| Chemical Abstract Number (CAS #) |
78342
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| Synonyms | Dioxathion |
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Phosphorodithioic acid, S,S'-p-dioxane-2,3-diyl O,O,O',O'-tetraethyl ester |
| Analytical Method |
EPA Method 8141A |
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| Molecular Formula | C12H26O6P2S4 |
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| Use | INSECTICIDE ON LIVESTOCK; ACARICIDE ON CITRUS FRUIT, DECIDUOUS
FRUITS, & NUTS
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| Consumption Patterns | ABOUT 65% AS AN ACARICIDE ON CITRUS FRUIT; ABOUT 25% AS AN
INSECTICIDE ON LIVESTOCK; AND ABOUT 10% AS AN ACARICIDE ON DECIDUOUS
FRUITS AND NUTS (1974)
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| Apparent Color | TAN LIQUID
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| Melting Point | -20 DEG C
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| Molecular Weight | 456.54
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| Density | 1.257 @ 26 DEG C/4 DEG C
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| Environmental Impact | Dioxathion, whose generic name is p-dioxane-2,3-diyl ethyl phosphorodithioate, is a
systemic insecticide, acaricide, and tickacide used to control livestock against external pests, and
to control outside areas, kennels, and ornamentals against insects, ticks, and mites. Some, if not
all, of its uses are restricted. Dioxathion may be released to the environment during these uses as
well as from its production, disposal of solutions for dipping livestock, and cleaning equipment
used to formulate and apply the insecticide. If released in soil, dioxathion will degrade with a
half-life ranging from 15 to 55 days in different soil types with dissipation being more rapid in
drier, sandy soils. If released into water, dioxathion would adsorb moderately to sediment and
particulate matter in the water column. Moderate bioconcentration in aquatic organisms would
also be anticipated. Otherwise its fate in water is unknown. Dioxathion would probably be
released into the atmosphere in the form of an aerosol and be subject to gravitational settling.
Otherwise its fate in the atmosphere is unknown. People may be exposed to dioxathion from
ingesting food that contains residues of the pesticide. Occupational exposure to dioxathion would
be by inhalation and dermal contact.
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| Environmental Fate | TERRESTRIAL FATE: The overall half-life of dioxathion applied as a dust to a variety
of soil samples are (soil type - half-life): fine sandy loam (pH 6.9, 0.8% organic matter) - 15 days,
silty clay loam (pH 7.3, 2.1% organic matter) - 55 days, clay (pH 7.3, 2.3% organic matter) - 45
days, sandy loam (pH 7.6, 1.8% organic matter) - 30 days . In all but the fine sandy soil, the
reaction was 1st order. Soil moisture was 40% of capacity, the temperature was 30 deg C, the
samples were covered, and illuminated with fluorescent light. Dissipation was more rapid from the
drier, sandy soils. The mechanism responsible for dioxathion's removal is not clear, but a catalytic
hydrolysis process appears to be most consistent with the results. Biodegradation is not likely
because it is generally more rapid in soils with higher organic carbon content. In this case the soil
with the least organics matter had the hazard degradation rate.
AQUATIC FATE: If released into water, dioxathion would adsorb moderately to sediment and
particulate matter in the water column. It would not be expected to photolyze or hydrolyze. Since
it is unstable on metal surfaces, there may be some catalytic, degradative processes that would
affect its persistence in natural waters. However no data is available to this effect. No information
is available concerning its biodegradability.
ATMOSPHERIC FATE: Dioxathion would probably be released into the atmosphere in the
form of an aerosol and be subject to gravitational settling. Otherwise its fate in the atmosphere is
unknown.
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| Drinking Water Impact | SURFACE WATER: Dioxathion was not detected in 82 water samples collected from
1964-1966 in New York State and another 30 samples collected in 1967 .
GROUNDWATER: In a Califorina study of 54 wells located near areas where
1,3-dichloropropane (D-D or Telone) had been used and which served primarily for municipal
supply systems werre analyzed, no dioxathion was detected . A further study that included
8.190 California wells monitored up to November 1984 identified 4 wells contaminated with
dioxathion . No levels of the pollutant was reported.
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