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					 Diazinon and Carbaryl
   Concentrations in
  Thornton Creek and
Comparison to Retail Sales
   Dean Wilson, Water Quality Scientist
           King County DNRP
              206-296-8252
    Dean-wpcd.wilson@metrokc.gov
Retail sales of active ingredients at
Lowe’s and Home Depot stores in King                   EPA announces diazinon
County 1997-2002*                                      phaseout (Dec 5, 2000)




                   97        98        99        00         01        02


* Source: CCI Triad, Reports for LHWMP (King County)
     DIAZINON & CARBARYL
DIAZINON                   CARBARYL
   Insecticide               Insecticide
   Organophosphate           Carbamate
   General garden and        General garden use,
    turf use                   slug/bug bait, turf
   Not allowed on golf       Promoted as “alternative”
    courses                    to diazinon
   Sales for urban uses      EPA may limit turf use
    ended Jan 1, 2005         Moderately toxic to fish
   Highly toxic to fish
Urban Runoff
                  Mobility Comparison
 DIAZINON                                         CARBARYL
 Soil half-life:        40 days                   Soil half-life:     10 days
 Koc:                   1000                      Koc:                300
 SWMI:*                 0.26                      SWMI:               0.37
  SWMI MODEL* PREDICTION                               Cp(x) = Rlabelfc(SWMI)
  Assume all diazinon replaced by carbaryl
  Assume products used at maximum rates allowed on label
  Result: carbaryl in streams would be 3-4 times previous diazinon
  levels.

*Chen W, et al. 2002. Envir Toxicol Chem 21:298-308.
          Thornton Creek Watershed
   Primarily urban
   12.1 square miles
   75,400 people, 33,362
    households
   38% single-family dwellings
   51% residential
   23% roads and shoulders
   8% commercial (includes
    Northgate Mall)
   4% parks, 4% schools
         Measured Diazinon (µg/l) in
              Thornton Creek



                              EPA standard=0.09




                        96    97    98   99       00   01   02




Data from U.S. Geological Survey
         Measured Carbaryl (µg/l) in
              Thornton Creek


                      Canadian guideline=0.2




                96     97          98   99     00   01   02



Data from U.S. Geological Survey
              Summary

 Diazinon concentrations have declined
  (p=.002, median decr. 3.2) along with
  sales
 Carbaryl concentrations have increased
  (p<0.001) along with sales
 More sales = more use = more pollution
 Other issues
Toxic Tradeoff: Two snapshots of insecticide
        mixture in Thornton Creek



                              Canadian chronic guideline




        +         =

                         97     98    99    00     01      02
                                                  Epilogue: 2003-2004*
DIAZINON                                                                                             CARBARYL
                      1                                                                                                    1
micrograms/liter




                                                                                                     micrograms/liter
                     0.1                                                                                                  0.1




                    0.01                                                                                                 0.01




                   0.001                                                                                                0.001
                       Oct 1   Apr 19   Nov 5   May 24   Dec 10   Jun 28   Jan 14   Aug 1   Feb 17                          Oct 1   Apr 19   Nov 5   May 24   Dec 10   Jun 28   Jan 14   Aug 1   Feb 17
                       2000     2001    2001     2002     2002     2003     2004    2004     2005                           2000     2001    2001     2002     2002     2003     2004    2004     2005

                                                         Date                                                                                                 Date




                   *NOTE: the 2004 data have not yet been officially released by USGS and
                   values may change.
                       The next chapter?




Source: CCI Triad (data for King County)
             Closing Thoughts
• Diazinon phaseout has reduced concentrations in
  Thornton Creek
• Consumers switched from diazinon to carbaryl in
  2002, leading to higher carbaryl concentrations in
  Thornton Creek
• Ortho began phasing out carbaryl lawn formulations
  after 2002 in favor of pyrethroids
• Thornton Creek carbaryl concentrations have dropped
  somewhat in 2003 and 2004 relative to peak in 2002.
• Retail sales combined with mobility models could help
  predict stream pesticide concentrations and identify
  future problems.

				
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