Chlorfenvinfos

Description

Chlorfenvinphos is a nonflammable, yellow oramber liquid with a mild odor. Molecular weight=359.58;Boiling point=110℃at 0.001 mmHg; 168-170℃at0.5 mmHg; Freezing/Melting point=-23-19℃. HazardIdentification (based on NFPA 704 M Rating System):Health 4, Flammability 1, Reactivity 0. Very slightly soluble in water

Chemical Properties

Chlorfenvinphos is a nonflammable, yellow or amber liquid with a mild odor.

Uses

Insecticide; acaricide.

Uses

From 1963 until the early 1990s, chlorfenvinphos was extensively used in veterinary products (dip, dust, and collars) for flea and tick control on pets and domestic animals, and in dairy barns, milk rooms, poultry houses, and other animal buildings. Agriculturally, it was used on potatoes, rice, and maize, and for control of soil insects and nematodes. All uses were canceled in the United States in 1991 and phased out in EU in 2006. Chlorfenvinphos continues to be used in Australia and New Zealand in veterinary products for combating ectoparasites on cattle and sheep.

Uses

Chlorfenvinphos is used to control soil insects such as root worms on vegetables, bulb flies in wheat and maize and phorid and sciarid flies in mushrooms. It is also used to control Colorado beetles on potatoes, scale insects and mite eggs in citrus and stern borers and hoppers on rice. Other uses are the control of mosquitoes and animal ectoparasites as a sheep and cattle dip.

Preparation

Chlorfenvinphos is synthesized by the Perkow reaction of triethyl phosphite with 2,4-α,α-tetrachloroacetophenone. Technical product is an E/Z isomer mixture with an E : Z ratio of 1 : 8–9 and an amber liquid, bp 167–170 ?C/0.5 mm Hg, vp 1 mPa (25 ?C), sparingly soluble in water (145 mg/L), and miscible with most common organic solvents such as acetone and aromatic hydrocarbons. Log Kow = 3.85. It is hydrolyzed slowly in slightly alkaline aqueous solutions and rapidly in strongly alkaline solutions; DT₅₀ values are >700 h (pH 1.1, 38 ?C), >400 h (pH 9.1, 38 ?C), and 1.28 h (pH 13, 20 ?C).

General Description

Amber-colored liquid with a mild chemical odor. Used for control of ticks, flies, lice, and mites on cattle and for blowfly, lice, ked, and itchmite on sheep. Controls fleas and mites on dogs; not used on cats. Applied on organic wastes and breeding places of fly larvae. Also used as a foliage insecticide for potatoes, rice, maize, and sugar cane. Used to control soil insects.

Air & Water Reactions

Slightly soluble in water.

Reactivity Profile

Organophosphates, such as Chlorfenvinfos, 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

A cholinesterase inhibitor.

Health Hazard

Highly toxic by all routes of exposure; however, more toxic in rat than in mouse and rabbit; cholinesterase inhibitor; exhibits acute,delayed, and chronic poisoning; toxic symptoms range from headache, twitching, salivation, blurred vision, and lacrimation togastrointestinal effects and respiratory paralysis; in humans permeation through skin at adosage level of 10–15 mg/kg may manifesttoxic effect.
LD50 oral (rat): 10 mg/kg
LD50 skin (rabbit): 300 mg/kg
LC50 inhalation (rat): 50 mg/m³ /4 h.

Health Hazard

Acute: cholinesterase inhibitor which affects central nervous system. Severe illness or death possible. Convulsions or coma and death.

Fire Hazard

(Non-Specific -- Organophosphorus Pesticide, Liquid, n.o.s.) Chlorfenvinfos may burn but does not ignite readily. Container may explode in heat of fire. Fire and runoff from fire control water may produce irritating or poisonous gases. Avoid iron, steel, and brass. Stable when stored in glass or polyethylene lined containers. Avoid alkaline aqueous solutions.

Safety Profile

Poison by ingestion, skin contact, intraperitoneal, subcutaneous, and intravenous routes. Human systemic effects by skin contact: unspecified blood system effects. Mutation data reported. A cholinesterase inhibitor. An insecticide. See also PARATHION. When heated to decomposition it emits very toxic fumes of Cland POx.

Potential Exposure

Used as a soil insecticide for root maggots, rootworms, and cutworms. Those engaged in the production, formulation, and application of this insecticide.

First aid

s chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek med?ical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Speed in removing material from skinis of extreme importance. Shampoo hair promptly if con?taminated. Seek medical attention immediately. If thischemical has been inhaled, remove from exposure, beginrescue breathing (using universal precautions, including606 Chlorfenvinphosresuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.Medical observation is recommended for 24-48 h afterbreathing overexposure, as pulmonary edema may bedelayed. As first aid for pulmonary edema, a doctor orauthorized paramedic may consider administering a corticosteroid spray.

Environmental Fate

The mechanism of toxicity of chlorfenvinphos is related to its binding and inhibition of the serine hydrolase AChE. In the nervous system, AChE hydrolyzes the neurotransmitter acetylcholine, thereby terminating its synaptic action. AChE inhibition increases the availability of acetylcholine at the neural synapse, leading to cholinergic overstimulation, autonomic and neuromuscular dysfunction, and at higher levels, resulting in coma and death. Major metabolites of chlorfenvinphos do not inhibit ChE. Chlorfenvinphos inhibits butyrylcholinesterase which may function as a molecular scavenger for anti-ChE compounds in the blood or substitute for AChE where it is low.
The stress responses to acute exposure of chlorfenvinphos are evidenced in rats by rapidly increased plasma corticosterone concentrations and a prolonged reduced sensitivity to psychostimulants such as amphetamine. These effects were attributed to the hyperactivity of the cholinergic system from ChE inhibition, leading to persistent alterations of the brain cholinergic–dopaminergic balance.
Other potentially more sensitive non-ChE targets that may influence the overall toxicity of chlorfenvinphos include lipid metabolism, oxidative stress, aromatic amino acid transferases, and cytotoxicity. Chlorfenvinphos may act via central noradrenergic mechanisms to induce hypotension by accelerating the noradrenaline turnover in the brain. Chlorfenvinphos induces hepatic CYPs.

Metabolic pathway

Chlorfenvinphos is a chlorovinyl organophosphate insecticide and the commercial material consists of an E/Z isomer mixture with a Z:E ratio of 8-9:1. The Z-isomer is usually the more insecticidal to most species of insect. Metabolism studies have generally used a stereochemical mixture; however, there is evidence that the E-isomer is photoisomerised to the more stable 2-isomer in the field. The breakdown of chlorfenvinphos has been extensively studied in soil, plants and mammals. The major routes of detoxification are by de-ethylation and hydrolysis and are similar in principle to those of related vinyl phosphates. The products of dealkylation and hydrolysis are desethylchlorfenvinphos and 2,2’,4’-trichloroacetophenone plus dimethyl phosphate, respectively. Further metabolism of the chloroacetophenone moiety then leads, via reduction or eventual hydrolysis of the side-chain chlorine substituent, to the formation of 1-(2,4- dichlophenyl)ethane-l,2-diol and 1-(2,4-dichlorophenyl)ethan-1-ol which are conjugated with glucose or glucuronic acid as the ultimate metabolites. Oxidation of the β carbon atom to give 2,4-dichloromandelic acid followed by decarboxylation gives 2,4-dichlorobenzoic acid which is conjugated with glycine in some mammals as the final metabolite. The 2,4dichlorophenyl moiety usually remains intact during metabolism although hydrolysis of ring chlorine has been reported in a soil degradation study. Metabolism studies have been reviewed by Beynon et al. (1973) and by the Pesticide Safety Directorate evaluation on chlorfenvinphos (PSD, 1994).

storage

Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Prior to working with chlorfenvinphos you should be trained on its proper handling andstorage. Should be protected from moisture and stored inglass-lined or polyethylene-lined containers. Keep awayfrom strong bases. Sources of ignition, such as smoking andopen flames, are prohibited where this chemical is used,handled, or stored in a manner that could create a potentialfire or explosion hazard

Shipping

UN3018 Organophosphorus pesticides, liquid, toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Toxicity evaluation

The toxicity is particularly high to rats (acute oral LD₅₀ 10–40 mg/kg) but is much lower to other mammals (acute oral LD₅₀ for mice 117–200, rabbits 300–1,000, dogs >12, 000 mg/kg). Inhalation LC50 (4 h) for rats is about 0.05 mg/L air. NOEL (2 yr) for rats and dogs is 1 mg/kg diet (0.05 mg/kg/d). ADI is 0.5 μg/kg b.w.
The selective toxicity of chlorfenvinphos to rats is attributed to the poor degradative activity of rat liver microsomal enzymes. In other mammals, liver microsomal mfo catalyzes the detoxification of the insecticide through oxidative deethylation to give 2- chloro-1-(2,4-dichlorophenyl)vinyl hydrogen phosphate. Ultimate metabolites include the glucuronides of 2,4- dichlorophenylethanediol and 1-(2,4-dichlorophenyl)ethanol and N-(2,4-dichlorobenzoyl)glycine. In soils, chlorfenvinphos is gradually decomposed to form α-dichlorophenylethanol, dichloroacetophenone, diethyl hydrogen phosphate, and desethyl chlorfenvinphos.

Degradation

Chlorfenvinphos is hydrolysed slowly in neutral, acidic and slightly alkaline aqueous solutions but hydrolysed rapidly in strongly alkaline solutions (PM). The E and Z stereoisomers are capable of interconversion by photoisomerisation (Beynon and Wright, 1967).

Incompatibilities

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Strong oxidizers may cause release of toxic phosphorus oxides. Organophosphates, in the presence of strong reducing agents such as hydrides, may form highly toxic and flammable phosphine gas. Keep away from alkaline materials. May be corrosive to metals in the presence of moisture.

Waste Disposal

Destruction by alkali hydrolysis or incineration. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Must be disposed properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office.