Jackie Morton

The speciation of inorganic and methylmercury in human hair by high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry

Inorganic and methylmercury content in human hair has previously been determined using different analytical techniques for each species. In this study a single method, allowing the separation and determination of mercury species in human hair, is developed. Using a HPLC-ICP-MS system it is possible to separate inorganic and methylmercury in hair, without any modifications to the existing instrumentation. The results showed that in order to determine methylmercury as well as inorganic mercury the hair sample must be cold digested with 2 ml of concentrated nitric acid plus 1 ml of hydrogen peroxide and that a minimum of 0.1 g hair is required. Hair washing procedures are also investigated to remove exogenously bound species. It is seen that when hair is soaked with simulated sweat solution containing both inorganic and methylmercury and then washed with 0.1 M HCl all the methylmercury, both existing and spiked, can be removed from the hair sample. However, only 65% of the spiked inorganic mercury can be removed by washing with 0.1 M HCl, the rest being irreversibly bound to the hair.

Arsenic mobility and speciation in a contaminated urban soil are affected by different methods of green waste compost application.

Application of green waste compost (GWC) to brownfield land is now common practice in soil restoration. However, previous studies have demonstrated both beneficial and detrimental effects on arsenic and metal mobility. In this paper, trace element behaviour was investigated following GWC application, either as surface mulch to, or mixed into soil from a previously described brownfield site in the U.K. Significant differences in arsenic mobility were observed between treatments. Mulching caused most disturbance, significantly increasing soil pore water As, together with Fe, P, Cr, Ni and dissolved organic carbon, the latter was a critical factor enhancing As mobilization. Arsenate was the main inorganic As species in soil pore water, increasing in concentration over time. An initial flush of potentially more toxic arsenite decreased 4 weeks after compost application. Biological processes appeared to play an important role in influencing As mobility. The results point to the necessity for careful management of As-contaminated soils.

Variance components of short-term biomarkers of manganese exposure in an inception cohort of welding trainees

Various biomarkers of exposure have been explored as a way to quantitatively estimate an internal dose of manganese (Mn) exposure, but given the tight regulation of Mn in the body, inter-individual variability in baseline Mn levels, and variability in timing between exposure and uptake into various biological tissues, identification of a valuable and useful biomarker for Mn exposure has been elusive. Thus, a mixed model estimating variance components using restricted maximum likelihood was used to assess the within- and between-subject variance components in whole blood, plasma, and urine (MnB, MnP, and MnU, respectively) in a group of nine newly-exposed apprentice welders, on whom baseline and subsequent longitudinal samples were taken over a three month period. In MnB, the majority of variance was found to be between subjects (94%), while in MnP and MnU the majority of variance was found to be within subjects (79% and 99%, respectively), even when controlling for timing of sample. While blood seemed to exhibit a homeostatic control of Mn, plasma and urine, with the majority of the variance within subjects, did not. Results presented here demonstrate the importance of repeat measure or longitudinal study designs when assessing biomarkers of Mn, and the spurious associations that could result from cross-sectional analyses.

µLC–ICP-MS Determinations of Unexposed UK Urinary Arsenic Speciation Reference Values

This study provides background levels for five arsenic species in urine, based on urinary data obtained from 95 nonoccupationally exposed volunteers based in the UK. Using a novel, sensitive, robust and reliable speciation methodology, five species of arsenic (arsenobetaine [AB], arsenite [As(3+)], arsenate [As(5+)], monomethylarsonic acid [MMA(5+)] and dimethylarsinic acid [DMA(5+)]) were determined in urine samples collected from 95 adults. The analytical instrumentation used to analyze the urine samples was a hyphenated micro liquid chromatography (μLC) system coupled to an inductively coupled plasma mass spectrometry (ICP-MS). Separation was achieved using an anion exchange micro-sized column. The results presented give the 95th percentile of concentrations, both uncorrected for creatinine (µg/L) and creatinine corrected (µmol/mol) in urine for the 95 volunteers. Statistical analysis was performed on the dataset using a Bayesian model to determine and quantify effects of gender, smoking and diet. The statistical results show that the consumption of fish, shellfish and red wine has a significant elevating effect on AB, DMA and MMA urinary concentrations; however, no significant effect was observed for smoking. The regression model results indicate that creatinine correction was effective for arsenic species As(3+), MMA, DMA and AB. The background levels established here can be used as reference values to help aid interpretation of arsenic speciation results and better assess exposure.

Development of a method for the simultaneous detection of Cr(III) and Cr(VI) in exhaled breath condensate samples using μLC-ICP-MS

The method described in this study is a robust and sensitive method for the simultaneous determination of trivalent and hexavalent chromium (Cr(III) and Cr(VI)) in an exhaled breath condensate (EBC) sample and drinking water proficiency testing material sample. The method uses a hyphenated micro liquid chromatography (μLC) system coupled to inductively coupled plasma mass spectrometry (ICP-MS). The optimised method incorporates a pH adjusted EDTA complexation step to stabilise Cr(VI) and Cr(III). Separation was achieved using an anion exchange micro-sized column. The limits of quantification were 0.040 μg L−1 and 0.013 μg L−1 for Cr(III) and Cr(VI) respectively. EBC is the non-invasive collection of condensate from cooled exhaled breath during regular tidal breathing. We propose that EBC may be a suitable alternative biological matrix to give a more comprehensive picture of exposure to Cr(VI) following an inhalation exposure. This study shows that water samples and EBC samples containing Cr(III) and Cr(VI) can be stored in the fridge (∼4 °C) for up to 6 weeks when they have been diluted 10 fold with an EDTA solution, and that EBC samples must not be frozen after collection if the integrity of Cr(VI) is to be maintained. This study has demonstrated a practical approach to collecting EBC samples from workers potentially occupationally exposed to hexavalent chromium and that the integrity of the chromium species will be maintained prior to analysis.

Trends in blood lead levels in UK workers, 1995–2007

Objectives This study evaluated blood lead data (including zinc protoporphyrin (ZPP) and haemoglobin levels) collected at the UKs Health and Safety Laboratory (HSL) in order to determine temporal changes in occupational exposure to lead between 1995 and 2007. Methods A total of 20 889 blood lead measurements and accompanying ZPP and haemoglobin results from 8810 workers at 972 companies from routine samples received by HSL over the period 1995–2007 were analysed. Time trends in blood lead levels for each industry sector were estimated using Bayesian mixed effects modelling. Results Reductions in median blood levels over the period 1995–2007 were seen in every sector except for those samples forwarded by occupational health providers, and range from 1.6% per year for workers in the smelting industry to 12% per year for workers in pottery and glazing industries. An overall reduction of 3.1% per year across all industries was determined. The percentage of results above the current UK suspension limit of 60 μg/dl fell from 4.8% in 1995 to 0.6% in 2007. ZPP and blood lead exhibited a strong association, but no significant correlation was found between blood lead and haemoglobin. Conclusions Occupational exposure to lead has fallen across UK industries in recent years, although it remains substantially above background levels. There is evidence that many workers are exposed to elevated lead levels over a long period of time and this deserves renewed consideration now that inorganic lead has been reclassified as a probable human carcinogen.

Multi-elemental analysis of human lung samples using inductively coupled plasma mass spectrometry

The aim of this study was to establish concentrations of a wide range of elements in human lung samples to allow better identification of potential exposures in subsequent cases. This study reports concentrations of 48 elements (Al, As, Au, B, Ba, Be, Bi, Br, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Gd, Ge, Hf, Hg, In, Li, Mn, Mo, Nb, Ni, Os, Pb, Pd, Pt, Rb, Re, Ru, Sb, Se, Sm, Sn, Sr, Ta, Te, Ti, Tl, Tm, V, W, Y, Zn and Zr) in fresh lung tissue samples from 54 hospital patients, of which 93% exhibited various forms of neoplasia. The lung samples were taken from unaffected, background tissue. The samples were stored as fresh tissue in alcohol, dried and microwave digested before analysis by inductively coupled mass spectrometry (ICP-MS). It was possible to establish 95th percentiles for all elements except for rhenium and for 40 elements mixed effects modelling was undertaken. Overall, the levels reported are commensurate with ranges for those elements that had been reported previously. The data were examined for gender, smoking and occupational exposures to metals. The results show that males have higher lung concentrations of Ni, Cr, Gd, Au and Be than females, but significantly lower lung concentrations of Co, Sn, W and In. Cadmium lung concentrations were significantly higher in smokers. Platinum lung concentrations were higher in those who had undergone chemotherapy and gadolinium concentrations were predictably high in those who had undergone imaging scans. More essential elements such as Cu, Br, Fe and also Ge varied the least within lung samples from individuals whilst Be, Hf and Pt had the greatest variances. Between individuals V and Li lung concentrations varied the most, whilst Cu varied least. Analysis of the data for those who reported as having previously worked with metals showed 24 of the 48 elements determined were higher than those from those who had not reported working with metals.

The use of bio-monitoring to assess exposure in the electroplating industry

Workers in the electroplating industry are potentially exposed to a range of hazardous substances including nickel and hexavalent chromium (chromium VI) compounds. These can cause serious health effects, including cancer, asthma and dermatitis. This research aimed to investigate whether repeat biological monitoring (BM) over time could drive sustainable improvements in exposure control in the industry. BM was performed on multiple occasions over 3 years, at 53 electroplating companies in Great Britain. Surface and dermal contamination was also measured, and controls were assessed. Air monitoring was undertaken on repeat visits where previous BM results were of concern. There were significant reductions in urinary nickel and chromium levels over the lifetime of this work in the subset of companies where initially, control deficiencies were more significant. Increased risk awareness following provision of direct feedback to individual workers and targeted advice to companies is likely to have contributed to these reductions. This study has shown that exposures to chromium VI and nickel in the electroplating industry occur via a combination of inhalation, dermal and ingestion routes. Surface contamination found in areas such as canteens highlights the potential for transferral from work areas, and the importance of a regular cleaning regime.

Investigation of saliva as an alternative matrix to blood for the biological monitoring of inorganic lead

INTRODUCTION Whole blood is the established matrix for biological monitoring of inorganic lead; however blood sampling is an invasive procedure. Saliva offers a potential non-invasive alternative. This study determines lead in whole blood and saliva. A novel method for saliva sampling and preparation is presented. METHODS Paired blood and saliva samples were obtained from 105 occupationally exposed UK workers. Saliva was collected using a StatSure sampling device, and a nitric acid digestion step was incorporated. The utility of the device for this application was evaluated. Whole blood was obtained by venepuncture. Analyses were carried out by ICP-MS. RESULTS The limit of detection for lead in saliva was 0.011 μg/L. Mean blank-corrected recovery from 10 μg/L spiked saliva was 65.9%. The mean result from blank saliva extracted through the StatSure device was 2.86 μg/L, compared to 0.38 μg/L by direct analysis. For the paired samples, median blood lead was 6.00 μg/dL and median saliva lead was 17.1 μg/L. Pearsons correlation coefficient for saliva lead versus blood lead was 0.457 (95% C.I. 0.291-0.596). CONCLUSIONS ICP-MS analysis allows sensitive determination of lead in saliva with low limits of detection. The StatSure device is effective for high occupational exposures, but contamination from the device could confound lower-level measurements. Saliva would only be effective as a surrogate for whole blood for highly-exposed populations, although with further work it may have applications as a biomarker of recent exposure.

Saliva as a matrix for biomonitoring of occupational and environmental exposure to lead

Abstract Background: To evaluate whether salivary lead can be used as a surrogate for blood lead, and if so, over what concentration range. Methodology: Three saliva devices were evaluated and one chosen to undertake this project. Paired saliva and blood samples were collected from 89 UK lead workers. Lead concentrations were determined using ICP-MS. In addition, haemoglobin and ZPP levels were determined in the blood samples and albumin was determined in the saliva samples to investigate standardisation using protein adjustments. Results: The chosen saliva device gave low but consistent recoveries for lead in saliva and the blank levels were low. The mean +/- SD blood lead level was 19.9 +/- 14 μg/dl; the mean +/- SD saliva lead level was 19.1 +/- 32.5 μg/l for 89 workers. Log10-transformed data showed correlation of r=0.69. The protein adjustments did not improve the blood-saliva correlation. Conclusions: This study has demonstrated that salivary lead measurement is feasible and correlated with blood lead levels, at least at occupational exposure levels, and may have value as a screening technique. Correlation may improve at environmental levels where exposures are generally more consistent and chronic, although this needs to be demonstrated in a genuine environmental population.