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Study of Pesticides in School Drinking Water

2012 USDA Study

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In the spring of 2012, 22 Oregon schools participated in the United States Department of Agriculture's (USDA) analysis of their drinking water. USDA's Monitoring Programs Division (Manassas, Virginia) is coordinating collection events like this in states across the country. In Oregon, all of the participating schools use groundwater wells as their source of drinking water and all are located in agricultural and rural areas. None of the 22 schools receive their drinking water from an off-site public water supply.

To assist participating Oregon schools, the Department of Environmental Quality (DEQ) Laboratory staff collected, packaged and shipped water samples from the schools, using sampling kits and instructions sent from USDA. Water samples were shipped to USDA's contract laboratory in Minnesota, where they were analyzed for PDF icon177 pesticides or pesticide breakdown products (pdf).

Purpose of sampling project

The purpose of this sampling project was to collect data on the national prevalence of pesticides and pesticide breakdown products in school well water. Participation in this project was voluntary and analytical results were provided to participating schools. The data collected in this project will be used for national research and risk assessments of these chemicals to specifically address the drinking water component for children during their developmental years. The data will be published in a nationwide summary produced by the USDA. The purpose of this summary is to describe and report on the collective test results in Oregon.

Summary information

Tables 1 and 2 below contain a basic summary of the results, which show that none of the pesticides or their breakdown products were found at levels that would cause a public health concern. The measured concentrations of pesticides or their breakdown products in the water are considered too low (parts per trillion range) to harm the health of children or school staff who drink it on a regular basis.

However, the detection of these pesticides in groundwater suggests that chemicals are getting into groundwater that is being used for drinking purposes. The Oregon Health Authority (OHA) recommends that schools consult with OHA and other experts to investigate how this is happening. State agency drinking water protection staff can assist the individual schools in developing a more detailed assessment of the sources of pesticides and develop a voluntary plan to minimize the applications and uses of these pesticides in the vicinity.

Table 3 below describes the common uses for the chemicals detected in Oregon school drinking water.

Table 4 below lists the 22 Oregon schools in the 2012 US Department of Agriculture study on pesticides in rural school drinking water. The table describes the location of each school, how many chemicals were detected in the water from each school, the names of the chemicals detected and whether or not levels of detected chemicals exceed health guidelines.


  • None of the pesticides or their breakdown products were found at levels of concern for public health (based on the comparison of health screening levels for individual pesticide concentrations).
  • Detection of multiple pesticides in the drinking water of some schools suggests that school drinking water in those locations may be influenced by chemicals used and applied on the surface.


  • Schools with multiple pesticides detected in their drinking water should contact OHA (Tom Pattee 541-726-2587 x24) or other experts to investigate and learn more about the connection between surface and groundwater supplying their wells.
  • Schools with multiple pesticides detected in their drinking water should contact the drinking water protection staff at DEQ (Sheree Stewart 503-229-5413) if they wish to initiate voluntary pesticide reduction efforts in their recharge area.

More information

Table 1. Summary information about pesticide and pesticide breakdown products in USDA school drinking water study (Oregon schools only)
Schools tested 22
Schools with no pesticides detected 11
Schools with only 1 pesticide detected 5
Schools with 5 or more pesticides detected 4
Schools with at least one form of atrazine or atrazine breakdown product detected 7
Maximum number of pesticides detected in water from any one school 12
Pesticides or pesticide breakdown products tested
(PDF iconsee full list - pdf)
Pesticides or pesticide breakdown products detected 20

Table 2. Summary information about the 20 pesticides detected in Oregon school drinking water
Chemical Number of
Schools with
Percent of Schools
with Detections (Out
of 22 schools tested)
measured1 (ppt)
Health Based
Value (ppt)
Health Based
Value Source2
ppt = Parts per trillion or nanograms per liter
1Maximum concentration found at any of the 22 schools tested. All other results for a given contaminant were lower than this level.
2Screening values were chosen according to the following order: First, the maximum contaminant level (MCL, explained below) was selected. Second, if an MCL wasn't available for a given chemical, OHA selected the lowest available health based value from the sources listed below. And third, some of the pesticide breakdown products (those marked with an *)did not have a screening value, and in these cases the MCL or screening value for the parent compound was chosen as a conservative substitute screening value.
*For these pesticide breakdown products, neither MCL nor any other screening value was available. In these cases the MCL or most health protective screening value for the parent compound was used as a substitute.
MCL = Environmental Protection Agency's Maximum Contaminant Level: This is a legally enforceable water quality standard for public drinking water systems. MCLs are usually expressed as parts per million, but because these results were measured in parts per trillion, MCLs were multiplied by 1,000,000 so that they could be directly compared with the results without using decimal points.
CA MCL = California MCL: This is a legally enforceable water quality standard in public drinking water for the state of California that is not enforced at the federal level.
USGS HBSL = United States Geological Survey's Health-Based Screening Level: This is not a legally enforceable standard. This is a human health risk-based screening value calculated using EPA's methods for developing lifetime health advisories.
EPA HHBP = EPA's Human Health Benchmarks for Pesticides in drinking water: These values are not legally enforceable but were developed by the EPA as human health-based screening values for drinking water.
EPA RSL = EPA's Regional Screening Levels for residential tap water: These values are not legally enforceable but they are human health risk-based concentrations for drinking water developed by the branch of the EPA that does clean-up at hazardous waste sites.


Alachlor or alachlor breakdown products
Alachlor ethanesulfonic acid (ESA) 3 14 76 2,000 MCL*
Alachlor oxanilic acid (OA) 1 5 4.8 2,000 MCL*
Atrazine or atrazine breakdown products
Atrazine 3 14 54 3,000 MCL
Desethyl atrazine 7 32 310 3,000 MCL*
Desethyl-desisopropyl atrazine 2 9 170 100,000 USGS HBSL
Desisopropyl atrazine 3 14 35 3,000 MCL*
Hydroxy atrazine 1 5 2 70,000 EPA HHBP
Metolachlor or metolachlor breakdown products
Metolachlor ethanesulfonic acid (ESA) 4 18 330 700,000 USGS HBSL*
Metolachlor oxanilic acid (OA) 2 9 28 700,000 USGS HBSL*
Norflurazon or Norflurazon breakdown products
Norflurazon 1 5 8 10,000 USGS HBSL
Norflurazon desmethyl 2 9 27 10,000 USGS HBSL*
Other herbicides
Bentazon 1 5 290 18,000 CA MCL
Bromacil 3 14 270 70,000 USGS HBSL
2,4-D 1 5 7.3 70,000 MCL
Diuron 4 18 44 2,000 USGS HBSL
Imazapyr 1 5 130 17,500,000 EPA HHBP
Prometon 2 9 0.3 190,000 EPA RSL
Propazine 3 14 9.8 100,000 USGS HBSL
Simazine 2 9 2.6 4,000 MCL


Imidacloprid (for sucking and some
chewing insects like fleas and termites)
1 5 13 399,000 EPA HHBP

Table 3. Common uses for the chemicals detected in Oregon school drinking water
Chemical Potential Contaminant Sources, Land Uses, Applications and Other Notes Primary Uses In Oregon
and Crop Types


2,4-D Agriculture, residential, recreation, utilities, forestry Lawns, turf, orchards, vegetables, wheat, grasses, canals, ditches, fence lines
Alachlor Agriculture, forestry Corn, sorghum, beans, trees
Atrazine Agriculture, residential, recreation, forestry (controls weeds, broadleaf, grasses) Grassland, corn, recreation areas, sorghum, home lawns
Bentazon Agriculture, residential, recreation (controls broadleaf, sedge weeds) Soybeans, corn, sorghum, peanuts, lawns
Bromacil Agriculture, utilities (controls weeds, brush) Non-crop areas, fence lines, right-of-ways
Diuron Agriculture, utilities, recreation (controls weeds, mosses, grasses) Citrus, grass seed, berry crops, vines, wheat, flowers, apple, mint, right-of-ways, pools
Imazapyr Agriculture, residential, utilities, forestry (controls weeds, grasses) Corn, right-of-ways, home lawns, non-crop areas, tree crops, nurseries, pasture
Metolachlor Agriculture (controls grasses, broadleaf) Corn, sorghum
Norflurazon Agriculture, utilities Cranberry, filberts, fruits, nuts, berry crops, fence lines, ditches
Prometon Agriculture, utilities (non-selective herbicide) Non-crop areas, right-of-ways
Propazine Agriculture (controls annual grasses, broadleafs) Ornamentals, sorghum, garden vegetables
Simazine Agriculture, residential, recreation Corn, turf, nuts, apple, home lawns, berry crops, tree nurseries, golf courses, cherry, seed crops, plum, peach, ponds


Imidacloprid Agriculture, residential, recreation Cereals, fruits, turf, leafy vegetables, pet flea control, nuts, beans, berry crops, potato, ornamentals, flowers, corn, tomato

Table 4: USDA school results by school
School Name City Sample Date Total Detections Chemical(s) Detected Levels of Chemicals Above Health Guidelines?
Pinehurst School Ashland 4/11/2012 0 None No
North Marion SD #15 High School Aurora 2/21/2012 0 None No
North Marion SD #15 Intermediate School Aurora 2/21/2012 0 None No
Bridges Academy Bend 4/16/2012 1 Desethyl atrazine No
Triangle Lake School Blachly 4/9/2012 1 Imazpyr No
Brookings Head Start Brookings 4/11/2012 0 None No
Dixie Elementary Corvallis 4/9/2012 12 Atrazine, Bromacil, Desethyl atrazine, Desethyl-desisopropyl atrazine, Desisopropyl atrazine, Diuron, Imidacloprid, Metolachlor ethanesulfonic acid (ESA), Norflurazon, Norflurazon desmethyl, Propazine, Simazine No
Fairplay Elementary Corvallis 4/9/2012 12 Alachlor ethanesulfonic acid (ESA), Atrazine, Desethyl atrazine, Desethyl-desisopropyl atrazine, Desisopropyl atrazine, Diuron, Hydroxy atrazine, Metolachlor ethanesulfonic acid (ESA), Norflurazon desmethyl, Prometon, Propazine, Simazine No
Mt View Elementary Corvallis 4/9/2012 0 None No
Eddyville Charter School Eddyville 4/9/2012 0 None No
Applegate Elementary Eugene 4/9/2012 7 Atrazine, Bromacil, Desethyl atrazine, Desisopropyl atrazine, Diuron, Prometon, Propazine No
Crow High School Eugene 4/9/2012 0 None No
Rogue Community College Grants Pass 4/11/2012 1 Desethyl atrazine No
Country Christian School Molalla 4/16/2012 0 None No
Rural Dell School Molalla 4/16/2012 0 None No
Clarkes School Mulino 4/16/2012 1 Bromacil No
Ewing Elementary School Newberg 4/16/2012 1 2,4-D No
Cairo Elementary Ontario 4/24/2012 4 Alachlor ethanesulfonic acid (ESA), Alachlor oxanilic acid (OA), Metolachlor ethanesulfonic acid (ESA), Metolachlor oxanilic acid (OA) No
Pioneer Elementary SD8C Ontario 4/24/2012 5 Alachlor ethanesulfonic acid (ESA), Bentazon, Desethyl atrazine, Metolachlor ethanesulfonic acid (ESA), Metolachlor oxanilic acid (OA) No
Pleasant Valley Elementary School SD 28J Portland 4/16/2012 0 None No
Jewell School District #8 Seaside 4/17/2012 0 None No
Sweet Home Charter School Sweet Home 4/9/2012 2 Desethyl atrazine, Diuron No