Resmethrin

338.44

338.44

233-940-7

0324

3082|3349|2902

DTXSID7022253

Waxy off-white to tan solid|Colorless crystals

29321900

39.4

3.46

0.958-0.968 g/cm³ @ Temp: 20 °C

43-48 °C

174 °C

closed cup:264.2°F (129°C)

1.5287 (20℃)

Solubility in water: none

0-6°C

Vapour pressure, Pa at 20°C:

Oral-rat LD50:1244 mg/kg; Oral-Mouse LD50: 300 mg/kg

Flammable; burning produces irritating fumes

Chrysanthemate odor

Henry's Law constant = 1.3X10-7 atm-cu m/mol at 25 °C (est)

Wax solid /Technical resmethrin/|... Contains 20-30% (1RS)-cis-and 80-70% (1RS)-trans-isomers.

Insoluble in water.

Esters, Sulfate Esters, Phosphate Esters, Thiophosphate Esters, and Borate Esters

A pyrethroid derivative.

Non-corrosive

III

9

3082

3

22-50/53

60/61-61-60

GZ1310000

Xn,N

Ventilated, low temperature and dry; stored separately from food materials in warehouse

Pyrethrins /are/ stable for long periods in water-based aerosols where emulsifiers give neutral water systems. /Pyrethrins/

P273-P301 + P312 + P330-P391-P501

H302-H410

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.|It could be ... buried in noncrop land away from water. In each of these cases it would be better to mix the product with lime. Incineration would be an effective disposal procedure where permitted. If an efficient incinerator is not available, the product should be mixed with large amt of combustible material. Recommendable methods: Hydrolysis, landfill, incineration, & open burning. Not recommendable method: Discharge to sewer. Peer-review: Mix with sawdust and burn at a remote place. (Peer-review conclusions of an IRPTC expert consultation (May 1985))|Incineration would be an effective disposal procedure where permitted. ... /Pyrethrin products/|Empty containers may be decontaminated by washing three times with detergent and water. Additionally, the container should be soaked overnight in 5% sodium hydroxide. Impermeable gantlets should be worn for all decontamination procedures. A deep soakage pit should be provided for the rinsings. Decontaminated containers must not be used for storage or transport of food or drink. Containers not decontaminated should be burned or crushed and buried below topsoil. Care must be taken to avoid contamination of water sources.|Disposal: Waste containing resmethrin should be burnt in a proper high-temperature incinerator with effluent scrubbing. Where no incinerator is available, contaminated absorbents or surplus products should be decomposed by hydrolysis at pH 12 or above. Contact with a suitable hydrolysing agent is required to ensure degradation of the active ingredient to a safe level. For emulsifiable material: 5% sodium hydroxide (caustic soda) solution or saturated (7-10%) sodium carbonate (washing soda) solution can be used. For non-emulsifiable material: use a 1:1 mixture (by volume) of either of the above solutions and a water/oil soluble solvent, such as denatured alcohol, monoethylene glycol, hexylene glycol, or isopropanol. Cover the material with the hydrolysing agent and put aside to stand for 7 days. Before disposal of the resultant waste, the material must be analysed to ensure that the active ingredient has been degraded to a safe level. Never pour untreated waste or surplus products into public sewers or anywhere where there is any danger of run-off or seepage into streams, watercourses, open waterways, ditches, fields with drainage systems, or the catchment areas of boreholes, wells, springs, or ponds.

Incompatibility: Strong oxidizers. /Pyrethrins/|... Incompatible with lime & ordinary soaps because acids & alkalies speed up processes of hydrolysis. /Pyrethrins/

WHO; Environmental Health Criteria 92: Resmethrins - Resmethrin, Bioresmethrin, Cisresmethrin (1989). EHC publications are monographs designed for scientists and administrators responsible for the establishment of safety standards and regulations and provide basic scientific risk evaluations of a wide range of chemicals and groups of chemicals.|USEPA/Office of Prevention, Pesticides and Toxic Substances; Reregistration Eligibility Decision Document - Resmethrin. EPA 738-R-06-003 (June 2006). The RED summarizes the risk assessment conclusions and outlines any risk reduction measures necessary for the pesticide to continue to be registered in the U.S.[Available from, as of May 26, 2009: http://www.epa.gov/pesticides/reregistration/status.htm]|USEPA, Office of Prevention, Pesticides, and Toxic Substances; Revised HED Human Health Risk Assessment for Resmethrin (10453-86-8) (October 18, 2005). EPA Docket No.: EPA-HQ-OPP-2005-0284-0003.|WHO/FAO; Data Sheets on Pesticides: No. 83 Resmethrin (10453-86-8) (July 1996).[Available from, as of May 26, 2009: http://www.inchem.org/pages/pds.html]

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]: Some may burn but none ignite readily. Containers may explode when heated. Some may be transported hot. For UN3508, be aware of possible short circuiting as this product is transported in a charged state. (ERG, 2016)|Liquid formulations containing organic solvents may be flammable.

|Warning|H302: Harmful if swallowed [Warning Acute toxicity, oral]|P264, P270, P273, P301+P312, P330, P391, and P501|H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]|Aggregated GHS information provided by 202 companies from 4 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.|P201, P202, P260, P264, P270, P281, P301+P312, P308+P313, P309+P311, P314, P330, P405, and P501

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]: As an 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, in the downwind direction, as necessary, the isolation distance shown above. FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2016)

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]: Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent dust cloud. Avoid inhalation of asbestos dust. SMALL DRY SPILL: With clean shovel, place material into clean, dry container and cover loosely; move containers from spill area. SMALL SPILL: Pick up with sand or other non-combustible absorbent material and place into containers for later disposal. LARGE SPILL: Dike far ahead of liquid spill for later disposal. Cover powder spill with plastic sheet or tarp to minimize spreading. Prevent entry into waterways, sewers, basements or confined areas. (ERG, 2016)

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]: Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing will only provide limited protection. (ERG, 2016)|Applicators using handheld fog equipment must wear: - coveralls over long sleeved shirt and long pants, - chemical-resistant gloves, - chemical-resistant footwear plus socks, - chemical-resistant headgear, if overhead exposure, - chemical-resistant apron when mixing, loading, and cleaning equipment or spills, and - A NIOSH-approved respriator with --a dust/mist filter with MSHA/NIOSH approval number prefix TC-21C or --any N* R, P, or He filter.|Pilots must use an enclosed cockpit. The cockpit must have a nonporous barrier that totally surrounds the occupants and prevents contact with pesticides outside the cab. Pilots must wear the PPE specified in this label for applicators.|Applicators using ground mechanical application equipment must use an enclosed cab that has a nonporous barrier that totally surrounds the occupants and prevents contact with pesticides outside the cab. Must be provided and have immediately available for use upon exiting the cab chemical-resistant gloves.|All mixers, loaders, applicators, and other handlers must wear: - long sleeved shirt and long pants, - socks plus shoes, and - chemical resistant gloves.

Liquid formulations containing organic solvents may be flammable.

Use carbon dioxide, foam, or dry chemical /on fires involving pyrethroids/. /Pyrethrum/|Fire-fighting: Self-contained breathing apparatus with a full facepiece operated in pressure-demand or other positive-pressure mode. /Pyrethrum/|Some solvents in pyrethroid formulations are highly flammable. Use dry powder, carbon dioxide, alcohol-resistant foam, sand. or earth for dealing with fires. DO NOT use water. Cool nearby drums with water spray. If pyrethroid products are involved in a major fire, or in a fire involving other products, advise the fire service that protective clothing and breathing apparatus should be worn. Also, warn the authorities that pyrethroids are highly toxic for fish, and that the use of water should be confined to the cooling of unaffected stock, thus avoiding the accumulation of polluted run-off from the site.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a POTW is acceptable only after review by the governing authority. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must meet Hazardous Material Criteria for disposal.|Spillages of pesticides at any stage of their storage or handling should be treated with great care. Liquid formulations may be reduced to solid phase by evaporation. Dry sweeping of solids is always hazardous: these should be removed by vacuum cleaning /SRP: with HEPA filter/, or by dissolving them in water, or other solvent in the factory environment. /Pesticides/|... Spillages should be washed away with large volumes of water and detergent.|Spillage: Avoid exposure, if possible by the use of appropriate protective clothing and masks. Empty any product remaining in damaged or leaking containers into a clean empty drum, and label. Absorb spillage with lime, damp sawdust, sand, or earth and dispose of safely. If spillage is large, contain it by building a barrier of earth or sandbags. Decontaminate empty, damaged, or leaking containers with a 10% sodium carbonate solution added at the rate of at least 1 L per 20-L drum. Puncture containers to prevent re-use.

SRP: Contaminated protective clothing should be segregated in such a manner so that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. Quality assurance to ascertain the completeness of the cleaning procedures should be implemented before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at end of shift, but should remain at employee's place of work for cleaning.|SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.|SRP: Local exhaust ventilation should be applied wherever there is an incidence of point source emissions or dispersion of regulated contaminants in the work area. Ventilation control of the contaminant as close to its point of generation is both the most economical and safest method to minimize personnel exposure to airborne contaminants.|Do not enter or allow worker entry into treated areas during the restricted entry interval (REI) of 12 hours.|For more Preventive Measures (Complete) data for RESMETHRIN (14 total), please visit the HSDB record page.

The chief effect from exposure ... is skin rash particularly on moist areas of the skin. ... May irritate the eyes.

Do NOT wash away into sewer. Do NOT let this chemical enter the environment. Sweep spilled substance into covered containers. If appropriate, moisten first to prevent dusting. Carefully collect remainder. Then store and dispose of according to local regulations.

Provision to contain effluent from fire extinguishing.

No indication can be given about the rate at which a harmful concentration of this substance in the air is reached on evaporation at 20 °C.

The substance is irritating to the eyes and skin.

NO open flames.

PREVENT DISPERSION OF DUST!

Use ventilation (not if powder), local exhaust or breathing protection.

Protective gloves.

Wear safety goggles.

INDOOR: Resmethrin was detected in indoor air of 10 commercial pest control firms in North Carolina at concentrations of 0.315.22 ug/cu m(1). Resmethrin was identified, not quantified, in indoor air of homes following its application from aerosol spray cans and compressed air sprayers(2). Resmethrin was detected at a mean concentration of 9.5 ug/sq m in one of six settled dust samples collected from Central New York farmers' non-air conditioned homes in 1999(3). A mean concentration of 4.5 ug/sq m was detected in four out of ten samples of carpet dust from the same farmers' homes; little difference was observed in a second series of samples taken after participants vacuumed(3).

highly toxic

/Pyrethroid/ detoxification ... important in flies, may be delayed by the addition of synergists ... organophosphates or carbamates ... to guarantee a lethal effect. ... /Pyrethroid/|Piperonyl butoxide potentiates /insecticidal activity/ of pyrethrins by inhibiting the hydrolytic enzymes responsible for pyrethrins' metabolism in arthropods. When piperonyl butoxide is combined with pyrethrins, the insecticidal activity of the latter drug is increased 2-12 times /Pyrethrins/|At dietary level of 1000 ppm pyrethrins & 10000 ppm piperonyl butoxide ... /enlargement, margination, & cytoplasmic inclusions in liver cells of rats/ were well developed in only 8 days, but ... were not maximal. Changes were proportional to dosage & similar to those produced by DDT. Effects of the 2 ... were additive. /Pyrethrins/

LD50 Rat oral 1400 mg/kg|LD50 Rat percutaneous >3000 mg/kg|LD50 Rat (male) dermal 2500 mg/kg|LD50 Rat (female) dermal 2500 mg/kg|For more Non-Human Toxicity Values (Complete) data for RESMETHRIN (22 total), please visit the HSDB record page.

/AQUATIC SPECIES/ Synthetic pyrethroids often have synergists added to improve effectiveness, yet decisions regarding the use of these pesticides are often based upon toxicity tests using technical material without the synergist, piperonyl butoxide ... Toxicity tests with brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) /were conducted/ to compare the toxicity of synergized and technical formulations of ...resmethrin ... The ability of exposed fish to swim against a current /was examined/. Fish exposed for 6 hr to synergized ... resmethrin had far less swimming stamina than those exposed to technical formulations.|/AQUATIC SPECIES/ This study investigated the toxicity of various concentrations of technical resmethrin and Scourge on adult and larval Palaemonetes pugio, a common grass shrimp species. Two types of tests were conducted for each of the resmethrin formulations using adult and larval grass shrimp life stages, a 96-hr static renewal aqueous test without sediment, and a 24-hr static nonrenewal aqueous test with sediment. For resmethrin, the 96-hr aqueous LC50 value for adult shrimp was 0.53 ug/L (95% confidence interval (CI): 0.46-0.60 ug/L), and for larval shrimp was 0.35 ug/L (95% CI: 0.28-0.42 ug/L). In the presence of sediment, technical resmethrin produced a 24-hr LC50 value for adult shrimp of 5.44 ug/L (95% CI: 4.52-6.55 ug/L), and for larval shrimp of 2.15 ug/L (95% CI: 1.35-3.43 ug/L). For Scourge, the 96-hr aqueous LC50 for adult shrimp was 2.08 ug/L (95% CI: 1.70-2.54 ug/L), and for larval shrimp was 0.36 ug/L (95% CI: 0.24-0.55 ug/L). The 24-hr sediment test yielded an LC50 value of 16.12 ug/L (95% CI: 14.79-17.57 ug/L) for adult shrimp, and 14.16 ug/L (95% CI: 12.21-16.43 ug/L) for larvae. Adjusted LC50 values to reflect the 18% resmethrin concentration in Scourge are 0.37 ug/L (adult), 0.07 ug/L (larvae) for the 96-hr aqueous test, and 2.90 ug/L (adult), 2.6 ug/L (larvae) for the 24-hr sediment test. Larval grass shrimp were more sensitive to technical resmethrin and Scourge than the adult life stage. The results also demonstrate that synergized resmethrin is more toxic to P. pugio than the nonsynergized form, and that the presence of sediment decreases the toxicity of both resmethrin and Scourge.|/AQUATIC SPECIES/ A comparative aquatic hazard assessment of resmethrin was conducted to investigate the need for its restricted use classification by the US. EPA as an adult mosquito control agent. ... Laboratory studies with constant 48- to 96-hr exposures show it is acutely toxic to fish and invertebrates in the 0.22-15.0 ug/L range. Daphnia magna, pink shrimp (Penaeus duorarum) and rainbow trout (Oncorhynchus mykiss) are the most sensitive and mollusks are the least sensitive species. Chronic laboratory studies indicate that the maximum acceptable toxicant concentrations (MATCs) for resmethrin and D. magna, Pimephales promelas, O. mykiss, and Cyprinodon variegatus are 0.58, 0.52, 0.43, and 10.3 ug/L, respectively. The acute-to-chronic ratios (1.1-7.3) for all species studied indicate that chronic toxicity will not be an issue for resmethrin. Furthermore, the characteristics of acute exposures (48- to 96-hr) used in the laboratory will not occur under field conditions because of the short half-life of resmethrin in fresh- and salt-water.|/AQUATIC SPECIES/ The acute toxicity of ... resmethrin ... to four species of aquatic non-target invertebrate organisms, found in estuarine and freshwater ecosystems, was evaluated. Artemia franciscana and Brachionus plicatilis larvae, as estuarine organisms, and Brachionus calyciflorus and Thamnocephalus platyurus larvae, as freshwater organisms, were exposed for 24 hr to concentrations of /resmethrin and/ the freshwater organisms were more sensitive ... than estuarine organisms tested. A. franciscana larvae were more tolerant organisms than B. plicatilis larvae. The freshwater organisms tested have demonstrated to be a good alternative to the standard acute toxicity assays using Daphnia, although Brachionus plycatilis larvae were more sensitive ... than T. platyurus.|For more Ecotoxicity Excerpts (Complete) data for RESMETHRIN (9 total), please visit the HSDB record page.

Chronic respiratory disease: In persons with chronic respiratory disease, especially asthma, the inhalation of /pyrethroids/ might cause exacerbation of symptoms due to its sensitizing properities. Skin disease: /Pyrethroids/ can cause dermatitis which may be allergic in nature. Persons with pre-existing skin disorders may be more susceptible to the effects of this agent. ... /Pyrethroids/

Resmethrin's production may result in its release to the environment through various waste streams; its use as contact insecticide(1) will result in its direct release to the environment(SRC).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 3.1X10+5(SRC), determined from a measured log Kow of 5.43(2) and a regression derived equation(3), indicates that resmethrin is expected to be immobile in soil(SRC). Volatilization of resmethrin from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.3X10-7 atm-cu m/mole(SRC), calculated from its vapor pressure, 1.1X10-8 mm Hg(4), and water solubility, 0.0379 mg/L(2). Resmethrin is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(2). Hydrolysis in moist soil surfaces is expected to be an important fate process for resmethrin under alkaline conditions(SRC). The second order aqueous hydrolysis rate constant for resmethrin has been estimated to be 0.17 L/mole sec at 25 °C(SRC) using a structure estimation method(7), which corresponds to aqueous hydrolysis half-lives of 1.3 yrs, and 47 days at pH 7 and 8, respectively(SRC). Photolysis may also be an important fate process for this compound on soil surfaces(SRC). The photolysis half-life of resmethrin films on glass plates ranged from about 20 to 90 minutes when exposed to forenoon and midday sunlight conditions, respectively(8). Although biodegradation data for resmethrin were not available(SRC, 2009), the pyrethroid class of insecticides is readily degraded by microorganisms(5,6).|TERRESTRIAL FATE: Resmethin is expected to have a 30-day half-life in soil based on values of other pyrethroid compounds(1).|AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 3.1X10+5(SRC), determined from a log Kow of 5.43(2) and a regression-derived equation(3), indicates that resmethrin is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(4) based upon an estimated Henry's Law constant of 1.3X10-7 atm-cu m/mole(SRC), derived from its vapor pressure, 1.13X10-8 mm Hg(5), and water solubility of 0.0379 mg/L(2). According to a classification scheme(6), an estimated BCF of 98 days(SRC), from its log Kow(2) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is moderate(SRC). Hydrolysis is expected to be an important environmental fate process for resmethrin, particularly in alkaline waters(SRC). The second-order aqueous hydrolysis half-lives are 1.3 yrs and 47 days at pH 7 and 8, respectively(SRC), using a structure estimation method(8). Photolysis on surface waters is also expected to be an important fate process(SRC). The predicted near-surface half-life for the photosensitized oxidation of resmethrin in natural water has been reported as 0.2 hrs(9). Although biodegradation data for resmethrin were not available(SRC, 2009), the pyrethroid class of insecticides is readily degraded by environmental microorganisms(10,11).|ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), resmethrin, which has a vapor pressure of 1.13X10-8 mm Hg at 30 °C(2) is expected to exist solely in the particulate phase in the ambient atmosphere. Particulate-phase resmethrin may be removed from the air by wet or dry deposition. Resmethrin undergoes rapid photolysis in the environment with half-lives on the order of several minutes to a few hours(3-5).

The second-order aqueous hydrolysis rate constant for resmethrin has been estimated to be 0.17 L/mole-sec at 25 °C(SRC) using a structure estimation method(1), which corresponds to aqueous hydrolysis half-lives of 1.3 yrs and 47 days at pH 7 and 8, respectively(SRC).|Resmethrin is stable when exposed to heat and to oxidation(1). It decomposes rapidly on exposure to air and light, though more slowly than pyrethrins(1). When films on glass were exposed to outdoor sunlight, (+)trans-resmethrin decomposed very rapidly (within 24 hr)(2). The photodegradation half-life of resmethrin (adsorbed to silica gel) irradiated with a sunlamp was observed to be about 200 min(3); virtually no degradation occurred in dark control(3); a 15 min exposure of resmethrin (adsorbed to silica gel) to sunlight resulted in a 29% photodecomposition(3); 90 min sunlamp exposures on a glass plate and on filter paper resulted in respective disappearances of 32% and 64%(3); a 60 min sunlamp exposure of resmethrin in water resulted in 25% photodecomposition(3). Photodecomposition products of resmethrin include chrysanthemic acid, phenylacetic acid, benzyl alcohol, benzaldehyde, benzoic acid, and various chrysanthemates(3). The predicted nearsurface half-life for the photosensitized oxidation of resmethrin in natural water has been reported as 0.2 hr(4). The photolysis half-life of resmethrin films on glass plates ranged from about 20 to 90 minutes when exposed to forenoon and midday sunlight conditions(5). The fastest rates were observed during midday sunlight and in the presence of the sensitizer methylene blue. Resmethrin was also shown to undergo direct photolysis when resmethrin aerosols were irradiated with sunlight(5).|Photodecomposition of (+)-cis-resmethrin produced cis-chrysanthemic acid; benzaldehyde; phenylacetic acid; 5-benzyl-5-hydroxy-2-oxo-2,5-dihydro-3- furylmethyl cis-chrysanthemate and 4-benzyl-5-hydroxy-3-oxo-cyclopent-1,2- enylmethyl cis-chrysanthemate.|Irradiation of the (+)-trans-isomer produced 11 photoproducts. The major component was trans-chrysanthemic acid. Other compounds observed included benzaldehyde (VIII); 2-benzyloxy-5-oxo-2,5-dihydro-3-furylmethyl trans-chrysanthemate (IV); compound III, compound V, benzyl alcohol, benzoic acid, phenylacetic acid and two epoxyresmethrin isomers.

An estimated BCF of 98 was calculated for resmethrin(SRC), using a log Kow of 5.43(1) and a regression derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is moderate(SRC).

1.00e+05 L/kg|The Koc of resmethrin is estimated at 3.1X10+5(SRC), using a measured log Kow of 5.43(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that resmethrin is expected to be immobile in soil(SRC).

The Henry's Law constant for resmethrin is estimated as 1.3X10-7 atm-cu m/mole(SRC) based upon its vapor pressure, 1.13X10-8 mm Hg(1), and water solubility, 0.0379 mg/L(2). This Henry's Law constant indicates that resmethrin is expected to be essentially nonvolatile from water surfaces(3). Resmethrin is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(1).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 27,596 workers (3,998 of these were female) were potentially exposed to resmethrin in the US(1). The NOES Survey does not include farm workers. Occupational exposure to resmethrin may occur through inhalation and dermal contact with this compound at workplaces where resmethrin is produced or used(SRC). Resmethrin was detected in indoor air of 10 commercial pest control firms in North Carolina at concentrations of 0.31-5.22 ug/cu m(2). Use data indicate that the general population may be exposed to resmethrin via inhalation and dermal contact with products containing this compound(SRC). Resmethrin was identified, but not quantified, in households after application from spray cans, pet shampoos and handpumped broadcast sprayers(3).

Pyrethrins with piperonyl butoxide are used for topical treatment of pediculosis (lice infestations). Combinations of pyrethrins with piperonyl butoxide are not effective for treatment of scabies (mite infestations). Although there are no well-controlled comparative studies, many clinicians consider 1% lindane to be pediculicide of choice. However, some clinicians recommend use of pyrethrins with piperonyl butoxide, esp in infants, young children, & pregnant or lactating women ... . If used correctly, 1-3 treatments ... are usually 100% effective ... Oil based (eg, petroleum distillate) combinations ... produce the quickest results. ... For treatment of pediculosis, enough gel, shampoo, or solution ... should be applied to cover affected hair & adjacent areas ... After 10 min, hair is ... washed thoroughly ... treatment should be repeated after 7-10 days to kill any newly hatched lice. /Pyrethrins/

Pesticides designed to control insects that are harmful to man. The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics. (See all compounds classified as Insecticides.)

The cis- & trans- isomers of the synthetic pyrethroid resmethrin, labeled with radiocarbon in either the alcohol or acid moiety, were individually admin orally to White Leghorn laying hens at 10 mg/kg. With each isomer & label position, >90% of the radiocarbon was eliminated in the excreta within 24 hr after the treatment. Radiocarbon residues in the egg white & yolk fractions were low, with peak levels observed 1 & 4-5 days after treatment in white & yolk, respectively. In birds sacrificed 12 hr after treatment, radiocarbon residues in tissues were low; the highest levels were found in the liver & kidney.|Resmethrin (insecticide) labeled with radiocarbon in either the acid or alcohol moiety & admin orally to lactating Jersey cows at 10 mg/kg was rapidly absorbed, metabolized, & excreted. The cis-isomer was eliminated primarily in the feces, but the trans-isomer was eliminated primarily in the urine. Tissue residues at 48 hr post-treatment were low (<1 ppm) except in liver & kidney which were generally higher with the alcohol labeled compounds. ...|Six days after admin of (14)C-resmethrin to rats at a dose of 1 mg/kg, 53-73% was accounted for in urine & feces. Low residue levels were observed in tissues. In urine, there were almost equal parts of free & conjugated metabolites.|When (14)C-[1RS,trans]-resmethrin labeled in the alcohol moiety was administered orally to Sprague-Dawley rats at 500 mg/kg, the radiocarbon was rapidly absorbed from the GI tract and it took 3 wk for the complete elimination of the radioactivity in the urine (36% of the dose) and feces (64%). A negligible amount (<0.1%) of the radiocarbon was expired as (14)CO2. The radiocarbon was not completely excreted, even after 2 wk, in rats given an iv dose of 50 mg/kg; notably, appreciable amounts of (14)C were found in feces.|For more Absorption, Distribution and Excretion (Complete) data for RESMETHRIN (10 total), please visit the HSDB record page.

The trans-isomers as Resmethrin are metabolized mainly through hydrolysis of ester linkage with subsequent oxidation and/or conjugation of component alcohol and acid moieties. 1/3 of acid-derived metab of (+)-trans-resmethrin admin to rats were characterized and among them cis-hydroxymethyl chrysanthemumic acid and cis-chrysanthemum dicarboxylic acid were identified. (+)-cis-resmethrin yielded trans isomers of acids.|Resmethrin isomers were metabolized in microsome-NADPH systems to the extent of 95 to 98%. The extent to which trans- and cis-isomers were metabolized differed. In the presence of NADPH, ester cleavage was much greater with tetraethylpyrophosphate-treated microsomes. An oxidative ester cleavage seemed to be most important with (-)-cis-resmethrin. In the latter case, alcohol moieties released include unstable compounds and protein-bound metabolites. Seventeen precent of the initial radiocarbon appeared in 11 ester metabolites (not identified) of (+)-trans-resmethrin. These were recovered only with tetraethylpyrophosphate-treated microsomes fortified with NADPH. Oxidized chrysanthemic acid derivatives (VIII to XXII and XXVI) were comparatively stable. The metabolites IV and VII were major products only in the presence of NADPH and the supernatant fraction. Compounds II, III, V and VI were not isolated.|Some degradative products of the resmethrins are 5-benzyl-3-furoic acid, chrysanthemic acid, the intermediary alcohol and aldehyde oxidation products, and conjugates of each of these acids. The isobutenyl moiety is oxidized products, and conjugates of each of these acids. The isobutenyl moiety is oxidized at either the cis-or trans-methyl group in (+)-cis-resmethrin, but only at the trans-methyl group in (+)-trans-resmethrin. An unanticipated metabolic pathway involves epimerization at C-3 of the cyclopropane ring. Some metabolites of (+)-trans-resmethrin are more toxic than the parent compound.|When four resmethrin isomers ([1R,trans]-, [1S,trans]-, [1R,cis]-, and [1S,cis]-) were incubated with mouse and rat microsomes in 50 mmol/L tris-HCl buffer (pH 7.4) at 37 °C for 1 hr, microsomal esterases readily cleaved the trans- but not the cis-isomers. The ester linkage also appeared to undergo oxidative cleavage when esterase attack was minimal. Ester metabolites were detected in significant amounts only with [1R,cis]-resmethrin in which case oxidation had occurred at isobutenyl moiety, with or without oxidation at the benzylfuryl methyl group. Most of the in vitro metabolites were identical with those in the excreta of rats given resmethrin orally. The preferred site of oxidation in the isobutenyl moiety varies with the resmethrin isomer and microsomal source. Mouse microsomes predominantly oxidized the trans-methyl group of both [1R,trans]- and [1S,trans]- resmethrin, the selectivity, however, being the greatest with [1S,trans]-resmethrin. Rat microsomes were relatively nonselective in attacking the isobutenyl methyl groups of [1R,trans]-resmethrin.|For more Metabolism/Metabolites (Complete) data for RESMETHRIN (12 total), please visit the HSDB record page.

Pyrethroids are divided into 2 classes (types I and II) based on their effects on cercal sensory nerves and on symptomatology they produced in dosed cockroaches. Type I incl resmethrin.|The interactions of natural pyrethrins and 9 pyrethroids with the nicotinic acetylcholine (ACh) receptor/channel complex of Torpedo electronic organ membranes were studied. None reduced (3)H-ACh binding to the receptor sites, but all inhibited (3)H-labeled perhydrohistrionicotoxin ((3H)H12-HTX) binding to the channel sites in presence of carbamylcholine. Allethrin inhibited binding noncompetitively, but (3)H-labeled imipramine binding competitively, suggesting that allethrin binds to the receptor's channel sites that bind imipramine. The pyrethroids were divided into 2 types according to their action: type A, which included allethrin, was more potent in inhibiting (3)H-H12-HTX binding and acted more rapidly. Type B, which included permethrin, was less potent and their potency increased slowly with time. The high affinities that several pyrethroids have for this nicotinic ACh receptor suggest that pyrethroids may have for this nicotinic ACh receptor suggest that pyrethroids may have a synaptic site of action in addition to their well known effects on the axonal channels. /Pyrethroids/|/In rat brain in vitro/ resmethrin (at 30 uM) induced the release of transmitters was not affected by manipulation of the Na+ current with either choline or tetrodotoxin agents ... . Resmethrin (at 2.2 uM) inhibited the ATP-dependent uptake of Ca+ ... also it displaced Ca+ from crude synaptosomal membranes.|Phosphoinositide breakdown in guinea pig cerebral cortical synaptoneurosomes induced by the Type I pyrethroids allethrin, resmethrin, and permethrin and the Type II pyrethroid deltamethrin and fenvalerate were investigated with various receptor agonists as well as sodium channel blockers and agents. Phosphoinositide breakdown was determined from inositol-phosphate formation by tritiated inositol labeled synaptoneurosomes. All five pyrethroids dose dependently induced phosphoinositide breakdown. Type II pyrethroids exhibited higher potency and deltamethrin was more efficacious than the Type I pyrethroids. Five micromolar tetrodotoxin, a blocker of voltage dependent sodium channels, partially inhibited deltamethrin (85%) and fenvalerate (60%) responses but not allethrin or resmethrin. Fenvalerate induced stimulation of phosphoinositide breakdown was additive with stimulation elicited by the receptor agonists carbamylcholine (1 mM) and norepinephrine (1000 uM) but less than additive with the sodium channel agents batrachotoxin, pumiliotoxin-B, and scorpion venom. Allethrin (100 uM) was less than additive with receptor agonists or sodium channel agents and actually significantly inhibited response to scorpion venom. Effects for 100 uM allethrin with either fenvalerate or deltamethrin were not different from allethrin alone. Ten micromolar allethrin slightly decreased response to 10 to 100 uM deltamethrin. The local anesthetic dibucaine, a sodium channel activation inhibitor, completely blocked deltamethrin induced phosphoinositide breakdown but was much less effective in inhibiting allethrin response. It appears likely that Type-I pyrethroids induce phosphoinositide breakdown through a mechanism other than sodium channel activation while Type-II pyrethroids act in a manner analogous to other sodium channel agents.|For more Mechanism of Action (Complete) data for RESMETHRIN (15 total), please visit the HSDB record page.

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]: Inhalation of material may be harmful. Contact may cause burns to skin and eyes. Inhalation of Asbestos dust may have a damaging effect on the lungs. Fire may produce irritating, corrosive and/or toxic gases. Some liquids produce vapors that may cause dizziness or suffocation. Runoff from fire control may cause pollution. (ERG, 2016)|Teratogens

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]: Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. (ERG, 2016)

Fresh air, rest.

Remove contaminated clothes. Rinse and then wash skin with water and soap.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Emergency and supportive measures: Treat bronchospasm and anaphylaxis if they occur. Observe patients with a history of large ingestions for at least 4-6 hours for any signs of CNS depression or seizures. /Pyrethrins and pyrethroids/|Decontamination: Inhalation: Remove victims from exposure and give supplemental oxygen if needed. Skin: Wash with copious soap and water. Topical application of vitamin E in vegetable oil was reported anecdotally to relieve paresthesias. Eyes: Irrigate with copious water. After irrigation, perform a fluorescein examination and refer the victim to an ophthalmologist if there is evidence of corneal injury. Ingestion: In the majority of cases, a subtoxic dose has been ingested and no decontamination in necessary. ... . Gastric lavage is not necessary after small or moderate ingestions if activated charcoal can be given promptly. /Pyrethrins and pyrethroids/|Enhanced elimination: These compounds are metabolized rapidly by the body, and extracorporeal methods of elimination would not be expected to enhance their elimination. /Pyrethrins and pyrethroids/|Skin decontamination. Wash skin promptly with soap and water ... . If irritant or paresthetic effects occur, obtain treatment by a physician. Because volatilization of pyrethroids apparently accounts for paresthesia affecting the face, strenuous measures should be taken (ventilation, protective face mask and hood) to avoid vapor contact with the face and eyes. Vitamin E oil preparations (dL-alpha tocopheryl acetate) are uniquely effective in preventing and stopping the paresthetic reaction. They are safe for application to the skin under field conditions. Corn oil is somewhat effective, but possible side effects with continuing use make it less suitable. Vaseline is less effective than corn oil. Zinc oxide actually worsens the reaction. /Pyrethroids/|For more Antidote and Emergency Treatment (Complete) data for RESMETHRIN (9 total), please visit the HSDB record page.

/HUMAN EXPOSURE STUDIES/ A dermal absorption estimate of 2.0% was selected based in part on a recent dermal absorption study of pyrethrins in humans that indicated 0.22% dermal absorption. In the /previous/ study with pyrethrins, the exposure period was 8 hours in four male volunteers. Subjects were monitored for 120 hours. Dermal penetration of 0.22% was calculated as the sum of urinary and fecal excretion. This study was further corroborated by other human dermal estimates with cypermethrin (0.3-1.8%) from which to estimate dermal penetration /Pyrethrins/.|/SIGNS AND SYMPTOMS/ Synthetic pyrethroids are neither cutaneous sensitizers nor irritants. Although these compounds do not cause signs of inflammation (edema, erythema, vesiculation), they do produce paresthesias after contact. Typically, symptoms begin several hours after cutaneous exposure, peak in the evening, and resolve by the following day. /Synthetic pyrethroids/|/SIGNS AND SYMPTOMS/ The allergenic properties of pyrethroids /with early pyrethrum preparations/ are marked in comparison with other pesticides. Many cases of contact dermatitis and respiratory allergy have been reported. Persons sensitive to ragweed pollen are particularly prone to such reactions. Preparations containing synthetic pyrethroids are less likely to cause allergic reactions than are the preparations made from pyrethrum powder. /Pyrethroids/|/SIGNS AND SYMPTOMS/ Some pyrethroid (eg, deltamethrin, fenvalerate, cyhalothrin, lambda-cyhalothrin, flucythrinate, and cypermethrin) may cause a transient itching and/or burning sensation in exposed human skin. /Synthetic pyrethroids/|/SIGNS AND SYMPTOMS/ The clinical manifestations of inhalation exposure to pyrethrins can be local or systemic. Localized reactors confined to the upper respiratory tract include rhinitis, sneezing, scratchy throat, oral mucosal edema, and even laryngeal mucosal edema. Localized reaction of the lower respiratory tract include cough, shortness of breath, wheezing, and chest pain. An asthma-like reaction occurs with acute exposures in sensitized patients. Hypersensitivity pneumonitis characterized by chest pain, cough, dyspnea, & bronchospasm may occur in an individual chronically exposed. /Pyrethrum and synthetic pyrethroids/

(5-benzyl-3-furyl)methyl 2,2-dimethyl-3-(2-methylpropenyl)cyclopropemecarboxylate

The substance can be absorbed into the body by inhalation of its aerosol and by ingestion.

Redness.

Redness.

Resmethrin is an ester of chrysanthemic acid and 5-benzyl-3-furylmethyl alcohol. It is a racemic mixture of 4 optical isomers: [1R,trans]-, [1R,cis]-, [1S,trans]-, and [1S,cis]-isomer. In technical products the ratio of these isomers is roughly 4:1:4:1. The [1R,trans]-isomer is called bioresmethrin and the [1R,cis]- isomer, cismethrin. Among the isomers, the [1R,trans]-isomer has the highest insecticidal activity, followed by the [1R,cis]-isomer. ...It is formulated as an aerosol, an oil formulation, or an emulsifiable concentrate, sometimes in combination with other insecticides and/or synergists.|Resmethrin is formulated as ready-to-use pressurized liquid spray, emulsifiable concentrate, and soluble concentrate.|Resmethrin /formulations/ contain 70%(+/-)trans-isomer and 30%(+/-)cis-isomer.|FOR-SYN|For more Formulations/Preparations (Complete) data for RESMETHRIN (244 total), please visit the HSDB record page.

The WHO Recommended Classification of Pesticides by Hazard identifies Resmethrin (technical grade) as Class III: slightly hazardous; Main Use: Insecticide.|For USDA meat and poultry inspection programs.|NIA 17370 discontinued by FMC Corporation|Compatible with other neutral insecticides and fungicides.|/Pyrethroids/ are modern synthetic insecticides similar chemically to natural pyrethrins, but modified to increase stability in the natural environment. /Pyrethroids/

Method: EPA 616; Procedure: gas chromatography; Analyte: resmethrin; Matrix: municipal and industrial wastewater; Detection Limit: 36 ug/L.|Method: EPA 1660; Procedure: high performance liquid chromatography with ultraviolet detection; Analyte: resmethrin; Matrix: municipal and industrial wastewater; Detection Limit: 2 ug/L.|Method: OSHA 2052; Procedure: high performance liquid chromatography using an ultraviolet detector; Analyte: resmethrin; Matrix: air; Detection Limit: 0.017 mg/cu m.|Product and residue analysis are by gas liquid chromatography with flame ionization detection with internal std such as dicyclohexyl phthalate or di-octyl phthalate. Cis- and trans-isomer. ... separated and est by high pressure liq chromatography or by gas liquid chromatography. Residues may be determined by gas liquid chromatography.|For more Analytic Laboratory Methods (Complete) data for RESMETHRIN (8 total), please visit the HSDB record page.

Residues of resmethrin are extracted from most food products with acetonitrile and from milk with acetonitrile-acetone (95+5). The extracts are cleaned up by partitioning with petroleum ether, followed by Florisil column chromatography and then alumina column chromatography. The initial extraction step is omitted for sugar samples, which are dissolved in distilled water. Resmethrin is determined by gas chromatography with a column of 3% OV-1 on Gas-Chrom Q and flame ionization detection. An alternative column of 3% OV-210 can be used if interfering peaks appear in the initial chromatogram. In a method tryout, EPA obtained resmethrin recoveries that ranged from 87 to 123% for milk samples fortified at the 0.1 and 1.0 ppm levels; recoveries ranged from 78 to 106% for bread samples fortified at the same levels. Product application: fruits, meat, milk, vegetables. Detection limt: 0.1 ppm.

Agrochemicals -> Insecticides|Health Hazards -> Teratogens|Pharmaceuticals|INSECTICIDES