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Non-Invasive Methods for Biomonitoring Trace Element Exposure

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Finger and toe nails don't seem very interesting at the best of times, but did you know they carry a record of your exposure to metals like lead and arsenic? …

Finger and toe nails don't seem very interesting at the best of times, but did you know they carry a record of your exposure to metals like lead and arsenic?

In this presentation I review how these materials can show if people are being exposed to trace metals and how they can be used to link exposure to possible early health effects.

The talk includes work from 3 PhD projects that I have been involved in and show how a project can develop from a humble beginning to cutting edge research.

Published in: Health & Medicine, Technology

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  • 1. Non-Invasive Methods for Biomonitoring Human Exposure to Trace Elements Dr Chris Harrington Deputy Director SAS Trace Element Laboratory, Royal Surrey County Hospital RSC TOXICOLOGY GROUP and SOCIETY FOR BROWNFIELD RISK ASSESSMENT Current Issues in Contaminated Land Risk Assessment - 2013 1
  • 2. Human Health Effects 2
  • 3. Biomonitoring Model Two classes of biomarker can be measured: Biomarkers of exposure and biomarkers of effect. 3
  • 4. Biomarkers of Exposure 4
  • 5. Biomarkers of Exposure • Random urine: guidance values for occupational exposure and defined species eg organic Pb. Requires creatinine correction. • Venous blood: guidance values for specific elements (Ag, Cd, Hg, Mn and Pb). • Hair: reference ranges available for some populations. Provides a timeline of exposure. Problems with surface contamination and cosmetic treatments. • Nails: similar to hair. Toe-nails better than finger-nails as less affected by contamination. • Zinc protoporphyrin in blood: blood drop from fingertip. Screening method for Pb and iron-deficiency anaemia. 5
  • 6. Study One: Arsenic Dietary Effects and Ethnicity 6
  • 7. Objectives Small scale preliminary study looking at:  Control groups from Leicester.  As in hair, urine and nails.  Development of life-style questionnaire.  Methods for cleaning hair and nails prior to analysis.  Total As and As speciation by ICP-MS and HPLC-ICP-MS. 7
  • 8. Results 1. Total As concentration in urine, hair and fingernail of three ethnic groups: Asian (n = 21), Somali (n = 22) and White (n = 20). (A) Total As concentration (μg/g creatinine) in urine. (B) Total As concentration (μg/kg) in hair and fingernail. E. I. Brima, P. I. Haris, R.O. Jenkins, A. G. Gault, D. A. Polya, C. F. Harrington. Understanding arsenic metabolism through a comparative study of arsenic levels in the urine, hair and fingernails of healthy volunteers from three unexposed ethnic groups in the United Kingdom. Toxicology and Applied Pharmacology, Vol. 216, 122-130, (2006). 8
  • 9. Results 2. Proportions of As species in the urine of three ethnic groups. Differences are predominantly related to dietary exposure: all participants refrained from seafood for 3 days prior to sampling. Higher proportion of DMA in Somali urine could relate to higher protein intake which promotes methylation. 9
  • 10. Study Two: Arsenic Devon Great Consols, Cornwall 10
  • 11. Objectives Small scale preliminary study looking at:  Exposure to As from abandoned mine site.  As in human hair, urine and nails.  Use of worms as sentinel organisms.  Use of bioaccessible fraction.  Used preparation methods and questionnaire from previous study.  Total As and As speciation by ICP-MS and HPLC-ICP-MS. 11
  • 12. Devon Great Consols, Cornwall Carmarthen Cheltenham Swansea Bristol Bath Taunton Devon Great Consuls Exeter Weymouth Plymouth Penzance 012.5 25 50 75 100 Kilometers ´ Nottingham garden used as control site. Total As (mg/kg) 255 - 289 331- 439 * 913 - 1005 1564 - 2980 5141 - 12466 0 0.25 ' •Total As in soil determined via ICP-MS following acid digestion. •Bioaccessible fraction 0.5 Kilometers by PBET. •SGV 32 – 640 mg/kg 12
  • 13. Devon Great Consols: Sampling 13
  • 14. Pathways of Exposure to Contaminated Soil 1. 2. 3. - - Inhalation Dermal uptake Ingestion Soil particles adhere to vegetables Geophagia Hand-to-mouth activities (‘Pica’ Children) 14
  • 15. Unified Bioaccessibility Method Stomach Phase Stomach + Intestine Phase Bioaccessible = Maximum concentration of arsenic available for gastro-intestinal absorption. (Bioavailable – Contaminant fraction that reaches the systemic circulation). 15
  • 16. Results: Stomach vs. Intestine Sample site 1 2 3 5 6 7 9 10 11 12 13 15 Control Total As (mg/kg-1) 3058 1564 996 238 11939 313 272 452 282 5232 2870 876 15.4 Stomach Only 578 298 308 44.2 340 94.8 60.9 43.8 36.5 1595 848 158 4.6 Stomach + Intestine 588 303 329 36.8 1603 73.0 72.2 40.5 35.3 1116 690 113 6.7 Bioaccessible As (%) 19.2 19.4 33.1 18.5 13.4 30.3 26.6 9.68 12.9 30.5 29.6 18.1 43.4 16
  • 17. Toe-Nail Levels: DGC Exposed Group Control Group Mean±SD min max Mean±SD min max Age 46 ± 26 41 ± 13 25 55 Male/Female (n) 5/3 Time outdoors (hr/wk) 11 ± 7 3 2 10 Toenail As (ug/kg) 5406 858 25981 122 73 273 Exogen. TN As (ug/kg) 506 102 3784 2.1 13 11 67 6/3 21 5±2 4.0 Total conc. As in toe-nail as a biomarker of exposure. Levels much higher in participants living near to DGC. Small cohort sizes. 17
  • 18. Publications From this Project M.J. Watts, M. Button, T.S Brewer, G.R.T. Jenkin and C. F. Harrington. The speciation of arsenic in two species of earthworms from a former mine site. Journal of Environmental Monitoring, Vol 10, 753-759, (2008). M.J. Watts, M. Button, T.S Brewer, C. F. Harrington and G.R.T. Jenkin. Toenails as a biomarker of exposure to elevated environmental arsenic levels in residents of an abandoned mine site, Devon, UK. Journal of Environmental Monitoring. Vol. 11, 610-617. (2009). Mark Button, Mark Cave, Chris F. Harrington, Michael J. Watts. Earthworms and in vitro physiologically based extraction tests: complimentary tools in a holistic approach towards understanding risk at arsenic contaminated sites. Environmental Geochemistry and Health, 31, 273-282, (2009). Button M, Jenkin GRT, Bowman, KJ, Brewer TS, Harrington CF, Jones GDD and Watts MJ (2008). Assessment of resistance to arsenic in earthworms from genotoxic contaminated soils using the Comet assay. Mutation Research: Genetic Toxicology and Environmental Mutagenesis, 696, 95-100, (2010). 18
  • 19. Study Three: Multielemental Panasqueira Mine, Portugal Panasquei ra Mine Castelo dam 19
  • 20. Objectives Investigate the effects on population health caused by mine waste contamination using a multistage approach integrate different biomarkers a better characterization of the risk Three groups: control (n = 35); occup. exp. (n = 34); environ. exp (n = 33). 20
  • 21. São Francisco de Assis village Geochemical sampling campaign undertaken in the vicinity of São Francisco de Assis village Mining site Village Soil samples (when compared to local background) As - 36x Cd - 4x Stream sediments (when compared to local background) As – 117x Cd – 23x 21
  • 22. Biomarkers of Effect - Genotoxicity: - T-cell receptor (TCR) mutation assay - Micronucleus (MN) - Chromosomal Aberrations (CA) - Comet Assay - Immunotoxicity-> Lymphocyte subset frequency - Susceptibility-> genetic polymorphisms (enzymes involved in the metabolism of metal(loid)s and DNA repair) 22
  • 23. COLLECTED SAMPLES / METHODS  Blood GFAAS and ICP-MS analysis  Urine  Nails  Hair ICP-MS analysis Digestion in microwave vessels with HNO3 (conc.) ICP-MS and ICP-OES analysis 23
  • 24. RESULTS – ICP-MS  Confounding factors  Gender - Cd in WB (↑ in males - E.E.) - Pb in WB (↑ in males - C. and E.E.)  Age - As in U ↑ older individuals - Hg in U - Se in U - Se in FN - ↑ younger individuals  Smoking Habits - Cd in WB (↑ in males - E.E.) 24
  • 25. RESULTS – ICP-MS C. vs. E.E. E.E. vs. O.E. C. vs. O.E. As ↑ WB*, FN* & TN* - ↑ FN* Cd ↑ FN* ↓ FN*,↑ H* ↑ H* Cr ↑ WB** ↓ WB** - Hg ↓ TN** & H* ↑ TN* & H* ↑ H* Mn - ↓ U*, ↑ H* ↑ H* Ni - - - Pb - ↑ WB* & H** ↑ WB* Se - ↓ FN* - * p<0,05 * *p<0,001 C. – Contol Group E.E. – Environmental Exposed Group O.E. – Occupational Exposed Group WB – Whole Blood FN – Fingernails TN – Toenails H – Hair U – Urine
  • 26. RESULTS – ICP-MS Correlations between elements & matrices Significant correlations between: • different elements / same matrix • same element / different matrices • different elements / different matrices were found for the majority of the elements showing a good synergy between these biomarkers. Elements concentrations vs. Reference/Published ranges Several elements exceed the reference ranges for WB and U samples, and for FN, TN and H the published ranges for non-exposed populations. 26
  • 27. Initial Conclusions Preliminary results for the biomarkers of effect: • Increased MN frequency -> genotoxicity • Elevated TCR mutation frequency -> mutagenicity • Alterations in the percentages of lymphocytes subsets -> immunotoxicity Increased risk of effects on health Related to the metal(loid) contamination from Panasqueira mine activities FURTHER DATA ANALYSIS IS UNDERWAY 27
  • 28. Publications From this Project Patrícia Clara dos Santos Coelho, Solange Costa, Susana Silva, Alan Walter, James Ranville, Ana Sousa, Carla da Costa, Marta Isabel Correia Coelho, Julia García-Lestón, M. Ramiro Pastorinho, Blanca Laffon, Eduardo Pásaro Mendez, Chris Harrington, Andrew Taylor and João Paulo Teixeira. Metal(loid) levels in biological matrices from human populations exposed to mining contamination - Panasqueira Mine (Portugal). Journal of Toxicology and Environmental Health, Part A. 2012, 75(13-15), 893-908. P. Coelho, S. Costa, C. Costa, S. Silva, A. Walter, J. Ranville, M.R. Pastorinho, C. Harrington, A. Taylor, V. Dall'Armi, R. Zoffoli, C. Candeias, E. Ferreira da Silva, S. Bonassi, B. Laffon J.P. Teixeira. Impact of Panasqueira mine activities on populations environmentally and occupationally exposed – quantification of several metal(loid)s in different biological matrices. Environmental Geochemistry and Health, published on-line. All publications relating to this work are available to download from Research Gate : www.researchgate.net/profile/Chris_Harrington/?ev=hdr_xprf 28
  • 29. Future Work: Vulnerable populations Ethically unacceptable to perform wide scale biomonitoring on children using invasive methods. 29
  • 30. Acknowledgements All colleagues and collaborators who helped with the different studies: Study One: De Montfort University Studentship (Dr Eid Brima). Study Two: British Geological Survey, NERC Award (Dr Mark Button). Study Three: FCT Portugal (Dr Patricia Coelho). Current work: NHS for on-going instrument time. All publications relating to this work are available to download from Research Gate : www.researchgate.net/profile/Chris_Harrington/?ev=hdr_xprf 30