2. .

4. “Exposure” VS “Exposome”
Exposure assessment of most
epi-studies is limited to a single
or a small group of toxicants.
Insufficient studies to observe
developmental stages.
Ref) Rappaport 2011

5. Can influence
health here
What happens
here
Prenatal programming of adult disease

6. Challenges to studying fetal chemical programming
Overcome
Limitations
1) Longitudinal birth cohort study :
- time consuming and expense
- measurements of maternal biomarkers
(not fetal biomarkers)
- cord blood is good matrix but largely detect
long half life chemicals and provide only
limited development period (over 3rd trimester)
* New human matrix
- retrospective
- objective
- capable of directly measuring fetal exposures
- provide time-series exposure data

7. Tooth provide time series exposure

8. Key aspects of methodology
Participants: 5 children (7 ~ 10 years old)
Collected matrix: deciduous teeth
Participants A B C D E
2nd, 3rd trimester dentine
Prenatal (2nd, 3rd trimester), postnatal dentine

9. Key aspects of methodology
Used equipment: QTOF-LC/MS (Agilent 6550 iFunnel QTOF with Jet Stream)
Purpose: global screening of small molecules

10. Classification of qualified compounds
1. Known unknowns (Database OK, reference standard OK) 2. Suspected unknowns (Database OK, no reference standard) 3. Unknown unknowns (no database, no reference standard)

11. Multi-chemical exposure profiles during prenatal and early childhood periods
Targeted analysis of organic compounds and metabolites accumulated in dentine formed during specific period

12. Bisphenol A (First report)
Mono-methyl phthalate (First report)
Mono-ethyl phthalate (First report)
Mono-butyl phthalate (First report)
Mono-benzyl phthalate (First report)
Mono-ethylhexyl phthalate (First report)
Hydroxycotinine (First report)
Cotinine
Nicotine

13. For suspected unknowns:
Compound matching with literature for prenatal and children’s exposures to environmental factors (Bellinger 2013; Gonzalez-Alzaga and others 2014; Lyall and others 2014; Meeker 2012).

14. Multi-chemical exposure profiles during prenatal and early childhood periods
Single measures of conventional biomarkers or use of whole teeth are vulnerable to assess exposome
BPA

15. Multi-chemical exposure profiles during prenatal and early childhood periods
Untargeted analysis of organic compounds and metabolites accumulated in dentine formed during prenatal period (Child C)

16. 1) Molecular Formula Generation (MFG) algorithm to generate chemical formulas of different peaks

17. 2) MassHunter Profinder was used to perform Batch Recursive Feature Extraction (BRFE)

18. 3) Compounds selection
Selected based on ion intensity in each tooth (n=100)
Comparisons were made for inter/intra child variablilty in nontargeted analysis profiles.
N = 309
N = 225

19. Metabolites pattern between pre- and post-natal samples for each child and between children

21. Conclusion and perspectives
Similar methods can be applied to permanent/adult teeth for the study of adult disease outcomes.

22. The computational tool
For targeted analysis
- Personal Compound Database (PCD)
- Find by Formula compiled by Agilent Tech.
For untargeted screening
- Molecular Feature Extraction (MFE)
- Batch Recursive Feature Extraction (BRFE)