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Historical Concentrations of Permethrin and Malathion in Surface 

Water and Bed Sediments throughout the United States 

Robert K. D. Peterson, Ph.D. 

Joseph Old Elk 

Jerome J. Schleier III, M.S. 

Department of Land Resources and Environmental Sciences 

Montana State University 

334 Leon Johnson Hall 

Bozeman, MT 59717-3120 

bpeterson@montana.edu

406-994-7927 

 
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Introduction 

On January 7, 2009, the Sixth Circuit vacated the U.S. Environmental Protection 

Agency’s 2007 rule exempting certain pesticide applications that are compliant with the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA) from the permitting requirements of the 

Clean Water Act (CWA). According to the ruling, the dischargers of pesticide pollutants are 

subject to the National Pollutant Discharge Elimination System (NPDES) permitting program 

under the CWA. As a result of the ruling, anyone who applies a pesticide in, over, or near waters 

of the U.S. will need a permit issued under the CWA. The permit requirements will affect more 

than 900,000 private and 350,000 commercial and government applicators in the United States. 

 The permit requirements will apply to mosquito and disease vector control districts 

throughout the U.S. But, what is the likelihood that insecticides used for adult mosquito 

management would be present in water in concentrations that would exceed U.S. EPA levels of 

concern? In the past few years, numerous human-health and ecological risk assessments, 

including aquatic assessments, have been conducted on insecticides used for adult mosquito 

management. These risk assessments have concluded that the risks from these insecticides are 

negligible (see list of journal articles and reports below). However, another approach would be 

to examine the aquatic concentrations of insecticides from all uses to assess the historical 

frequency and amounts of those that are used for adult mosquitoes. This would provide an 

evaluation of the potential for mosquito adulticides, which are used at much lower rates than 

agricultural and residential uses, to be detected in waters of the U.S. 

In this report, we use the U.S. Geological Survey National Water-Quality Assessment 

(NAWQA) Program (http://infotrek.er.usgs.gov/apex/f?p=136:1:0::NO) to determine the 

historical concentrations for malathion and permethrin in surface water and bed sediments in the 

U.S. from all residential and agricultural uses. Malathion and permethrin are the only mosquito 

adulticides that are measured as part of NAWQA. 

Methods 

The data used in this report came from the USGS National Water-Quality Assessment 

(NAWQA) Program Data Warehouse Surface Water/Bed Sediment data located at 

http://infotrek.er.usgs.gov/nawqa_queries/swmaster/index.jsp. Under the database parameter 

group of ‘Organics, pesticide’ the query groups of interest were: 

 63326 – Malaoxon solids recoverable dry weight, μg/kg 

 61652 – Malaoxon Water filtered recoverable, μg/L 

 39531 – Malathion bed sediment recoverable dry weight, μg/kg 

 63327 – Malathion solids recoverable dry weight, μg/kg 

 39533 – Malathion suspended sediment recoverable, μg/L 
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 39532 – Malathion water filtered recoverable micrograms per liter, μg/L 

 39530 – Malathion water unfiltered recoverable, μg/L 

 49349 – cis-Permethrin bed sediment smaller than 2 millimeters wet sieved (native water) 

 field recoverable dry-weight, μg/kg 

 63365 – cis-Permethrin solids recoverable dry weight, μg/kg 

 82687 – cis-Permethrin water filtered (0.7 micron glass fiber filter) recoverable, μg/L 

 49350 – trans-Permethrin bed sediment smaller than 2 millimeters wet sieved (native 

 water) field recoverable dry-weight, μg/kg 

 63366 – trans-Permethrin solids recoverable dry weight, μg/kg 

 Malaoxon’s values were included as malathion values. Only “39531” malathion bed 

sediment was used for malathion bottom sediment readings. Both the cis and trans isomers of 

permethrin were counted together and only “49349” and “49350” cis- and trans-permethrin bed 

sediment were used in determining permethrin bottom sediment readings. Also, because the 

readings represent both scales in microgram per kilogram and microgram per liter the 

concentrations are expressed in parts per billion (ppb). 

 Concentrations below the Minimum Reporting Level (MRL) or Laboratory Reporting 

Levels (LRLs) were treated as a single value of non-detect (ND). Estimated concentrations (E) 

were valued higher than ND because they represent a confirmed detection but an unknown 

concentration. They were ranked according to increasing value, but it is not possible to confirm 

the true concentration so they should only be used as a possible indication of detection rather 

than an actual concentration. Ranked highest were the confirmed concentrations listed in order of 

increasing value. Also, to give a more accurate representation of the data we decided to include a 

90th percentile value in addition to the median and peak values. 

 Values were listed according to their NAWQA Study Unit Identification (SUID’s) (Fig. 

1). They represent a series of interconnected drainage areas except for NSQN which is the 

National Stream Quality Accounting Network (NASQAN). Only the CHEY, CORE, HPGW, 

and POTO study units produced no readings of permethrin and malathion. The COOK and 

NROK study units contained no concentrations above the level of detection for either pesticide. 

The only verifiable concentration for malathion in bottom sediment was found in the WHMI 

study unit, but because there were only three readings it was listed twice as both the peak and 

90th percentile values. 

Sampling frequency was determined by taking the number of readings for a drainage area 

and dividing it by the number of months between the beginning and end dates of the sampling 

range, excluding any significantly long period where readings were absent. 
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Figure 1. Study units of the U.S. Geological Survey National Water-Quality Assessment 

Program (http://water.usgs.gov/nawqa/map/cyc2_browse.gif). 

Results and Discussion 

The values in Table 1 represent detections/non-detections for all isomers and degradates 

of malathion and permethrin over all residential and agricultural uses. The drainages sampled 

span the U.S. and each drainage has numerous sampling locations. Many of the locations began 

sampling in the early 1990’s and sampling frequency was at least once per month. There are 

approximately 29,000 samples in which malathion and permethrin were sampled. 

The results clearly reveal the infrequency of detections of the two insecticide active 

ingredients and their degradates (Table 1). Out of the thousands of surface water samples, 

permethrin was only detected twice at peak levels above the U.S. EPA level of concern for 

aquatic invertebrates (Daphnia magna, 0.055 ppb) (see highlighted cells). The two values were 

well below levels of concern for aquatic vertebrates. At least 90% of the readings were below 

the reporting limit (i.e., the limit of detection) for permethrin. 
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Malathion was detected more frequently in surface water. Ten samples were above 

USEPA levels of concern for aquatic invertebrates (D. magna, 0.5 ppb) (see highlighted cells). 

However, all 90th percentile values for malathion were well below levels of concern. 

For bottom sediment samples, malathion was only measured in a few locations and was 

above the detection limit once. For permethrin, except for one location, all measurements were 

below the limit of detection at the 90th percentile of total samples. Permethrin was detected seven 

times at peak levels above levels of concern. The data for bottom sediments should be 

interpreted cautiously because the concentrations in ppb are not necessarily bioavailable as they 

are often absorbed strongly to colloids. 

Overall, the NAWQA data suggest that (1) permethrin and malathion from all uses rarely 

occur in surface water at levels that exceed U.S. EPA levels of concern, (2) because of greatly 

lower use rates for mosquitocide applications compared to agricultural and residential uses, the 

contributions to water from permethrin and malathion mosquito applications would be 

negligible, and (3) if measured, naled, resmethrin, and sumithrin would most likely never be 

found above limits of detection because of use patterns and rates. 

Selected Relevant Literature 

Currier, M., M. McNeill, D. Campbell, N. Newton, J.S. Marr, E. Perry, S.W. Berg, D.B. Barr, 

G.E. Luber, S.M. Kieszak, H.S. Rogers, S.C. Backer, M.G. Belson, C. Rubin, E. AzzizBaumgartner, and Z.H. Duprey. 2005. Human exposure to mosquito-control pesticides---

Mississippi, North Carolina, and Virginia, 2002 and 2003. MMWR Morbidity and 

Mortality Weekly Report 54: 529-532. 

Davis, R.S., R.K.D. Peterson, and P.A. Macedo. 2007. An ecological risk assessment for 

insecticides used in adult mosquito management. Integrated Environmental Assessment 

and Management 3: 373-382. 

Duprey, Z., S. Rivers, G. Luber, A. Becker, C. Blackmore, D. Barr, G. Weerasekera, S. Kieszak, 

W.D. Flanders, and C. Rubin. 2008. Community aerial mosquito control and naled 

exposure. Journal of the American Mosquito Control Association 24: 42-46. 

Karpati, A.M., M.C. Perrin, T. Matte, J. Leighton, J. Schwartz, and R.G. Barr. 2004. Pesticide 

spraying for West Nile virus control and emergency department asthma visits in New 

York City, 2000. Environmental Health Perspectives 112: 1183-1187. 

Macedo, P.A., R.K.D. Peterson, and R.S. Davis. 2007. Risk assessments for exposure of 

deployed military personnel to insecticides and personal protective measures used for 

disease-vector management. Journal of Toxicology and Environmental Health, Part A 70: 

1758–1771. 

Macedo, P. A., J. J. Schleier III, M. Reed, K. Kelley, G. W. Goodman, D. A. Brown, and R. K. 

D. Peterson. 2010. Evaluation of efficacy and human health risk of aerial ultra-low 

volume applications of pyrethrins and piperonyl butoxide for adult mosquito management 
6 

in response to West Nile virus activity in Sacramento County, California. Journal of the 

American Mosquito Control Association 26:57-66. 

NYCDOH (New York City Department of Health). 2005. Adult mosquito control programs: 

environmental impact statement (EIS). New York, NY, USA. 

O'Sullivan, B.C.Y., J. Lafleur, K. Fridal, S. Hormozdi, S. Schwartz, M. Belt, and M. Finkel. 

2005. The effect of pesticide spraying on the rate and severity of ED asthma. American 

Journal of Emergency Medicine 23: 463-467. 

Peterson, R.K.D., P.A. Macedo, and R.S. Davis. 2006. A human-health risk assessment for West 

Nile virus and insecticides used in mosquito management. Environmental Health 

Perspectives 114: 366-372. 

Schleier III, J.J., R.S. Davis, L.M. Barber, P.A. Macedo, and R.K.D. Peterson. 2009a. A 

probabilistic risk assessment for deployed military personnel after the implementation of 

the “Leishmaniasis Control Program” at Tallil Air Base, Iraq. Journal of Medical 

Entomology 46: 693-702. 

Schleier III, J. J., R. S. Davis, L. M. Shama, P. A. Macedo, and R. K. D. Peterson. 2008. Equine 

risk assessment for insecticides used in adult mosquito management. Human and 

Ecological Risk Assessment 14:392-407. 

Schleier III, J.J., P.A. Macedo, R.S. Davis, L.M. Shama, and R.K.D. Peterson. 2009b. A twodimensional probabilistic acute human-health risk assessment of insecticide exposure 

after adult mosquito management. Stochastic Environmental Research and Risk 

Assessment 23: 555-563. 

Schleier III, J.J., R.K.D. Peterson, P.A. Macedo, and D.A. Brown. 2008. Environmental 

concentrations, fate, and risk assessment of pyrethrins and piperonyl butoxide after aerial 

ultralow-volume applications for adult mosquito management. Environmental 

Toxicology and Chemistry 27: 1063-1068. 

Schleier III, J. J. and R. K. D. Peterson. 2010. Deposition and air concentrations of permethrin 

and naled used for adult mosquito management. Archives of Environmental 

Contamination and Toxicology 58:105-111. 

Suffolk County (Suffolk County Department of Public Works and Department of Health 

Services). 2006. Draft generic environmental impact statement. Suffolk County, NY. 

USEPA (U.S. Environmental Protection Agency). 2006a. Reregistration Eligibility Decision 

(RED) for Permethrin. PDF Case No. 2510, U.S. Environmental Protection Agency, 

Washington D.C. 

USEPA (U.S. Environmental Protection Agency). 2006b. Reregistration Eligibility Decision 

(RED) for Malathion. Case No. 0248. Washington D.C. 1-101. 
SUID Drainage name # of locations # of readings Sampling frequency Time span median 90th percentile peak median 90th percentile peak median 90th percentile peak 

ACAD Acadian‐Pontchartrain Drainages 56 646 4/ month 05/14/98 ‐ 06/10/09 ND ND ND ND ND 0.0251 ND ND ND 

ACFB Apalachicola‐Chattahoochee‐Flint River Basins 145 1138 5/month 08/11/92 ‐ 08/05/09 ND ND ND ND ND 0.0156 na na na 

ALBE Albemarle‐Pamlico Drainages 104 821 3/ month 05/08/92 ‐ 10/14/09 ND ND ND ND ND 0.012 na na na ALMN Allegheny‐Monongahela River Basins 19 100 2/ month 06/19/96 ‐ 08/29/00 ND ND 18 ND ND ND na na na CAZB Central Arizona Basins 17 128 1/ month 02/07/96 ‐ 10/14/09 ND ND 8.6 ND ND ND na na na CCYK Central Columbia Plateau (CCPT)‐Yakima River Basin (YAKI) 146 1022 4/ month 11/18/91 ‐ 09/23/09 ND 7.6 26 ND ND 0.01 na na na CNBR Central Nebraska Basins 25 678 3/ month 05/01/92 ‐ 08/06/09 ND ND ND ND ND ND na na na 

CONN Connecticut, Housatonic, and Thames River Basins 86 487 2/ month 10/19/92 ‐ 04/23/09 ND ND ND ND ND 0.003 E na na na 

COOK Cook Inlet Basin 10 37 1/ month 05/27/98 ‐ 07/05/01 ND ND ND ND ND ND na na na 

DELR Delaware River Basin 95 724 5/ month 07/13/98 ‐ 10/14/09 ND ND ND ND ND ND na na na EIWA Eastern Iowa Basins 25 821 4/ month 09/18/95 ‐ 08/10/09 ND ND ND ND ND ND na na na GAFL Georgia‐Florida Coastal Plain Drainages 97 710 3/ month 08/11/92 ‐ 07/29/09 ND ND ND ND ND ND na na na GRSL Great Salt Lake Basins 66 345 2/ month 08/03/98 ‐ 08/07/09 ND ND ND ND ND ND na na na 

HDSN Hudson River Basin 73 669 3/ month 08/23/93 ‐ 03/09/09 ND ND ND ND ND ND na na na 

KANA Kansas River Basin 17 81 5/ month 08/21/96 ‐ 12/15/97 ND ND 7.9 ND ND ND na na na LERI Lake Erie‐Lake St. Clair Drainages 16 663 3/ month 03/06/92 ‐ 08/06/09 ND ND ND ND ND ND na na na LINJ Long Island‐New Jersey Coastal Drainages 60 410 2/ month 01/22/96 ‐ 07/27/09 ND ND ND ND ND ND na na na LIRB Lower Illinois River Basin 19 412 2/ month 05/16/96 ‐ 08/11/09 ND ND ND ND ND ND na na na LSUS Lower Susquehanna River Basin 163 497 5/ month 09/14/92 ‐ 09/26/00 ND ND ND ND ND ND na na na MISE Mississippi Embayment 16 657 3/ month 08/22/95 ‐ 08/13/09 ND ND ND ND ND ND na na na MOBL Mobile River Basin 49 499 3/ month 08/11/98 ‐ 07/14/09 ND ND ND ND ND ND na na na NECB New England Coastal Basins 39 247 2/ month 09/14/98 ‐ 09/13/07 ND ND 12 ND ND ND na na na 

NROK Northern Rockies Intermontane Basins 14 67 2/ month 06/18/98 ‐ 08/30/00 ND ND ND ND ND ND na na na 

NSQN National Stream Quality Accounting Network (NASQAN) 51 4015 23/ month 10/05/95 ‐ 08/13/09 na na na ND ND 0.11 na na na NVBR Nevada Basin and Range 25 460 2/ month 09/14/92 ‐ 07/31/09 ND ND ND ND ND 0.0356 na na na 

OAHU Oahu 15 74 2/ month 08/26/98 ‐ 06/20/01 ND ND 15.1 ND ND ND na na na 

OZRK Ozark Plateaus 52 347 1/ month 08/18/92 ‐ 06/30/09 ND ND ND ND ND 0.001 E na na na 

PODL Potomac River Basin (POTO) & Delmarva Peninsula (DLMV) 139 1059 5/ month 06/01/92 ‐  08/11/09 ND ND ND ND ND ND na na na 

PUGT Puget Sound Drainages 50 427 3/ month 09/18/95 ‐ 09/19/07 ND ND ND ND ND ND na na na REDN Red River of the North Basin 60 324 3/ month 08/04/92 ‐ 08/31/00 ND ND ND ND ND ND na na na RIOG Rio Grande Valley 23 254 1/ month 09/22/92 ‐ 09/18/07 ND ND ND ND ND ND ND ND ND SACR Sacramento River Basin 19 369 2/ month 10/11/95 ‐ 06/24/09 ND ND ND ND ND ND ND ND ND 

SANA Santa Ana Basin 28 253 2/ month 09/14/98 ‐ 08/10/09 ND ND ND ND ND ND na na na 

SANJ San Joaquin‐Tulare River Basins 57 1649 8/ month 04/15/92 ‐ 07/23/09 ND ND 16 ND ND 0.146 na na na SANT Santee River Basin & Coastal Drainages 34 460 2/ month 08/07/95 ‐ 06/02/09 ND ND ND ND ND ND na na na 

SCTX South‐Central Texas 17 251 1/ month 08/07/95 ‐ 09/16/09 ND ND ND ND ND ND na na na 

Table 1. Surface water and bed sediment concentrations of permethrin and malathion from study unit sites in the U.S. Geological Survey National Water‐Quality Assessment Program.

Permethrin (ppb)

Bottom Sediment Surface Water Bottom Sediment 

Malath

SCTX South Central Texas 7 5 / month 08/07/95 09/ 6/09 N N N N N N na na na SOFL Southern Florida Drainages 12 332 2/ month 09/05/95 ‐ 09/19/07 ND ND ND ND ND ND na na na 

SPLT South Platte River Basin 54 612 3/ month 09/10/92 ‐ 08/10/09 ND ND ND ND ND 0.022 na na na TENN Tennessee River Basin (UTEN & LTEN) 99 838 5/ month 07/25/95 ‐ 08/05/09 ND ND ND ND ND ND na na na TRIN Trinity River Basin 30 602 3/ month 08/04/92 ‐ 08/05/09 ND ND ND ND ND 0.002 E na na na 

UCOL Upper Colorado River Basin 18 153 1/month 10/05/95 ‐ 8/24/06 ND ND ND ND ND 0.00295 E na na na 

UIRB Upper Illinois River Basin 11 350 2/ month 04/11/96 ‐ 09/08/09 ND ND ND ND ND ND na na na 

UMIS Upper Mississippi River Basin 44 535 3/ month 07/11/95 ‐ 07/08/09 ND ND ND ND ND ND na na na USNK Upper Snake River Basin 62 489 2/ month 08/18/92 ‐ 07/23/09 ND ND ND ND ND ND na na na WHMI White, Great (WHIT) & Little Miami (MIAM) River Basins 98 1629 7/ month 10/03/91 ‐08/12/09 ND ND ND ND ND 0.011 ND 0.2 0.2 WILL Willamette Basin 67 821 4/ month 08/22/92 ‐ 08/05/09 ND ND ND ND ND 0.019 na na na WMIC Western Lake Michigan Drainages 70 629 3/ month 08/24/92 ‐ 08/11/09 ND ND ND ND ND 0.005 na na na YELL Yellowstone River Basin 23 249 2/ month 02/22/96 ‐ 07/09/09 ND ND ND ND ND ND na na na 

na ‐ Not available (no ND  ‐ Non detect (below E  ‐ Estimated concentr

ND < E