WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
DATA SHEETS ON PESTICIDES No. 34
It must be noted that the issue of a Data Sheet for a
particular pesticide does not imply endorsement of the pesticide by
WHO or FAO for any particular use, or exclude its use for other
purposes not stated. While the information provided is believed to
be accurate according to data available at the time when the sheet
was compiled, neither WHO nor FAO are responsible for any errors or
omissions, or any consequences therefrom.
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not constitute formal publication. Il ne doit faire
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without the agreement of the l'autorisation de l'Organisation
Food and Agriculture des Nations Unies pour
Organization of the United l'Alimentation et l'Agriculture
Nations or of the World Health ou de l'Organisation Mondiale de
Organization. la Santé.
Primary Use: Insecticide
Chemical Group: Chrysanthemic acid ester
Date Issued: June 1978
1. GENERAL INFORMATION
1.1 COMMON NAME:
The (+)-trans-isomer (bioresmethrin) occurs in resmethrin (NRDC 104)
and makes up 35-40% of that insecticide.
Bio NRDC 104
A highly effective broad spectrum insecticide with a good knockdown
performance and low mammalian toxicity. It is rapidly detoxified in
mammals and on exposure to sunlight. Bioresmethrin is more toxic to
houseflies and less toxic to rats than the mixture of isomers known
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics
Liquid boiling point 180°C at 0.01 mmHg.
Insoluble in water; soluble in most organic solvents.
Somewhat more stable to light than natural pyrethrins, hydrolyses
readily under alkaline conditions. Less than 5% decomposition of 30%
formulation in 6 months at 40°C.
1.3.4 Vapour pressure
(volatility) - No information.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations
Aerosols containing bioresmethrin 0.1% with related compounds, e.g.
bioallethrin. Ready for use oil formulations 0.25% w/v with or
without a synergist.
1.4.2 Pests mainly controlled
A contact insecticide of high activity, effective against flies,
wasps, cockroaches, ants, grain weevils, moths, etc.
1.4.3 Use pattern
For control of flying insects and as a residual spray in granaries,
bakeries, kitchens, animal houses and for aircraft disinsection.
1.4.4 Unintended effects
Not phytotoxic when used as recommended. Not persistent. Safe to use
in the presence of foodstuffs. Toxic to fish at low concentrations;
very toxic to bees.
1.5 PUBLIC HEALTH PROGRAMMES
Large-scale urban fogging trials for fly control have given good
results at dosages as low as 10 g per hectare. ULV applications from
helicopters have also been successful at 3 g per hectare.
1.6 HOUSEHOLD USE
As a hand-held aerosol spray for use against houseflies. Liquid and
aerosol formulations for use by home gardeners.
2. TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route
Readily absorbed from intestinal tract. Dermal absorption of little
2.1.2 Mode of action
Nervous system stimulation proceeding from excitation to convulsions
to tetanic paralysis and muscular fibrillation.
Bioresmethrin undergoes rapid hydrolysis in orally treated rats
yielding 5-benzyl-3-furyl methanol and chrysanthemic acid followed
by oxidization of the alcohol moiety to yield benzylfuroic acid and
several oxidized derivatives of this acid which are excreted in free
or conjugated form. Excretion is through kidneys, the liver via the
bile and the lachrymal glands via the nasal passages.
2.1.4 Toxicity, single dose
Oral: LD50 Rat (M) 7071 mg/kg
(F) 8000 mg/kg
Dermal: LD50 (F) > 10 000 mg/kg
(The acute oral toxicity of the (+) cis isomer is more than 48
times higher than that of (+) trans isomer - bioresmethrin.)
2.1.5 Toxicity, repeated doses
Oral: Two groups of rats were dosed at 1000 mg/kg/bw/day and
2000 mg/kg/bw/day respectively six days per week for three weeks. A
slight aging of the thymus was observed in most rats at the higher
Groups of beagle dogs (both sexes) were dosed at 500 mg/kg/bw/day
for seven days followed by 1000 mg/kg/bw/day for a further 14 days
followed by dosing at 2000 mg/kg for a further seven days. No signs
of clinical toxicity were observed during the three-week trial
Dermal: No information.
Cumulation of compound: Following single high oral doses to rats
bioresmethrin is rapidly absorbed from the intestinal tract and
widely distributed through the body three hours after dosing. The
metabolites arising from the alcohol moiety, however, are
concentrated in fatty tissue and are only slowly excreted over three
weeks. There is no information on cumulation of these metabolites
following repeated high doses.
Cumulation of effect: No cumulative toxic effects observed.
2.1.6 Dietary studies
Short-term: Male and female rats were fed bioresmethrin at levels
of 300, 1000 and 3000 mg/kg diet for 90 days. Body weights not
affected. The only statistically significant effects were slight
changes in liver weight (females in 300 and 1000 mg/kg groups) and
kidney weight (males in 300 and 3000 mg/kg groups).
In another experiment bioresmethrin was given in the diet to groups
of rats for 91 days at concentrations of 400, 1200 and 4000/
8000 mg/kg diet (concentrations 4000 mg/kg for 30 days, 8000 mg/kg
for 61 days). There was a significant depression of body weight at
the top level only; clinical symptoms were slight transient nasal
discharge and diarrhoea, a slight but significant depression of red
blood cell counts, and an increase in liver weight. The no-effect
level was 1200 mg/kg diet.
Groups of beagle dogs (both sexes) were fed at levels up to
500 mg/kg diet for 90 days. There were no adverse effects or
2.1.7 Supplementary studies of toxicity
Carcinogenicity: No information.
Teratogenicity: Rabbits were dosed orally at 10, 20, 40 and
80 mg/kg/bw on days 8 to 16 inclusive of pregnancy. The study was
terminated on day 28. Dead foetuses occurred in the highest dose
Neurotoxicity: No information.
Irritation and skin sensitization: Tests on guinea-pigs showed
that both bioresmethrin in mineral oil and mineral oil alone
produced a low degree of primary irritation but no significant
sensitizing effect. The pure active ingredient was not irritant to a
2.1.8 Modification of toxicity
2.2 TOXICOLOGY - MAN
The oral route is the only route of any significance in human
2.2.2 Dangerous doses
Single: No information
Repeated: No information
2.2.3 Observations on occupationally exposed workers
2.2.4 Observations on exposure of the general population
No information available but general population should not be
affected by the normal use of bioresmethrin.
2.2.5 Observations of volunteers
2.2.6 Reported mishaps
2.3 TOXICITY TO NON-MAMMALIAN SPECIES
Toxic to fish. Guppy LC50 between 0.5 and 1.0 ppm at 48 hours
after dosing. Harlequin fish 24, 48 and 96-hour median lethal
concentrations were 0.028 ppm, 0.018 ppm and 0.014 ppm respectively.
Very low toxicity to domestic birds. Hens and cockerel chicks LD50
(oral) > 10 000 mg/kg.
Canaries and budgerigars were exposed to high atmospheric
concentrations of aerosol formulations, some dermal irritancy but no
other toxic effects.
2.3.3 Other species
Very toxic to bees. Oral LD50 0.003/µg/insect. Topical application
3. FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY
(for definition of categories see introduction)
All current formulations category 5.
3.2 TRANSPORTATION AND STORAGE
Should be transported and stored in clearly labelled leakproof
containers out of reach of children, away from food and drink.
Avoid contact with metals other than aluminum or tin.
All formulations - No facilities other than those needed for the
handling of any chemical need be required.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS
All formulations - Containers may be decontaminated (for method
see paragraph 4.3 of Part 4). Decontaminated containers should not
be used for food and drink. Containers that are not decontaminated
should be burned or should be crushed and buried below topsoil. Care
must be taken to avoid subsequent contamination of water sources.
3.5 SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS
Warning of workers to avoid contact desirable. Pre-employment and
periodic medical examination not required.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
No special regulations recommended.
Minimum cautionary statement: None
3.8 RESIDUES IN FOOD
The Joint FAO/WHO Meeting on Pesticide Residues has considered
bioresmethrin and has recommended residue limits in raw and
4. PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
Bioresmethrin is of low mammalian toxicity, rapidly absorbed from
the intestinal tract and metabolized.
4.1.2 Manufacture and formulation
T.L.V.: not available. Has not caused any problems. No record of
dermatitis or allergies.
4.1.3 Mixers and applicators
When opening the container and when mixing care should be taken to
avoid contact with the mouth and eyes. Mixing, if not mechanical,
should always be carried out with a paddle of appropriate length.
Splashes must be washed from the skin and eyes with large quantities
of water. Before eating, drinking or smoking, hands and other
exposed skin should be washed.
4.1.4 Other associated workers (including flagmen in aerial
Persons exposed to bioresmethrin and associated with its application
should observe the precautions described in 4.1.3 under "mixers and
4.1.5 Other populations likely to be affected
4.2 ENTRY OF PERSONS INTO TREATED AREAS
Persons can enter treated areas immediately after spraying without
being exposed to hazardous amounts of bioresmethrin. Residues
disappear rapidly from foliage and the surface of ponds.
4.3 SAFE DISPOSAL OF CONTAINERS AND SPILLAGES
Residues in containers should be emptied in a diluted form into a
deep pit taking care to avoid ground waters. The empty container may
be decontaminated by rinsing two or three times with water and
detergent and scrubbing the sides. Hands should be protected during
this work. Decontaminated containers should not be used for food and
Spillage should be removed as much as possible by washing the area
with large quantities of water.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning
Early symptoms may include sneezing, nasal discharge and nasal
4.4.2 Treatment before person is seen by a physician if these
symptoms appear following exposure
If toxicity is suspected following exposure to bioresmethrin the
person should stop work, remove contaminated clothing and wash the
affected skin with soap and water, if available, and flush the area
with large quantities of water. In mild cases of ingestion, no
active measures. If oil-based materials are swallowed, give a glass
of milk; do not give an emetic.
5. FOR MEDICAL AND LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT OF CASES OF POISONING
5.1.1 General information
Bioresmethrin is rapidly absorbed from the gastrointestinal tract
and distributed into the tissues. It is also absorbed by the
respiratory route, but not to a significant degree through the skin.
It is rapidly excreted as oxidation and hydrolysis products in
faeces and in the urine.
5.1.2 Symptoms and signs
Some individuals may have nasal symptoms including sneezing, nasal
congestion and discharge. Little information is available on the
acute toxic effect of bioresmethrin but based upon animal studies,
high doses may produce over-stimulation of the central nervous
There are no practical laboratory methods for determining
bioresmethrin in body fluids.
If a large quantity of bioresmethrin has been ingested, unless the
patient is vomiting, gastric lavage should be performed using 5%
sodium bicarbonate solution if available. If there are convulsions
or muscular fibrillation, diazepam should be used.
Chance of complete recovery from any toxic effect of bioresmethrin
5.2 SURVEILLANCE TESTS
There are no practical surveillance tests.
5.3 LABORATORY METHODS
References only are given.
5.3.1 Detection and assay of compound
The analytical methods for resmethrin (the mixed isomers) have been
reviewed by Brown (1973), Murano et al. (1971), Murano (1972) and
Desmarchelier (1975). The methods include ultra-violet absorption
spectrophotometry, colorimetry, thin layer and gas-liquid
chromatography. The methods apply equally to bioresmethrin. A
refinement of high sensitivity is described by Miyamoto et al.
(1974) where the chrysanthemic acid is quantitatively condensed with
2,4-dichlorbenzyl chloride to give a derivative which can be
determined by electron capture.