H. Trevor Delves

Platinum concentrations in urban road dust and soil, and in blood and urine in the United Kingdom †

Increasing Pt concentrations from vehicle catalysts have been reported from a number of countries. Analysis of Pt and Pd in soils and road dusts taken from areas of high and low traffic flows in SE England show concentrations of Pt in the range < 0.30-40.1 ng g-1 and Pd in the range < 2.1-57.9 ng g-1. Higher concentrations of Pt are associated with high traffic densities. Samples taken from streets of lower traffic flows were found to contain the lower concentrations of the ranges. Pilot studies of Pt concentrations in blood and urine using ICP-MS have been carried out. Platinum concentrations in whole blood were: precious metal workers, 780-2170, mean 1263 pmol l-1 (0.152-0.423, mean 0.246 microgram l-1); motorway maintenance workers, 645-810, mean 744 pmol l-1 (0.126-0.158, mean 0.145 microgram l-1); Imperial College staff, 590-713, mean 660 pmol l-1 (0.115-0.139, mean 0.129 microgram l-1). Platinum concentrations in urine in pmol Pt per mmol creatinine were: precious metal workers, 122-682, mean 273 [0.21-1.18, mean 0.47 microgram Pt (g creatinine)-1]; motorway maintenance workers, 13-78, mean 33.7 [0.022-0.135, mean 0.058 microgram Pt (g creatinine)-1]; Imperial College staff, 28-130, mean 65.6 [0.048-0.224, mean 0.113 microgram Pt (g creatinine)-1]. Detection limits were 0.03 microgram l-1 for both blood and urine. The possible health effects of increasing Pt in the environment are discussed. Platinum provides an excellent example of the significance of speciation in metal toxicity. Platinum allergy is confined to a small group of charged compounds that contain reactive ligand systems, the most effective of which are chloride ligand systems. Metallic Pt is considered to be biologically inert and non allergenic and since the emitted Pt is probably in the metallic or oxide form, the sensitising potential is probably very low. Platinum from road dusts, however, can be solubilised, and enter waters, sediments, soils and the food chain. There is at present no evidence for any adverse health effects from Pt in the general environment, particularly allergic reactions.

Simple direct method for the determination of total mercury levels in blood and urine and nitric acid digests of fish by inductively coupled plasma mass spectrometry

A simple direct method was developed to determine Hg by ICP-MS in diluted urine, diluted blood and HNO3 digests of fish. Wash-out times of 80% within 5% for urine. There was successful participation in three QA schemes for urine and one for blood. NIST Albacore Tuna gave 95% recovery of the target, 0.95 µg g–1, and good precision, 0.90±0.01 µg g–1 (n=3). The method did not discriminate between inorganic and organic Hg. Detection limits for Hg, using 3σ at or near the blank level, were 0.13 µg l–1 in blood, 0.27 µg l–1 in urine and 0.004 µg g–1 in fish. The developed methods were used to analyse samples collected from four sites in the Tapajos Valley of Brazil in an EC funded study of exposure to Hg as a result of gold mining. All but one of the subjects (n=106) had Hg levels in either blood or urine that exceeded the upper 95% limits for non-exposed subjects, 55% had blood Hg levels above the 95% limit in industrial workers (19 µg l–1) and 17% exceeded the urine Hg limit at which industrial workers should be removed from exposure (50 µg l–1). Subjects living in a fishing village, Jacareacanga, 100 km from mining activities, had significantly higher blood Hg levels (mean 81 µg l–1) than the other three groups (p<0.004), presumed to be related to fish consumption. Fish Hg levels were similar to those found in other polluted areas, mean 0.379 mg kg–1 (n=52). The EC study provided the strongest evidence to date in 1991 that Hg in fish in the Amazon basin posed much more of a general health problem than Hg vapour since it affected a larger proportion of the population than just the gold miners, ancillary workers and traders. The methods were also used in the routine clinical analysis of blood and urine samples within the UK National Health Service. Investigations included a case of acute mercury poisoning in a 28-month-old boy who had swallowed a battery who had an initial blood Hg of 394 nmol l–1 and urine Hg of 16 nmol mmol–1 creatinine. He was successfully treated with the chelating agent British Anti-Lewisite.

Measurements of total lead concentrations and of lead isotope ratios in whole blood by use of inductively coupled plasma source mass spectrometry

Methods are described for the accurate and precise determination of total lead and its isotopic composition in whole blood using inductively coupled plasma source mass spectrometry (ICP-MS). The sample preparation is a simple 1 + 24 dilution of blood (400 µl for total lead; 2000 µl for isotope ratios) using a diluent containing ammonia solution, (NH4)2H2EDTA, NH4H2PO4 and Triton X-100, which allows prolonged pneumatic aerosol generation without blockage of the Meinhard nebuliser.Sensitivities of up to 3 × 106 counts s–1 for 208Pb at a total lead concentration of 5 µmol l–1(1 µg ml–1) enabled total blood lead levels to be measured in 4 min per sample, with a detection limit of 0.072 µmol l–1(15 µg l–1). The agreement between ICP-MS and atomic absorption spectrometry (AAS) for this analysis was excellent: ICP-MS = 0.996 × AAS – 0.0165 µmol l–1; r= 0.994.Isotope ratio measurements required 15 min to achieve the required accuracy and precision both of which were generally better than 0.5% for 206Pb : 207Pb and 208Pb : 206Pb isotopic lead ratios. The ICP-MS data for these ratios in ten quality control blood specimens had a mean bias relative to isotope dilution mass spectrometry of –0.412% for 206Pb : 207Pb ratios and of +0.055% for the 208Pb : 206Pb ratios. This level of accuracy and that of the total blood lead measurements is sufficient to permit application of these ICP-MS methods to environmental studies.

Determination of total selenium in serum, whole blood and erythrocytes by ICP-MS

A simple method for measuring selenium in serum by ICP-MS using a 1+14 dilution of a 100 µl sample in a diluent containing 1.0% v/v butan-1-ol to eliminate interferences at 78 Se from argon adduct ions has been shown to be accurate and precise in a 24 month evaluation for routine clinical assays and has been developed to allow analysis of whole blood and erythrocytes. Excellent performances were achieved in two External Quality Control Assessment programmes for the measurement of selenium in serum: Centre du Toxicologie de Quebec and Trace Element Quality Assessment Scheme from the University of Surrey (Guildford). The regression equation for our ICP-MS data versus target values for analysis of Se in 109 sera from November 1996 to March 1998 was: ICP-MS=0.969x Target+0.031 µmol l –l , r=0.996. For serum analysis the detection limit was 0.02 µmol l –1 , and the RSDs at 0.3-2.0 µmol l –1 were 2.0-4.0% within-run and 4.3-10.0% between-run. Initial applications of this method to measuring selenium in whole blood (1+14 dilution) and red blood cells (1+29 dilution) gave detection limits of 0.02 µmol l –1 ; RSDs of 2.1-5.8% within-run, and of 5.0-8.1% between-run, at concentrations of 0.3-2.0 µmol l –1 . Analysis of a whole blood reference sample (Seronorm 404107), with a target concentration of 1.01 µmol l –1 and acceptable range of 1.01-1.15 µmol l –1 , gave 1.06±0.06 µmol l –1 (mean±s).

Accurate and precise determination of lead isotope ratios in clinical and environmental samples using inductively coupled plasma source mass spectrometry

Methods are described for the accurate and precise determination of lead isotope ratios in human tissues and environmental samples including blood, teeth, paint, lead plumbing and UK petrol vehicle exhaust residue. Over a four-month period 33 measurements of the 206Pb : 207Pb ratio in a quality control blood sample with a known lead isotopic composition gave a between-batch relative standard deviation of 0.35% with an accuracy of –0.09% relative to thermal ionisation-isotope dilution mass spectrometry (TI-IDMS). This performance was sufficient to allow source apportionment in instances of excessive lead exposure in some children for whom deviations in the 206Pb : 207Pb ratio of up to 2.3% were observed.

Simple Method for the Accurate Determination of Selenium in Serum by Using Inductively Coupled Plasma Mass Spectrometry

A simple 1+15 dilution of 200 µl volumes of serum with a diluent containing 1.0% v/v butan-l-ol; 0.66% Triton X-100; 0.01 mol l -1 NH 3 , 0.0002 mol l -1 (NH 4 ) 2 H 2 EDTA and 0.002 mol l -1 NH 4 H 2 PO 4 enables ICP-MS to provide accurate and precise measurements of total selenium concentrations. Interferences from argon-adduct ions on selenium isotopes 77 Se, 78 Se are eliminated and are considerably reduced at 82 Se by the presence in the diluent of butan-l-ol. The other reagents prevent blockage of the torch injector tube during prolonged, ≥6 h, analytical runs. The detection limit (3 s blank) is 0.02 µmol l -1 (1.5 µg l -1 ) and within-run RSDs range from 3.4 to 7.5% at 0.3 µmol l -1 , to 1.5 to 2.0% at 2.1 µmol l -1 . Analyses of 12 sera from an external quality assessment program, of a commercially available reference serum material (Nycomed) and of in-house internal quality control sera gave excellent agreements with median/target concentrations over the range 0.3 to 3.3 µmol l -1 . The ICP-MS data showed small, but acceptable, negative biasses at 1.0 µmol l -1 of: -3.8% and -5.0% at 77 Se and 78 Se, respectively.

Determination of aluminium in different tissues of the rat by atomic absorption spectrometry with electrothermal atomization

Atomic absorption spectrometry with electrothermal atomization was used for the determination of aluminium in brain, liver, spleen, kidney cortex, skeletal muscle and bone of the rat following digestion by nitric acid and in serum following simple dilution and in situ oxygen ashing. The method of standard additions in the presence of a chemical modifier, ammonium dihydrogen-phosphate, was essential for bone tissues. The detection limits ranged from 3 to 58 ng per gram of wet mass of tissue and were 4-19 times lower than the observed physiological levels of aluminium. The between-day precision for serum was 8.9% at a mean concentration of 6.8 micrograms I-1 and 2.4% at a mean concentration of 125.3 micrograms I-1. Additionally, repeated analyses of National Institute of Standards and Technology Standard Reference Material 1577b Bovine Liver gave a relative standard deviation of 12.2% (mean concentration = 0.8 microgram g-1). Of the tissues studied, bone had at least ten times higher levels of aluminium than others (0.959 +/- 0.322 micrograms g-1). The aluminium concentration in cerebellum (0.073 +/- 0.043 micrograms g-1) was approximately twice that in the cerebral hemisphere (0.034 +/- 0.009 micrograms g-1).

Double-blind comparison of absorbable colloidal bismuth subcitrate and nonabsorbable bismuth subnitrate in the eradication of Helicobacter pylori and the relief of nonulcer dyspepsia

Background. Bismuth is widely used for the eradication of H. pylori, especially in developing countries, although there are concerns over its neurotoxicity. Whether bismuth has to be absorbed in humans to act against H. pylori is not known. In this study, we compared “absorbable” (colloidal bismuth subcitrate) and “nonabsorbable” (bismuth subnitrate) bismuth as part of triple therapy in the eradication of H. pylori.

The coelomic cavity — A reservoir for metals

OBJECTIVE The concentrations of metals in fluids surrounding the first-trimester fetus were measured. STUDY DESIGN Atomic absorption spectrometry was used to measure concentrations of metals in matched samples of amniotic and extraembryonic coelomic fluids in 17 women between 9 and 12 weeks of pregnancy. RESULTS Concentrations of calcium, magnesium, iron, copper, and manganese (but not zinc, cadmium, or lead) were significantly higher in coelomic than in amniotic fluid. There was no significant difference between levels of iron, manganese, and lead in controls and amniotic fluid or between concentrations of manganese, cadmium, and lead in controls and coelomic fluid. There was no relationship between the concentrations of each metal in amniotic and coelomic fluid. CONCLUSION The extraembryonic coelom is an important site of concentration of metals in early pregnancy. This might represent a store of metals essential for normal embryonic and fetal development or constitute a defense mechanism against environmental conditions adverse to the fetus.

UPTAKE OF ALUMINUM AND GALLIUM INTO TISSUES OF THE RAT: INFLUENCE OF ANTIBODY AGAINST THE TRANSFERRIN RECEPTOR

Transport of aluminum and gallium from blood into rat tissues following continuous iv infusion of metals in different chemical forms has been investigated. Tissue uptake of aluminum and gallium was similar and highly dependent on the chemical species of the metals. Aluminum and gallium accumulated in liver and spleen when infused in the chloride form. Raised citrate markedly enhanced aluminum and gallium uptake into renal cortex and bone; in contrast with gallium-transferrin, citrate increased uptake of67Ga into renal cortex and bone by 8- and 14-fold respectively. Uptake of67Ga with citrate into renal cortex was around 3 times smaller than that of aluminum. The antitransferrin receptor antibody OX-26 enhanced67Ga uptake from gallium citrate into all rat tissues.67Ga from purified gallium-transferrin was also taken into all tissues in the presence of OX-26, the effect being greatest in renal cortex and bone. No influence of antibody on aluminum transport into rat tissues was, however, observed when aluminum was infused in the citrate form. Therefore, transport of aluminum and gallium into tissues is not similar under all conditions. Transport of each metal occurs into all tissues in the presence of antitransferrin receptor antibody. The potential for such transport is much greater in the case of gallium. Transport of aluminum and gallium citrate complexes appears important especially in the renal cortex and bone.