Occupational exposure of firefighters to polycyclic aromatic hydrocarbons in non-fire work environments

This work aims to characterize personal exposure of firefighters to polycyclic aromatic hydrocarbons (PAHs) in non-fire work environments (fire stations), and assesses the respective risks. Eighteen PAHs (16 considered by USEPA as priority pollutants, dibenzo[a,l] pyrene and benzo[j] fluoranthene) were monitored in breathing zones of workers at five Portuguese fire stations during a normal shift. The obtained levels of PAHs fulfilled all existent occupational exposure limits as well as air quality guidelines with total concentrations (Sigma PAHs) in range of 46.8-155 ng m(-3). Light compounds (2-3 rings) were the most predominant congeners (74-96% of Sigma PAHs) whereas PAHs with 5-6 rings accounted 3-9% of Sigma PAHs. Fuel and biomass combustions, vehicular traffic emissions, and use of lubricant oils were identified as the main sources of PAHs exposure at the studied fire corporations. Incremental lifetime cancer risks were below the recommend USEPA guideline of 10(-6) and thus negligible for all the studied subjects, but WHO health-based guideline level of 10(-5) was exceeded (9-44 times) at all fire corporations. These results thus show that even during non-fire situations firefighters are exposed to PAHs at levels that may promote some adverse health outcomes; therefore the respective occupational exposures to these compounds should be carefully controlled. (C) 2017This work was supported by European Union (FEDER funds through COMPETE) and National Funds (Fundação para a Ciência e Tecnologia) through projects UID/QUI/50006/2013, POCI/01/0145/FEDER/007265 and UID/EQU/00511/2013-LEPABE, by the FCT/MECwith national funds and co-funded by FEDER in the scope of the P2020 Partnership Agreement. Additional financial support was provided by Fundação para Ciência e Tecnologia through fellowships SFRH/BD/80113/2011 and SFRH/BPD/105100/2014. The authors are thankful to all firefighters involved in the study and to collaborators from Escola Superior de Saúde from Instituto Politécnico de Bragança.info:eu-repo/semantics/publishedVersio

Biomonitoring of firefighters occupational exposure to polycyclic aromatic hydrocarbons during the 2014 hot season

Human biomonitoring is an important tool in environmental medicine that is used to assess the level of internal exposure to environmental pollutants. Firefighters are one of the most exposed and least studied occupations. During fire suppression, firefighters are heavily exposed to a wide range of chemicals. Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants that are considered as the largest known group of carcinogens due to their cytotoxic and mutagenic properties. Smoke and ashes released during a fire are important sources of PAH. Firefighters can be also exposed to PAH through smoking, via polluted ambient air, water, soil, and through consumption of food. Metabolites of PAH (OH-PAHs), such as 1-hydroxynaphthalene (1OHNapt), 1-hydroxyacenaphthene(1OHAce), 1-hydroxypyrene (1OHPy) and 3-hydroxybenzo[a]pyrene (3OHB[a]P) have been used as biological markers for measurements of human internal exposure to PAH. The present work aims to quantify the urinary metabolites of PAH, namely 1OHNapt, 1OHAce, 1OHPy and 3OHB[a]P in study population of firefighters. Firemen exposed to fires that occurred during 2014 season were asked to fill a post-fire questionnaire and to collect urinary samples. A control study population group was selected to collect samples of urines during the pre-fires season (winter). Among all participating firemen only healthy no-smoking subjects were considered. OH-PAHs were analysed by high-performance liquid chromatography with fluorescence detection. Overall, 1OHNapt and 1OHAce were the most abundant OH-PAHs in firemen urine samples, accounting for approximately 90% of the total OH-PAHs. The urinary OH-PAHs in exposed firefighters were higher than those of control group. Data collected with the individual questionnaire were further used to analyse the concentrations of OH-PAH between (and within) control and exposed groups of firemen. Additionally, 1OHPy concentrations in the exposed firefighters will be compared with the available proposed guidelines

Urinary levels of monohydroxyl PAH metabolites in portuguese firefighters: background levels and impact of tobacco smoke

Firefighting occupational exposure is classified as possible carcinogen to humans by the International Agency for Research on Cancer and the US National Institute for Occupational Safety and Health [1,2]. Tobacco smoke is a very important factor in the assessment of occupational exposure of workers, since the prolonged exposure to tobacco smoke is by itself the major cause of lung cancer [3]. The consumption of tobacco is responsible for the exposure to many smoke components including more than sixty known carcinogens, including some polycyclic aromatic hydrocarbons (PAHs) [4]. PAHs are ubiquitous compounds formed during pyrolysis or incomplete combustion of organic matter, being well-known for their toxic, mutagenic, and carcinogenic properties to humans [5,6]. So far, the impact of tobacco smoke on firefighters’ total exposure to PAHs is very limited.info:eu-repo/semantics/publishedVersio

Chaotic Diffusion on Periodic Orbits: The Perturbed Arnol'd Cat Map

Chaotic diffusion on periodic orbits (POs) is studied for the perturbed Arnol'd cat map on a cylinder, in a range of perturbation parameters corresponding to an extended structural-stability regime of the system on the torus. The diffusion coefficient is calculated using the following PO formulas: (a) The curvature expansion of the Ruelle zeta function. (b) The average of the PO winding-number squared, $w^{2}$, weighted by a stability factor. (c) The uniform (nonweighted) average of $w^{2}$. The results from formulas (a) and (b) agree very well with those obtained by standard methods, for all the perturbation parameters considered. Formula (c) gives reasonably accurate results for sufficiently small parameters corresponding also to cases of a considerably nonuniform hyperbolicity. This is due to {\em uniformity sum rules} satisfied by the PO Lyapunov eigenvalues at {\em fixed} $w$. These sum rules follow from general arguments and are supported by much numerical evidence.Comment: 6 Tables, 2 Figures (postscript); To appear in Physical Review

Firefighters exposure to fire emissions: Impact on levels of biomarkers of exposure to polycyclic aromatic hydrocarbons and genotoxic/oxidative-effects

Firefighters represent one of the riskiest occupations, yet due to the logistic reasons, the respective exposure assessment is one of the most challenging. Thus, this work assessed the impact of firefighting activities on levels of urinary monohydroxyl-polycyclic aromatic hydrocarbons (OHPAHs; 1-hydroxynaphthalene, 1-hydroxyacenaphthene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, 1-hydroxypyrene, 3-hydroxybenzo(a)pyrene) and genotoxic/oxidative-effect biomarkers (basal DNA and oxidative DNA damage) of firefighters from eight firehouses. Cardiac frequency, blood pressure and arterial oxygen saturation were also monitored. OHPAHs were determined by liquid-chromatography with fluorescence detection, while genotoxic/oxidative-effect biomarkers were assessed by the comet assay. Concentrations of total OHPAHs were up to 340% higher (p≤0.05) in (nonsmoking and smoking) exposed workers than in control subjects (non-smoking and non-exposed to combat activities); the highest increments were observed for 1-hydroxynaphthalene and 1-hydroxyacenaphthene (82–88% of ΣOHPAHs), and for 2-hydroxyfluorene (5–15%). Levels of biomarker for oxidative stress were increased in non-smoking exposed workers than in control group (316%; p≤0.001); inconclusive results were found for DNA damage. Positive correlations were found between the cardiac frequency, ΣOHPAHs and the oxidative DNA damage of non-smoking (non-exposed and exposed) firefighters. Evidences were raised regarding the simultaneous use of these biomarkers for the surveillance of firefighters’ health and to better estimate the potential short-term health risks.info:eu-repo/semantics/publishedVersio

Incompatible sets of gradients and metastability

We give a mathematical analysis of a concept of metastability induced by incompatibility. The physical setting is a single parent phase, just about to undergo transformation to a product phase of lower energy density. Under certain conditions of incompatibility of the energy wells of this energy density, we show that the parent phase is metastable in a strong sense, namely it is a local minimizer of the free energy in an $L^1$ neighbourhood of its deformation. The reason behind this result is that, due to the incompatibility of the energy wells, a small nucleus of the product phase is necessarily accompanied by a stressed transition layer whose energetic cost exceeds the energy lowering capacity of the nucleus. We define and characterize incompatible sets of matrices, in terms of which the transition layer estimate at the heart of the proof of metastability is expressed. Finally we discuss connections with experiment and place this concept of metastability in the wider context of recent theoretical and experimental research on metastability and hysteresis.Comment: Archive for Rational Mechanics and Analysis, to appea

The leading Ruelle resonances of chaotic maps

The leading Ruelle resonances of typical chaotic maps, the perturbed cat map and the standard map, are calculated by variation. It is found that, excluding the resonance associated with the invariant density, the next subleading resonances are, approximately, the roots of the equation $z^4=\gamma$, where $\gamma$ is a positive number which characterizes the amount of stochasticity of the map. The results are verified by numerical computations, and the implications to the form factor of the corresponding quantum maps are discussed.Comment: 5 pages, 4 figures included. To appear in Phys. Rev.

Scaling Solutions and reconstruction of Scalar Field Potentials

Starting from the hypothesis of scaling solutions, the general exact form of the scalar field potential is found. In the case of two fluids, it turns out to be a negative power of hyperbolic sine. In the case of three fluids the analytic form is not found, but is obtained by quadratures.Comment: 5 pages, 2 figures, some changes in references and figures caption

Generalized Chaplygin Gas, Accelerated Expansion and Dark Energy-Matter Unification

We consider the scenario emerging from the dynamics of a generalized $d$-brane in a $(d+1, 1)$ spacetime. The equation of state describing this system is given in terms of the energy density, $\rho$, and pressure, $p$, by the relationship $p = - A/\rho^{\alpha}$, where $A$ is a positive constant and $0 < \alpha \le 1$. We discuss the conditions under which homogeneity arises and show that this equation of state describes the evolution of a universe evolving from a phase dominated by non-relativistic matter to a phase dominated by a cosmological constant via an intermediate period where the effective equation of state is given by $p = \alpha \rho$.Comment: 5 pages, 4 figures, revte

Potential-density pairs for axisymmetric galaxies: the influence of scalar fields

We present a formulation for potential-density pairs to describe axisymmetric galaxies in the Newtonian limit of scalar-tensor theories of gravity. The scalar field is described by a modified Helmholtz equation with a source that is coupled to the standard Poisson equation of Newtonian gravity. The net gravitational force is given by two contributions: the standard Newtonian potential plus a term stemming from massive scalar fields. General solutions have been found for axisymmetric systems and the multipole expansion of the Yukawa potential is given. In particular, we have computed potential-density pairs of galactic disks for an exponential profile and their rotation curves.Comment: 8 pages, no figures, corrected version to the one that will appear in Gen. Relativ. Gravit., where a small typo in eq. (13) is presen