Description
Fenamiphos is a colourless crystal or a tan, waxy solid. It is non-corrosive to metals and breaks down readily in strong acids and bases. Fenamiphos is used as a nematicide and an insecticide for use on a wide variety of field, vegetable, and fruit crops. Fenamiphos has been used primarily to control nematodes and thrips on various agricultural crops (i.e., citrus, grapes, peanuts, pineapples, tobacco, etc.) and non-agricultural (i.e., turf and ornamentals) sites.Alternatively, it can also be used for the treatment of other kinds of invertebrates such as sucking insects and spider mite. Fenamiphos takes effects through inhibiting the acetylcholinesterase in the pests. There are no residential uses for fenamiphos and is a Restricted Use Pesticide (RUP) due to high acute toxicity and toxicity to wildlife.
References
https://pubchem.ncbi.nlm.nih.gov/compound/fenamiphos#section=Top
http://extoxnet.orst.edu/pips/fenamiph.htm
Description
Fenamiphos is a colorless crystalline substance. Solubility in water is
400 mg/L (20 ?C). It is soluble in polar organic solvents.
Log Kow = 3.3(20 ?C). It is stable in aqueous media; DT
50
(22 ?C) at pH 4, 7, and 9 are 1, 8, and 3 yr.
Chemical Properties
Yellow Solid
Chemical Properties
Fenamiphos is a colorless crystal or a tan, waxy solid. It is non-corrosive to metals and breaks down readily in strong acids and bases. Fenamiphos is used as a nematicide and an insecticide. It is sparingly soluble in water, but readily soluble in dichloromethane, isopropanol, and toluene. It is used primarily for the control of nematodes and thrips on citrus, grapes, peanuts, pineapples, tobacco, turf, and ornamentals. There are no residential uses for fenamiphos. The US EPA has grouped fenamiphos as an RUP owing to its high acute toxicity and toxicity to wildlife. Reports have indicated that the manufacture and sale of fenamiphos is to be phased out by 2007–2008.
Uses
Fenamiphos is primarily used to control nematodes in a wide
range of crops and in turf. It will also control mites and sucking insects in crops.
Uses
Nematocide and insecticide.
Uses
Systemic broad spectrum nematocide with anticholinesterase activity. Nematocide.
Definition
ChEBI: Fenamiphos is a phosphoramidate ester, an organophosphate insecticide and an organophosphate nematicide. It has a role as an EC 3.1.1.7 (acetylcholinesterase) inhibitor, an agrochemical and an acaricide. It is functionally related to a 4-(methylsulfanyl)-m-cresol.
General Description
Brown waxy solid or colorless solid. Used as a nematocide.
Air & Water Reactions
Fenamiphos is hydrolyzed by strong acids and strong alkalis.
Reactivity Profile
Organothiophosphates, such as Fenamiphos, 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.
Hazard
Toxic by inhalation and skin contact. Questionable carcinogen.
Health Hazard
Fenamiphos is highly toxic orally, by inhalation, and by absorption through the skin. (Non-Specific -- Parathion) Death may occur from respiratory failure.
Health Hazard
Occupational exposures to fenamiphos cause severe toxicity and adverse health effects. It inhibits the activity of the cholinesterase enzyme in humans, leading to over stimulation of the nervous system. The symptoms of poisoning include, but are not restricted to, nausea, dizziness, confusion, impaired memory, disorientation, severe depression, irritability, headache, speech diffi culties, delayed reaction times, nightmares, sleepwalking, and drowsiness or insomnia. Very high exposures, such as accidental ingestion and/or major spillage, cause respiratory paralysis and death. Laboratory studies have indicated that the teratogenic effects of fenamiphos occurred only at levels that caused overt maternal toxicity and are likely indirect consequences of this toxicity. Other studies have indicated that fenamiphos is non-mutagenic and also have no evidence suggesting that fenamiphos is carcinogenic to animals and humans.
Fire Hazard
(Non-Specific -- Organophosphorus Pesticide, n.o.s.) Container may explode in heat of fire. Fire and runoff from fire control water may produce irritating or poisonous gases. Emits toxic fumes of nitrogen oxides, phosphorus oxides, and sulfur oxides when heated to decomposition.
Flammability and Explosibility
Not classified
Agricultural Uses
Nematicide, Insecticide: A U.S. EPA restricted Use Pesticide (RUP).
Fenamiphos is an organophosphate nematicide used to
control a wide variety of nematode (roundworm) pests.
Nematodes can live as parasites on the outside or the inside
of a plant. They may be free living or associated with cyst
and root-knot formations in plants. Fenamiphos is used on
a variety of plants including tobacco, turf, bananas, pineapples,
citrus and other fruit vines, some vegetables, and
grains. The compound is absorbed by roots and is then distributed
throughout the plant. Fenamiphos, as is typical of
other organophosphates, blocks the enzyme acetylcholinesterase
in the target pest. The pesticide also has secondary
activity against other invertebrates such as sucking insects
and spider mites.
Trade name
BAY 68138®; Bayer 68138®;
NEMACUR®; NEMACURP®
Safety Profile
Poison by ingestion,
inhalation, and skin contact. When heated to
decomposition it emits very toxic fumes of
NOx, POx, and SOx.
Potential Exposure
AgriculturalChemical; Reproductive Effector. Those involved in themanufacture, formulation, or application of this nematocide.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contactsthe skin, remove contaminated clothing and wash immediately with soap and water. Speed in removing materialfrom skin is of extreme importance. Shampoo hairpromptly if contaminated. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions,including resuscitation mask) if breathing has stopped andCPR if heart action has stopped. Transfer promptly to amedical facility. When this chemical has been swallowed,get medical attention. Give large quantities of water andinduce vomiting. Do not make an unconscious personvomit.
Environmental Fate
Soil. Oxidizes in soil to the corresponding sulfone and sulfoxide (Lee et al., 1986). Fenamiphos rapidly degraded in Arredondo soil to fenamiphos sulfone and at the sametime to the corresponding phenol. The half-life in this soil is 38–67 days (Ou and Rao, 1986).
Surface Water. In estuarine water, the half-life of fenamiphos was 1.80 days (Lacorte et al., 1995).
Chemical/Physical. Emits toxic fumes of phosphorus, nitrogen and sulfur oxides when heated to decomposition (Sax and Lewis, 1987; Lewis, 1990).
Metabolic pathway
Fenamiphos is an effective nematicide with both protectant and curative
action. Free-living, ecto- and endo-parasitic, cyst-forming and root knot
nematodes are controlled. Foliarly applied compound is translocated in
plants to the roots and there is evidence that both translocation and optimum
anti-cholinesterase and nematicide activity require oxidation of the
thiomethyl group to the sulfoxide or the sulfone. These thiooxidation
products are much more easily hydrolysed than fenamiphos itself and
hydrolytic degradation in the environment most probably occurs via the
formation of these intermediates.
Metabolism
The oxidation of the thiomethyl group to the sulfoxide
and sulfone is required for both translocation and
nematicidal activity in plants. The oxidation products are
more susceptible to hydrolysis than fenamiphos itself.
In mammals, orally administered fenamiphos is rapidly
metabolized to the sulfoxide and sulfone, followed by subsequent hydrolysis, conjugation, and excretion in the
urine. N-Dealkylation also occurs. The DT
50 in soils
is several weeks; the major degradation products are
fenamiphos sulfoxide and sulfone and their phenols.
storage
Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Store in tightly closed containers in a cool, well-ventilated area.
Shipping
This material falls under Organophosphorus pesticides, solid, toxic, n.o.s. This compound requires a shipping label of “POISONOUS/TOXIC MATERIALS.” It fallsin Hazard Class 6.1 and Packing Group I.
Degradation
For an organophosphorus compound, fenamiphos is relatively stable to
hydrolysis. The DT
50s at pH values 4, 7 and 8 were 1 year, 8 years and
3 years respectively (PM). Fenamiphos was fairly stable in phosphate
buffers at pH values 5 and 7 at 30-50 °C in the dark but in natural pond
water containing silt the DT
50 was about 5 days. In pH 9 buffer the DT
50
was about 13 days. Under basic conditions the main product of hydrolysis
was the phenol (2) (Waggoner and Khasawinah, 1974).
Walia and Dureja (1990) have studied the photolysis of fenamiphos in
methanol solution irradiated by an unfiltered high pressure mercury
lamp. The photosensitiser and singlet oxygen generator Rose Bengal was
also included in one of the experiments. Analysis and characterisation
were carried out by TLC, MS and
1H NMR. In the presence of Rose Bengal
the major product was fenamiphos sulfoxide (3). Since singlet oxygen is
generated on soil surfaces and in silty water this experiment may be of
relevance to the activation of fenamiphos in the environment. In the
absence of a photosensitiser, the compound was cleaved to produce the
phenol, 3-methyl-4-(methylthio)phenol (2) and its O-methylated derivative
(not shown in Scheme 1), indicative of the involvement of methanol
in the reaction. In an experiment which more closely mimicked the conditions
for photodegradation in the environment, Barcelo et al. (1993)
examined the photolysis of fenamiphos in water containing 24% methanol
irradiated by a xenon arc (suntest) lamp. Metabolites were analysed
and characterised by HPLC, thermospray MS and W (diode array)
spectra. Fenamiphos was photodegraded to the extent of 98% after 90 min
of irradiation. The main degradation product identified was fenamiphos
sulfoxide (3). Products of the hydrolysis and photolysis of fenamiphos are
shown in Scheme 1.
Toxicity evaluation
The acute oral LD
50 for rats is about 6 mg/kg.
Inhalation LC50 (4 h) for rats is about 0.12 mg/L air.
NOEL (2 yr) for rats is 1 mg/kg diet (0.05 mg/kg/d). ADI is
0.5 μg/kg b.w.
Incompatibilities
May hydrolyze under alkaline conditions.Keep away from moisture.
