The Link Between Exposure and Risk

1
Assessment of Exposure to Organophosphate
Pesticides in Migrant Farm Workers and Their
Children
Linda McCauley, Rachelle Mann-Gaytan, William
Lambert, Juan Muniz, Michael Lasarev Caren
Ebbert Oregon Health Science University Oregon
Child Development Coalition
Presented by Rachelle Mann-Gaytan
2
Migrant Farm Workers
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Purpose of this analysis

• To characterize the extent of exposure to
  organophosphate (OP) pesticides for children of
  migrant farm workers
• To identify factors influencing residential
  levels of these pesticides
• To compare the level of exposure in farm worker
  families with a reference group of grower families

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Methods

• With the Oregon Child Development Coalition
  (OCDC), we recruited families through the Migrant
  HeadStart Program and the growers association
• OCDC and OHSU teams conducted interviews and
  collected environmental samples in homes in
  summers of 1998 and 1999
• Carpets were sampled with HSV3 vacuum
• Pesticide residues were analyzed by GC/MS
• Urinary metabolites were analyzed by GC with
  flame photometric detection

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Results of Floor Dust Samples

• Azinphos methyl (AZM) was found in carpet dust
  from 22 of 25 farm worker homes
• Few other pesticides detected
• Median 1.45 ppm (range 0.3 12.0)
• AZM levels decreased with greater distance from
  the orchards
• AZM levels increased with number of household
  members working in agriculture

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Floor Dust AZM Levels by Distance to Orchard
o
10.0
p-value 0.04
5.0
o
o
Azinphos Methyl (ppm)
o
o
o
o
o
o
o
o
o
o
o
o
o
1.0
o
o
o
o
0.5
o
o
5
10
50
100
Meters
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Home AZM Levels by Number of Workers in Household
o
10.0
p-value 0.002
5.0
o
o
Azinphos Methyl (ppm)
o
o
o
o
o
o
o
o
o
o
o
o
1.0
o
o
o
o
o
0.5
o
o
1
2
3
4
5
Number of persons working in agriculture
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Differences in Homes of Workers and Owners
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AZM in Floor Dust of Worker and Owner Homes
Max
75
Median
25
Min
10
Characteristics of Households
p 0.02 p lt 0.001
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Other factors influence indoor levels

• Lower indoor AZM levels were observed when male
  farm workers or owners reported that they
• Removed shoes before entering home
• Changed out of work clothes before entering home
• Changed out of work clothes within 30 minutes
  after arriving home
• Washed up within 30 minutes of arriving home

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Workers Do you take off your boots before
entering your home?
p 0.27, Wilcoxon rank sum test
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Owners Do you take off your boots before
entering your home?
p 0.28, Wilcoxon rank sum test
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Urinary Metabolites in Adults
Max
75
Median
25
Min
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Urinary metabolite concentrations in younger vs.
older children
250
0 6 years old
200
150
Median DMTP ? g/ g Cr
100
7 11 years old
50
0
M
M
J
J
S
F
A
A
O
Month
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Urinary metabolite concentrations in adult
thinners vs. non-thinners
150
Thinners
100
Median DMTP ? g/ g Cr
Non-thinners
50
0
F
M
A
M
J
J
A
S
O
Month
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Urinary metabolites in children of migrant farm
workers
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Implications

• Dissemination of video to educate farm workers on
  practical ways to reduce exposures for their
  children
• Deep cleaning of homes to remove accumulated
  dust and pesticide residues

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Acknowledgments

• This research is supported by a grant from the
  National Institute of Environmental Health
  Sciences (RO1 ES08707)