Determination of Total Mercury in Residual Dried Bloodspots of Newborns from the Lake Superior
Basin Region of Minnesota, Wisconsin, and Michigan
Betsy L. Edhlund1, Jeffrey J. Brenner1, and Patricia J. McCann2, 1Public Health Laboratory, 2Environmental Health, Minnesota Department of Health
4.0E-02
y = 0.00107x + 0.00019
R² = 0.99997
3.5E-02
Net Intensity
MDL
Report Level
Report Level
Verification
3.0E-02
Precision
2.5E-02
Accuracy
2.0E-02
1.5E-02
1.0E-02
5.0E-03
0.0E+00
0
10
20
30
40
Total Mercury Concentration (µ
µg/L)
50
Frequency
400
300
100
46
186103 3 1 3 1 3 3 1 1
1
111
2
Total Mercury Concentration (µ
µg/L)
120
QC Sample Recoveries
100
91%
RPD = 6.4%
86%
82%
80%
Old PT sample on cards; 15.9 µg/L
Hg; n = 92
92%
84%
80
RSD = 8.8%
SN, Butala S, Ball RW, Braniff CT, 2009. Pilot study for utilization of dried
blood spots for screen.doi:10.1038/jes.2008.19
40
SRM 966
20
SRM 966 spotted on filter paper
0
12/3/2009
• Method Performance
• Reproducible, linear calibration curves
• ≥ 80% recoveries for a variety of control samples
• Very consistent percent recoveries over time
• Compares well to mercury in RDBS study conducted in UT1
• Similar MDLs (0.65 µg/L vs. 0.70 µg/L)
• Smaller RDBS punches and lower volumes than UT
• 8% of infants tested had mercury levels above the U.S. EPA
reference dose for methylmercury of 5.8 µg/L
• Supports the need for education on mercury exposure
and fish consumption to women of child-bearing age
• Due to limited availability of blood spots leftover after newborn
screening, only 2-3mm discs were used for mercury analysis
• Increased the MDL; limited characterization of low end of
exposure distribution
• Limits ability to re-analyze if QC issues
• Speciation- unlikely to consistently have enough residual
sample to speciate mercury
• Useful for characterizing high end of exposure distribution and
as a screen for follow-up
• However preference would be to screen mothers to
prevent exposure
• Uncertainty regarding future restrictions on use of RDBS for
public health research
• Correlation of bloodspot mercury with cord blood and maternal
blood would be an interesting follow-up study
1Chaudhuri
60
RSD = 6.8%
199.9
211.1
166.7
177.8
188.9
122.5
133.5
144.6
155.7
89.2
100.3
111.4
78.2
56.0
67.1
33.9
45.0
<MDL
11.8
0
Blind Reference Samples, SRM 966
on cards; n = 26
Old PT sample on cards;
5.36 µg/L; n = 93
500
200
Average of SRM 966 spotted on
cards duplicates
SRM 966; 31.4 µg/L; n = 214
SRM 966 on cards; n = 219
• 1465 infants, born 2008 – 2010
• MN = 1130, WI = 140, MI = 200
• 44% of samples < 0.70 µg/L (study MDL)
• Median = 0.83 µg/L
• Maximum concentration = 211 µg/L
• MN results suggest a seasonal exposure
pattern
600
0.70 µg/L
2.13 µg/L
2.13 µg/L spotted on cards; n = 78
Conclusions
Study Results
721
700 639
Method Performance
Calibration Curve
4.5E-02
800
Percent Recovery
5.0E-02
Mercury Analysis
• Two 3-mm punches placed in a 96-well
filter plate
• Added 0.15 mL 0.05% 2-mercaptoethanol,
0.001% L-cysteine,0.005% EDTA, 0.01%
Triton X-100, and 10 µg/L Iridium
• Followed by 0.15 mL 2% Hydrochloric acid
• 30 minutes of agitation and stored
overnight
• 20 minutes of re-agitation followed by
vacuum filtration
• Analyzed by ELAN DRC-II ICP-MS
equipped with a ESI SC-FAST autosampler
• 5-point aqueous calibration curve
containing a mixture of inorganic and
methylmercury
22.8
Introduction
A method was developed to determine the
concentration of total mercury in residual dried
bloodspots (RDBS). This method was used for the
analysis of total mercury in RDBS from 1465
infants born 2008 through 2010 to mothers
residing in the US portion of the Lake Superior
Basin. This study was conducted to determine the
range of mercury concentrations in these infants
and to assess the feasibility of using RDBS from
infants as an indicator of mercury exposure. The
level of mercury found
in the newborns’ blood
is indicative of the
mothers’ exposure to
mercury during pregnancy.
Acknowledgments
Blind Reference Samples, SRM 966
5/2/2010
9/29/2010
Date Analyzed
2/26/2011
Thank you to the MN, WI, and MI Newborn Screening Programs and the US EPA and
Minnesota State Legislature for funding support.
Information on any of the MN EHTB pilot projects can be found at:
http://www.health.state.mn.us/divs/eh/tracking/biomonitoringpilot.htm
Funding for this work was provided by the Great Lakes National Program Office under the United States
Environmental Protection Agency, grant number GLNPO 2007-942. Although the research described in this work has
been partly funded by the US EPA, it has not been subjected to the agency's required peer and policy review and
therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred.