1. Interpreting Population Level Biomonitoring
Data in a Risk-Based Context:
A Canadian Perspective
Annie St-Amand1, Kate Werry1, Andy Nong1,
Sean M. Hays2, Lesa L. Aylward2
1Healthy Environments and Consumer Safety Branch, Health Canada;
2Summit Toxicology LLP
September 10, 2013

2. Population Biomonitoring Data:
Canadian Health Measures Survey
Survey Parameters
• Cross‐sectional survey design
• Ongoing: 2007‐2009 (Cycle 1), 2009‐
2011 (Cycle 2), 2012‐2013 (Cycle 3 –
data collection in progress)
• National estimates for general
population:
N= 5600‐6400
• Ages 3‐79 years (3‐5, 6‐11, 12‐19, 20‐
39, 40‐59, 60‐79)
• Health questionnaire – home interview
• Direct measures (blood/urine)– mobile
clinic

3. Interpretation Tools

4. Biomonitoring Equivalents (BE)
“Safe” human dose
RfD, TDI: mg/kg-d
Uncertainty
Factors
Human (equivalent)
Point of Departure
Human
urine/blood level
BE: µg/L
Uncertainty
Factors
Human
Pharmacokinetics
BE - Concentration of biomarker that is
consistent with existing exposure guidance
or reference values such as RfDs, TDIs,
etc (Hays et al., 2007).
POD: mg/kg-d
Human
urine/blood level
BEPOD: µg/L

5. Screening of Biomonitoring Data
One Chemical
BEPOD
Medium
priority
BE
Low
priority
Hazard Quotient (HQ)
Increasing priority for
follow-up
High
priority
Many Chemicals
Source: LaKind et al., 2008
HQ = [ Biomarker ]
BE
HQ > 1
indicates biomonitoring data
exceeds exposure guidance
value

7. HQ Screening: Persistent Chemicals
CHMS 2007‐11

8. Cadmium
CHMS 2009‐11 (urine)
High
BEPOD
4.6 µg/L
Medium
BE
1.5 µg/L
Low

9. HQ Screening: Short‐lived Chemicals
CHMS 2009‐11 (urine)

10. Inorganic Arsenic: DMA + MMA
(µg As/L urine)
High
BEPOD
16 µg/L
Medium
BE
5.8 µg/L
Low
10

11. Estimated Cancer Risk Levels
CHMS 2009‐11
1.E-02
Cancer Risk
1.E-03
1.E-04
1.E-05
1.E-06
1.E-07
Arsenic (6-79 years) DDT (20-79 years) HCB (20-79 years)

12. Discussion
• HQs < 1 for majority of biomarkers
– suggest exposure levels are below existing
guidance values
• HQs > 1 at upper bound of the CHMS
population distributions for inorganic arsenic
and cadmium.
• BEs do not represent diagnostic criteria
• BEs are interim values (screening)

13. Conclusion
• Cadmium and inorganic arsenic: more detailed
examinations required
• Useful for prioritization efforts
www.health.gc.ca/biomonitoring
Thank you!