B

As cadmium may be involved in the etiology of head and neck cancers, we investigated in the present work, the cytotoxic and genotoxic effects of Cd on human larynx cells. SQ20B cells were exposed to 25 and 50 μM Cd for 48 and 72 h. Results showed a dose-dependent decrease in cell viability, especially after 48 h, associated with mitochondria alterations as showed by transmission electronic microscopy. Surprisingly, the flow cytometry shows that the cells treated with Cd have a normal proliferative cycle like the untreated cell especially in G1 or G2 phase of cell cycle. DNA damages were investigated by comet assay and immunofluorescence for gamma layer of the H2AX (g-H2AX) foci formation. Results show a strong induction of DNA double-strand breaks after Cd exposure. Overall, our results demonstrate the cytotoxicity and genotoxicity of Cd in human larynx cells and support the view that Cd could be an etiologic factor of head and neck cancers.

Cancer risk in waterpipe smokers: a meta-analysis

Objectives

To quantify by meta-analysis the relationship between waterpipe smoking and cancer, including cancer of the head and neck, esophagus, stomach, lung and bladder.

Methods

We performed a systematic literature search to identify relevant studies, scored their quality, used fixed and random-effect models to estimate summary relative risks (SRR), evaluated heterogeneity and publication bias.

Results

We retrieved information from 28 published reports. Considering only highquality studies, waterpipe smoking was associated with increased risk of head and neck cancer (SRR 2.97; 95 % CI 2.26–3.90), esophageal cancer (1.84; 1.42–2.38) and lung cancer (2.22; 1.24–3.97), with no evidence of heterogeneity or publication bias. Increased risk was also observed for stomach and bladder cancer but based mainly on poor-quality studies. For colorectum, liver and for all sites combined risk estimates were elevated, but there were insufficient reports to perform a meta-analysis.

Conclusions

Contrary to the perception of the relative safety of waterpipe smoking, this meta-analysis provides quantitative estimates of its association with cancers of the head and neck, esophagus and lung. The scarcity and limited quality of available reports point out the need for larger carefully designed studies in well-defined populations.

Waterpipe smoking and cancer: systematic review and meta-analysis

OBJECTIVE

Although accumulating evidence suggests harmful effects of waterpipe smoking, there is limited information about its direct association with chronic diseases, notably cancer. We provide an up-to-date systematic review and meta-analysis of the association between waterpipe smoking and cancer.

DATA SOURCES

Systematic search of articles indexed in main biomedical databases: Pubmed, EmBase, Google Scholar and Web of Science, published between 1962 and September 2014. Search keywords included a combination of waterpipe or hookah, sheesha, nargile, hubble-bubble, goza or gaylan, and cancer.

STUDY SELECTION

Focus on observational studies (cohort, case-control, cross-sectional) that evaluated the association between waterpipe smoking and cancer. Studies with mixed exposures excluded.

DATA EXTRACTION

Two investigators independently extracted data and reached consensus on all items.

DATA SYNTHESIS

13 case-control studies met the inclusion criteria and were considered for meta-analysis. The methodological quality of included studies was assessed using the Newcastle-Ottawa Scale (NOS). Meta-analysis revealed a positive association between waterpipe smoking and lung cancer (OR=4.58 (2.61 to 8.03); I²=44.67%), and oesophageal cancer (OR=3.63 (1.39 to 9.44); I² =94.49%). The majority of studies had a NOS score of 5-6 or 7, indicating 'fair' or 'good' quality, respectively.

CONCLUSIONS

Our findings support a positive association between waterpipe smoking and cancer risk. However, high-quality studies with standardised exposure measurements are needed to clarify the contribution of waterpipe smoking to chronic diseases. More investments in initiatives for surveillance, intervention and regulatory policy for waterpipe smoking are urgently warranted.

Association between levels of urinary heavy metals and increased risk of urothelial carcinoma

OBJECTIVES

To evaluate possible sources of exposure to heavy metals in the general population, and to determine the association between urinary heavy metals and urothelial carcinoma risk.

METHODS

We recruited 205 patients with urothelial carcinoma and 406 control participants for a case-control study between June 2011 and December 2013. The control participants were frequency-matched with cases according to sex and age. We measured the urinary levels of arsenic, cadmium, chromium, nickel and lead by using inductively coupled plasma mass spectrometry. We collected environmental exposure-related information through questionnaires. Multivariate logistic regression and 95% confidence intervals were applied to estimate the urothelial carcinoma risk and potential effects of urothelial carcinoma-related risk factors on the levels of urinary heavy metals.

RESULTS

Patients with urothelial carcinoma showed higher urinary levels of arsenic, cadmium, chromium, nickel and lead than the controls. After considering other potential risk factors, a significantly increased risk for urothelial carcinoma was observed in patients with increased urinary levels of cadmium, chromium, nickel and lead. Smokers showed a high urinary cadmium level. In addition to cadmium, a high urinary lead level was associated with cumulative cigarette smoking and herbal medicine use.

CONCLUSION

Environmental factors might contribute to higher urinary levels of heavy metals and ultimately result in urothelial carcinoma carcinogenesis. These findings can promote proper environmental surveillance of exposure to heavy metals in the general population.

Estimation of Nickel in Different Smokeless Tobacco Products and Their Impact on Human Health of Oral Cancer Patients

It has been extensively investigated that the chewing of smokeless tobacco (SLT) products may enhance the inflammation of the oral cavity. The aim of the present study is to evaluate the relationship between nickel (Ni) exposure via different SLT products with oral cancer (different sites) incidence in the population of Sindh, Pakistan. The different brands of SLT products (mainpuri, gutkha, and moist snuff) commonly consumed by the studied population were analyzed for Ni contents. The biological samples of oral cancer patients and noncancerous control subjects of both genders, who have or have not consumed SLT products, were collected. The concentration of Ni in biological samples and SLT products were measured by electrothermal atomic absorption spectrophotometer after microwave-assisted acid digestion. The validity and accuracy of the methodology were checked by using certified reference materials. The results of this study showed that the Ni level was significantly higher in scalp hair and blood samples of oral cancer patients compared to controls (P < 0.01). The study suggested that exposure of Ni as a result of chewing different SLT products may be synergistic with risk factors associated with oral cancer.

Analysis of serum levels of 15 trace elements in breast cancer patients in Shandong, China

Experimental and epidemiological studies suggest that serum levels of trace elements may be associated with breast cancer risk. We compared serum levels of 15 trace elements between breast cancer patients and normal controls from Shandong, China, for the first time to assess whether serum levels of trace elements were associated with breast cancer risk. Eighty-eight breast cancer patients and 84 healthy controls were enrolled in the study. A Spectraspan V direct current plasma atomic emission spectrometer was used to determine the serum levels of 15 trace elements including Zn, Mn, Al, Cd, Fe, Mg, Ca, Pb, Cu, Se, Ni, Ti, Co, Li, and Cr. Breast cancer patients had significantly higher serum levels of Cd (p = 0.000), Mg (p = 0.001), Cu (p = 0.000), Co (p = 0.006), and Li (p = 0.003) and borderline higher Cr (p = 0.052), while significantly lower Mn (p = 0.000), Al (p = 0.000), Fe (p = 0.000), and Ti (p = 0.000) compared to their matched controls. However, there were no significant differences in serum levels of Zn (p = 0.824), Ca (p = 0.711), Pb (p = 0.274), Se (p = 0.236), and Ni (p = 0.185) between the two groups. Our study showed a possible association between serum levels of trace elements and breast cancer risk in eastern China, though it warrants further investigations to confirm the association. If confirmed, modulation of trace elements may help reduce breast cancer risk.

Cadmium and nickel in blood of Tunisian population and risk of nasosinusal polyposis disease

Nasosinusal polyposis (NSP) is a chronic inflammatory disease of the nasal mucosa. Although the pathophysiology underlying NSP formation is not fully understood, environmental factors appear to be contributed the development of this disease. A case-control study of Tunisian patients was examined to assess the levels of cadmium (Cd) and nickel (Ni) in blood and reparse the association between the exposure to these metals and the risk of nasosinusal polyposis disease. Mean blood levels of Cd in patients (2.2 ± 12.8 μg/L) were significantly higher than those of controls (0.5 ± 0.7 μg/L). Levels of blood Cd were positively correlated with tobacco smoking and chewing among controls. The Cd and Ni concentrations among control (p = 0.001) and patient (p = 0.018) tobacco consumers (smoking, chewing, and shisha) were significantly higher than those nonconsumers. Additionally, Ni blood levels of patient and control smokers were significantly higher than those of nonsmokers. Cd levels in blood samples of NSP patients occupationally exposed for more than 14 years were eight times higher than that of nonexposed. Drinking water was also found to be incriminated as exposure sources. Among risk factors, shisha consumption, environmental exposure, and occupational exposure presented the most significant association with NSP disease (odds ratio (OR) = 14.1, 10.1, and 1.7, respectively). High levels of blood Cd (OR = 3.5) were strongly associated with NSP disease (p = 0.027). Ni blood levels were shown to be associated with the four stages of polyps in both nasal cavities (right and left) (p < 0.05). This investigation suggested a potential role of toxic metals in the mechanism of NSP disease development. Exposure assessment investigations encompassing a wider population are needed.

Ni(ii) ions cleave and inactivate human alpha-1 antitrypsin hydrolytically, implicating nickel exposure as a contributing factor in pathologies related to antitrypsin deficiency

Ni(ii) ions cleave AAT hydrolytically, inactivating the protein.

Heavy metals in normal mucosa and nasal polyp tissues from Tunisian patients

Despite growing evidence that bacteria, fungi, allergens, and superantigens play a prominent role in the pathophysiology of nasal polyps (NP), the exact cause of polyposis is still unknown. The etiology of NP is considered multifactorial. Until now, there is no information on the presence of heavy metals, such as cadmium (Cd), chromium (Cr), nickel (Ni), and arsenic (As) or of their role, in the pathogenesis of NP disease. In this study, concentrations of these four metals in tissue of NP were determined using Atomic Absorption Spectrometry. The Ni, Cr, and As levels in NP tissues were 2.1-, 3.2-, and 8.0-fold higher than those of normal mucosa (p < 0.05), respectively. A strong effect of cumulative smoking as expressed in the number of pack per year (PY), Ni, As, and Cd levels in NP tissue samples of patients ever-smokers (1-20 and >20 PY) are significantly higher than those of non-smokers (p = 0.006, 0.002, and < 0.001, respectively). The highest As concentrations among patients lived at polluted areas (1-25 and > 25 years) were observed in both nasal mucosa and NP tissues. The Ni and As in both nasal mucosa and NP tissues of patients occupationally exposed were significantly higher than non-exposed group. Cr and As levels were found to be associated with NP stage classification (p < 0.05). This is the first report to describe an association between concentrations of metals (Cr, As, and Ni) in human NP tissues and the risk of NP disease. Tissue metal levels have increased due to smoking, environmental, and occupational exposure. Therefore, heavy metal exposure may increase the risk of NP in the Tunisian population. The considerable risk in the category of highest cumulative exposure argues for an association between heavy metals exposure and nasal polyposis risk. Future investigations with larger samples should better elucidate this association.

Nickel nanoparticles exposure and reproductive toxicity in healthy adult rats

Nickel is associated with reproductive toxicity. However, the reproductive toxicity of nickel nanoparticles (Ni NPs) is unclear. Our goal was to determine the association between nickel nanoparticle exposure and reproductive toxicity. According to the one-generation reproductive toxicity standard, rats were exposed to nickel nanoparticles by gavage and we selected indicators including sex hormone levels, sperm motility, histopathology, and reproductive outcome etc. Experimental results showed nickel nanoparticles increased follicle stimulating hormone (FSH) and luteinizing hormone (LH), and lowered etradiol (E₂) serum levels at a dose of 15 and 45 mg/kg in female rats. Ovarian lymphocytosis, vascular dilatation and congestion, inflammatory cell infiltration, and increase in apoptotic cells were found in ovary tissues in exposure groups. For male rats, the weights decreased gradually, the ratio of epididymis weight over body weight increased, the motility of rat sperm changed, and the levels of FSH and testosterone (T) diminished. Pathological results showed the shedding of epithelial cells of raw seminiferous tubule, disordered arrangement of cells in the tube, and the appearance of cell apoptosis and death in the exposure group. At the same time, Ni NPs resulted in a change of the reproductive index and the offspring development of rats. Further research is needed to elucidate exposure to human populations and mechanism of actions.

Determination of nickel in blood and serum samples of oropharyngeal cancer patients consumed smokeless tobacco products by cloud point extraction coupled with flame atomic absorption spectrometry

Oropharyngeal cancer is a significant public health issue in the world. The incidence of oropharyngeal cancer has been increased among people who have habit of chewing smokeless tobacco (SLT) in Pakistan. The aim of present study was to evaluate the concentration of nickel (Ni) in biological samples (whole blood, serum) of oral (n = 95) and pharyngeal (n = 84) male cancer patients. For comparison purposes, the biological samples of healthy age-matched referents (n = 150), who consumed and did not consumed SLT products, were also analyzed for Ni levels. As the Ni level is very low in biological samples, a preconcentration procedure has been developed, prior to analysis of analyte by flame atomic absorption spectrometry (FAAS). The Ni in acid-digested biological samples was complexed with ammonium pyrrolidinedithio carbamate (APDC), and a resulted complex was extracted in a surfactant Triton X-114. Acidic ethanol was added to the surfactant-rich phase prior to its analysis by FAAS. The chemical variables, such as pH, amounts of reagents (APDC, Triton X-114), temperature, incubation time, and sample volume were optimized. The resulted data indicated that concentration of Ni was higher in blood and serum samples of cancer patients as compared to that of referents who have or have not consumed different SLT products (p = 0.012-0.001). It was also observed that healthy referents who consumed SLT products have two to threefold higher levels of Ni in both biological samples as compared to those who were not chewing SLT products (p < 0.01).

Heavy Metal Content in Thoracic Tissue Samples from Patients with and without NSCLC

Objectives. Environmental factors expose an individual to heavy metals that may stimulate cancer growth preclinically including non-small cell lung cancer (NSCLC) cells. Here, we examine the prevalence of four heavy metals present in postsurgical tissues from individuals with and without NSCLC. Materials and Methods. Thoracic tissue samples from two separate sample sets were analyzed for cadmium (Cd), arsenic (As), mercury (Hg), and lead (Pb) content. Results. In the first sample set, there was no significant measurable amount of Pb and Hg found in either NSCLC tissue or nonmalignant lung tissue samples. Cd was the most prevalent heavy metal and As was present in moderate amounts. In the second sample set, Cd was measurable across all tissue types taken from 28 NSCLC patients and significantly higher Cd was measurable in noncancer benign lung (n = 9). In the NSCLC samples, As was measurable in moderate amounts, while Hg and Pb amounts were negligible. Conclusion. Cd and As are present in lung tissues for patients with NSCLC. With existing preclinical evidence of their tumorigenecity, it is plausible that Cd and/or As may have an impact on NSCLC development. Additional studies examining the prevalence and association between smokers and nonsmokers are suggested.

DNA repair gene polymorphisms and risk of head and neck cancer in the Tunisian population

Altered activity of DNA repair enzymes may be involved in modulating cancer susceptibility and pathogenesis of head and neck cancer (HNC). We conducted a case-control study to test the association between three common single-nucleotide polymorphisms of XRCC1, ERCC2, and ERCC3 genes with HNC risk in Tunisian patients. To the best of our knowle dge, this is the first report on polymorphisms in XRCC1, ERCC2, and ERCC3 and susceptibility to HNC in our population. The genotype analyses of XRCC1 Arg399Gln, ERCC2 Lys751Gln, and ERCC3 7122 A>G polymorphisms for 169 HNC patients, and 261 controls were performed using the PCR-based restriction fragment length polymorphism. Stratification of the populations according to smoking and drinking habits and occupational exposure highlighted the importance of tobacco, alcohol, and toxic substance as three risk co-factors for the development of HNC. Our study suggests that only the XRCC1 Arg399Gln polymorphism was associated with the risk of HNC in the Tunisian population (OR = 2.04; P = 0.001). Furthermore, the risk of HNC was associated with XRCC1 Arg399Gln polymorphism stratified by occupational exposure status (OR = 2.29; P = 0.024). However, no statistically significant association was observed between the risk of developing HNC and the ERCC2 Lys751Gln and ERCC3 A>G polymorphisms. These data suggest that the XRCC1 Arg399Gln polymorphism is associated with an increased risk of developing HNC, because it correlates with occupational exposure in Tunisian population.

Cytogenetic abnormality in exfoliated cells of buccal mucosa in head and neck cancer patients in the Tunisian population: impact of different exposure sources

Chromosome/DNA instability could be one of the primary causes of malignant cell transformation. The objective of the present study was to evaluate the spontaneous genetic damages in exfoliated cells of buccal mucosa of head and neck cancer (HNC) by counting micronucleus (MN) and binucleated (BN) cells frequencies. MN and BN frequencies were significantly increased in HNC patients compared with controls (5.53 ± 3.09/1000 cells, 5.63 ± 2.99/1000 cells versus 2.36 ± 2.11/1000 cells, 3.09 ± 1.82/1000 cells, P < 0.001). Regarding the gender and the age, the frequencies of the MN and BN were significantly higher than those of controls (P < 0.01). The evaluation of the MN and BN frequencies revealed a significant increase (P < 0.001) in the cases in relation to the control group after controlling the risk factors (tobacco smoking and chewing and occupational exposure) of HNC. Moreover, MN and BN frequencies were significantly increased in smokers and chewers compared with nonsmokers and nonchewers among patients (P < 0.05). MN frequency was significantly (P = 0.014) different between patients occupationally exposed (6.99 ± 3.40/1000 cells) and nonexposed (4.70 ± 2.48/1000 cells) among HNC group. The logistic regression model illustrated that HNC was significantly associated with frequencies of MN (OR = 8.63, P < 0.0001) and BN (OR = 5.62, P = 0.001). Our results suggest that increased chromosome/DNA instabilities may be associated with HNC.

Arsenic, cadmium, chromium and nickel in cancerous and healthy tissues from patients with head and neck cancer

Chronic exposure to heavy metals has long been recognized as being capable to increase head and neck cancer incidence among exposed human populations. Head and neck cancer is a significant public health issue in Tunisia. The aim of the present study was to evaluate the concentrations of As, Cd, Cr and Ni in healthy and tumor tissues of head and neck cancer patients. Metal concentrations were determined in tumor and healthy tissues of 101 head and neck cancer patients, using Atomic Absorption Spectrometry. The As, Cd, Cr, and Ni levels in tumor tissues were 3.4, 2.5, 1.3 and 1.5 times higher than those of healthy tissues (p<0.05), respectively. Tumor tissue metal levels were higher in men than in women. As and Cd levels in tumor and healthy tissue samples of patients smokers are significantly higher than those of non-smokers (p<0.05). A strong effect of cumulative smoking as expressed in the number of pack per year, and tumor tissue Cd levels were positively associated with three groups of age (<40, 51-60 and >60 years) in both never-smokers and ever-smokers (<20 and ≥20 pack per year). Healthy tissue Cd levels were negatively associated with age in those three groups of smokers. The highest Cd and Cr concentrations among both workers and non-workers were observed in tumor tissues. The Cd and Cr in tissues of farmers, bricklayers and painters were all significantly higher among the workers as compared with the non-workers group. Tissue metal levels have increased due to smoking and occupational exposure. Heavy metal exposure via tobacco smoking and occupational exposures may increase the risk of head and neck in the Tunisian population.