Uncertainty evaluation in the analysis of biological samples by sector field inductively coupled plasma mass spectrometry. Part A: Measurements of Be, Cd, Hg, Ir, Pb, Pd, Pt, Rh, Sb, U, Tl and W in human serum

Human biomonitoring to assess exposure to thallium following the contamination of drinking water

In 2014, in some parts of the water distribution system of the municipality of Pietrasanta (Tuscany, Italy), thallium (Tl) levels above the recommended limits were measured and some restrictions to water usage for drinking and food preparation were imposed. The study aimed to assess Tl exposure and possible health effects by means of a human biomonitoring survey. In the 2014–2016 time frame, 2154 urine and 254 hair samples were taken from different population groups and from a control group. The levels of Tl found in urine and hair were statistically higher in exposed groups than in controls and compared to the reference values for the general population. Concentrations in urine were significantly associated with the geographical origin of the sample, the consumption of drinking water and food grown in local gardens. A significant association was found between urine and hair. No positive associations were found between the Tl levels in hair or urine and several self-reported symptoms and health effects, except for sleep disturbance. The study indicates that the concentration of Tl in drinking water can be traced by urine analysis. Urine and hair have proven to be biological matrices that can be effectively used for the evaluation of Tl exposure. To date, the study represents the most extensive human biomonitoring campaign for the evaluation of the Tl exposure available at international level.

Purine DNA Lesions at Different Oxygen Concentration in DNA Repair-Impaired Human Cells (EUE-siXPA)

Xeroderma Pigmentosum (XP) is a DNA repair disease characterized by nucleotide excision repair (NER) malfunction, leading to photosensitivity and increased incidence of skin malignancies. The role of XP-A in NER pathways has been well studied while discrepancies associated with ROS levels and the role of radical species between normal and deficient XPA cell lines have been observed. Using liquid chromatography tandem mass spectrometry we have determined the four 5’,8-cyclopurines (cPu) lesions (i.e., 5′R-cdG, 5′S-cdG, 5′R-cdA and 5′S-cdA), 8-oxo-dA and 8-oxo-dG in wt (EUE-pBD650) and XPA-deficient (EUE-siXPA) human embryonic epithelial cell lines, under different oxygen tension (hyperoxic 21%, physioxic 5% and hypoxic 1%). The levels of Fe and Cu were also measured. The main findings of our study were: (i) the total amount of cPu (1.82–2.52 lesions/10⁶ nucleotides) is the same order of magnitude as 8-oxo-Pu (3.10–4.11 lesions/10⁶ nucleotides) in both cell types, (ii) the four cPu levels are similar in hyperoxic and physioxic conditions for both wt and deficient cell lines, whereas 8-oxo-Pu increases in all cases, (iii) both wt and deficient cell lines accumulated high levels of cPu under hypoxic compared to physioxic conditions, whereas the 8-oxo-Pu levels show an opposite trend, (iv) the diastereoisomeric ratios 5′R/5′S are independent of oxygen concentration being 0.29 for cdG and 2.69 for cdA for EUE-pBD650 (wt) and 0.32 for cdG and 2.94 for cdA for EUE-siXPA (deficient), (v) in deficient cell lines Fe levels were significantly higher. The data show for the first time the connection of oxygen concentration in cells with different DNA repair ability and the levels of different DNA lesions highlighting the significance of cPu. Membrane lipidomic data at 21% O₂ indicated differences in the fatty acid contents between wild type and deficient cells, envisaging functional effects on membranes associated with the different repair capabilities, to be further investigated.

Inductively Coupled Plasma Mass Spectrometry: Introduction to Analytical Aspects

Inductively coupled plasma mass spectrometry (ICP-MS) is an analytical technique that can be used to measure elements at trace levels in biological fluids. Although older techniques such as atomic absorption and atomic emission are still in use by some laboratories, there has been a slow shift toward ICP-MS, particularly in the last decade. As this shift is likely to continue, clinical scientists should be aware of the analytical aspects of ICP-MS, as well as the potential for both spectroscopic and non-spectroscopic interference, and strategies that can be employed to eliminate or mitigate these issues.

Discrete sampling based-flow injection as an introduction system in ICP-MS for the direct analysis of low volume human serum samples

Discrete sampling based on the flow injection options offered by advanced autosamplers has been tested and applied for the direct analysis of low volume samples (human serum) for multi-elemental purposes (simultaneous Al, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Ni, Pb, Rb, Se, V, and Zn assessment). Serum samples (200 µL aliquots) were directly diluted to 2.0 mL with 1% (v/v) HNO₃, and discrete sampling operating conditions were optimized to allow cleaning, loading (300 µL injection loop), and measuring steps by using a volume lower than 2.0 mL (diluted serum sample). Matrix effect has been overcome by using the standard addition technique, and accurate results implied the use of kinetic energy discrimination (KED) mode (He as a collision gas) for measurements. The proposed method has been found to be reliable for serum samples analysis because of the low sample volume requirements, the minimal sample preparation required, and high sampling rate (each replicate analysis takes 2.50 min). In addition, validation results show good precision and accuracy (both analytical recovery and analysis of certified reference materials), and acceptable sensitivity. Applicability of the proposed method has been finally demonstrated by analysing several serum samples from healthy adults.

The response to oxidative stress and metallomics analysis in a twin study: The role of the environment

Inefficient response to oxidative stress has been associated with ageing and health risk. Metals are known to inhibit DNA repair and may modify the antioxidant response. How genetic variability and lifestyle factors modulate the response to oxidative stress is poorly explored. Our study aims to disentangle the contribution of genetics and environmental exposures to oxidative stress response using data from twin pairs. The non-enzymatic antioxidant capacity (NEAC), the repair capacity of 8-oxo-7,8-dihydroguanine (OGG activity) and the levels of 12 metals were measured in blood of 64 monozygotic and 31 dizygotic twin pairs. The contributions of genetic and environmental effects were assessed using standard univariate twin modelling. NEAC and OGG activity significantly decreased with age. Gender-, age- and body mass index-associated differences were identified for some metals. Principal Component Analysis identified two groups of metals whose levels in blood were highly correlated: As, Hg, Pb, Se, Zn and Al, Co, Cr, Mn, Ni. The environmental influence was predominant on OGG activity and NEAC variance whereas for most metals the best-fitting model incorporated additive genetic and unique environmental sources of variance. NEAC and OGG activity were both inversely correlated with blood levels of various metals. The inhibition of OGG activity by Cd was largely explained by smoking. Our data show a substantial role of environmental factors in NEAC and OGG activity variance that is not explained by twins' age. Exogenous environmental factors such as metals contribute to oxidative stress by decreasing NEAC and inhibiting repair of oxidatively-induced DNA damage.

Human biomonitoring of metals in adults living near a waste-to-energy incinerator in ante-operam phase: Focus on reference values and health-based assessments

The human biomonitoring (HBM) of metals is a part of the ongoing project SPoTT for the longitudinal health surveillance of the population living near a waste-to-energy (WTE) incinerator (Turin, Italy). The HBM of metals in the SPoTT population aimed to evaluate: i) reference values (RVs) before the WTE incinerator started operation; ii) differences in exposure by variables; iii) variations respect to other HBM studies; iv) exposure that exceeds the available health-based benchmarks as the Biomonitoring Equivalents (BEs) for urine Cd and Human Biomonitoring (HBM-I and HBM-II) values for urine Hg, Tl, and blood Pb; v) risk assessment by generating hazard quotients (HQs) for the single metal and hazard index (HI) for the co-occurrence of metals. Eighteen metals in urine and Pb in blood were determined by sector field inductively coupled plasma mass spectrometry. Metal concentrations were comparable with RVs reported in other countries, except for slightly higher As, Be, Ir, Pd, Pt, Rh, and Tl levels. Smoking was associated with Cd; age with Pb; drinking bottled water with As and Cd; consumption of fish with As and Hg; amalgams with Hg and Sn; dental restorations with Pd and Pt; use of jewelry with Co and Rh, and piercing with Ni. While HQs for urine Cd, Hg, Tl and blood Pb suggested that adverse effects were unlikely, the HQ value raised the question of whether additive interactions of these metals could produce health concern. The obtained HBM data can be an early warning for accumulations of metals and identification of subgroups at risk.

Current role of ICP–MS in clinical toxicology and forensic toxicology: a metallic profile

As metal/metalloid exposure is inevitable owing to its omnipresence, it may exert toxicity in humans. Recent advances in metal/metalloid analysis have been made moving from flame atomic absorption spectrometry and electrothermal atomic absorption spectrometry to the multi-elemental inductively coupled plasma (ICP) techniques as ICP atomic emission spectrometry and ICP–MS. ICP–MS has now emerged as a major technique in inorganic analytical chemistry owing to its flexibility, high sensitivity and good reproducibility. This in depth review explores the ICP–MS metallic profile in human toxicology. It is now routinely used and of great importance, in clinical toxicology and forensic toxicology to explore biological matrices, specifically whole blood, plasma, urine, hair, nail, biopsy samples and tissues.

Uncertainty evaluation in the analysis of biological samples by sector field inductively coupled plasma mass spectrometry. Part B: measurements of As, Co, Cr, Mn, Mo, Ni, Sn and V in human serum

This protocol was developed to estimate the uncertainty of measurements in the sector field inductively coupled plasma mass spectrometry analysis of As, Co, Cr, Mn, Mo, Ni, Sn and V in human serum by utilizing in-house validation data. The approach is outlined in the Eurachem/Citac Guide and other relevant publications. The results generated were the followings: (i) coefficients of regression >0.9995 over two orders of magnitude of metal concentration; (ii) method quantification limits between 0.05 µg/L (Cr, Mn) and 0.49 µg/L (As); (iii) mean trueness checked against a certified reference material between 95.4% (As) and 107.7% (Ni); (iv) repeatability better than 10.2% over the range 0.1-2.0 µg/L; (v) reproducibility better than 12.0% over the range 0.1-2.0 µg/L; and (vi) expanded uncertainty budget comprised between 14.7% (Mn) and 27.9% (Cr) over the range 0.1-2.0 µg/L.