## Effects of Chronic Manganese Exposure


## on Neurobehavior and School
Performance in 4 th 

## Grade Students



## A Pilot Study

# Manganese

 Neurotoxin

 Adults

– occupational

 Adults

– chronic environmental

 Children

 Diet vs. inhaled



##  USEPA reference standard

- .05 um/m3

 ATSDR reference standard

- .04 um/m3

# Marietta, Ohio

 4 miles North and East of largest and longest active ferro

- manganese alloy plant in the United States



##  Average emissions of 450,000 pounds per year since 1988.

 University of Cincinnati air modeling shows Marietta exposed to an average of between .09 and .19 ug/m3/year

# Air monitors

 1 air monitor in service since 2001
located 4

– 5 miles N

- NE from emission

 For the three years 2001

– 2003 avg. = 

## 0.23 um/m3, two monthly readings over
1.2 um/m3

 In spite of stable TRI reports, amount at monitor decreased to an average of just
over .1 after 2003

# Air Monitors, continued

 In April, 2007, three more air monitors were installed, 2 across the river in WV,
the other on the West side of Marietta



##  WV monitors, located 1 and 4 miles from emission, averaged 0.15 and 0.17um/m3 respectively (8 months data)

 Marietta monitor (4 miles) averaged 0.1um/m3 for the eight months

# Study design

 Surveys and consent forms sent home

with all 4 th 

## grade students (295 total)

 68 returned (23%)



##  30 qualified as life

- long residents

 Athens, Ohio chosen as a control due to 

## similar population, median income, ethnic diversity and school expenditure

– 45 miles to the north and west

# Study design continued

 Surveys and consent forms sent home

with all 4 th 

## grade students in Athens (168 total)



##  36 returned (21%)

 19 students matched for age (within 2 

## months), gender, ethnicity, and number of years of parental education (within 2 years of mother, 3 years overall)

# Study design: tests

 WRAT spelling test

 Rapid naming

 Multistep directions



##  Month recitation

 Time



##  Direction

 Balance

 Attention

# Study design: tests

 Midline crossing

 Santa Anna Dexterity

 Visual Contrast Sensitivity (VCS)



##  One Hour Memory

 Social Skills Rating System



##  4 th 

## Grade Proficiency Tests (writing, reading, math, citizenship (social studies), and science

# Results

Test Athens

mean Athens

std dv. Martta

mean Martta

std dv. Paired

t

- test p

WRAT spelling 18.00 7.19 12.80 5.36 0.011*

Rapid Naming 40.60 5.07 45.23 12.18 0.195

Multistp
Direct 7.67 2.05 7.07 2.81 0.109

Month
recite 1.13 1.85 0.73 1.33 0.339

Time 1.53 0.83 1.67 0.72 0.165

# Results continued

Test Athens

mean Athens

std dv. Martta

mean Martta std

dv. Paired t

test p

Direction 4.60 0.63 4.47 0.99 0.353

Balance 13.74 9.15 8.64 8.44 0.005**

Midline crossing 34.38 6.14 41.84 18.09 0.089

Santa Ana

Dominant 34.40 6.15 36.06 4.97 0.231

Santa Ana

Non

- dom. 30.40 5.23 33.27 4.92 0.148

One hr.

memory 0.93 0.26 0.67 0.49 0.005**

# Results

- Fourth Grade Proficiency

Ohio

Mean Athens

Mean Athens

Sample

Mean Athens

Stnd.

Dev. Mariet.

Mean Mariet.

Sample

Mean Mariet.

Stnd.

Dev. P

- value

Writ. 5.00 5.00 6.00 1.37 5.00 4.31 1.78 0.002

**

Read. 217.0 223 227.1 20.56 220 219.4 20.70 0.105

Math 214.0 225 229.2 32.18 219 220.8 34.77 0.184

Ctzn

ship 221.0 242 249.6 29.84 226 226.6 24.81 0.012

*

Sci. 211.0 228 235.4 37.37 221 214.9 43.4 0.048

*

# Results

- Visual Contrast Sensitivity

# Shortcomings

 Small sample size (19 matched pairs)

 Possible sampling error

 Differences between Marietta and

Athens

 Not blinded



##  No biological samples

– does not relate
effect to dose of Mn

# Nevertheless...

 Children born and raised in Marietta have some of the highest environmental exposure to Mn (.1

- .2 um/m3/year) in


## the United States

 They also performed significantly worse
on 5 of the 12 tests administered: WRAT Spelling, 4 th 

## Grade Proficiency, Balance, VCS, and Memory

# Implications

 Children are likely the most sensitive population

 Very few studies have been done on the 

## effects of chronic Mn exposure in
children

 Results presented here, while not proof, 

## are disturbing

 Study on this issue is desperately
needed