Marina Patriarca

Environmental exposure to metals of newborns, infants and young children

Anthropogenic emissions, such as those from combustion of fossil fuel, waste incineration and industrial use, contribute to higher levels of metal pollutants, including Cd, Pb and Sb, in the urban environment. These widespread and persistent environmental pollutants have the potential for developmental and reproductive toxicity. Health risks are particularly associated with exposure in utero and the early years of life, since the developing organism is at greater risk from permanent damage, and both absorption and retention can be considerably greater in infants than adults. In order to assess risk to humans, the information on environmental levels of pollutants (environmental monitoring) should be integrated with information on biomarkers of exposure, effect or susceptibility in biological fluids or tissues (biological monitoring). The analysis of tissue from the target organ obtained at autopsy provides a direct record of the accumulation of toxins and allows temporal and geographical trends to be studied. Few literature reports on tissue content of potentially toxic elements include data on newborns and young children since collections of autopsy samples in this age range are rare. Existing data are sometime questionable, because of inadequate sensitivity of the analytical techniques, insufficient control of contamination and lack of validation. Our recent work aimed to establish reliable reference values for the content of Cd, Pb and Sb in the liver of pediatric subjects.

Clinical and biological materials, foods and beverages

This Update refers to papers published approximately between September 2005 and August 2006. In a new development we have introduced a section specifically to discuss the emerging field of metallomics. This allows the inclusion not just of the essential analytical work but also applications involving the structural and functional roles of metals and metalloids. This work is directed towards understanding the metabolism of elements, their involvement in the biochemistry of molecules such as proteins and nucleic acids, and their mechanisms of action. In the period covered by this review we can see the development of several elegant but complex methods to provide for an integral approach which links the quantitative analysis with information about structural and functional activity. At a time when analytical equipment is so sophisticated it should not be necessary to ask questions on the validity of published results. However, as those who review submitted papers will appreciate, this can never be taken for granted and it has been demonstrated that the quality of data (judged by the spread of ‘normal results’) is related to the attention devoted to quality control in the written report. A number of new pieces of work were seen in this review period. Use of exhaled breath as a novel biological sample type was reported. A preconcentration column located in the arm of an autosampler used for ETAAS was applied to measurements of Pt in foods and beverages. Interferences associated with the determination of Cd in urine by ETAAS were removed with a neat piece of manipulation. The sample was placed in the furnace and Cd concentrated onto Pd modifier using an electrolytic process, after which the sample solution, together with interferents, was drawn back into the capillary and sent to waste. The popularity of ICP-MS continues to grow, largely fuelled by collision cell applications and by work on getting the right gas for the job. Following on from the considerable Pb in bone work achieved with in vivo XRF, this technique is now being used to measure Cd, although the sensitivity requires improvement if normal concentrations are to be determined. Work on selenium is as popular as ever in both the clinical and food areas, with several reviews seen and fundamental work on sample stability, extraction, speciation, bioavailability, and the identification of novel compounds in yeast and other samples, many of which involve Se/S substitutions. Selenosugars are recognised as important metabolites and now arsenosugars have been identified. In recent years we have looked without much success for data related to organically produced food but now there are some data for milk. Of 45 elements measured, Mo was increased while Ba, Eu, Mn and Zn were reduced, when compared with conventional cow’s milk. Among the more unusual studies seen were measurements of Pb in alligator bones and essential elements in royal jelly.

Evaluation of uncertainty of measurement from method validation data: An application to the simultaneous determination of retinol and α-tocopherol in human serum by HPLC

An isocratic RP-HPLC method for the determination of retinol and alpha-tocopherol in serum, with fluorescence and UV/VIS detection, respectively, was developed and validated according to international guidelines. Detection (retinol 0.015 mg/L, alpha-tocopherol 0.29 mg/L) and quantification (retinol 0.05 mg/L, alpha-tocopherol 0.95 mg/L) limits were determined. Repeatability was <3.3% and <2.9% and intermediate precision was <4.6% and <3.2%, for retinol and alpha-tocopherol, respectively. Certified reference materials were utilised to assess bias and guarantee traceability to SI units. Expanded uncertainties (retinol 8.9%; alpha-tocopherol 7.9%), estimated according to the EURACHEM/CITAC guide from method validation data, satisfied fit-for-purpose requirements based on biological variability.

Quality Specifications for the Determination of Copper, Zinc, and Selenium in Human Serum or Plasma: Evaluation of an Approach Based on Biological and Analytical Variation

BACKGROUND Trace element external quality assessment schemes monitor laboratory performance and provide a stimulus for improvement in accuracy. However, monitoring of participant performance varies according to the scheme and can lead to conflicting conclusions. METHODS Quality specifications based on biological intra- and interindividual variability were calculated and compared to those currently used by various trace element external quality assessment schemes for plasma or serum copper, zinc, and selenium concentrations. For this purpose, we evaluated results reported by participating laboratories in different schemes, at key concentrations, using z scores. RESULTS Minimal quality specifications developed from the biological intra- and interindividual variability were, for Cu, +/-0.84 micromol/L or 12% of the assigned target concentration, whichever is greater; for Zn, +/-1.20 micromol/L or 15% of the assigned target concentration, whichever is greater; and for Se, +/-0.072 micromol/L or 12% of the assigned target concentration, whichever is greater. Reported performance of the participating laboratories depended on analyte, concentration, and the selected quality specification. In addition, the most commonly used methods for the determination of Cu, Zn, and Se may give different results. CONCLUSIONS The proposed minimal quality specifications based on biological variation are generally slightly less stringent than those currently in use, although they do not drastically change the performance evaluation in the different schemes. These specifications are a first step in the harmonization of practices among the schemes and remain to be evaluated.

Determination of ascorbic acid in blood plasma or serum and in seminal plasma using a simplified sample preparation and high-performance liquid chromatography coupled with UV detection

Abstract A simplified method of sample preparation and high-performance liquid chromatography procedure using UV detection is described for the determination of ascorbic acid (AA) in blood plasma or serum and seminal plasma. Within two hours from collection samples are treated with dithioerythritol (DTE) and then stored under Argon at -80°C. Prior to analysis, protein precipitation is initiated with the addition of cold methanol. AA elution is carried out on a C18 reverse phase column using dodecyltrimethylammonium bromide as an ion-pairing agent. the detection is accomplished by measuring ultraviolet absorption at 265 nm. the analysis time for sample is 10.5 min, the retention time of AA being 9.7 min. Within- and between-day coefficients of variation are 2.9% and 4.9% for blood serum, 1.0 % and 2.3 % for seminal plasma. Mean analytical recovery of 102.5 ± 3.7% was found analyzing a serum pool after addition of a standard amount of AA. AA levels are stable for at least 43 days under the described storage...

Association of selected social, environmental and constitutional factors to blood lead levels in men aged 55–75 years

Blood lead (B-Pb) levels were determined in 1802 out of 1856 non-occupationally exposed men aged 55-75 years living in the Rome area who participated, between 1989 and 1990, in an epidemiological survey for coronary heart disease (New Risk Factors Project). The median B-Pb level was 113 micrograms/l (10th-90th centiles: 74-180 micrograms/l) and only 0.7 per cent (n = 14) of the subjects had B-Pb values higher than 300 micrograms/l. B-Pb levels were significantly and positively associated to alcohol consumption. Moderate and heavy drinkers had median B-Pb level of 143 micrograms/l (10th-90th centiles: 92-233) and 165 micrograms/l (10th-90th centiles: 102-285) respectively, whereas non-drinkers had a median B-Pb level of 96 micrograms/l (10th-90th centiles: 66-143). The influence of smoking habits was less relevant. Subjects who never smoked and subjects smoking more than 20 cigarettes daily had median B-Pb levels of 103 and 133 micrograms/l, respectively. Individuals classified as habitual car-drivers had slightly higher Pb levels than non-drivers. Subjects classified as manual workers had higher B-Pb levels in comparison with non-manual workers and retired subjects. B-Pb levels were directly related to HDL-cholesterol (HDL-C, r = 0.2252) and gamma-glutamyltransferase (gamma-GT, r = 0.2207) serum levels. The alleged alcohol consumption was more related to B-Pb level (r = 0.3848) than to serum level of HDL-C (r = 0.2474) or gamma-GT (r = 0.2469). A significant correlation (r = 0.2409) also existed between B-Pb and blood cadmium levels (B-Cd). Subjects with a low Gaensler ratio, an index of respiratory function, had higher B-Pb levels. In multiple regression analyses alcohol intake was the most important predictor of B-Pb level, explaining more (14.27%) of the total variance than did B-Cd (4.98%), HDL-C (1.89%), driving habits (1.46%), gamma-GT (1.09%), skinfold thickness (0.96%), and Gaensler index (0.38%). The risk ratio of having B-Pb level higher than 180 micrograms/l (90th centile of B-Pb distribution in our subjects) was 5.3 (95% CI: 2.7-10.4) for drinkers versus non-drinkers and 1.9 (95% CI: 1.2-3.1) for current smokers versus subjects who had never smoked. B-Pb was, at least in our subjects, a more specific and sensitive objective index of alcohol consumption than gamma-GT and HDL-C.(ABSTRACT TRUNCATED AT 400 WORDS)

Age dependence of potentially toxic elements (Sb, Cd, Pb, Ag) in human liver tissue from paediatric subjects

Toxic elements are present at low concentrations in the environment. This work was undertaken to investigate the age dependence of the liver content of selected elements in paediatric populations, as an index of internal exposure. Liver samples were collected at autopsy from 157 subjects, aged < 1 day to 6 years, as part of investigations on a possible role of Sb compounds in sudden infant death syndrome (SIDS). In addition to Sb, the concentrations of Ag, Cd and Pb were also determined by inductively coupled plasma mass spectrometry on the remaining digest. Comparison of 95% confidence intervals of the median concentrations of the four elements suggested that there were no differences between the two categories of cause of death, SIDS or those who had died of an identified disease. Cadmium, lead and antimony median concentrations were lower than corresponding values observed in adult populations. Silver concentrations were significantly higher at birth and decreased with age. Cadmium levels were almost negligible in neonates and infants, but increased in older children. The finding of non-negligible concentrations of both Ag and Pb in neonatal liver provides further direct evidence that these elements cross the human placental barrier. The reported data, by far the largest collection observed in subjects less than 1 year old, are the result of exposure, during pregnancy and in early childhood, to present levels of these elements in the environment. They can serve as a reference to compare post-mortem values from individuals or groups of subjects in this age range when an exposure risk is suspected and to highlight trends in human exposure.

Determination of low concentrations of potentially toxic elements in human liver from newborns and infants

One hundred and fifty-seven liver samples from newborns and infants who had died from sudden infant death syndrome (SIDS) or other known causes have been analysed by ICP-MS for Ag, Cd, Co, Pb and Sb. The median concentrations found were: 15.4 (Ag), 2.9 (Cd), 15.9 (Co), 65.2 (Pb) and 1.8 (Sb) ng g-1 wet mass. There was no measurable difference in the concentrations of any of these elements between the SIDS and non-SIDS groups. The validity of the results was assessed by analysis of appropriate reference materials, interlaboratory comparison and isotope dilution analysis. The instrumental limits of detection were 0.25 (Ag), 0.14 (Cd), 0.21 (Co), 3.8 (Pb) and 0.38 (Sb) ng g-1 wet mass. The limits of detection of the method depend on the reagent blank and the extent of background contamination.

Determination of selected nickel isotopes in biological samples by inductively coupled plasma mass spectrometry with isotope dilution

The bis-(1-pyrrolidinecarbodithioato) nickel(II) complex was extracted from acid-digested samples of blood, urine and faeces into 4-methylpentan-2-one. The organic extracts were evaporated to dryness and dissolved in 2.8% v/v HNO3 prior to analysis by inductively coupled plasma mass spectrometry (ICP-MS). The extraction procedure freed m/z 60, 61 and 62 from polyatomic interferences, allowing 61Ni and 62Ni to be used for combined isotope dilution (ID) and tracer studies. Satisfactory recovery was obtained for naturally abundant Ni added to serum (97.1 ± 1.9%) and urine samples (100.8 ± 2.8%) using ID with 62Ni. Average recovery of 62Ni added to plasma, serum, red blood cells, faeces and urine, determined using ID-ICP-MS with 61Ni, was 99.8 ± 3.2%.

The performance of Italian laboratories in the determination of trace elements in blood

Abstract The analytical performance of a group of Italian laboratories with regard to the determination of blood lead (BPb), blood cadmium (BCd), serum aluminum (SAl), serum copper (SCu), and serum zinc (SZn) was estimated from the results of quality assurance programs carried out in Italy between 1983 and 1990. Mean imprecision, mean inaccuracy, and percentage of acceptable results provided, according to preset limits, were adopted as indexes of performance. Positive trends were observed, over the course of the years, toward smaller bias and lower percentage of laboratories with poor performance. At present, taking into account results from all participants, mean absolute inaccuracy can be evaluated as 40 μg/liter (mean concentration: 440 μg/liter) for BPb, 0.55 μg/liter (mean concentration: 3.6 μg/liter) for BCd, and 13.4 μg/liter (mean concentration: 77 μg/liter) for SAl. At mean concentrations of 0.94 mg/liter of SCu and 1.08 mg/liter of SZn, mean absolute inaccuracies were 0.130 mg/liter and 0.162 mg/liter, respectively. The percentage of laboratories providing results within established limits for at least 80% of the examined samples is rather high for BCd (61.9%), SCu (43.8%), and BPb (41.2%). On the contrary, only 15.7% of laboratories achieved good performance in SZn analysis and none in SAl determination.