A new Scientific Committee on Toxicology and Environmental Health at IATDMCT. Scope and goals. Nicolas Venisse Clinical Investigation Center, CIC INSERM 1402 and Toxicology and Pharmacokinetics Department, University Hospital, Poitiers, France
[email protected]
Introduction - Huge
variety of chemicals are constantly being introduced in the environment - Toxicological
significance of exposure to these compounds and consequences on health for the general population are of increasing concern - Knowledge
on human exposures and how they can affect health outcomes is mandatory in order to create healthy environments and improve health
Approaches to human exposure assessment
Questionnaire administration
EDDS cohort Endocrine Disruptor in Deux-Sèvres
Objective : estimate exposure of french pregnant women to ED occuring through water comsuption
Approaches to human exposure assessment Other indirect approach
Dr Takashi Azuma Distribution of Pharmaceuticals in Clinical Wastewater from Medical Institutions and Development of Advanced Water Treatment Systems
Approaches to human exposure assessment
Direct measurement of pollutants in human matrices
HBM
→ Reference method
Nieuwenhuijsen M, Environ Int. 2006
Uses of HBM Advantage : reflect the total body burden resulting from all routes of exposure
Inter-individual variations in pollutant disposition (TK)
Needham LL, Int J Hyg Environ Health 2007
Biological monitoring or Human Biomonitoring (HBM) What is Human Biomonitoring ? “Measurement of environmental chemicals, their metabolites, or specific reaction products in human biological specimens to assess internal exposure” Calafat AM, Needham LL, EHP 2009
What is not HBM
HBM differs from biochemical effect monitoring Quantification of the reaction products of reactive substances with biological molecules (DNA, proteins, …) HBM differs from biological effect monitoring Measurement of early biological effects caused by chemical substances Angerer, Int J Hyg Environ Health 2007
Uses of HBM - Development of reference ranges of exposure : - HBM values derived by the Human Biomonitoring Commission of the German Environment Agency
- Identify temporal and/or spatial trends
LaKind JS, Environ Res 2015
BPA daily intake over the period 2003-2015 estimated from urinary BPA concentration
- Identify population at risk and life-style contributing factors - Assess association with health outcomes Needham LL, Int J Hyg Environ Health 2007
HBM Growing interest for HBM since 2010
Number of papers
150 « Human Biomonitoring »
100 50 0 1990
1995
2000
2005
2010
2015
Publication date
Number of papers published by year using the keyword « human biomonitoring » in PubMed
National initiatives To develop HBM studies within general population
HBM uses methods already developed for Clinical Toxicology - Bioanalysis : adequacy of HBM data depends strongly on reliable analytical measurements - Toxicokinetics : understanding of ADME processes required in order to choose the adequate biomarker of exposure - Toxicokinetic modeling : conventional TK or PB-TK models to support the interpretation of HBM data
HBM uses methods already developed for Clinical Toxicology - Bioanalysis : adequacy of HBM data depends strongly on Dr N Van den Eede reliable analytical measurements Optimizing human - Toxicokinetics : understanding of ADME processes biomonitoring targets for required in order to choose thecontaminants adequate biomarker of environmental based on in vitro metabolism exposure experiments- a case study of - Toxicokinetic modeling : conventional flame retardants TK or PB-TK models to support the interpretation of HBM data
HBM uses methods already developed for Clinical Toxicology - Bioanalysis : adequacy of HBM data depends strongly on Pr S Haddad reliable analytical measurements Physiologically based - Toxicokinetics : understanding of ADME processes pharmacokinetic modeling as required in order to for choose the adequate of biomarker of tool the interpretation biomonitoring data in the exposure exposure assessment of - Toxicokinetic modeling : conventional TK or PB-TK models environmental contaminants to support the interpretation of HBM data
Focus on bioanalysis Analytical capabilities are at the core of HBM - Environmental pollutants present in biological matrices at trace-level - Require highly sensitive, specific and selective quantification method
- Biological matrices are complex : blood, urine,
Major challenge
milk, fat, placental tissue, hair, nails, teeth …
→ Careful bioanalytical validation required to obtain reliable HBM data
Validation guidelines Published bioanalytical methods Incomplete validation / lack of information regarding method validation
A great variety of bioanalytical validation guidelines used (non-exhaustive list)
Validation guidelines Environmental matrices Not biological NORMAN 2009
Incomplete
Selectivity / Specificity
Linearity LOD LLOQ
3 times LOD
Matrix-specific LOQ and LOD
ULOQ Accuracy and precision Stability
Matrix Effect
Covering the whole range of concentrations
Validation guidelines Matrix effect
Methods for studying and avoiding matrix effects available for years.
Avoiding contamination Specific issue - Ubiquitous environmental contaminants : phtalates, polybrominated diphenyl ethers, polyfluoroalkyl chemicals, bisphenol A - Detected in indoor air and dust blank samples - Contamination of collection materials preliminary screening
- Contamination from laboratory material : ultrapure reagents, solvents BPA contamination from mobile phase prepared with lower grade analytical quality methanol
Avoiding contamination from BPA
- Glass materials (heated 500°C, 5h) for sampling - Glass SPE cartridges, tubes and volumetric pipets - High purity solvents : ULC/MS grade water and methanol - Inclusion of blank samples
Basal contamination in human matrices - Calibration standards and QCs prepared by spiking the
biological matrix of interest in order to mimic the study samples avoid bias in bioanalytical performance : ME, recovery, specificity - Target analytes present in
Compound name: methylparaben Correlation coefficient: r = 0.996448, r^2 = 0.992909 Calibration curve: 1.21359 * x + 0.202812 Response type: Internal Std ( Ref 12 ), Area * ( IS Conc. / IS Area ) Curve type: Linear, Origin: Exclude, Weighting: 1/x, Axis trans: None
2.00 1.80
preparation of calibration and QC
1.40
Response
biological matrices used for
1.60
1.20 1.00 0.80 0.60 0.40 0.20
samples, with variable concentration
from batch to batch
-0.00 -0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
Conc 1.60
Calibration curve for methylparaben in urine
Ways to deal with basal contamination in human matrices - Standard addition : sample consuming and labor intensive !!
- Depletion of the analyte from the biological matrix using chemical or enzymatic reactions matrix is altered (ME) - Subtract blank values from results : difficult if high basal contamination
- Use of surrogate matrix : synthetic urine or plasma may introduce a significant bias due to ME, what validation needed ? - Use of surrogate analyte : SIL analog
Synthetic urine and CSF
Deconjugation Pollutant present in biological matrix as parent compound or conjugated form BPA 1st pass-effect BPA
BPA
BPA
BPA-G BPA-S
BPA
BPA
BPA
P
BPA-G BPA-S
Urinary excretion BPA
Direct mesurement
P BPA-S P
BPA-G
BPA-G BPA-S
conjugated-BPA = total BPA - BPA Indirect / deconjugation β-glucuronidase / sulfatase
Deconjugation - Suboptimal deconjugation arising from : - inappropriate concentration or choice of enzyme, or - unfavorable hydrolysis conditions (pH, temperature, dilution, solvent of incubation)
- Incomplete deconjugation underestimation of the total amount and of conjugate concentration mis-interpretation of the relationships between parent and conjugates
Deconjugation efficiency has got to be routinely controlled
Deconjugation
Marker of enzymatic (βglucuronidase and sulfatase) deconjugation efficiency in plasma and urine
Routinely assess deconjugation efficiency within the frame of a quality system, an essential step to obtain reliable data
Need for harmonization - In addition to common validation parameters : linearity, accuracy, precision, matrix effect, LOQ, LOD, specificity, ME - Specific issues that need to be addressed : - Contamination - Deconjugation process - Validation for surrogate matrix → develop a framework / recommendations for bioanalytical validation
Objectives of the new SC (1) - To promote and disseminate research in this area (human exposure) : - link / awareness with national toxicology societies - To develop a framework / recommendations for bioanalytical
validation purpose including key elements : contamination, ME, deconjugation …
Objectives of the new SC (2) - Oral and poster session and symposium at IATDMCT meetings, satellite meeting
- To
bring together scientists and enhance collaboration between
groups working in the field : International Consortium for HBM for harmonization, biobanking, cohort development …
Acknowledgements Pr Loralie Langman and the executive committee for endorsing the creation of the new scientific committee Pr Yusuke Tanigawara and the organizing committee for offering a slot for this symposium Pr David Kinniburgh, the vice-chair of the committee Members of the Toxicology and Environmental Health scientific committee
HEDEX research group / INSERM CIC 1402 at University Hospital of Poitiers for fruitful discussions
