Dieldrin
PESTICIDE NAME:
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Trade name(s): Dieldrite
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Manufacturer(s): Shell International Chemical Co., Ltd
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Shell Center
London, S.E. 1 7 P.B., U.K.
I. Basic information
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A. Molecular structure: C12H8Cl6O
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B. Chemical name: 1,2,3,4,10,10-Hexachloro-6,7-Epoxy-1,4,4a,5,
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6,7,8,8a-octahydro-1,4,5,8-Dimethanonaphthalene
C. Derivatives: Dieldrin is the epoxide of the insecticide aldrin
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D. Molecular weight: 380.9 g/mole
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E. Solubility in water: 0.186 mg/l
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F. Common physical appearance: colorless crystals (pure compound);
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buff to brown flakes (technical material)
G. Oral LD50(rat): 46 mg/kg
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H. Pesticide classification: chlorinated hydrocarbon insecticide
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I. Restricted use list (N.Y.): yes
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EPA priority pesticide list: yes
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J. Crop use: No information available
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II. Text
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Dieldrin, the epoxide of aldrin, is a synthetic cyclic hydrocarbon
of high toxicity and persistence in soil. The degradation and
transport of dieldrin is widely treated in the scientific literature.
It is immobile and the 95% disappearance rate is 5-25yrs.
Volatilization is responsible for much of the dieldrin lost from the
soil surface. Persistence is affected by soil type, soils with high
organic matter content showing higher dieldrin persistence than sandy
soils.
III. Soils information
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A. Degradation and transformation
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Dieldrin is a product of the degradation of the pesticide aldrin.
The conversion of aldrin to dieldrin is lowest in soils which are high
in organic matter: 4.5yrs after application of aldrin, the dieldrin
concentration was 54.8% of the initial aldrin concentration in muck
soil and 88.1% in sandy and sandy loam soils(9). Additionally,
dieldrin is more persistent in soils with high organic matter content.
The degradation of dieldrin in soils is slow due to the stability of
the chlorinated ring. With an average dose of 1-3 lb/Ac dieldrin, the
95% disappearance time was 5-25yrs(6,16); however, this is dependent
upon soil type as another study on sandy loam soil with illite as the
predominant clay found a 180d loss of 96.4% of the applied
dieldrin(1). In a study reporting an initial application of dieldrin
at 8.4ppm, the dieldrin concentration at 7wks was 0.64ppm(17).
Temperature is another factor which affects dieldrin degradation.
In a subtropical silt loam soil, the concentration of dieldrin
decreased by 25% in fall and winter with a half-life of 7.5mo. The
persistence was shorter than under similar conditions in temperate
regions(13).a Another study reported a loss of 27% of the insecticidal
activity of applied dieldrin in 56d at 40deg F whereas at 78deg F the
loss was 44% and at 112deg F the loss was 86%(9).
The tables below present data concerning degradation and
transformation of dieldrin in soils. The reference is given in
parentheses at the end of each title.
Ppm dieldrin 7yrs after application to 3 Hawaiian soil materials(2)
Coral Sandy loam Clay
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applied found applied found applied found
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107 1.73 142 1.69 151 2.14
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Dieldrin recovery in a 9yr study with initial applications of 10
and 100 lbs a.i./Ac(16)
10lbs/A: 3yrs - 49-53%recovery; 8yrs - 11.1%recov. (cultiv.)
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19.1%recov. (uncul.)
100lbs/A: 3yrs - 63% recovery; 8yrs - 21% recov. (cultiv.)
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23.1%recov. (uncul.)
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Concentration of dieldrin in silt loam soil(16)
Time(yrs) Mean ppm (0-23cm)
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0 1.44
0.47 1.40
0.92 1.38
1.51 1.03
1.93 1.02
2.43 1.05
3.49 1.08
4.45 0.80
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Recovery of aldrin+dieldrin in varied soils 56d after application of
aldrin(9)
Soil type %recovery aldrin+dieldrin
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muck 88
silt loam 69
sandy 55
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B. Adsorption and transport
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The adsorptive capacity of different substrates for dieldrin has
been reported to be: organic soil>sediment>sandy loam> sand(10).
Dieldrin is considered to be immobile with little lateral movement on
level land(3,16) and no significant vertical movement in either fine
sandy loam or silty clay although some movement to the soil surface was
in evidence. Volatilization could then take place(3). In a Gila silt
loam it was reported that volatilization correlates with soil-water
content and inversely correlates with water loss from soil. As
relative humidity decreases, dieldrin loss decreases. It is the soil
water content and not the loss of water from soil which affects
dieldrin volatilization(5). If soil water content is less than a
monolayer of molecules on the surface, pesticide adsorption sites are
available and volatilization decreases with decreasing soil water
content(5). If soil water content is greater than a monolayer, the
volatilization of dieldrin is unaffected by water loss from the soil.
Relative humidity affects pesticide volatilization by affecting soil
water content; however, pesticide loss is independent of soil water
loss(5).
The tables below present data concerning dieldrin adsorption and
transport in soils. The reference is given in parentheses at the end
of each title.
Freundlich isotherm for dieldrin adsorption in various soils(10)
organic sediment sandy loam sand
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l/n 1.08 0.91 0.89 0.88
K 4246 445 338 106
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Dieldrin concentration with depth in various soils(loam soils sampled
9yrs after initial application, silt loam - 10 yrs)(ll)
ppm at depth(in) % init.
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Soil lb/A 0-2 2-4 4-6 6-8 8-10 10-12 remain.
____ ____ _______________________________________ _______
L 4 1.67 0.21 0.02 nd nd nd 25
L 6 2.96 1.36 0.68 0.22 0.11 - 35
SiL 6 1.00 0.71 0.30 0.10 0.06 tr 15
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Percent of initial dieldrin concentration remaining over time and at
varying depths of a silt loam soil(4)
Depth(cm) 0 years 2.42 years
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0-7.5 75.7 +a12% 80.7 +a9%
7.5-17.7 22.2 +a12 16.9 +a8
17.7-30 2.1 +a3.4 2.4 +a1.7
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Dieldrin residues (ug/g) in 3 light sandy soils at varying depths(14)
Plot Year 0-10 10-20 20-30 30-40 40-50 50-60(cm)
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B 1969 1.25 0.23 0.02 0.01 - -
1973 0.77 0.71 0.17 0.03 0.02 0.04
C 1969 2.29 0.86 0.02 0.01 - -
1973 1.73 1.72 0.33 0.04 0.02 0.02
D 1969 7.33 2.50 0.05 0.03 0.02 0.01
1973 7.3 8.0 1.3 0.25 0.10 0.11
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Dieldrin (in kg/ha) not recovered as parent compound (original
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application = 21kg/ha)(3)
Silty Clay Fine sandy loam
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depth(cm) 1yr 2yr 1yr 2yr
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irrigated 0-7.5 3.8kg/ha 6.6 - 5.1
7.5-15 1.2 5.8 0.3 -
non-irrig. 0-7.5 1.4 5.1 1.9 0.6
7.5-15 - 4.0 - 0.3
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Percent of initial dieldrin application remaining after 10yrs in a silt
loam soil under disked and non-disked conditions(8)
Depth(in) %dieldrin
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non-disked 0-2 27
2-4 31
4-6 24
6-9 18
disked 0-2 25
2-4 29
4-6 29
6-9 17
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IV. id
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Zone. 17. 200-6.
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*8.Lichtenstein, E.P., T.W. Fuhremann and K.R. Schulz. 1971.
J.Ag.FoodChem. 19. 718-21.
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*9.Maclang, F.A. 1967. Sugar News. 43. 135-8.
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*10.Sharom, M.S., J.R.W. Miles, C.R. Harris, and F.L. McEwen. 1980.
Water Research. 14. 1095.
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*11.Stewart, D.K.R. and C.J.S. Fox. 1971. J.Econ.Ento. 64. 367-71.
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12.Suzuki, M. Y. Yamato and T.Watanabe. 1975.
Bull.Environ.Contam.Tox. 14. 520-9.
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13.Talekar, N.S., L.T. Sun, E.M. Lee and J.S. Chen. 1977.
J.Ag.FoodChem. 25. 348-52.
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*14.Voerman, S. and A.F.H. Besemer. 1975. Bull.Environ.Contam.Tox.
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13. 501-5.
*15.Willis, G.H., J.F. Parr, S. Smith and B.R. Carroll. 1972. JEQ. 1.
___
193-6.
*16.Wingo, C.W. 1966. Mo.Ag.Res.Sta.Bull. No. 914.
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17.Zorgani (El-), G.A. 1976. Bull.Environ.Contam.Toxicol. 15. 378-82.
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