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HuagongsheHuagongshe Chemistry Print Report · For research reference only
HCID 32739Generated: October 27, 2026

Chlormephos

DOTAN · MC2188 · P 2188 · ai3-25533 · CHLORMEFOS · CHLORMEPHOS · caswellno195b · Chlormethylfos

https://huagongshe.com/en/chemical/32739

Chlormephos molecular structure

Identifiers & Physical Properties

CAS No.24934-91-6
Molecular formulaC5H12ClO2PS2
Average molar mass234.7 g/mol
Monoisotopic mass233.9704867 g/mol
SMILESCCOP(=S)(OCC)SCCl
InChIKeyQGTYWWGEWOBMAK-UHFFFAOYSA-N
PubChem CID32739
ChEMBLCHEMBL1882960
ChEBICHEBI:38603
EC No.246-538-1
DTXSIDDTXSID1037511

Chemical & Physical Properties

XLogP3.1
Topological polar surface area75.9
Hydrogen bond donors0
Hydrogen bond acceptors4
Rotatable bonds6
Heavy atoms11
Formal charge0
Complexity134
LogP (partition coefficient)3.0 (estimated)
Density1.26 (EPA, 1998) - Denser than waterwill sink1.260 at 20 °CRelative density (water = 1): 1.261.26 @25 °Cd20 1.260
Color/FormColorless liquidPale-colored liquid.
Solubility60 mg/l water at 20 °CMiscible with most organic solventsSolubility in water, g/100ml at 20 °C: 0.006 (very poor)60 mg l-1(20 °C)
CorrosivityCorrosive to some metals.
Flash point>100 °C
Boiling point178 to 185 °F at 0.1 mmHg (EPA, 1998)81-85 °C at 0.1 mm Hgbp1mm 93-95°bp0.1 Torr 81-85°
Vapor pressure0.0056 mmHg at 86 °F (EPA, 1998)7.6 Pa at 30 °CVapor pressure at 20 °C: negligible0.0056 [mm Hg] @30 °C7.6 Pa (30 °C)
Refractive indexIndex of refraction: 1.5244nD220 1.5244
Physical DescriptionChlormephos is a colorless liquid. Used as a soil insecticide. Not registered as a pesticide in the U.S. (EPA, 1998)Water-white liquid[Merck Index] Colorless liquid[ICSC]COLOURLESS LIQUID.
Stability/Shelf LifeStable in neutral and weakly acidic media at room temp, but hydrolyzed by dilute acids and alkalis at 30 °C. Rapidly hydrolyzed in alkaline media.
Kovats Retention Index1399141414261411.9143314371427.11433.1
Melting point25°C
Storage conditions0-6°C
Physical stateliquid
Henry's law constant3.4×10-2 mol/(m3Pa) at 25℃, Duchowicz et al. (2020)
EWG's Food Scores4-5
FDA UNII1N10F47JUS
EPA Substance Registry SystemChlormephos (24934-91-6)
GHS pictogramGHS06,GHS09
Signal wordDanger
GHS hazard statementsH300+H310-H410
GHS precautionary statementsP273-P280-P301+P310+P330-P302+P352+P310-P391-P501
Hazard symbolsT+,N
Risk statements (R)27/28-50/53
Safety statements (S)28-36/37-45-60-61-27
UN transport number3018
RTECS numberTD5170000
Hazard class6.1(a)
Packing groupII
Hazardous substances data24934-91-6(Hazardous Substances Data)
ToxicityLD50 in rats (mg/kg): 7 orally27 dermallyLC50 in fish: 1.5 mg/l (Lynch)

Safety & Regulations

GHS classificationDangerH300: Fatal if swallowed [Danger Acute toxicity, oral]H310: Fatal in contact with skin [Danger Acute toxicity, dermal]H400: Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]H410: Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]P262, P264, P270, P273, P280, P301+P316, P302+P352, P316, P321, P330, P361+P364, P391, P405, and P501 (click each P-code to see the statement)
Regulatory information2002/2076The New Jersey Worker and Community Right to Know Act requires public and private employers to provide information about hazardous substances at their workplaces. (N.J.S.A. 34:5A-1 et. seq.)
DOT labelPoison
Fire hazards(Non-Specific -- Organophosphorus Pesticide, Liquid, n.o.s.) Container may explode in heat of fire. Fire and runoff from control water may produce irritating or poisonous gases. (EPA, 1998)Combustible. Gives off irritating or toxic fumes (or gases) in a fire.
Health hazards(Non-Specific -- Organophosphorus Pesticide, Liquid, n.o.s.) This material is poisonousit may be fatal if inhaled, swallowed, or absorbed through the skin. (EPA, 1998)
Hazards summaryA non-systemic cholinesterase inhibitor[Merck Index] May be absorbed through skinA cholinesterase inhibitor[ICSC] The average of two baseline respective cholinesterase activity determinations three days apart, with no exposures to enzyme inhibiting pesticides for at least 30 days, is recommended for each worker prior to exposure to cholinesterase inhibitors because of large inter-individual differences in published baseline values. To be established at least once a year. Removal from workplace exposures is recommended until the cholinesterase activity returns to within 20% of baseline. [TLVs and BEIs]
Reactive groupEsters, Sulfate Esters, Phosphate Esters, Thiophosphate Esters, and Borate EstersHalogenated Organic Compounds
EC classification

Applications & Uses

Description

Chlormephos is an organophosphate, colorlessliquid. Molecular weight=234.70; Boiling point =81-85℃ at 0.1 mmHg. Hazard Identification (based onNFPA 704 M Rating System): Health 3, Flammability 2,Reactivity 0. Soluble in water; solubility=60 mg/L at20℃.

Uses

Insecticide primarily for soil applications.

Uses

Chlormephos is used to control soil insects such as wireworms in a number of crops.

Uses

Chlormefos has agricultural applications. Useful for preparing compositions for controlling plant diseases.

General Description

Colorless liquid. Used as a soil insecticide. Not registered as a pesticide in the U.S.

Symbol: T+, N
R: 27/28-50/53
S: (1/2)-28-36/37-45-60-61
UN classificationUN Hazard Class: 6.1UN Pack Group: I
Reactivity ProfileOrganophosphates, such as CHLORMEPHOS, 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.
Chemical DangersDecomposes on burning. This produces toxic and corrosive fumes including phosphorus oxides and sulfur oxides. Attacks some metals.
Flammable LimitsCombustible.
Packaging and LabellingMarine pollutant. Do not transport with food and feedstuffs.
Fire fighting(Non-Specific -- Organophosphorus Pesticide, Liquid, n.o.s.) Stay upwindkeep out of low areas. Move container from fire area if you can do it without risk. Fight fire from maximum distance. Dike fire control water for later disposaldo not scatter the material. Wear positive pressure breathing apparatus and special protective clothing.(Non-Specific -- Organophosphorus Pesticide, Liquid, n.o.s.) This material may burn, but does not ignite readily. For small fires, use dry chemical, carbon dioxide, water spray, or foam. For large fires, use water spray, fog, or foam. (EPA, 1998)Use water spray, foam, powder, carbon dioxide.
First aid measuresFresh air, rest. Artificial respiration may be needed. Refer immediately for medical attention.Remove contaminated clothes. Rinse and then wash skin with water and soap. Refer immediately for medical attention. Wear protective gloves when administering first aid.First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.Rinse mouth. Give a slurry of activated charcoal in water to drink. Refer immediately for medical attention.
First aidWarning: Effects may be delayed up to 12 hours. Caution is advised.Note: Chlormephos is a cholinesterase inhibitor.Signs and Symptoms of Chlormephos Exposure: Acute exposure to chlormephos may produce the following signs and symptoms: sweating, pinpoint pupils, blurred vision, headache, dizziness, profound weakness, muscle spasms, seizures and coma. Mental confusion and psychosis may occur. Excessive salivation, nausea, vomiting, anorexia, diarrhea, and abdominal pain may also occur. The heart rate may decrease following oral exposure or increase following dermal exposure. Chest pain may be noted. Hypotension (low blood pressure) may be observed, although hypertension (high blood pressure) is not uncommon. Respiratory symptoms include dyspnea (shortness of breath), pulmonary edema, respiratory depression, and respiratory paralysis.Emergency Life-Support Procedures: Acute exposure to chlormephos exposure may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.Inhalation Exposure:1. Move victims to fresh air. Emergency personnel should avoid self-exposure to chlormephos.2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer 100% humidified oxygen or other respiratory support.3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.4. Rush to a health care facility.Dermal/Eye Exposure:1. Remove victims from exposure. Emergency personnel should avoid self-exposure to chlormephos.3. Remove contaminated clothing as soon as possible.4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.5. Wash exposed skin areas three times with soap and water.6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.7. Rush to a health care facility.Ingestion Exposure:1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.2. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
Safe storageProvision to contain effluent from fire extinguishing. Separated from food and feedstuffs. Well closed. Store in an area without drain or sewer access.
Exposure control and personal protectionBiological Exposure Indices (BEI) [ACGIH] - Acetylcholinesterase activity in red blood cells = 70% of individual's baselineButylcholinesterase activity in serum or plasma = 60% of individual's baselineSample at end of shift[TLVs and BEIs]
Fire fighting proceduresFor small fires, use dry chemical, carbon dioxide, water spray, or foam. For large fires, use water spray, fog, or foam.If material on fire or involved in fire: Do not extinguish fire unless flow can be stopped or safely confined. Use water in flooding quantities as fog. Solid streams of water may be ineffective. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. Use "alcohol" foam, carbon dioxide or dry chemical. /Organophosphorus pesticides, liquid, NOS/
Storage conditionsRooms used for storage only should be soundly constructed & fitted with secure locks. Floors should be kept clear & pesticides clearly identified. If repacking is carried out in storage rooms, adequate light should be availablefloors should be impervious & sound ... . /Pesticides/Pesticides containers must be provided with labels indicating the degree of toxicity of the product they contain. The labels must not only give a short description of how to use the prepn, but also state basic precautions to be taken when applying it. /Organophosphorus pesticides/Pesticides of any degree of toxicity should be transported in containers which are clearly labelled, leak-proof, and not easily damaged. They should never be transported /or stored/ beside, or above any type of food, and all spillages should be immediately reported. /Pesticides/
Nonfire spill response(Non-Specific -- Organophosphorus Pesticide, Liquid, n.o.s.) Stay upwindkeep out of low areas. Ventilate closed spaces before entering them. Remove and isolate contaminated clothing at the site. Do not touch spilled material. Use water spray to reduce vapors. Take up small spills with sand or other noncombustible absorbent material and place in containers for later disposal. Dike far ahead of large spills for later disposal. (EPA, 1998)
Disposal methodsSRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.All organic pesticides, whether of botanical or synthetic origin, can be destroyed by incineration. /Organic pesticides/Manufacturers or formulators of very large amounts of pesticides may find it advantageous to build incinerators adequate to destroy all organic pesticides and equipped with scrubbers to remove acid wastes. /Organic pesticides/
Spillage disposalPersonal protection: complete protective clothing including self-contained breathing apparatus. Do NOT let this chemical enter the environment. Collect leaking and spilled liquid in sealable plastic containers as far as possible. Absorb remaining liquid in sand or inert absorbent. Then store and dispose of according to local regulations.
Preventive MeasuresIn some situations where personnel may become accidently contaminated ... it is necessary to provide shower bath in addition to the usual washing facilities. Special arrangements for cleaning clothing & overalls may be necessary ... /Pesticides/Special aircraft should preferably be used for spraying or dusting toxic organophosphorus pesticides. ... aerial spraying or dusting gives rise to clouds which spread over larger surfaces than clouds produced by ground application. Aerial spraying should therefore be carried out on windless days only. Residential areas, water supply sources, etc must be avoided. ... When aircraft approaches, signalmen /guiding the aircraft/ should leave the windward side. ... The local population should be informed about the site & time of aerial pesticide treatment. Access of unauthorized persons & especially children to the area to be treated must be ... forbidden. Warning signs should be placed at the limits of the area. Ground spraying must be carried out with compressed-air spraying equipment towed by tractors with closed cabs. /Organophosphorus pesticides/Small packages of pesticides are preferable for individual application in order to limit the quantities to be weighed & metered. A special vessel with long stirring rod for dilution & suspension of the poison must be available in order to reduce manual handling to a minimum. The strict observance of hygiene rules--no smoking & no food intake during work. Thorough washing with soap after work, changing protective clothing before going home--is of utmost importance. /Organophosphorus pesticides/Containers ... should be cleaned with a suspension of bleaching powder in water or with other alkaline soln after soaking for 24 hr and then be rinsed with hot water. /Organophosphorus pesticides/For more Preventive Measures (Complete) data for CHLORMEPHOS (8 total), please visit the HSDB record page.
Isolation and EvacuationExcerpt from ERG Guide 152 [Substances - Toxic (Combustible)]:IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary.FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directionsalso, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)
InteractionsSome phenothiazines may antagonize & some may potentiate the toxic anticholinesterase effects of ... /organophosphorus insecticides/. /Organophosphate cholinesterase inhibitors/In long term therapy, adrenocorticoids antagonize the antiglaucoma effects of anticholinesterases (incr ocular pressure). ... Anticholinergics antagonize the miotic (antiglaucoma) & other muscarinic effects of anticholinesterases on the autonomic & central nervous systems. Tricyclic antidepressants (anticholinergic effects) antagonize the antiglaucoma (miotic) effects of anticholinesterases in glaucoma. ... Antihistamines with anticholinergic effects antagonize the miotic (antiglaucoma) & CNS effects of anticholinesterases. Anticholinesterases potentiate tranquilizing & behavioral changes induced by antihistamines. The actions of anticholinesterase agents on autonomic effector cells, & to some extent those on CNS, are antagonized by atropine, an antidote of choice. Barbiturates are potentiated by anticholinesterases. ... Dexpanthenol potentiates the effects of anticholinesterases. Fluorophosphate insecticides potentiate the effects of other anticholinesterases. /Anticholinesterases/BARBITURATES ARE POTENTIATED BY ANTICHOLINESTERASES. ALTHOUGH BARBITURATES MAY BE USED CAUTIOUSLY IN TREATING CONVULSIONS, EXTREME CARE IS ESSENTIAL IN HANDLING POISONINGS DUE TO ANTICHOLINESTERASES, PARTICULARLY ORGANOPHOSPHORUS PESTICIDES. ECHOTHIOPHATE, A CHOLINESTERASE INHIBITOR USED AS MIOTIC, POTENTIATES OTHER SUCH INHIBITORS ... USED FOR OTHER PURPOSES (ADDITIVE EFFECTS) OR POSSIBLY SYNERGISTIC. THOSE EXPOSED TO ORGANOPHOSPHATE INSECTICIDES MUST TAKE STRICT PRECAUTIONS. ... ORGANOPHOSPHORUS INSECTICIDES: ADDITIVE ANTICHOLINESTERASE EFFECTS. HAZARDOUS. PATIENTS ON ANTICHOLINESTERASES (EVEN TOPICAL, SUCH AS EYE DROPS) SHOULD AVOID AREAS WHERE ORGANOPHOSPHORUS INSECTICIDES ... RECENTLY ... USED. /ANTICHOLINESTERASE/ANTICHOLINESTERASE (ORGANOPHOSPHORUS) INSECTICIDES ANTAGONIZE POLARIZING MUSCLE RELAXANTS. PHENOTHIAZINES /AND THIOXANTHENES/: ... MAY ENHANCE TOXIC EFFECTS OF ORGANOPHOSPHORUS INSECTICIDES. /INSECTICIDES, ORGANOPHOSPHORUS/
Ecotoxicity valuesLC50 Harlequin fish (Rasbora heteromorpha) 4.8 mg/L/24 hr, Flow-throughLC50 Harlequin fish (Rasbora heteromorpha) 3.5 mg/L/48 hr, Flow-throughLC50 Harlequin fish (Rasbora heteromorpha) 2.5 mg/L/96 hr, Flow-throughLD50 Quail oral 260 mg/kgLC50 harlequin fish = 1.5 mg/L /Conditions of bioassay not specified/
Environmental fateIn soil, chlormephos is converted to ethion.TERRESTRIAL FATE: Based on a recommended classification scheme(1), an estimated Koc value of 1100(SRC), determined from an estimated log Kow of 3.0(2,SRC) and a recommended regression-derived equation(3), indicates that chlormephos is expected to have low mobility in soil(SRC). Volatilization of chlormephos from moist soil surfaces may be important(SRC) given an estimated Henry's Law constant of 2.9X10-4 atm-cu m/mole(SRC), from its experimental values for vapor pressure, 0.057 mm Hg(4), and water solubility, 60 mg/l(4). Volatilization may be inhibited by adsorption to soil(SRC). In soil, chlormephos is converted to ethion(4). The half-life of chlormephos in a sandy loam soil was 28 days(5).AQUATIC FATE: Based on a recommended classification scheme(1), an estimated Koc value of 1100(SRC), determined from an estimated log Kow of 3.0(2,SRC) and a recommended regression-derived equation(3), indicates that chlormephos is expected to adsorb to suspended solids and sediment in water(SRC). Chlormephos may volatilize from water surfaces(3,SRC) based on an estimated Henry's Law constant of 2.9X10-4 atm-cu m/mole(SRC), from its experimental values for vapor pressure, 0.057 mm Hg(4), and water solubility, 60 mg/l(4). Estimated volatilization half-lives for a model river and model lake are 9.1 hours and 7.5 days, respectively(3,SRC). Volatilization may be inhibited by adsorption to sediment in the water column(SRC). According to a classification scheme(5), an estimated BCF of 120(3,SRC), from an estimated log Kow(2,SRC), suggests that bioconcentration in aquatic organisms is high(SRC).ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), chlormephos, which has a measured vapor pressure of 0.057 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase chlormephos is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC)the half-life for this reaction in air is estimated to be about 3.9 hours(3,SRC).
Adverse effectsOther Poison - Organophosphate
Exposure routesThe substance can be absorbed into the body in hazardous amounts by inhalation, through the skin and by ingestion.
Signs and SymptomsDizziness. Nausea. Sweating. Muscle twitching. Pupillary constriction, muscle cramp, excessive salivation. Laboured breathing. Convulsions. Unconsciousness.MAY BE ABSORBED! See Inhalation.Blurred vision.Abdominal cramps. Diarrhoea. Vomiting. Further see Inhalation.
ICSC Environmental DataThe substance is toxic to aquatic organisms. This substance does enter the environment under normal use. Great care, however, should be taken to avoid any additional release, for example through inappropriate disposal.
Medical SurveillanceWorkers handling & applying pesticides must undergo an annual medical examination at the beginning of each agricultural season. Contraindications /meaning further clinical evaluations/ for work with /organophosphorus pesticides/ are organic diseases of the central nervous system, mental disorders & epilepsy, pronounced endocrine & vegetative disorders, pulmonary tuberculosis, bronchial asthma, chronic respiratory diseases, cardiovascular diseases & circulatory disorders, gastrointestinal diseases (peptic ulcer), gastroenterocolitis, diseases of liver & kidneys, eye diseases (chronic conjunctivitis & keratitis). The blood cholinesterase activity must be determined before work starts. In the event of prolonged work periods, this activity should be determined at intervals of 3-4 days. Persons exhibiting a fall in cholinesterase activity of 25% or more must be transferred to other work where they are not exposed to organophosphorus pesticides until this activity is completely restored. Persons with initial signs of indisposition should /be protected from exposure from/ pesticides. /Organophosphorus pesticides/... Surveillance of workers could be carried out through measurement of blood or urinary levels of the cmpd to which they are exposed, or through measurement of a metabolite. /Organic phosphorus pesticides/... There is no change in red blood cell cholinesterase activity in adults associated with age. ... Activity of this enzyme increases progressively during the first year of life, it is higher in children under 3 yr of age than in older children, and it is markedly higher in 5 yr old children than in 3 yr olds. /Organic phosphorus pesticides/Cholinesterase activity of plasma is significantly higher in men than in women, and this is true no matter which of several choline esters are used as substrate in measuring the enzyme activity. According to some, the difference is confined to young people. There is no sex difference in the red cell enzyme activity. Serum cholinesterase activity of blacks tends to be lower than whites of the same sex. /Organic phosphorus pesticides/
Soil Adsorption/MobilityThe Koc of chlormephos is estimated as approximately 1100(SRC), using an estimated log Kow of 3.0(1) and a regression-derived equation(2,SRC). According to a recommended classification scheme(3), this estimated Koc value suggests that chlormephos is expected to have low mobility in soil(SRC).
TSCA Test SubmissionsChlormephos technical (CAS # 24934-91-693.4% pure) was evaluated for acute oral toxicity in young, pure-bred beagle dogs (1 male and 1 female/dose level) administered single doses of 10, 12.5, 15 and 20 mg/kg in gelatin capsules. Both dogs of a 20 mg/kg dose were sacrificed in extremis at 4 hours and 6 hours post-dosing respectively. Also, the dogs of a 15 mg/kg dose died overnight on the day of dosing and the male of a 12.5 mg/kg dose was dead on Day 2. An approximate Oral LD50 for beagle dogs was 12.5 mg/kg. Universal pharmacotoxic signs were resolved by Day 2 in the female of a 12.5 mg/kg dose and both animals of a 10 mg/kg dose surviving treatment and 2-week post-treatment observation. A transient weight loss noted in these surviving dogs was also resolved without apparent sequelae within a few days of dosing. Overt toxic signs including subdued behavior, muscular fasciculations, vomiting, and high- stepping gait with hind limb incoordination ensued from 60 to 90 minutes after dosing at all treatment levels. Blood stained liquid feces, blood stained mucous, dark feces, ataxia, violent muscular spasms, ptosis, prostration and shallow breathing characterized the responses to doses over 10 mg/kg. Upon terminal macroscopic examination, survivors of 14-day observation after dosing at 10 mg/kg exhibited no gross pathology related to treatment. The surviving female of a 12.5 mg/kg dose was found with focal congestion of the duodenum and pyloric antrum, close to the sphincter. Macroscopic findings associated with treatment among study lethalities included blood at the anal sphincter (12.5 mg/kg), severe duodenal congestion enclosing free blood (12.5 mg/kg male), moderate to severe mucosal congestion of the small and large intestine (12.5-20 mg/kg), free digested blood in the gastrointestinal tract (15-20 mg/kg), and mucosal congestion of the urinary bladder (15-20 mg/kg).94.4% pure) was evaluated for acute oral toxicity. Based on preliminary results from pilot study, Sprague-Dawley derived outbred albino rats (10/sex/group) were administered single doses of 15, 25, 35, 50 and 75 mg/kg bodyweight (10 ml/kg in corn oil) by oral gavage. Treatment was associated with mortality comprising an LD50 of 27 mg/kg b.w. with 95% confidence limits of 21.3 - 34.3 mg/kg b.w. in males and 18 mg/kg b.w. with 95% confidence limits of 14.0 - 23.2 mg/kg b.w. in females as follows: 15 mg/kg b.w. (2/10M, 2/10F)25 mg/kg b.w. (4/10M, 9/10F), 35 mg/kg b.w. (8/10M, 10/10F), 50 mg/kg b.w. (7/10M, 10/10F), and 75 mg/kg b.w. (10/10M, 10/10F). The average time-to-death was greater for males than females except following 75 mg/kg doses, whereupon average survival was 0.7 days for females and 0.2 days for males. The surviving rats showed signs of recovery of toxic effects with weight gains by Day 4, save the solitary surviving female of a 25 mg/kg b.w. dose which did not gain weight until Day 10. Pharmacotoxic signs included mild to severe depression, trembling, salivation, lacrimation, wet belly, occasional ataxia, prostration and death. A shorter time to onset and greater severity of toxic signs reflected increasing dose levels. All survivors were cleared of overt toxicity by post-treatment Day 7. Hyperemic liver and kidneys, hemorrhagic lungs and urinary bladders, and sloughing and/or inflammation with erosion of the stomach mucosa were noted upon macroscopic examination of the study lethalities. Survivors of 14-day post-treatment observation were free of any treatment-related gross pathology on terminal necropsy.Chlormephos (CAS # 24934-91-6) technical was evaluated for acute dermal toxicity. New Zealand albino rabbits (6/sex/treatment level) were administered single dermal applications of 10, 20, 40, 70 and 100 mg/kg bodyweight (2 ml/kg) for 24 hours, upon occluded abraded and intact application sites in half (3/6) of each treatment group respectively. Actual doses adjusted for a minimal purity level of 93% (purity as determined by GLC was 94.4%) were calculated as 10.2, 20.4, 40.8, 70.2 and 101.2 mg/kg b.w.The substance pH was 3.01. During the 24-hour treatment period, treated rabbits were immobilized in stocks and observed frequently for acute signs of toxicity. Treatment-related mortality was consistent with a Dermal LD50 in male rabbits of 31 mg/kg b.w.. with 95% confidence limits of 16.8 to 57.4 mg/kg b.w. and in female rabbits of 62 mg/kg b.w. with 95% confidence limits of 36.5 to 105.4 mg/kg b.w. (by a method of Litchfield & Wilcoxon) as follows: 10 mg/kg (2/6M, 0/6F), 20 mg/kg (1/6M, 0/6F), 40 mg/kg (3/6M, 2/6F), 70 mg/kg (5/6M, 3/6F), and 100 mg/kg (6/6M, 6/6F). Excepting the deaths of a male and a female of 10 mg/kg b.w. doses on Day 1 and Day 5 respectively, all mortality occurred on the day of treatment (Day 0). No distinction in mortality or time-to-death was noted between treatment upon abraded or intact skin. Overt toxicity was universal among treatment levels and characterized by depression, dyspnea, ataxia, and diarrhea at 10 mg/kg b.w.Tremor, salivation, cyanosis and convulsions were additionally observed in association with exposures above 10 mg/kg b.w.. The severity of symptoms bore a positive correlation to level of treatment. Weight loss accorded Day 0 (treatment day) due to restraint of the rabbits in stocks was regained by post-treatment Day 7 in the study survivors of 14-day observation. Upon necropsy, early lethalities (within a few hours of treatment) exhibited no gross pathological indicators of toxic etiology as was the case with most of thChlormephos (CAS # 24934-91-6) was evaluated for acute inhalation toxicity in CFHB strain albino rats (10/sex/treatment level) administered whole-body exposures to nominal aerosol concentrations of 0, 1.0, 3.0, 4.0 and 5.0 mg/l for one hour. The liquid sample was injected by syringe through an atomizer and into a current of dry air at rates regulated for the generation of serial aerosol concentrations by a Palmer slow injection apparatus. The aerosol was generated continuously for respective hour-long exposure periods and supplied to solitary rats restrained inside exposure chambers. Actual aerosol concentrations were less than target concentrations as evidenced by substance precipitate recovered on the chamber lids, however no attempt was made during the exposures to measure ambient concentrations. Mortality associated with treatment was consistent with an 1-Hour LC50 of 3.8 mg/l as follows: 1 mg/l (0/10M, 0/10F), 3.0 mg/l (1/10M, 4/10F), 4.0 mg/l (8/10M, 4/10F), and 5.0 mg/l (7/10M, 6/10F). Death occurred from 0.5 hours to 3 days post-exposure. Pharmacotoxic signs were noted from concentration levels of 1 mg/l, increasing in severity and with lesser time to onset with increasing exposure levels. At 1 mg/l, study investigators noted salivation, skin and body tremors, polyuria and increased ocular secretion, slight ataxia and hypoactivity. At doses of 4.0 and 5.0 mg/l, mortality was heralded by emaciation, ataxia, hypoactivity and coma. Food and water consumption were diminished during the first day in all treated animals, with first week weight losses reflective of the exposure level. Acute signs of irritation subsequently resolved in all surviving animals during the first week following exposures, with behavior and rates of weight gain normalizing during the 2nd week of 2-week post-treatment observation. Lethargy was the only persisting treatment-related observation at the termination of 14-day study. Necropsy of the study lethalities revealed moderately generalizFor more TSCA Test Submissions (Complete) data for CHLORMEPHOS (8 total), please visit the HSDB record page.
Human Toxicity ExcerptsAll the organophosphorus insecticides have a cumulative effect by progressive inhibition of cholinesterase ... /Organophosphorus insecticides/The symptoms of chronic poisoning due to organophosphorus pesticides include headache, weakness, feeling of heaviness in head, decline of memory, quick onset of fatigue, disturbed sleep, loss of appetite, & loss of orientation. Psychic disorders, nystagmus, trembling of the hands & other nervous system disorders can be observed in certain cases. Sometimes neuritis, paresis & paralysis develop. /Organophosphorus pesticides/Organophosphate insecticides ... are potent cholinesterase enzyme inhibitors that act by interfering with the metabolism of acetylcholine, which results in accumulation of acetylcholine at neuroreceptor transmission sites. Exposure produces a broad spectrum of clinical effects indicative of massive overstimulation of the chlorinergic system, including muscarinic effects (parasympathetic), nicotinic effects (sympathetic and motor), and CNS effects. These effects present clinically as feeling of headache, weakness, dizziness, blurred vision, psychosis, respiratory difficulty, paralysis, convulsions, and coma. Typical findings are given by the mnemonic "SLUD." which stands for salivation, lacrimation, urination, and defecation. A small percentage of patients may fail to demonstrate miosis, a classic diagnostic hallmark. Onset of clinical manifestation of organophosphate poisoning usually occurs within 12 hr of exposure. /Organophosphate insecticides/A woman at 34 to 35 weeks' gestation presented in acute respiratory distress with cyanosis and tachypnea and bilateral rhonchi and crepitation. Her heart rate was 78 beats per min and her blood pressure 120/80 mm Hg, with a fetal heart rate of 140 beats per min. The mother was salivating markedly and her pupils were reduced to "pinpoint size." An uncorrected metabolic acidosis was diagnosed. Serum and erythrocyte acetylcholinesterase determinations were near zero. Cholinesterase inhibitor poisoning was felt to be the likely cause of her disorders. Administration of atropine 2.4 mg iv bolus with infusion of 0.02 mg/kg/hr lead to unacceptable fetal tachycardia. The woman had shown increased cooperativeness and secretion control until the atropine had to be stopped. A cesarean section was performed for delivery of a hypotonic infant with a 1 min Apgar score of 3. The baby was mechanically ventilated for 2 days and required atropine therapy at 0.1 mg/kg/hr for 8 days. The mother required 8 days of mechanical ventilation and 11 days of atropine therapy. In this case, the infant appeared relatively less poisoned than the mother by a presumed organophosphate exposure. /Organophosphate poisoning/For more Human Toxicity Excerpts (Complete) data for CHLORMEPHOS (17 total), please visit the HSDB record page.
Artificial Pollution SourcesChlormephos's use as a soil insecticide in maize, sugar beet, fodder beet, sugar cane, potatoes, tobacco, cereals, and other crops(1) may result in its release to the environment(SRC).
CERCLA reportable quantitiesReleases of CERCLA hazardous substances are subject to the release reporting requirement of CERCLA section 103, codified at 40 CFR part 302, in addition to the requirements of 40 CFR part 355. Chlormephos is an extremely hazardous substance (EHS) subject to reporting requirements when stored in amounts in excess of its threshold planning quantity (TPQ) of 500 lbs.
RTECS numberTD5170000
UN transport number3018
ToxicityLD50 in rats (mg/kg): 7 orally27 dermallyLC50 in fish: 1.5 mg/l (Lynch)
Risk statements (R)27/28-50/53
Signal wordDanger
GHS pictogramGHS06,GHS09
Hazard symbolsT+,N
Safety statements (S)28-36/37-45-60-61-27
Hazard class6.1(a)
Packing groupII
GHS hazard statementsH300+H310-H410
GHS precautionary statementsP273-P280-P301+P310+P330-P302+P352+P310-P391-P501
Hazardous substances data24934-91-6(Hazardous Substances Data)