Alan Walter

Metal(Loid) Levels in Biological Matrices from Human Populations Exposed to Mining Contamination—Panasqueira Mine (Portugal)

Mining activities may affect the health of miners and communities living near mining sites, and these health effects may persist even when the mine is abandoned. During mining processes various toxic wastes are produced and released into the surrounding environment, resulting in contamination of air, drinking water, rivers, plants, and soils. In a geochemical sampling campaign undertaken in the Panasqueira Mine area of central Portugal, an anomalous distribution of several metals and arsenic (As) was identified in various environmental media. Several potentially harmful elements, including As, cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se), were quantified in blood, urine, hair, and nails (toe and finger) from a group of individuals living near the Panasqueira Mine who were environmentally and occupationally exposed. A group with similar demographic characteristics without known exposure to mining activities was also compared. Genotoxicity was evaluated by means of T-cell receptor (TCR) mutation assay, and percentages of different lymphocyte subsets were selected as immunotoxicity biomarkers. Inductively coupled plasma–mass spectrometry (ICP-MS) and inductively coupled plasma–atomic emission spectrometry (ICP-AES) analysis showed elevated levels of As, Cd, Cr, Mn, and Pb in all biological samples taken from populations living close to the mine compared to controls. Genotoxic and immunotoxic differences were also observed. The results provide evidence of an elevated potential risk to the health of populations, with environmental and occupational exposures resulting from mining activities. Further, the results emphasize the need to implement preventive measures, remediation, and rehabilitation plans for the region.

Iodine deficiency in UK women of child-bearing age

Iodine deficiency in pregnant women can lead to an inadequate supply of thyroid hormones to the fetus resulting in impaired fetal brain development, reduced intelligence scores and impaired motor skills in the offspring of deficient women. The importance of adequate iodine intake in pregnancy is such that WHO recommendations of 150mg/d for non-pregnant adults are increased to 250mg/d in pregnancy. Although the UK is normally considered to be iodine sufficient, concern has been expressed recently about the iodine status of UK women. A cross-sectional pilot study was therefore undertaken in thirty-one women of child-bearing age (median age 23 years) to investigate the iodine status of Surrey women. Urine collections (24 h) were obtained and their total volume measured. Iodide concentration was measured using inductively-coupled plasma MS. Total 24 h iodide excretion was calculated and used to assess the individual risk of deficiency. Daily iodine intake was calculated assuming that the 24 h urinary iodide excretion represents 92% of daily iodine intake. The Figure shows the 24 h iodide excretion for each subject and the categorisation of iodine status according to Thomson et al. and Als et al.. One subject (3.2%) was classified as moderately deficient, eight (25.8%) had mild deficiency, ten (32.3%) had marginal iodine status and the remaining twelve subjects (38.7%) had adequate iodine status. The median total 24 h iodide excretion was 140.5mg, categorising the group as a whole as having marginal iodine status. Calculation of iodine intake (extrapolated from urinary iodide excretion) indicated that 48% did not meet the WHO adult requirement of 150mg/d, 42% had an intake below the UK reference nutrient intake and 87% would not meet the 250mg/d WHO intake requirement for pregnancy.

Interference of gadolinium on the measurement of selenium in human serum by inductively coupled plasma-quadrupole mass spectrometry

Selenium is an important clinical biomarker of nutritional status; however, the occurrence of gadolinium in a patients serum as a result of the contrast agents used during magnetic resonance imaging investigations, results in a significant positive bias in its measurement by inductively coupled plasma-quadrupole mass spectrometry.

Removal of the gadolinium interference from the measurement of selenium in human serum by use of collision cell quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS)

Background Measurement of selenium in serum is an important clinical biomarker of nutritional status. The presence of gadolinium (Gd) in samples following administration of the contrast agents used for magnetic resonance imaging (MRI) results in a significant positive bias when using quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). Methods Three instrumental set-ups were assessed: standard mode with no collision gas and collision cell mode with either a hydrogen:helium mixture or hydrogen. The effect of Gd on the selenium (Se) signal was assessed using external quality assurance (EQA) specimens and internal quality control (IQC) materials, both unspiked and spiked with Gd. Serum previously shown to contain high concentrations of Gd-containing contrast agents were also analysed. Results Recoveries of Se in the spiked compared to the unspiked samples were: between 500% and 1300% using standard mode; 100% and 29,000% using collision cell mode with hydrogen:helium mixture; and between 99% and 103% using hydrogen. The use of H2 in the collision cell provided accurate results, indicating that the charge exchange reaction (CER) of Gd2+ with H2 removes this interference. Analysis of patient serum known to contain the Gd contrast agent using the method gave results within the selenium reference range (adults 0.89–1.65 µmol/L). The presence of Gd, as low as 0.2 mg/L, in serum samples causes a positive interference on the measurement of Se by ICP-MS. Conclusions Using a CER mode with pure H2 in the collision cell it was possible to fully remove the interference due to Gd2+ from the signal for Se.