Chemical Properties
Abate is the trade name for Temephos, the known organophosphate larvicide. Abate is
used to treat water infested with disease-carrying fl
eas, to control mosquito, midge, and
black fl
y larvae. Abate quickly controls mosquito and other insect populations because it
kills insect larvae before they mature, and the residual activity of abate prevents further
insect populations. On decomposition, abate produces oxides of carbon, phosphorous, and
sulfur.
Chemical Properties
Temephos is a solid at room temperature and is composed of colorless crystals. As a liquid,
it is brown and viscous. Temephos is a non-systemic insecticide. It is insoluble in water,
hexane, and methyl cyclohexane, but soluble in common organic solvents. It is combustible
and the liquid formulations contain organic solvents that may be flammable. Temophos
decomposes on heating or burning, producing toxic fumes such as phosphorus oxides
and sulfur oxides. Temephos reacts with strong acids and strong bases. The US EPA has
grouped temephos as a GUP. Temephos is used for the control of mosquito, midge, and
black fl y larvae. It is used in lakes, ponds, and wetlands. It may also be used to control fl eas
on dogs and cats and to control lice on humans.
General Description
White crystalline solid or liquid. Boiling point 87°F. Used as an insecticide. Technical grade is a viscous brown liquid.
Reactivity Profile
Organothiophosphates are susceptible to formation of highly toxic and flammable phosphine gas in the presence of strong reducing agents such as hydrides. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides.
Health Hazard
Exposures to high concentrations of temephos for a prolonged period of time cause poisoning
to occupational workers. The symptoms include, but are not limited to, nausea,
salivation, headache, loss of muscle coordination, and diffi culty breathing. Workers
exposed to a combination of temephos and malathion suffer potentiation of toxicity
of temephos. Exposures to granules of temephos formulation may cause irritation.
Prolonged and repeated skin contact may cause irritation. Inhalation may cause respiratory
irritation and chemical pneumonities. There are no reports on the prolonged effects
of temephos.
Health Hazard
to avoid contamination of water, food, or feed, abate should be stored in a secure, dry,
Uses
Temephos is an organophosphate larvicide used to treat water infested with disease-carrying insects.
Uses
Temephos is used to control mosquito and black fly larvae in
aqueous environments and as a human and veterinary ectoparasiticide.
Definition
ChEBI: Temephos is an organic sulfide that is diphenyl sulfide in which the hydrogen at the para position of each of the phenyl groups has been replaced by a (dimethoxyphosphorothioyl)oxy group. It has a role as an EC 3.1.1.7 (acetylcholinesterase) inhibitor, an acaricide, an agrochemical and an ectoparasiticide. It is an organic thiophosphate, an organothiophosphate insecticide and an organic sulfide. It is functionally related to a 4,4'-thiodiphenol.
Hazard
Cholinesterase inhibitor. Questionable carcinogen.
Agricultural Uses
Insecticide, Larvicide: Temephos is one of the few organophosphates that is
registered to control mosquito larvae. It is a non-systemic
insecticide for use on wetlands, ponds, lakes and other
moist areas to control mosquito, gnat, black fly, midge,
pinkie and sandfly larvae. Banned for use in EU countries[
115]. Registered for use in the U.S.
Trade name
27165®; ABAT®; ABATE®; ABATE®
1-SG; ABATE® 2-CG; ABATE® 4-E; ABATE® 5CG;
ABATHION®; AI3-27165®; AC 52160®; AMERICAN
CYANAMID AC-52,160®; AMERICAN CYANAMID
CL-52160®; AMERICAN CYANAMID E. I.52,160®;
BIOTHION®; BITHION®; CL 52160®; DIFENPHOS®;
DIFENTHOS®; DIFOS®; DIPHOS®; ECOPRO®;
ECOPRO® 1707; EI 52160®; NEPHIS®; NEPHIS® 1G;
NIMITEX®; NIMITOX®
Carcinogenicity
The EPA noted a chronic dog
study (period of exposure not specified) in which significant
inhibition of plasma and RBC cholinesterase occurred at
dietary exposures equivalent to 12.5 mg/kg/day but not at
0.46 mg/kg/day .
No evidence of carcinogenicity or other treatment-related
effects occurred in rats fed a diet that contained 0, 10, 100, or
300 ppm temephos (equivalent to about 0.5, 5.0, or 15 mg/kg/
day) for 2 years . The animals in the treated groups
were exposed in utero from gestation day 12 through parturition
to 100 ppm of the test material, and at weaning pups
were randomly allocated to the three treatment groups and
the treatment initiated.
Metabolic pathway
Temephos is comparatively stable to metabolic degradation in both animals
and plants. The main pathway is via thiooxidation to the sulfoxide
and through hydrolysis to yield 4,4’-thiodiphenol and its thiooxidised
derivatives which are conjugated as glucosides in plants and as sulfate
esters in rats. Oxidative desulfuration to temephos oxon is apparently a
minor pathway.
Degradation
Temephos is hydrolysed by strong acids and alkalis; its maximum stability
is at pH 5-7 (PM). When a methanolic solution of temephos was
exposed to sunlight it was rapidly decomposed resulting in the formation
of at least eight photoproducts of which only temephos sulfoxide (2) and
temephos sulfone (3) were identified. The sulfoxide was the major initial
product but it was further photolysed to the sulfone (3) which was
apparently refractory to further degradation suggesting that the other
unidentified photoproducts arose directly from temephos or from the
sulfoxide (2) (Rosen, 1972) (Scheme 1).
Toxicity evaluation
Temephos has a
very low mammalian toxicity; acute oral LD50 for male
and female rats is 4204 and >10,000 mg/kg, respectively.
NOEL (2 yr) for rats is 300 mg/kg diet (15 mg/kg/d).
Temephos administered orally to rats is eliminated in
the feces and urine. The major elimination compound
is unchanged temephos. Other urinary metabolites are
sulfate ester conjugates of 4,4 -thiodiphenol, its sulfoxide,
and sulfone.
