Neurochemical Biomarkers to Assess Effects of Toxic Substances

on Wildlife in the Great Lakes

GLC Atmospheric Toxics Webinar Series – Mar 15, 2011

NIL BASU

Department of Environmental Health SciencesSchool of Public Health, University of MichiganAnn Arbor, MI

niladri@umich.edusitemaker.umich.edu/ecotoxicology.lab

1

A) GLAD Multimedia Hg Study (Evers, Wiener)

- Co-leader, “Wildlife” group (w/Mike Meyer)

- Temporal and spatial gradients of mercury

- Biological effects in wildlife

Talk Overview – 2 Parts

- Participants noted at end

B) GLAD Neurochemical Biomarkers

- Hg exposure/effect in eagles, otters, mink,etc

- Jen Rutkiewicz*, Peter Dornbos*, Sean Strom, Tom Cooley, + many more (*=students)

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Goal: Top predator fish will be safe for consumption by all wildlife.Status: Goal is not met in any Great Lake.http://www.epa.gov/glnpo/glindicators/fishtoxics/topfisha.html [accessed Oct 1, 2009]

3

Number of Lake Acres Under Advisory for Various Pollutants in 20042004 National Listing of Fish Advisories (www.epa.gov/waterscience/fish)

4

A Simplified Mercury Cycle

Hg0Hg2+

*** all steps are extremely complex!!!

Hg-S

MeHg

5

U.S. EPA 1999 National Emissions Inventory and 1995-1999 Environment Canada database6

National Atmospheric Deposition of Hg

7

Herring Gulls as sentinels

Rutkiewicz et al. 2010. Environ Poll 158: 2733-27378

Lake Superior

Lake

St. Marys River

St. Lawrence River

Hg Temporal Trends (CWS, 1974-2009)

Significant decline

No trend

N

Lake Michigan

LakeHuron

Lake Erie

Lake Ontario

N

Niagara River

Detroit River

Lake St. Clair

St. Clair River

SLIDE COURTESY: CHIP WESELOH, CWS

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Collection Year

1890 1920 1950 1980 2010

Feath

er

Hg C

oncentr

ation (

µg/g

)

0

10

20

30

40

B. Great Blue Heron

flank feather

Collection Year

1890 1920 1950 1980 2010

Feath

er

Hg C

oncentr

ation (

µg/g

)

0

2

4

6

8

10

12

A. Common Tern

flank feather

Collection Year

1890 1920 1950 1980 2010

Fea

ther

Hg

Con

cen

tration (

µg/g

)

0

10

20

30

40

50

60

70

C. Herring Gull

flank feather

•Museum specimens to analyze feather Hg 1895 -2007 from three Michigan birds

•0.09 – 0.16 ppm decrease/year

•Corroborate sediment data

Head et al., under review. Ecotoxicology

10

Bald Eagles as sentinels

Map of states, birds received

Michigan (40)

Wisconsin (12)

Minnesota (61)

Iowa (10)

Overall mean THg:2.80 ppm

Overall range THg:0.20-34.01 ppm

4.60 ppm(0.29-34.01)

2.10 ppm(0.20-12.71])

1.47 ppm(0.81-2.23)

a

ab

b

abIowa (10)

0.20-34.01 ppm

www.eduplace.com

3.02 ppm(0.61-7.61)

(0.29-34.01)

Ohio (12)1.30 ppm(0.27-2.86)

b

ab

11

7

St Lawrence R

Inland L Ontario

7

Kingston*

*

*

0123456789

10

To

tal H

g (

ug

/g d

ry w

t)

K

G

Mink as sentinels

Mercury levels in mink liver from the lower Great Lakes Basin

1999-2006, mostly AOCs, n=6-18/site

Eastern Lake ErieLong Point

Western Lake Erie

Walpole IsLake St. Clair

Kingston

**

*

**

*

*

Bay of Quinte

*

*

Niagara River

*Hamilton Harbour

Detroit River

*Inland L Erie

K

Credit: Pam Martin, Environment Canada12

- Hg levels in wildlife have decreased over time in many regions

… but levels in some species > criteria values

… and hotspots still exist across Great Lakes

- data integration via GLAD Multimedia Group

Mid-Talk Summary

- data integration via GLAD Multimedia Group outputs, Ecotoxicology publications, and ICMGP meeting should increase understanding

- good at judging “exposures”; poor at assessing “harm” � Pt 2 of talk

13

>1ppm Hghigh levels

What we know

cell

ind

ivid

ual

tissu

e

org

an

po

pu

lati

on

Increasing Biological Organization →→→→

Irre

ve

rsib

leD

am

ag

e

14

>1ppm Hghigh levels

< 1ppm Hgrelevant levels

???

What we do not know

cell

tissu

e

org

an

po

pu

lati

on

Increasing Biological Organization →→→→

Irre

ve

rsib

leD

am

ag

e

???

ind

ivid

ual

15

NEUROTOXIC

MERCURY

BRAINCHEMISTRY

SILENTDAMAGECHEMISTRYDAMAGE

ind

ivid

ual

org

an

po

pu

lati

on

Increasing Biological Organization →→→→

Irre

ve

rsib

leD

am

ag

e

16

“persistent morphological and/or biochemical injury which remains clinically unapparent unless unmasked by experimental or natural processes…

Silent Damage

… the concept is so attractive and intuitive that one often forgets how little hard experimental data exist to directly support it.”

- Kenneth R. Reuhl (1991) “Delayed expression of neurotoxicity: the problem of silent damage” Neurotoxicology 12: 341-346.

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“neurodevelopmental disorders caused by industrial chemicals has created a silent pandemic in our modern society…

…1 out of 6 children has neurodevelopmental

… or a “Silent Pandemic”?

…1 out of 6 children has neurodevelopmental disability… costs are estimated to have ranged from US$110 billion to $319 billion each year”

-Grandjean and Landrigan. 2006. “Developmental neurotoxicity of industrial chemicals” The Lancet 368:2167-78.

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Research Hypothesis

Neurochemical research can further our knowledge of the mechanisms and impacts of aquatic pollutants towards the health of humans, wildlife, and ecosystems.

���� BRAIN CHEMISTRY ����

humans, wildlife, and ecosystems.

objective/quantitative method to assess early/subtle effects

Mercury Neurotoxic

19

mA

Ch

Re

ce

pto

r B

ma

x

(fm

ol/m

g)

800

1000

1200

1400

Adverse clinical

outcomes

Changes in neurochemistry

Field study –Hg αααα mAChR?

Total Hg (ppm)

0.1 1 10

mA

Ch

Re

ce

pto

r B

ma

x

(fm

ol/m

g)

0

200

400

600

800

Environ Toxicol Chem 24: 1444-1450

r = 0.546, p < 0.001 LOAEL1,2

1 Wren et al. 1987 2 Wobesor et al. 1976

20

mA

Ch

re

cep

tor

(fm

ol/m

g)

1500

2000

2500

3000

Laboratory Datay = 129.8Ln(x) + 1507.5

R2 = 0.175

Lab study – corroboration?

Total Brain Hg (ppm, d.w.)

0.1 1 10 100

mA

Ch

re

cep

tor

(fm

ol/m

g)

0

500

1000

1500

Toxicological Sciences 91: 202-20921

Lab study – corroboration?

mA

Ch

re

ce

pto

r (f

mo

l/m

g)

1500

2000

2500

3000

Laboratory Datay = 129.8Ln(x) + 1507.5

R2 = 0.175

Total Brain Hg (ppm, d.w.)

0.1 1 10 100

mA

Ch

re

ce

pto

r (f

mo

l/m

g)

0

500

1000

1500

Field Datay = 118.8Ln(x) + 629.4

R2 = 0.299

SIMILAR SLOPE-RESPONSE RELATIONSHIPSToxicological Sciences 91: 202-209

22

200

300

400m

AC

h r

ecep

tor

(fm

ol/m

g)

Hg & mAChR: BALD EAGLE

0.1 1 10 100

0

100

200

r = 0.50, p < 0.001

Brain Total Hg (ppm, d.w.)

mA

Ch

recep

tor

(fm

ol/m

g)

Ecotoxicology 17: 93-10123

mA

Ch

recep

tor

(fm

ol/m

g)

150

200

250

Hg & mAChR: COMMON LOON

Brain Total Hg (ppm, d.w.)

0.1 1 10 100

mA

Ch

recep

tor

(fm

ol/m

g)

0

50

100

r = 0.41, p < 0.01

Ecotoxicology 17: 93-10124

mA

Ch

re

ce

pto

r d

en

sit

y (

fmo

l/m

g)

800

1000*

150

200

*

cerebral cortex cerebellum

Hg & mAChR: LAB RAT

Coccini et al., 2006. Neurotoxicology. 27: 468-477

Control MeHg

mA

Ch

re

ce

pto

r d

en

sit

y (

fmo

l/m

g)

0

200

400

600

(1 mg/kg/d)Control MeHg

0

50

100

(1 mg/kg/d)

25

3H

-MK

801

bin

din

g (

fmo

l/m

g)

1000

1200

WILD MINK

3H

-MK

801

bin

din

g (

fmo

l/m

g)

800

1000

1200

WILD EAGLES

Hg and NMDA-glutamate receptors

1400

1600

1800

2000

POLAR BEARS

Brain Total Mercury (ppm, d.w.)

0.1 1 10

3H

-MK

801

bin

din

g (

fmo

l/m

g)

0

200

400

600

800

r = -0.618, p < 0.001

Brain Total Mercury (ppm, d.w.)

0.1 1 10

3H

-MK

801

bin

din

g (

fmo

l/m

g)

0

200

400

600

800

r = -0.441, p < 0.001

Brain Stem THg (µg/g)

0.1 0.3 1

NM

DA

-Glu

tam

ate

R

ecep

tor

Levels

(fm

ol/m

g)

200

400

600

800

1000

1200

1400

26

0 0.50.1 1 2

Uptake ?????? Lesions1,2 Behaviour1,2

[Dietary] ppm

Historic and High Exposure

Levels

Ecologically Relevant Levels of Hg, especially

in the Great Lakes region

NeurochemicalEffects

1 Wren et al. 19872 Wobesor et al. 1976

Toxicol Sci 91: 202-209

Environ Toxicol Chem 24: 1444-1450

Environ Sci Technol 39: 3585-3591

Total Brain Hg (ppm, d.w.)

0.1 1 10 100

mA

Ch

recep

tor

(fm

ol/m

g)

0

500

1000

1500

2000

2500

3000

Laboratory Datay = 129.8Ln(x) + 1507.5

R2 = 0.175

Field Datay = 118.8Ln(x) + 629.4

R2 = 0.299

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1956:first case of human Minamata disease (mercury poisoning) reported in Japan

1951:“citizens noticed that many of the town’s cats, rats, crows, and

fish behaved strangely. For no apparent reason they exhibited

frenzied behavior, throwing themselves against stone walls, frenzied behavior, throwing themselves against stone walls,

staggering as though intoxicated, and frequently hurling

themselves into Minamata Bay, where many drowned.”

Harada, 1995. Crit Rev Toxicol 25:1

Eto, 1997. Toxicol Pathol 25:614

Aronson, 2005. Med Health RI 88:209

28

“In ecoepidemiology, the occurrence of an association in more than one species and species population is very strong evidence for causation.”

Glen Fox. 1991. J Toxicol Environ Health 33: 359-373

“our fate is connected with the animals.”

Rachel Carson. 1962. Silent Spring

29

Pla

tele

t M

AO

Acti

vit

y

(nm

ol/m

in)

26

28

30

32

34

abab

a

b

Control 35 mg/kg 75 mg/kg

Pla

tele

t M

AO

Acti

vit

y

0

10

20

30

40

50

60

*

MeHg Exposure

Rat PlateletsChakrabarti et al., 1998Neurotoxicol Teratol 20:161

MA

O A

cti

vit

y (

nm

ol/

mg

/min

)

600

800

1000Otter BrainBasu et al., 2007Hum Exp Toxicol 26:213

JECFA

Increased risk of Hg toxicosis

Changes in peripheral neurochemistry

Neurotoxicology 27: 429-436

Blood Mercury Quartiles (ppb)

Q1 Q2 Q3 Q4

Pla

tele

t M

AO

Acti

vit

y

(nm

ol/m

in)

20

22

24

(0.2 - 0.5) (0.6 - 1.3) (3.4 - 17.0)(1.4 - 3.3)

Brain MeHg (ppm, d.w.)

1 10

MA

O A

cti

vit

y (

nm

ol/

mg

/min

)

0

200

400

r = -0.483, p < 0.001

Control 5 ug/g 10 ug/gS

alm

on

Bra

in M

AO

Acti

vit

y

0

20

40

60

80

100

120

*

Dietary MeHg Exposure

Salmon BrainBerntssen et al., 2003Aquat Toxicol 65:55

JECFA (WHO), Health Canadablood guideline> 20 ppb

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- Pt 1. Piscivorous wildlife as sentinels of mercury exposure (spatial, temporal)

- Pt 2. Neurochemical biomarkers provide mechanistic link between exposure & disease

- Continuum of effects established, with real-

Final Summary

- Continuum of effects established, with real-

world levels α neurochemical change

- Multiple neurochemical pathways and brain regions tease apart toxicant-specific impacts and physiological/ecological relevance

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Funding & Collaborators

A) GLAD-sponsored Multimedia Mercury Measurements Workshop --- WILDLIFE Team-Nil Basu and Mike Meyer (co-leaders); Members: Dave Evers, Kevin Kenow, Sean Strom, Bill Route, Chip Weseloh, Pam Martin, Tony Scheuhammer, Tom Custer, Mike Wierda, Bill Bowerman, Madeline Turnquist

B) GLAD-sponsored “Neurochemical Biomarkers in Wildlife” grantB) GLAD-sponsored “Neurochemical Biomarkers in Wildlife” grant-Nil Basu (PI); Key Collaborators: Sean Strom (Wisc DNR), Bill Route (NPS), Tom Cooley(MI DNR), Dennis Bush(MI DNR), Kay Neuman (SOAR), Mike Meyer (Wisc DNR), Irene Bueno (Raptor Center), Ling Shen (Minn DNR), Dave Sherman (OH DNR); Students at Michigan: Dong-Ha Nam, Jennifer Rutkiewicz, Peter Dornbos

C) University of Michigan School of Public Health Dean’s Office

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NIL BASU, PhD

Questions?

NIL BASU, PhD

Assistant ProfessorDepartment of Environmental Health SciencesSchool of Public Health, University of MichiganAnn Arbor, MI

niladri@umich.edusitemaker.umich.edu/ecotoxicology.lab

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