Marina Buratti

The speciation of the chemical forms of arsenic in the biological monitoring of exposure to inorganic arsenic

Total As content may be determined in blood and urine by means of an AAS method that involves reduction of As to its volatile hydride and ashing at 600 degrees C with MgO and Mg (NO3)2. Separation of inorganic As (InAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMAA) by ion-exchange chromatography, followed by direct AAS analysis, allows the determination of each As species in the urine. In a reference population of 148 subjects with only normal environmental exposure to As, total As concentration in the urine averages 17.2 +/- 11.1 micrograms/l. Urinary As consists of 10% each of InAs, MMAA and DMAA, the remaining 70% consisting of other forms of organic As. Blood As concentration averages 5.1 +/- 6.9 micrograms/l and correlates significantly with the urinary concentration of InAs and the sum of its metabolites (InAs + MMAA + DMAA). Inorganic arsenic undergoes methylation in the organism. After ingestion of high quantities of As2O3, the time course of excretion of its metabolites indicates that As methylation occurs by a saturable mechanism. In workers exposed to As2O3, InAs, MMAA and DMAA are the only chemical forms of As excreted in the urine that are relevant to a study of occupational exposure. Blood As concentration is proportional to exposure and correlates only with urinary DMAA excretion; DMAA seems to be the most appropriate single indicator of exposure. At high levels of exposure (total As excretion above 200 micrograms/l), As accumulates in the organism and DMAA excretion reflects its accumulation. At low levels of exposure (total As excretion below 50 micrograms/l) a short-term accumulation does not occur and the best biological indicator of exposure is InAs excretion. Seafood ingestion brings about a marked increase in urinary excretion of total As that lasts for 24-48 h and is not accompanied by any increase in InAs, MMAA or DMAA excretion. Organic As from seafood does not mix with the pool of inorganic As in the organism and may be separately detected in urine. In the biological monitoring of human exposure to As, particularly in the case of high urinary values, the speciation of the chemical forms of As in urine is necessary in order to establish with certainty the source, industrial or alimentary, of exposure.

Monitoring low benzene exposure : comparative evaluation of urinary biomarkers, influence of cigarette smoking and genetic polymorphisms

Benzene is a human carcinogen and an ubiquitous environmental pollutant. Identification of specific and sensitive biological markers is critical for the definition of exposure to low benzene level and the evaluation of the health risk posed by this exposure. This investigation compared urinary trans,trans-muconic acid (t,t-MA), S-phenylmercapturic acid, and benzene (U-benzene) as biomarkers to assess benzene exposure and evaluated the influence of smoking and the genetic polymorphisms CYP2E1 (RsaI and DraI) and NADPH quinone oxidoreductase-1 on these indices. Gas station attendants, urban policemen, bus drivers, and two groups of controls were studied (415 subjects). Median benzene exposure was 61, 22, 21, 9 and 6 μg/m3, respectively, with higher levels in workers than in controls. U-benzene, but not t,t-MA and S-phenylmercapturic acid, showed an exposure-related increase. All the biomarkers were strongly influenced by cigarette smoking, with values up to 8-fold higher in smokers compared with nonsmokers. Significant correlations of the biomarkers with each other and with urinary cotinine were found. A possible influence of genetic polymorphism of CYP2E1 (RsaI and/or DraI) on t,t-MA and U-benzene in subjects with a variant allele was found. Multiple linear regression analysis correlated the urinary markers with exposure, smoking status, and CYP2E1 (RsaI; R2 up to 0.55 for U-benzene). In conclusion, in the range of investigated benzene levels (<478 μg/m3 or <0.15 ppm), smoking may be regarded as the major source of benzene intake; among the study indices, U-benzene is the marker of choice for biomonitoring low-level occupational and environmental benzene exposure.

Headspace solid-phase microextraction for the determination of benzene, toluene, ethylbenzene and xylenes in urine

A method for the determination of benzene, toluene, ethylbenzene and xylenes (BTEX) in urine of people exposed to these airborne pollutants present in the living environment, has been described. Solid-phase microextraction has been used for sampling BTEX from the headspace of urine and gas chromatography-mass spectrometry has been applied for the selective analysis of chemicals. The method has the following features: small volume of urine (2 ml) needed, linearity in the range of interest (from the limit of detection up to 5000 ng/l) with coefficient of correlation > or =0.998, limit of detection in the range 12-34 ng/l, good repeatability (coefficient of variation 2-7%), high specificity. The stability of the urine sample during storage (-20 degrees C) was evaluated: BTEX remained stable for up to 2 months. The assay has been successfully applied to the biological monitoring of two subjects environmentally exposed to airborne BTEX in an urban area.

Biological and environmental monitoring of exposure to airborne benzene and other aromatic hydrocarbons in Milan traffic wardens

Environmental and biological monitoring of airborne aromatic hydrocarbons has been performed in 20 policemen working as traffic wardens exposed to motor vehicle exhausts and in 19 peers employed as clerks. Airborne benzene, toluene, ethylbenzene and xylene concentrations, measured during the workshift, resulted in significantly higher outdoor than indoor concentrations (benzene and related aromatic hydrocarbons mean values, respectively of 53 and 350 micrograms/m3 vs. 29 and 180 micrograms/m3). Blood benzene, toluene, ethylbenzene and xylene concentrations did not differ significantly between indoor and outdoor workers; no differences were found between values obtained at the beginning (07:30 h) and the end of shift (00:30) in either group. Blood hydrocarbon concentrations seem to reflect airborne pollution, whilst the blood benzene concentration determined after the workshift poorly reflects airborne benzene morning peaks. Endshift blood benzene mean concentration in smokers (462 ng/l, n = 9) differs significantly from non-smokers (292 ng/l, n = 39).

Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons as biomarkers of exposure in asphalt workers

Abstract Background. Fumes and vapours released during laying of hot asphalt mix have been recognised as a major source of exposure for asphalt workers. Objectives. We investigated the relationships between inhalation exposure to asphalt emissions and urinary biomarkers of polycyclic aromatic hydrocarbons (PAHs) in asphalt workers (AW, n=75) and in ground construction workers (CW, n=37). Methods. Total polyaromatic compounds (PAC) and 15 priority PAHs in inhaled air were measured by personal sampling. Hydroxylated PAH metabolites (OH-PAHs) (2-naphthol, 2-hydroxyfluorene, 3-hydroxyphenanthrene, 1-hydroxypyrene, 6-hydroxychrysene and 3-hydroxybenzo[a]pyrene) were determined in urine spot samples collected in three different times during the work week. Results. Median vapour-phase PAC (5.5 µg m–3), PAHs (≤50 ng m–3) and OH-PAHs (0.08–1.11 µg l–1) were significantly higher in AW than in CW, except in the cases of air naphthalene and 2-naphthol. Airborne levels of particle-phase contaminants were similar in the two groups and much lower than vapour-phase levels; metabolites of particulate PAHs were never found in quantifiable amounts. An appreciable increase in OH-PAH levels during the work day and work week was found in AW; median levels for 2-hydroxyfluorene, 3-hydroxyphenanthrene and 1-hydroxypyrene were, respectively, 0.29, 0.08 and 0.18 at baseline; 0.50, 0.18 and 0.29, pre-shift; 1.11, 0.44 and 0.44 µg l–1, post-shift. Each OH-PAH exhibited a characteristic profile of increase, reflecting differences in half-lives of the parent compounds. In non-smoking subjects, positive correlations were found between vapour-phase PAC or PAHs and OH-PAHs both in pre- and post-shift samples (0.34 ≤ r≤69). Smokers exhibited 2–5-fold higher OH-PAHs than non-smokers, at any time and at both workplaces. Conclusions. Our results suggest that OH-PAHs are useful biomarkers for monitoring exposure to asphalt emissions. The work-related exposure to PAC and PAHs was low in all AW, but urinary metabolites reflected exposure satisfactorily.

Evaluation of Exposure to PAHs in Asphalt Workers by Environmental and Biological Monitoring

Abstract:  In the present article we assessed exposure to polycyclic aromatic hydrocarbons (PAHs) in Italian asphalt workers (AW, n= 100), exposed to bitumen fumes and diesel exhausts, and in roadside construction workers (CW, n= 47), exposed to diesel exhausts, by means of environmental and biological monitoring. 1‐Hydroxypyrene (OH‐Py) was determined in urine spot samples collected, respectively, after 2 days of vacation (baseline), before, and at the end of the monitored work shift, in the second part of the workweek. Median airborne levels during the work shift of 15 PAHs (both vapor and particulate phases), from naphthalene (NAP) to indeno(1,2,3‐cd)pyrene, ranged from below 0.03 to 426 ng/m3. Median excretion values of OH‐Py in baseline, before‐ and end‐shift samples were 228, 402, and 690 ng/L for AW and 260, 304, and 378 ng/L for CW. Lower values were found in nonsmokers compared to smokers (e.g., in AW 565 and 781 versus 252 and 506 ng/L in before‐shift and end‐shift samples, respectively). In all subjects a weak correlation between personal exposure to the sum of airborne 15 PAHs and OH‐Py was observed (r= 0.30). The results of this article show that AW experienced a moderate occupational exposure to airborne PAHs, resulting in a significant increase of urinary OH‐Py during the workday and the workweek. The contribution of working activities to internal dose was in the same order of magnitude of the contribution of cigarette smoking.

Behaviour of plasma and urinary aluminium levels in occupationally exposed subjects

SummaryAluminium in urine (A1U) and in plasma (AlP) was determined in seven subjects occupationally exposed to environmental concentrations of aluminium below or equal to the TWA (5 mg/m3). The AlU levels in these workers were markedly higher than those found in the control group. The levels of the indicator were definitely higher at the end of the shift than at the beginning of the same working day; also, the AlU levels were higher on Friday morning than on Monday morning. After an interruption in work of two weeks, the values of the indicator underwent a marked reduction and were then only slightly higher than those of the control group. Occupational exposure to fumes produced higher AlU levels than exposure to dusts, and in the subjects exposed to fumes the AlU levels were clearly influenced by the degree of exposure. The levels of aluminium in plasma in the exposed workers on the other hand, hardly differed from the levels found in the control group. These data appear to indicate that, whereas AlU allows daily and weekly exposure to be evaluated, AlP cannot be used as an indicator of occupational exposure, at least in the case of brief exposures to environmental concentrations below or equal to the TWA.

Fast liquid chromatographic determination of urinary trans,trans-muconic acid

trans, trans-Muconic acid (1,3-butadiene-1, 4-dicarboxylic acid, MA), a minor urinary metabolite of benzene exposure, was determined, after clean-up by solid-phase anion-exchange chromatography, by reversed-phase HPLC on a C18 column (5 x 0.46 cm I.D., 3 microns particle size), using formic acid-tetrahydrofuran-water (14:17:969) as mobile phase and UV detection at 263 nm. The recovery of MA from spiked urine was > 95% in the 50-500 microgram/l range; the quantification limit was 6 micrograms/l; day-to-day precision, at 300 micrograms/l, was C.V. = 9.2%; the run time was less than 10 min. Urinary MA excretion was measured in two spot urine samples of 131 benzene environmentally exposed subjects: midday values obtained in non-smokers (mean +/- S.D. = 77 +/- 54 micrograms/l, n = 82) were statistically different from those of smokers (169 +/- 85 micrograms/l, n = 30) (P < 0.0001); each group showed a statistically significant increase between MA excretion in midday over morning samples. Moreover, in subjects grouped according to tobacco-smoke exposure level, median values of MA were positively associated with and increased with daily smoking habits.

Dermal exposure to polycyclic aromatic hydrocarbons in asphalt workers

Objectives To assess dermal exposure to 16 polycyclic aromatic hydrocarbons (PAHs) in asphalt workers by applying polypropylene pads to six body sites (neck, shoulder, upper arm, wrist, groin, ankle), to identify the compounds and exposure sites most representative, and to integrate dermal exposure results with environmental and biological data. Methods Twenty-four asphalt workers were recruited. Dermal exposure was assessed during a single work shift. Sixteen PAHs (from naphthalene to indeno[1,2,3-cd]pyrene) were quantified via gas chromatography-mass spectrometry. Airborne exposure, urinary PAHs and monohydroxy metabolites were also investigated. Results Phenanthrene (PHE), present in all samples, was the most abundant compound (median 0.805–1.825 ng/cm2). Benzo[a]pyrene (BaP) was present in 75% of the samples (0.046–0.101 ng/cm2). Wrist had the highest contamination, with median PHE, pyrene (PYR), and BaP concentrations of 1.825, 0.527, and 0.063 ng/cm2. PHE and PYR on wrist correlated with almost all 3- to 4-ring PAHs (0.405≤r≤0.856), but not with BaP; BaP correlated with almost all 4- to 6- ring PAHs (0.584≤r≤0.633). Significant correlations were observed between PHE level, airborne exposure, and the corresponding urinary PHE and monohydroxy metabolites. For PYR, significant correlations existed only between urinary PYR and monohydroxy metabolites. Multiple linear regression analysis revealed that 42% of the end-of-shift monohydroxy metabolites were the result of airborne exposure, dermal exposure, and baseline levels of biomarkers. Conclusions Dermal exposure to PAHs was in the low ng/cm2 range. PHE or PYR and BaP were the most representative compounds and the wrist was the best location to perform dermal exposure assessments. Both dermal and airborne exposure contributed to the total body burden of PAHs, though the relative contribution was analyte-dependent.

Unmetabolized Polycyclic Aromatic Hydrocarbons in Urine as Biomarkers of Low Exposure in Asphalt Workers

The aim of the study was the assessment of low-level exposure to polycyclic aromatic hydrocarbons (PAHs) by biological monitoring focusing on measurement of unmetabolized PAHs in urine. Italian asphalt workers (AW, n = 100) and roadside construction workers (CW, n = 47) were investigated by measurement of unmetabolized PAHs and 1-hydroxypyrene (OH-Py) in urine spot samples collected respectively after two days of vacation (baseline), before and at the end of the monitored workshift, in the second part of the workweek. Personal exposure was also assessed by use of active samplers collecting both vapor- and particulate-phase PAHs. Median airborne levels during the workshift of 15 PAHs (both vapor and particulate phases), from naphthalene to indeno(1,2,3-cd)pyrene, ranged from below 0.03 to 426 ng/m 3 . Median excretion values of OH-Py in end-shift samples was 690 ng/L for AW and 378 ng/L for CW (p < 0.01). Urinary low-boiling PAHs were detected in the majority of the samples. Median levels for urinary naphthalene, phenanthrene, fluoranthene, and pyrene in end-shift samples were 117, 50, 8, and 6 ng/L in AW and 104, 19, 5, and 4 ng/L in CW, respectively. Significantly higher levels of most of the unmetabolized compounds were found in AW than in CW. Moreover, in AW samples the urinary excretion of most analytes increased during the work shift (before-shift vs. end-shift) and the workweek (baseline vs. before-shift). Urinary high-boiling PAHs were found in less than 10% of the samples. Significant correlations between airborne and urinary PAHs were observed. The results of this study show that low-boiling unmetabolized PAHs in urine may be suggested as biomarkers of low-level exposure to PAHs.