Understanding the significance of exposure science in WHS issues Presented by Dr Len Turczynowicz, AESH, Uni of Adelaide

1. “”” Understanding the significance of
exposure science in WHS issues
Dr Len Turczynowicz
Senior Research Fellow, University of Adelaide
SA Safety Symposium 20 October 2023

2. Presentation Outline
 What is exposure science?
 Exposome and epigenetics
 Exposure science in workplace health and safety
 Exposure science tools
 The application of exposure science logic
 Retrospective pesticide exposure assessments
 Impacts of latency and growing epidemiological evidence
 Emerging contaminants (silica; PFAS/PFOA)
 Time-dependent exposures – where to?
 Key issues and concluding comments

3. What is exposure science?
Definition
 Exposure science addresses the intensity and
duration of contact of humans or other organisms
with those agents (defined as chemical, physical, or
biologic stressors) and their fate in living systems.”
(National Academy of Sciences, 2012, p33)

4. What is exposure
science?
What is exposure science?
(from NRC, 2012)

5. What is exposure
science?
What is exposure science?
 The study of stressors, populations (receptors), and their
contacts in the context of space and time
 The science linking human and ecologic behaviour to
environmental processes in such a way that the information
generated can be used to mitigate or prevent future adverse
exposures
 Predominantly observational performed in the field within
normal living and working situations
 Exposure science is a multidisciplinary field, both an art and a
science.

6. What is exposure
science?
What is exposure science?
(from NRC, 2012)

7. What is exposure
science?
The Exposome
 It comprises the totality of exposures to which an individual is
subjected from conception to death, including those resulting from
environmental agents, socioeconomic conditions, lifestyle, diet, and
endogenous processes.
 The exposome is a concept with limited application at present (e.g.,
cohorts)
 Often generated from consecutive cross-sectional studies
 Exposomics – technologies for characterizing the exposome

8. What is exposure
science?
The Exposome
(from Wild, 2012)

9. What is exposure
science?
The Exposome
(from Wild, 2012)

10. What is exposure
science?
Epigenetics
Epigenetics is the study of how
your behaviors and environment
can cause changes that affect the
way your genes work.
Unlike genetic changes,
epigenetic changes are reversible
and do not change your DNA
sequence, but they can change
how your body reads a DNA
sequence.
(from CDC, 2020)

11. What is exposure
science?
Epigenetics
(Harvard Magazine 2022, (Illustration by Jude Buffam))

12. What is exposure
science?
Epigenetics
(from Obri et al., (2020)
[Consider early life exposures = Carcinogens,
asthmagens, nutrition, exercise]

13. What is exposure
science?
Exposure science in workplace health and safety
(from https://hsewatch.com/occupational-hazard/)

14. What is exposure
science?
Exposure science in workplace health and safety
(enHealth, 2012, p50, adapted from National Academy of Sciences, 1991)

15. What is exposure
science?
Exposure science in workplace health and safety

16. What is exposure
science?
Exposure science tools
Direct methods - Personal monitoring
 ‘Point of contact’ as it occurs
 Inhalation - reflects ‘breathing zone’ capture as it occurs
 Passive vs active, ~higher results than ‘static’ monitoring1
 Relevant at the individual level hence occupational
 Ingestion, e.g., dietary assessments, soil consumption
 Dermal, e.g., patches, whole-body dosimeters, removal methods
(rinsing, wiping, and tape stripping), and optical methods (treating the
chemical of concern with a nontoxic fluorescent tracer)

17. What is exposure
science?
Exposure science tools
Direct methods - Biological monitoring
 Assessing chemical exposures by measuring the chemical or its
breakdown products in a biological sample (usually urine, blood or
breath).
 Common in occupational hygiene (phthalates, PAHs)
 Not as common in environmental assessment (lead)
 Need to understand a range of characteristics of your contaminant of
interest (MOA, ADME).
 Reverse dosimetry tools

18. What is exposure
science?
Exposure science tools
(from Lauro et al., 2019)

19. What is exposure
science?
Exposure science tools
 Complex PBPK model adapted from pg 13 of 1,4-dioxane IRIS (US EPA, 2010)

20. What is exposure
science?
Exposure science tools
(from US EPA, 1998)
 Predictive and reconstruction
assessments (see dark blue
arrows)
 Also referred to as reverse
dosimetry
 Need adequately
described/validated PBPK models
 Most accurate exposure
assessment

21. What is exposure
science?
The application of exposure science logic
Retrospective pesticide exposure assessments/reverse passive dosimetry
(from Solomon, 2019 )

22. The application of exposure science logic
Retrospective pesticide exposure assessments/reverse passive dosimetry
(RISK21 plots, Pastoor et al 2014)
[exposure measurement] [biological marker
exposure measurement]

23. What is exposure
science?
The application of exposure science logic
Impacts of latency and growing epidemiological evidence
(from Mahoney et al, 2023 )
Age-standardised rate (per 100,000 population) of
people diagnosed with mesothelioma, by year and
sex, 1982 to 2020
Age-standardised incidence rates for leukaemia, by
sex, 1982 to 2018
(from
https://www.canceraustralia.gov.au/cancer-
types/leukaemia/statistics)

24. What is exposure
science?
The application of exposure science logic
Emerging contaminants (silica)
https://www.monash.edu/medicine/news/lates
t/2023-articles/worlds-most-comprehensive-
study-of-stone-benchtop-workers-reveals-an-
alarming-high-prevalance-of-silicosis
https://www.abc.net.au/news/2023-07-31/silicosis-
tradies-ban-on-engineered-stone/102665316
 The first Australian case of silicosis associated with artificial
stone was reported in 2015
 Artificial stone products have a higher silica content (>90%)
when compared to natural alternatives (2–30%)
 The prevalence of and risk factors for silicosis among a large
cohort of screened stone benchtop industry (SBI) workers (544)
found 95% worked with artificial stone and 86.2% were exposed
to dry processing of stone

25. What is exposure
science?
The application of exposure science logic
Emerging contaminants (silica)

 117 (28.2%) were diagnosed with silicosis (median age at
diagnosis 42.1 years (IQR 34.8–49.7)), and all were male
 Silicosis was associated with longer SBI career duration (12 vs
8 years), older age, lower body mass index and smoking
 Significant potential for lung cancer development
 AESH intensively involved in research on understanding
exposure1
(from Newbigin et al, 2019; Hoy et al 2023; 1Ramkissoon et al 2022 )
https://www1.racgp.org.au/newsgp/clinical/
great-concern-for-predicted-silicosis-rates

26. What is exposure
science?
The application of exposure science logic
Emerging contaminants
(Per-and polyfluoroalkyl substances (PFAS)/ Perfluorooctanoic Acid
(PFOA), Perfluorooctane Sulfonate (PFOS)
 Toxicology equivocal so what is important?
 Understanding physicochemical and toxico-kinetic characteristics – important for
exposure science
 Incalcitrant and highly water soluble but albumin bound = ↑ body burden/retention
(Biological t1/2 range = 1.0 to 4.7 years (Li et al., 2019)
 This means minute exposures are important and understanding environmental
distribution pathways and exposures critical for risk assessment

27. What is exposure
science?
The application of exposure science logic
Emerging contaminants (PFAS/PFOA/PFOS)

28. Time-dependent exposures – where to?
?
The application of exposure science logic
Road-side exposures to ultrafines

29. Time-dependent exposures – where to?
?
The application of exposure science logic
Indoor exposures to trichloroethylene from vapour intrusion

30. What is exposure
science?
Key issues
 Spatio-temporal variability (especially for outdoor and
inhalational exposures)
 Real-time assessment (time-dependency)
 Mixtures and mixed exposures
 Retrospective exposures
 Poor dosimetry in epidemiological studies
 Heterogeneity of source media
 Practicalities, ethics, and costs

31. What is exposure
science?
Concluding comments
 Exposure science is complex and evolving
 It is important that exposure monitoring and surveillance
are sustained
 A need to facilitate Australian research studies in the field
to understand exposures and their significance
 Relevance of research objectives should match
community and industry needs

32. Thank you
SA Safety Symposium 20 October 2023