Elizabeth Leese

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.

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.

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.

The Investigation of Unexpected Arsenic Compounds Observed in Routine Biological Monitoring Urinary Speciation Analysis

This study investigates the identity of two unexpected arsenic species found separately in a number of urine samples sent to the Health and Safety Executive’s Health and Safety Laboratory for arsenic speciation (arsenobetaine, AB; arsenite, As3+; arsenate, As5+; monomethylarsonic acid, MMA5+; and dimethylarsinic acid, DMA5+). Micro liquid chromatography coupled to inductively coupled plasma mass spectrometry (µLC-ICP-MS) and electrospray time of flight tandem mass spectrometry (ESI-QqTOF-MS/MS) were used to identify the two arsenic peaks by comparison to several characterized arsenicals: arsenocholine, AC; trimethyl arsine oxide, TMAO; dimethylarsenoacetate, DMAA; dimethylarsenoethanol, DMAE; thio-dimethylarsinate, thio-DMA; thio-dimethylarsenoacetate, thio-DMAA and thio-dimethylarsenoethanol, thio-DMAE. The results from both the ICP-MS and ESI-QqTOF-MS/MS investigations indicate that the unexpected arsenic species termed peak 1 was thio-DMA. While the unexpected arsenic species termed peak 2 has yet to be identified, this investigation shows that it was not AC, TMAO, DMAA, DMAE, thio-DMA, thio-DMAA or thio-DMAE. This study demonstrates the incidence of unexpected arsenic species in both routine and non-routine urine samples from both workers and hospital patients.

Exhaled breath condensate: a novel matrix for biological monitoring to assess occupational exposure to respirable crystalline silica

Biological monitoring (BM) is a useful way of determining overall exposures to chemical substances; however, in the case of respirable crystalline silica (RCS), this has not been analytically feasible in conventional biological matrices. The aim of this study was to investigate the utility of exhaled breath condensate (EBC) as a potential biological matrix in which to determine exposure to RCS. A small pilot study was undertaken collecting EBC from six quarry workers and six occupationally unexposed persons; the samples were analysed using both single particle inductively coupled plasma mass spectrometry (spICP-MS) and transmission electron microscopy (TEM). The results showed that EBC obtained from the occupationally unexposed persons exhibited low background levels of dissolved silica whilst silica particles of various sizes were present in samples from quarry workers. This is the first study to report EBC as a potential biological matrix that allows differentiation of RCS concentrations between samples from workers and occupationally unexposed controls. The results shown here confirm the presence of RCS in EBC by both spICP-MS and TEM. However, there are difficult analytical challenges still to be overcome before this can be used as a BM method to determine workplace exposure, these are currently being investigated.

Homicidal arsenic poisoning.

The case of a 50-year-old man who died mysteriously after being admitted to hospital is reported. He had raised the possibility of being poisoned prior to his death. A Coroner’s post-mortem did not reveal the cause of death but this was subsequently established by post-mortem trace element analysis of liver, urine, blood and hair all of which revealed very high arsenic concentrations.