MALATHION

Malathion is a broad-spectrum organophosphorus insecticide and acaricide used in agriculture, stored-product protection, public-health vector control, and selected veterinary and medicinal applications.
It is a non-systemic active substance that acts primarily through contact and ingestion.
Malathion requires good application coverage because it is not transported systemically through plant tissues.

Its pesticidal activity results from metabolic conversion to Malaoxon, a more potent inhibitor of acetylcholinesterase.
Malathion is commercially supplied as technical material and in emulsifiable concentrates, oil-in-water emulsions, ultra-low-volume liquids, wettable powders, and dustable powders.

CHEMICAL IDENTITY AND COMMON NAMES

CAS Number: 121-75-5
EC Number: 204-497-7
CLP Index Number: 015-041-00-X
CIPAC Number: 12
Molecular Formula: C10H19O6PS2
Molar Mass: 330.36 g/mol
PubChem CID: 4004
InChIKey: JXSJBGJIGXNWCI-UHFFFAOYSA-N
IRAC Classification: Group 1B, organophosphate acetylcholinesterase inhibitor
Chemical Class: Organophosphorus insecticide, organothiophosphate, phosphorodithioate ester
Systematic Name: Diethyl 2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate
IUPAC Name: S-1,2-bis(ethoxycarbonyl)ethyl O,O-dimethyl phosphorodithioate
CAS Name: Butanedioic acid, [(dimethoxyphosphinothioyl)thio]-, diethyl ester

Malathion contains a stereogenic carbon center, and conventional commercial material is supplied as a racemic composition unless a stereochemically defined material is specified.

Synonyms and Common Names: Malathion, Malathion ISO, Maldison, Malathon, Mercaptothion, Mercaptotion, Carbofos, Carbophos, Karbofos, Malation, O,O-Dimethyl S-(1,2-dicarbethoxyethyl) phosphorodithioate, O,O-Dimethyl S-(1,2-bis(ethoxycarbonyl)ethyl) phosphorodithioate, S-(1,2-Dicarbethoxyethyl) O,O-dimethyl phosphorodithioate, S-1,2-bis(ethoxycarbonyl)ethyl O,O-dimethyl phosphorodithioate, Diethyl 2-[(dimethoxyphosphorothioyl)sulfanyl]succinate, Diethyl 2-[(dimethoxyphosphinothioyl)thio]butanedioate, Diethyl (dimethoxyphosphinothioylthio)succinate, Diethyl [(dimethoxyphosphinothioyl)thio]succinate, Diethyl mercaptosuccinate S-ester with O,O-dimethyl phosphorodithioate, O,O-Dimethyl dithiophosphate of diethyl mercaptosuccinate, 1,2-Bis(ethoxycarbonyl)ethyl O,O-dimethyl phosphorodithioate

TECHNICAL IDENTIFICATION

Malathion consists of a phosphorodithioate group connected through sulfur to a diethyl succinate structure.
The molecule contains two methyl phosphorothioate ester groups and two ethyl carboxylate groups.
Technical identification commonly combines chromatographic retention data with infrared or mass-spectrometric confirmation.

Gas chromatography is widely used for assay determination and for quantifying Malaoxon, Isomalathion, and other relevant manufacturing or storage impurities.
The impurity profile is a central element of Malathion quality because some oxidation and isomerization products have substantially greater cholinesterase-inhibiting potency than the parent active substance.

PHYSICAL AND CHEMICAL PROPERTIES

Appearance: Clear, colorless to light amber oily liquid in high-purity technical form
Odor: Characteristic mercaptan-like, garlic-like, or sulfurous odor
Physical State: Liquid near normal ambient temperature
Melting or Freezing Point: Approximately 2.9°C
Thermal Behavior: Decomposition begins at approximately 174°C under atmospheric pressure
Boiling Behavior: Malathion decomposes before reaching a conventional atmospheric boiling point
Reduced-Pressure Boiling Range: Approximately 156°C to 157°C at 0.7 mmHg
Density: Approximately 1.23 g/cm3 at 25°C
Refractive Index: Approximately 1.4985 at 25°C
Water Solubility: Approximately 145 mg/L to 148 mg/L at 20°C to 25°C
Vapor Pressure: Approximately 4.5 × 10−4 Pa at 25°C
Log Kow: Approximately 2.7
Flash Point: Above approximately 160°C for the active substance
Acid-Base Behavior: Malathion does not materially dissociate in water

Malathion has limited water solubility but dissolves readily in many alcohols, ketones, esters, ethers, aromatic hydrocarbons, and vegetable oils.
Its solubility and partitioning characteristics support the preparation of solvent-based concentrates, emulsions, and oil-compatible ultra-low-volume formulations.
Commercial formulations can have physical properties that differ substantially from the technical active substance because of their solvents, surfactants, carriers, and active concentration.
Solvent-based emulsifiable concentrates can have considerably lower flash points than technical Malathion.

CHEMICAL STABILITY AND DEGRADATION

Malathion undergoes hydrolysis, oxidation, photochemical transformation, and biological degradation.
Hydrolysis accelerates strongly under alkaline conditions.
Representative hydrolysis half-lives at 25°C are approximately 107 days at pH 5, 149 hours at pH 7, and 11.8 hours at pH 9.

Acidic to near-neutral dilution water generally provides greater tank stability than alkaline water.
Prolonged contact with alkaline materials can cause rapid active-content loss during mixing, storage, or application.

Oxidative desulfuration converts Malathion into Malaoxon.
Malaoxon is a substantially more potent acetylcholinesterase inhibitor and is therefore controlled as a relevant impurity.
Malathion can also isomerize to Isomalathion during manufacture or storage.

Elevated temperature, moisture, acidic or alkaline contamination, and unsuitable formulation components can promote decomposition or impurity formation.
Commercial shelf-life performance depends on controlling active content, acidity, water exposure, temperature, and relevant impurities throughout production and storage.

FUNCTIONAL CHARACTERISTICS

Malathion is a non-systemic insecticide with contact and stomach action.
It also provides acaricidal activity against susceptible mites and related pests.
After entering a target organism, Malathion is oxidatively converted to Malaoxon.

Malaoxon inhibits acetylcholinesterase and causes acetylcholine to accumulate at nerve junctions.
The resulting continuous nerve stimulation produces paralysis and death in susceptible pests.
Mammals can detoxify Malathion through carboxylesterase-mediated hydrolysis more efficiently than many target insects.

This metabolic difference contributes to the lower acute mammalian toxicity of Malathion compared with several older organophosphate insecticides.
Malathion nevertheless remains an organophosphate poisoning hazard, particularly through concentrated exposure, repeated exposure, inhalation of aerosols, or exposure to material containing elevated levels of toxic impurities.

Malathion is nonselective and can harm pollinators, aquatic organisms, and beneficial arthropods.
Application timing, droplet control, drift reduction, runoff prevention, and adherence to registered restrictions are essential components of responsible use.

PRODUCTION AND COMMERCIAL FORM

Malathion is manufactured through the controlled addition of O,O-dimethyl phosphorodithioic acid to diethyl maleate or a corresponding fumarate intermediate.
Reaction temperature, feed ratio, residence time, oxygen exposure, and purification conditions are controlled to maximize Malathion formation and suppress Isomalathion and other by-products.

Post-reaction operations can include vacuum stripping, purification, filtration, and adjustment to the required technical specification.
The manufacturing process must also minimize oxidation to Malaoxon.
Technical Malathion is generally supplied at a concentration of at least 950 g/kg.

Technical material is an industrial intermediate intended for conversion into registered pesticide formulations.
It is not an end-use product unless it has been formulated, packaged, labeled, and authorized for a specific application.
Ultra-low-volume formulations can contain a very high proportion of Malathion and are designed for controlled atomization in specialized vector-control or large-area pest-control equipment.

Emulsifiable concentrates contain Malathion in an organic solvent system with emulsifiers that create an oil-in-water emulsion after dilution.
Oil-in-water emulsions contain dispersed Malathion-rich oil droplets in a continuous aqueous phase.

Wettable powders contain Malathion on a solid carrier with wetting and dispersing agents.
Dustable powders contain a lower active concentration distributed through a finely divided carrier for direct application under registered conditions.

APPLICATIONS AND INDUSTRIES

Agricultural Crop Protection

Malathion is used against susceptible sucking and chewing insect pests in registered fruit, vegetable, cereal, oilseed, field-crop, orchard, ornamental, and nursery applications.
Registered pest targets can include aphids, thrips, leafhoppers, scale insects, fruit flies, beetles, caterpillars, and other label-listed insects.
Because Malathion is non-systemic, effective treatment depends on uniform coverage of the target surface and direct exposure of the pest.
Application rates, crop intervals, maximum treatment numbers, pre-harvest intervals, and worker re-entry intervals are defined by the authorized product label.

Stored-Product Protection

Malathion has been used in stored-grain facilities, warehouses, empty storage structures, and selected stored commodities for the control of susceptible beetles, moths, and other storage pests.
Stored-product uses require formulations and labels specifically authorized for the commodity, facility, and treatment method.
Residue limits and food-market requirements are important purchasing criteria for this application.

Public-Health Vector Control

Malathion is used in organized vector-control programs against adult mosquitoes and other disease-vector insects.
Ultra-low-volume ground application, aerial application, cold fogging, and thermal-fogging systems can be employed where the corresponding formulation and use pattern are authorized.
Droplet-size control is critical in ultra-low-volume application because biological performance, airborne behavior, deposition, and off-target exposure depend on the generated aerosol spectrum.
Public-health products require controlled active content, impurity limits, viscosity, atomization performance, storage stability, and packaging compatibility.

Locust and Grasshopper Control

High-strength and ultra-low-volume Malathion formulations have been used in large-area programs against locusts and grasshoppers.
These programs require specialized application equipment, trained operators, environmental controls, and strict observance of authorized treatment zones.

Premises and Veterinary Applications

Selected Malathion formulations can be used in livestock premises, animal housing, and other authorized non-crop environments.
Direct animal use is permitted only when the formulation and label specifically authorize the animal species, treatment method, concentration, and withdrawal conditions.

Medicinal Applications

Malathion is used as an active ingredient in certain finished topical medicinal products for the treatment of head lice.
Medicinal products are manufactured under pharmaceutical requirements and are distinct from agricultural or public-health pesticide grades.
Technical pesticide material must not be substituted for a registered finished medicinal product.

Resistance Management

Malathion belongs to IRAC Group 1B.
Repeated use of Group 1B insecticides can select for resistant pest populations.
Resistance programs rotate Malathion with effective products having different modes of action and integrate cultural, biological, monitoring, and sanitation measures.

GRADE SELECTION AND PRODUCT SUITABILITY

Technical Material

Technical Malathion is selected by formulators manufacturing registered pesticide products.
The principal purchasing factors are active content, Isomalathion, Malaoxon, trimethyl phosphorothioate impurities, acidity, appearance, density, water content, and storage stability.

Ultra-Low-Volume Liquid

Ultra-low-volume liquid is selected for specialized ground or aerial atomization.
Viscosity, active concentration, flash point, low-temperature behavior, atomization quality, droplet-size distribution, and storage stability are essential selection criteria.

Emulsifiable Concentrate

Emulsifiable concentrate is appropriate when rapid dilution into spray water and strong active-solvent compatibility are required.
Emulsion stability, spontaneous emulsification, persistent foam, low-temperature stability, solvent flash point, dilution-water tolerance, and packaging compatibility determine product suitability.

Oil-in-Water Emulsion

Oil-in-water emulsion can reduce the amount of organic solvent while retaining a liquid formulation and effective surface coverage.
Pourability, dilution stability, pH, particle or droplet distribution, wet-sieve residue, foam, and long-term physical stability are key quality parameters.

Wettable Powder

Wettable powder is selected where a solid, water-dispersible product form is required.
Wettability, suspensibility, wet-sieve residue, active uniformity, dust generation, moisture content, and storage stability are central specification items.

Dustable Powder

Dustable powder is used only for specifically authorized direct-dusting applications.
Particle-size distribution, flow, dustability, active uniformity, apparent density, moisture resistance, and operator-exposure controls are important.

Analytical Reference Material

High-purity analytical material is used for chromatographic calibration, residue analysis, formulation control, impurity testing, and research.
Certified concentration, identity, uncertainty, traceability, storage conditions, and expiration information distinguish analytical reference material from commercial technical pesticide material.

FORMULATION AND PROCESS CONSIDERATIONS

Malathion formulations should be designed to maintain chemical stability while providing the required dispersion, wetting, spreading, adhesion, and atomization behavior.
Alkaline carriers, alkaline water, strongly basic additives, and high-pH tank mixtures accelerate hydrolysis.

The pH of aqueous formulations and dilutions is therefore controlled within a compatible acidic to near-neutral range.
Compatibility with emulsifiers, dispersants, solvents, stabilizers, antioxidants, carriers, and packaging materials must support the intended shelf life.

Heat exposure during blending should be minimized because prolonged elevated temperature can increase decomposition and Isomalathion formation.
Oxygen exposure should be controlled during high-temperature processing or extended bulk storage.

Water introduced into solvent-based concentrates can impair physical stability and promote chemical degradation.
Emulsifiable concentrates require a solvent-emulsifier system that forms a stable emulsion across the intended range of water hardness and temperature.

Oil-in-water emulsions require controlled droplet size and an interfacial system resistant to creaming, coalescence, sedimentation, and phase separation.
Wettable powders require efficient milling and blending without excessive process heat.
Ultra-low-volume products require controlled products require controlled viscosity and a clean liquid profile to support reliable atomization without nozzle blockage.

Tank mixtures must follow the registered label and should avoid strongly alkaline pesticides, fertilizers, lime-containing materials, and other incompatible products.
Prepared spray mixtures should be used promptly, particularly when dilution water is warm or alkaline.

QUALITY, SPECIFICATIONS AND DOCUMENTATION

A recognized technical-material purchasing benchmark uses the following composition profile.
Malathion Content: Not less than 950 g/kg
Malaoxon: Not more than 1 g/kg
Isomalathion: Not more than 4 g/kg
O,O,S-Trimethyl Phosphorodithioate: Not more than 15 g/kg
O,O,O-Trimethyl Phosphorothioate: Not more than 5 g/kg
Acidity: Not more than 2 g/kg, calculated as sulfuric acid
Appearance: Clear, colorless to light amber liquid without visible extraneous matter

A complete technical-material specification can additionally include identity testing, density, water content, refractive index, color, and accelerated-storage results.
Impurity testing is particularly important because total active content alone does not describe the toxicological and storage-quality profile of Malathion.
The harmonized European CLP entry specifically identifies Malathion ISO containing no more than 0.03% Isomalathion.
The measured Isomalathion content must therefore be considered when assigning the applicable European classification and regulatory identity.

Emulsifiable-concentrate specifications normally include active content, relevant impurities, acidity or alkalinity, emulsion stability, re-emulsification, persistent foam, low-temperature stability, and accelerated-storage stability.
Oil-in-water-emulsion specifications normally include active content, relevant impurities, pH, pourability, dilution stability, persistent foam, wet-sieve residue, and accelerated-storage stability.
Ultra-low-volume specifications normally include active content, impurity profile, density, viscosity, flash point, low-temperature stability, and atomization performance.

Wettable-powder specifications normally include active content, impurity profile, wettability, suspensibility, wet-sieve residue, moisture, persistent foam, and storage stability.
Dustable-powder specifications normally include active content, fineness, active distribution, flow, apparent density, moisture, and storage stability.

Procurement documentation should include a batch-specific Certificate of Analysis, Safety Data Sheet, Technical Data Sheet, formulation specification, manufacturing date, shelf life, packaging description, transport classification, and applicable registration documentation.
For residue-sensitive uses, documentation should also address the target crop, destination market, maximum residue limits, pre-harvest interval, and authorized formulation.

SAFETY AND REGULATORY CONSIDERATIONS

Malathion is an organophosphate cholinesterase inhibitor.
Acute exposure can produce headache, dizziness, weakness, anxiety, nausea, vomiting, abdominal cramps, diarrhea, sweating, salivation, tearing, pinpoint pupils, blurred vision, chest tightness, wheezing, muscle twitching, impaired coordination, confusion, convulsions, respiratory failure, and coma.

Symptoms can be delayed after exposure.
Repeated occupational exposure can depress blood cholinesterase activity even when early symptoms are mild.
The European harmonized classification for the defined Malathion entry includes Acute Toxicity Category 4 by the oral route, Skin Sensitization Category 1, Aquatic Acute Category 1, and Aquatic Chronic Category 1.

The corresponding hazard statements identify Malathion as harmful if swallowed, capable of causing an allergic skin reaction, and very toxic to aquatic life with long-lasting effects.
The active substance carries the signal word Warning under this classification.
Malathion has an IARC Group 2A hazard classification, meaning that it is considered probably carcinogenic to humans.

Hazard classification and use-specific risk assessment address different questions.
Exposure controls, formulation concentration, application method, personal protective equipment, impurity content, treatment frequency, and label restrictions determine operational risk.
Malathion and its formulations can be highly hazardous to fish, aquatic invertebrates, bees, and other non-target arthropods.

Application must prevent contamination of surface water, drains, irrigation channels, and sensitive habitats.
Treatment during active bee foraging and direct contamination of flowering crops must be prevented wherever required by the registered label.

The hazard classification of a commercial formulation also incorporates the properties of its solvents, surfactants, carriers, and active concentration.
Solvent-containing concentrates can present aspiration, flammability, inhalation, or additional irritation hazards that are not represented by the active-substance classification alone.

Authorization is specific to the jurisdiction, formulation, crop or site, target pest, application method, and use rate.
Only the registered product label defines legal use conditions.
In the European Union, the active-substance approval for Malathion currently extends to 15 July 2028.

In Türkiye, Malathion remains represented among registered plant-protection active-substance groups and authorized formulation categories.
Food uses must comply with applicable maximum residue limits, pre-harvest intervals, treatment limits, and destination-market requirements.

FIRST AID

General: Obtain immediate medical or poison-center assistance after suspected significant exposure.
Contaminated rescuers can become secondary exposure cases, so protective gloves and suitable respiratory protection should be used during rescue and decontamination.

Inhalation: Move the affected person to fresh air and keep the person at rest in a position that supports breathing.
Provide oxygen or assisted ventilation through trained medical personnel when breathing is impaired.

Skin Contact: Remove contaminated clothing and footwear immediately.
Wash exposed skin thoroughly with soap and running water for at least 15 to 20 minutes.

Eye Contact: Rinse cautiously with clean water for at least 15 to 20 minutes while holding the eyelids open.
Remove contact lenses after the initial rinsing period when this can be done easily.

Ingestion: Rinse the mouth and obtain urgent medical advice.
Do not induce vomiting unless specifically instructed by a physician or poison center.
A solvent-containing formulation can present an aspiration hazard if vomiting occurs.

Note to Physicians: Treat clinically significant exposure as organophosphate poisoning and monitor respiratory function, cardiac status, neurological signs, and plasma or red-blood-cell cholinesterase activity.
Atropine is used under medical supervision to control muscarinic symptoms.
An oxime such as pralidoxime can be considered early in clinically significant poisoning according to established medical protocols.
Atropine must not be administered prophylactically to an asymptomatic worker.
The solvent and surfactant composition of the exact formulation should be considered during treatment.

HANDLING AND STORAGE

Handle Malathion in closed systems or with effective local exhaust ventilation wherever practical.
Prevent contact with skin, eyes, clothing, and respiratory aerosols.

Wear chemical-resistant gloves, protective clothing, safety goggles, and a face shield when splash exposure is possible.
Use respiratory protection appropriate for the formulation and exposure route during operations that generate mist, aerosol, vapor, or dust.

Do not eat, drink, smoke, or store food in handling areas.
Wash hands, face, and exposed skin thoroughly after handling and before breaks.
Remove contaminated clothing promptly and wash it separately before reuse.

Maintain workplace hygiene and exposure-monitoring programs for personnel who handle organophosphate pesticides routinely.
Store Malathion in a cool, dry, locked, and well-ventilated pesticide area.

Protect containers from direct sunlight, excessive heat, moisture, and physical damage.
Keep the product in its original labeled container or an approved compatible bulk system.
Segregate Malathion from food, feed, seed, medicines, drinking water, oxidizing agents, strong acids, strong bases, and alkaline materials.

Use secondary containment for drums, intermediate bulk containers, and bulk tanks.
Prevent access by children, unauthorized personnel, and animals.
Do not transfer the product into beverage, food, or unmarked containers.

Do not reuse empty pesticide containers for any other purpose.
For spills, isolate the area, eliminate ignition sources when the formulation is combustible, and wear appropriate protective equipment.
Stop the leak when this can be done safely.

Dike the liquid and absorb it with a compatible inert, noncombustible material.
Prevent the spill and contaminated wash water from entering drains, soil, surface water, or groundwater.
Collect contaminated absorbent, soil, and damaged packaging in labeled containers for authorized hazardous-waste disposal.

Combustion and thermal decomposition can generate toxic oxides of carbon, phosphorus, and sulfur together with hazardous organophosphorus fumes.
Suitable extinguishing media include alcohol-resistant foam, dry chemical, carbon dioxide, and water fog.
Firefighting water must be contained to prevent environmental contamination.

PACKAGING AND PROCUREMENT CONSIDERATIONS

Technical and high-strength liquid Malathion is supplied in compatible, tightly closed, pesticide-rated drums or intermediate bulk containers.
Liquid formulations commonly use compatible high-density polyethylene, fluorinated high-density polyethylene, or appropriately lined packaging systems.

Wettable and dustable powders require moisture-resistant multilayer bags, lined fiber drums, or other sealed barrier packaging.
Packaging materials must resist permeation, swelling, paneling, stress cracking, corrosion, and active-content loss throughout the declared shelf life.
Closures must prevent leakage during storage and transport.

Container headspace, seal materials, induction liners, venting requirements, and filling temperature should be matched to the formulation.
Technical Malathion and environmentally hazardous liquid formulations are commonly transported as UN 3082, Environmentally Hazardous Substance, Liquid, N.O.S. (Malathion), Class 9, Packing Group III, and Marine Pollutant.

The complete transport classification of each formulation is determined by its concentration, solvent composition, flash point, package size, and applicable transport rules.
A procurement request should state the required formulation code, active concentration, packaging size, total quantity, intended country of use, application sector, registration requirements, and delivery terms.
The active concentration should be specified clearly in g/kg, percentage by mass, or g/L at the stated reference temperature.

For liquid formulations expressed in g/L, density data should accompany the specification when conversion to mass percentage is required.
Technical-material purchasing should include explicit limits for Malaoxon, Isomalathion, O,O,S-trimethyl phosphorodithioate, O,O,O-trimethyl phosphorothioate, acidity, and water content.
Public-health and ultra-low-volume purchasing should additionally define viscosity, flash point, low-temperature stability, atomization characteristics, packaging compatibility, and accelerated-storage performance.

Agricultural formulation purchasing should align the concentration and formulation type with the registration held in the intended market.
Residue-sensitive crop programs should align the product label with the maximum residue limits of both the production country and the destination market.
Ataman Kimya supports Malathion sourcing and procurement discussions based on required concentration, formulation type, impurity profile, packaging, documentation, application sector, destination market, and order quantity.

For product availability, specifications, documentation, packaging options, and commercial inquiries, contact Ataman Kimya at +90 216 577 10 10 or info@atamankimya.com.