In-house validation of AF4-MALS-UV for polystyrene nanoplastic analysis.

The suitability of asymmetric flow field-flow fractionation (AF4) coupled on-line to multi-angle light scattering (MALS) and UV diode array (UV-DAD) detectors was tested to simultaneously detect polystyrene nanoplastics (PS-NPs) and collect information about their size. A mixture of four sizes of PS-NPs at 20 nm, 60 nm, 100 nm and 200 nm was prepared by dilution with ultrapure deionized water and gentle mixing and was used as test sample for a polydisperse nanoplastic system. The AF4 method separated each single size of PS-NP mixture in a total time of 48 min by using 0.2% SDS as carrier solution. Then, the PS-NPs were sized and detected by following their MALS (90° scattering angle) and UV (215 nm) signals. Quality control (QC) performances as linearity, between-day repeatability, resolution factor, trueness/recovery, limit of detection (LoD) and selectivity were calculated, according to the ISO/TS 21362:2018. Method uncertainty was calculated following the ISO/TS 21748:2002 by summing between-day repeatability and trueness or recovery uncertainties. In-house validation results demonstrated good peak resolution and selectivity, R2 linearity of 0.998-0.999 in the range 50-1000 µg/mL, between-day repeatability of ca. 10%, trueness/recovery above 90% and LoD between 15 µg/mL (20 nm) and 33 µg/mL (200 nm). Expanded uncertainty was 16.1-17.9% on PS-NP size between 60 and 200 nm and 10.4-14.7% on PS-NP concentration between 100 and 1000 µg/mL. Compared to traditional single-technique analysis, this hyphenated method offers great promise for separating and analysing diverse populations of PS-NPs present in real matrices, which is critical for health and risk assessment studies and any regulatory action.

Neurocognitive impact of metal exposure and social stressors among schoolchildren in Taranto, Italy.

BACKGROUND: Metal exposure is a public health hazard due to neurocognitive effects starting in early life. Poor socio-economic status, adverse home and family environment can enhance the neurodevelopmental toxicity due to chemical exposure. Disadvantaged socio-economic conditions are generally higher in environmentally impacted areas although the combined effect of these two factors has not been sufficiently studied. METHODS: The effect of co-exposure to neurotoxic metals including arsenic, cadmium, manganese, mercury, lead, selenium, and to socio-economic stressors was assessed in a group of 299 children aged 6-12 years, residing at incremental distance from industrial emissions in Taranto, Italy. Exposure was assessed with biological monitoring and the distance between the home address and the exposure point source. Children's cognitive functions were examined using the Wechsler Intelligence Scale for Children (WISC) and the Cambridge Neuropsychological Test Automated Battery (CANTAB). Linear mixed models were chosen to assess the association between metal exposure, socio-economic status and neurocognitive outcomes. RESULTS: Urinary arsenic, cadmium and hair manganese resulted inversely related to the distance from the industrial emission source (ß - 0.04; 95% CI -0.06, - 0.01; ß - 0.02; 95% CI -0.05, - 0.001; ß - 0.02 95% CI -0.05, - 0.003) while the WISC intellectual quotient and its sub-scores (except processing speed index) showed a positive association with distance. Blood lead and urinary cadmium were negatively associated with the IQ total score and all sub-scores, although not reaching the significance level. Hair manganese and blood lead was positively associated with the CANTAB between errors of spatial working memory (ß 2.2; 95% CI 0.3, 3.9) and the reaction time of stop signal task (ß 0.05; 95% CI 0.02, 0.1) respectively. All the other CANTAB neurocognitive tests did not show to be significantly influenced by metal exposure. The highest socio-economic status showed about five points intellectual quotient more than the lowest level on average (ß 4.8; 95% CI 0.3, 9.6); the interaction term between blood lead and the socio-economic status showed a significant negative impact of lead on working memory at the lowest socio-economic status level (ß - 4.0; 95% CI -6.9, - 1.1). CONCLUSIONS: Metal exposure and the distance from industrial emission was associated with negative cognitive impacts in these children. Lead exposure had neurocognitive effect even at very low levels of blood lead concentration when socio-economic status is low, and this should further address the importance and prioritize preventive and regulatory interventions.

Hexavalent chromium in tattoo inks: Dermal exposure and systemic risk.

BACKGROUND: The presence of hexavalent chromium (Cr[VI]), which is carcinogenic to humans and a dermal sensitizer, in tattoo inks may represent a serious health concern. The level of this impurity is limited to 0.2 mg/kg in tattoo inks by the European Resolution ResAP(2008)1. OBJECTIVES: To analyse 29 tattoo inks, produced in Europe and the United States, of different colours and brands, for Cr(VI) to assess their conformity with ResAP(2008)1 and to characterize dermal and systemic risks. METHODS: Ion chromatography and inductively coupled plasma mass spectrometry were used to determine the levels of Cr(VI) in inks; risk characterization was performed by calculating the systemic exposure dosage (SED) and margin of safety (MoS). RESULTS: Ninety per cent of inks contained Cr(VI) (range: 0.22-4.09 mg/kg), ie, above the maximum allowed level, and no information appeared on the label. More than 1 mg/kg Cr(VI) was detected in 27.6% of inks; these might represent a possible cause of dermal adverse reactions. Exposure to Cr(VI) in inks resulted in negligible SED values and MoS values of >100 (safety threshold), indicating no appreciable systemic risk. CONCLUSIONS: The minimization of Cr(VI) contamination and the use of technology compliant with good manufacturing practices is recommended to increase the safety of tattoo inks.

[Exploratory biomonitoring study among workers of livestock farms of the Taranto Province]. / Studio esplorativo di biomonitoraggio tra gli allevatori delle masserie della Provincia di Taranto.

OBJECTIVE: to conduct a survey on blood levels of metals and organochlorine compounds (dioxins and PCBs) among workers of livestock farms, and to identify the factors able to explain the magnitude and variability of the measured concentrations. DESIGN: exploratory human biomonitoring study. SETTING AND PARTICIPANTS: a sample of 45 workers from farms (masserie) located in the Province of Taranto was included in the study. The farms, located between 6 and 43 km from the industrial area, are family owned and animals (mainly sheep and goats) are locally reared outdoors. The study subjects have similar eating habits, including food consumption resulting from their production. RESULTS: manganese concentrations and, to a lesser extent, arsenic, cadmium and lead are in the medium-high range of levels observed in the Italian general population. This study does not identify factors able to explain the variability in the blood levels of metals. The amount of dioxins and PCBs, on the other hand, is strongly associated both with subjects age and the distance of farm from the industrial site. CONCLUSION: the results of this survey are suggestive of research hypotheses that need to be confirmed by biomonitoring studies of adequate design and size, in particular the hypothesis that the blood level of dioxins and PCBs decreases with increasing distance from the industrial site. We recommend ad hoc studies to better characterize the exposure of farmers (also associated with agricultural activities), and of the inhabitants of Taranto, to environmental persistent pollutants, also in terms of food matrices locally produced and consumed.

The effects of the exposure to neurotoxic elements on Italian schoolchildren behavior.

Neurodevelopmental disorders are constantly increasing on a global scale. Some elements like heavy metals are known to be neurotoxic. In this cross-sectional study we assessed the neurobehavioral effect of the exposure to trace elements including lead, mercury, cadmium, manganese, arsenic and selenium and their interactions among 299 schoolchildren residing in the heavily polluted Taranto area in Italy. Whole blood, urine and hair were collected for metal analyses, while the Child Behavior Checklist and the Social Responsiveness Scale, administered to the main teacher and the mothers were considered to identify behavioral problems in children. Blood lead mainly influenced social problems, aggressive behavior, externalizing and total problems. Urinary arsenic showed an impact on anxiety and depression, somatic problems, attention problems and rule breaking behavior. A significant interaction between lead and arsenic was observed, with a synergistic effect of the two metals increasing the risk of attention problems, aggressive behavior, externalizing problems and total problems. Overall, we were able to test that higher blood lead, urinary arsenic concentrations and their interaction increase the risk of neurobehavioral problems. This is in line with the U.S. Environmental Protection Agency's priority list of hazardous substances where arsenic and lead are ranked as first and second respectively.

Silver and gold nanoparticles characterization by SP-ICP-MS and AF4-FFF-MALS-UV-ICP-MS in human samples used for biomonitoring.

The rapid increase in the use of silver (Ag) and gold (Au) nanoparticles (NPs) can be a potential risk to humans. Ag and Au NPs may enter the blood, accumulate in organs and be cleared from the body. It is therefore necessary to develop detection and quantification methods for Ag and Au NPs in human matrices. To this end, the inductively coupled plasma mass spectrometry was used as single particle detector (SP-ICP-MS) and coupled on-line with asymmetric flow field flow fractionation (AF4-FFF-ICP-MS), multi-angle scattering (MALS) and UV. Both methods enabled the qualitative and quantitative measurement of mixtures of Ag NPs (20, 60 and 100 nm) and Au NPs (5, 20, 40 and 60 nm) in human urine, blood and serum. Methods were validated by estimating linearity, limit of detection, resolution, repeatability, recovery and stability of Ag and Au NPs measurements in fluids. The SP-ICP-MS showed concentration limits for Ag and Au NPs lower than AF4-FFF-ICP-MS (pg/mL vs. ng/mL, respectively), while AF4-FFF-ICP-MS could detect smaller sized NPs (2-5 nm vs. 7-14 nm for SP-ICP-MS) with good resolution between monodispersed NPs fractions. In addition, MALS detector was more promising respect to higher sizes of Ag and Au NPs (>40 nm), while UV for lower sized particle (<20 nm). The observed performances will allow to use ICP-MS-based methods, also coupled to other detectors, to carry out human biomonitoring campaigns dedicated to the analysis of metallic NPs in the general population and in exposed subjects.

Quantitative analysis of metals and metal-based nano- and submicron-particles in tattoo inks.

Exposure to metals and metal-based nano- (NPs, 1-100 nm) and submicron-particles (SPs, 0.1-1 µm) contained in tattoo inks and related health safety is currently receiving a great deal of interest. Twenty inks of different brands and colours were sampled in Italy in 2019. The SemiQuant Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis allowed quantifying the concentration of 18 metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Ti, Zn) in inks. The Single Particle ICP-MS was used to detect the diameters and concentration of NPs and SPs of 9 metals (Al, Co, Cr, Cu, Hg, Ni, Pb, Ti and Zn). Concentration of metals in tattoo inks were below the recommended concentrations reported in the Resolution ResAP (2008)1 indicating ink production have shifted to purer materials and best manufacturing practices. Regarding particles, Al was found at nano- (62-80 nm) and submicron-sizes (105-140 nm). Sizes of Cr, Cu, Pb and Zn were in the intervals 42-62 nm, 44-96 nm, 26-28 nm and 26-59 nm, respectively. Titanium was at submicron-diameters (166-383 nm). In addition, Cr and Ti particles accounted for the 47% and 80% of their total concentration, respectively. Tattooing practice exposed humans to metal-based NPs and SPs and the presence of a combination of particles of different metals and/or their dynamics (e.g., dissolution) may change their bioavailability and toxicity.

Children exposure to inorganic and organic arsenic metabolites: A cohort study in Northeast Italy.

The aim of this study was to provide urinary levels of total arsenic (TAs) and As species as arsenobetaine (AsB), arsenocholine (AsC), inorganic As (i.e., [As(III)+As(V)]), methylarsonic acid (MMA) and dimethylarsinic acid (DMA) in 7 year-old-children (n = 200) enrolled in the Northern Adriatic Cohort II (NACII), a prospective cohort in a coastal area of Northeast Italy. TAs was determined by sector field-inductively coupled plasma mass spectrometry (SF-ICP-MS) and AsB, AsC, As(III), As(V), MMA and DMA by ion chromatography coupled to ICP-MS (IC-ICP-MS). The geometric mean (GM) for TAs was 12.9 µg/L and for [iAs + MMA + DMA] was 4.26 µg/L. The species AsB (GM of 5.09 µg/L) and DMA (GM of 3.20 µg/L) had the greatest percentage contribution to TAs levels; a greater percentage contribution from AsB is seen at TAs >10 µg/L and from DMA at TAs <10 µg/L. Urinary [iAs + MMA] levels were positively associated with [iAs + MMA + DMA] and DMA with AsB levels. Fish, shellfish and crustaceans consumption increased the AsB and TAs levels, while rice intake, mothers' education level and selenium (Se) concentration influenced the DMA concentration. Children have a high capacity to metabolize and detoxify the iAs because of the higher secondary methylation index (ratio DMA/MMA) with respect to primary methylation index (ratio MMA/iAs). In addition, the median level of [iAs + MMA + DMA] in the whole population of children was lower than the Biomonitoring Equivalent (BE) value for non-cancer endpoints. Also the Margin of Safety (MOS) value based on the population median was greater than 1, thus the exposure to the toxicologically relevant As species was not likely to be of concern.

Alkynylation of aryl halides with perfluoro-tagged palladium nanoparticles immobilized on silica gel under aerobic, copper- and phosphine-free conditions in water.

The utilization of perfluoro-tagged palladium nanoparticles immobilized on fluorous silica gel through fluorous-fluorous interactions (Pd(np)-/FSG) or linked to silica gel by covalent bonds (Pd(np)-) in the alkynylation of terminal alkynes with aryl halides under aerobic, copper- and phosphine-free conditions in water, and their recovery and re-utilization, is described.

Metals contained and leached from rubber granulates used in synthetic turf areas.

The aim of this study was to quantify metals contained in and leached from different types of rubber granulates used in synthetic turf areas. To investigate the total content of metals, ca 0.5 g of material was added with HNO(3), HF and HClO(4) and microwave digested with power increasing from 250 W to 600 W. Leachates were prepared by extraction of about 5.0 g of material at room temperature for 24 h in an acidic environment (pH 5). Leaching with deionized water was also performed for comparison. Aluminium, As, Ba, Be, Cd, Co, Cr, Cu, Hg, Fe, Li, Mg, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Tl, V, W and Zn were quantified by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and ICP optical emission spectrometry (ICP-OES). Results indicated that the developed method was accurate and precise for the multi-element characterization of rubber granulates and leachates. The total amount and the amount leached during the acidic test varied from metal to metal and from granulate to granulate. The highest median values were found for Zn (10,229 mg/kg), Al (755 mg/kg), Mg (456 mg/kg), Fe (305 mg/kg), followed by Pb, Ba, Co, Cu and Sr. The other elements were present at few units of mg/kg. The highest leaching was observed for Zn (2300 microg/l) and Mg (2500 microg/l), followed by Fe, Sr, Al, Mn and Ba. Little As, Cd, Co, Cr, Cu, Li, Mo, Ni, Pb, Rb, Sb and V leached, and Be, Hg, Se, Sn, Tl and W were below quantification limits. Data obtained were compared with the maximum tolerable amounts reported for similar materials, and only the concentration of Zn (total and leached) exceeded the expected values.

Human primary macrophages scavenge AuNPs and eliminate it through exosomes. A natural shuttling for nanomaterials.

The use of nanomaterials is increasing but the real risk associated with their use in humans has to be defined. In fact, nanomaterials tend to accumulate in organs over a long period of time and are slowly degraded or eliminated by the body. Exosomes are nanovesicles actively shuttle molecules, including chemical products and metals, through the body. Macrophages scavenge the body from both organic and inorganic substances, and they use to release high amounts of exosomes. We hypothesized that macrophages may have a role in eliminating nanomaterials through their exosomes. We treated human primary macrophages with 20 nm gold nanoparticles (AuNPs), analyzing the presence of AuNPs in both cells and the released exosomes by the implementation of different techniques, including SP-ICP-MS and NTA. We showed that macrophages endocytosed AuNPs and released them through exosomes. Our study on one hand provide the evidence for a new methodology in the early identification of the nanomaterials levels in exposed subjects. On the other hand we depict a way our body shuttle virtually intact nanoparticles through macrophage-released exosomes.

Phosphine-free perfluoro-tagged palladium nanoparticles supported on fluorous silica gel: application to the Heck reaction.

The immobilization of phosphine-free perfluoro-tagged palladium nanoparticles Pd-1 on fluorous silica gel (FSG) and their utilization in the Heck reaction have been investigated. High yields of vinylic substitution products have been obtained. Recycling studies have shown that the solid-supported palladium catalyst can be readily recovered and reused several times without significant loss of activity. Reactions and recovery of the solid-supported palladium catalyst system can be carried out in the presence of air, without any particular precaution.

ICP-MS based methods to characterize nanoparticles of TiO2 and ZnO in sunscreens with focus on regulatory and safety issues.

This study sought to develop analytical methods to characterize titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs), including the particle size distribution and concentration, in cream and spray sunscreens with different sun protection factor (SPF). The Single Particle Inductively Coupled Plasma-Mass Spectrometry (SP ICP-MS) was used as screening and fast method to determine particles size and number. The Asymmetric Flow-Field Flow Fractionation (AF4-FFF) as a pre-separation technique was on-line coupled to the Multi-Angle Light Scattering (MALS) and ICP-MS to determine particle size distributions and size dependent multi-elemental concentration. Both methods were optimized in sunscreens in terms of recovery, repeatability, limit of detection and linear dynamic range. Results showed that sunscreens contained TiO2 particles with an average size of ≤107 nm and also a minor number of ZnO particles sized ≤98 nm. The higher fraction of particles <100 nm was observed in sunscreens with SPF 50+ (ca. 80%); the lower percentage (12-35%) in sunscreens with lower SPF values. Also the higher TiO2 (up to 24% weight) and ZnO (ca. 0.25% weight) concentrations were found in formulations of SPF 50+. Creamy sunscreens could be considered safe containing TiO2 and ZnO NPs less than the maximum allowable concentration of 25% weight as set by the European legislation. On the contrary, spray products required additional considerations with regard to the potential inhalation of NPs. The developed methods can contribute to the actual demand for regulatory control and safety assessment of metallic NPs in consumers' products.

Cancer 'chemotherapia specifica' ninety years after Paul Ehrlich.

From his student days throughout his whole life, Paul Ehrlich tried hard to obtain 'chemotherapia specifica' for the harmless systemic therapy of infectious diseases. Given the poor therapeutic benefit obtained with cytotoxic therapeutic agents and empirical radiopharmaceuticals, so far used only for neoadjuvant and adjuvant treatments of cancer, we have tried to develop Paul Ehrlich's 'chemotherapia specifica' for safe and effective therapy of cancers in cigarette smokers. With the help of sector-field inductively coupled plasma mass spectrometry, we have tried to find the metabolic action of cigarette smoke constituents in the cancerous organ. On the basis of these results we are synthesizing pharmaceuticals and radiopharmaceuticals to purge the tobacco-constituent metabolic products that cause cancer. The purity, stability and chemical nature of the pharmaceuticals and radiopharmaceuticals required for therapy have been studied by chromatography and electrophoresis. The cancer specificity of the therapeutic agent has been examined by the total body distribution of its gamma- and beta-labelled species in solution. At present, a bladder cancer-specific therapeutic agent is being developed.

Determination of mercury in hair: Comparison between gold amalgamation-atomic absorption spectrometry and mass spectrometry.

Mercury is a heavy metal that causes serious health problems in exposed subjects. The most toxic form, i.e., methylmercury (MeHg), is mostly excreted through human hair. Numerous analytical methods are available for total Hg analysis in human hair, including cold vapour atomic fluorescence spectrometry (CV-AFS), inductively coupled plasma mass spectrometry (ICP-MS) and thermal decomposition amalgamation atomic absorption spectrometry (TDA-AAS). The aim of the study was to compare the TDA-AAS with the ICP-MS in the Hg quantification in human hair. After the washing procedure to minimize the external contamination, from each hair sample two aliquots were taken; the first was used for direct analysis of Hg by TDA-AAS and the second was digested for Hg determination by the ICP-MS. Results indicated that the two data sets were fully comparable (median; TDA-AAS, 475ngg-1; ICP-MS, 437ngg-1) and were not statistically different (Mann-Whitney test; p=0.44). The two techniques presented results with a good coefficient of correlation (r=0.94) despite different operative ranges and method limits. Both techniques satisfied internal performance requirements and the parameters for method validation resulting sensitive, precise and reliable. Finally, the use of the TDA-AAS can be considered instead of the ICP-MS in hair analysis in order to reduce sample manipulation with minor risk of contamination, less time consuming due to the absence of the digestion step and cheaper analyses.

Determination of Cd, Cu, Pb and Zn in neoplastic kidneys and in renal tissue of fetuses, newborns and corpses.

The incidence of kidney tumors in USA and Europe (in particular, Central Europe and Italy) has been dramatically increasing since the 1970s, possibly as a consequence of ongoing environmental pollution. Environmental factors have been considered responsible for at least 80% of the incidence of neoplastic diseases. To shed some light on this issue, the amounts of Cd and Pb were measured in neoplastic tissue and adjacent normal part of kidney excised for carcinoma and compared with those in renal tissues of fetuses, newborns and subjects that died of non-neoplastic diseases. Cd and Pb were determined by Inductively Coupled Plasma Atomic Emission Spectrometry and Atomic Absorption Spectrometry with Electrothermal Atomization. Metallothionein immunoperoxidase staining technique was used to localize the accumulation of Cd and Zn in the nephrons. Content of Cd and Pb in kidneys of fetuses and newborns was extremely low. However, it was significantly increased in adjacent-normal tissues of kidneys with carcinomas, and significantly higher compared to kidneys of individuals that died of non-neoplastic diseases. In tumoral tissues of the excised kidneys, Cd content was very low, while that of Pb significantly elevated. High amounts of Cd and Pb in the adjacent-normal parts of kidneys with carcinomas are suggestive of possible, individual or synergistic, effects of these pollutants on enzymatic systems, priming an oncogenic pathway. Detection of metallothioneins, primary ligands of Cd, exclusively in the cells of proximal tubuli, i.e. wherein renal carcinoma develops in over 80% of cases, strongly supports the assumption that Cd exerts a carcinogenic effect.

Evaluation of carboplatin pharmacokinetics in pediatric oncology by means of inductively coupled plasma mass spectrometry.

Carboplatin is widely used in pediatric oncology to treat different tumors. Aim of the present study was to assess the potential of sector field inductively coupled plasma mass spectrometry (SF-ICPMS) in evaluating the area under the plasma platinum concentration vs time curve in pediatric patients presenting solid tumors and treated with carboplatin 349-1000 mg m-2. Seventeen patients were enrolled and 23 courses of chemotherapy were evaluated. Plasma was ultrafiltered and free carboplatin was measured in ultrafiltrates as platinum by SF-ICP-MS. Comparison was made between different equations to obtain a target AUC. Limits of detection and of quantification, intra- and inter-day repeatability of the measurements, recovery of the 'free-carboplatin' confirmed SF-ICP-MS as a reliable technique in the quantification of serum platinum in anticancer carboplatin-based therapies.

Calcium, copper, iron, magnesium, silicon and zinc content of hair in Parkinson's disease.

The aetiology of Parkinson's disease (PD) is still unknown, but some hypotheses have focused on the imbalances in body levels of metals as co-factors of risk. To assess whether hair could be a reliable marker of possible changes, calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), silicon (Si) and zinc (Zn) were determined in hair from 81 patients affected by PD and 17 age-matched controls. Care was taken to eliminate external contamination of the hair by thorough washing. Digestion of the matrix was achieved by an acid-assisted microwave procedure. Quantification of the elements was performed by inductively coupled plasma atomic emission spectrometry. Results indicated significantly lower levels of Fe in the hair of patients (p=0.018) compared with controls. Ca and Mg levels were slightly lower while Zn levels were higher in patients, although these differences were not significant; neither were variations in Cu and Si. Ca and Mg were at least 1.5 times higher in females than in males in both controls and patients. In addition, Ca correlated positively with Mg in both groups and in both sexes (p-value always less than 0.03), and negatively with age in patients (p<0.01). Finally, element levels did not correlate with either the duration or the severity of the disease or with anti-Parkinson treatment.

Development of methods for the quantification of essential and toxic elements in human biomonitoring.

Analytical methods using sector field ICP-MS and ICP-AES were developed for the determination of Al, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Si, Sn, Sr, Tl, V, W, Zn and Zr in cerebrospinal fluid, urine, serum and blood. Sample treatment procedures merging high sample throughput, simplicity and low contamination risk were set up. Method performances were evaluated in terms of detection limits, accuracy and precision. The limits were below 0.05 ng ml(-1) for all the elements, except for Al (all matrices), Hg (blood), Pb (blood) and Sn (serum and blood). The accuracy varied from 86% to 110% and the precision was always below 6%.

Assessment of reference values for selected elements in a healthy urban population.

Reference values for 26 elements, namely Al, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Si, Sn, Sr, Tl, V, W, Zn and Zr are proposed in serum and blood of 110 healthy adults of the urban area of Rome. They were included in the study on the basis of strict criteria of eligibility and exclusion. With the exception of Ba, Bi, Co, Cr, Ni, Sb, Sn Tl in serum, and Bi, Hg, Si, V and W in whole blood, experimental data for each all the other analytes were found to approach a normal distribution. The estimated 5-95% references ranges (in ng ml(-1)) were reported. For several elements the reference ranges observed overlapped information available in the literature. Gender, age, body mass index, smoking habits and alcohol consume were used as grouping variables. Mutual associations were observed for several elements, as follows: Be, Ca, Co, Cr, Cu, Li, Mo, Pb and Zn with sex; Ca, Pb and Si with age (< and > 45 years); Co, Cr, Mo, Sb and Tl with body mass index; Cd and Pb with smoking habit; Cr and Pb with alcohol consume.