Permethrin is a synthetic insecticide of the pyrethroid and organochlorine families.
This pesticide is commonly used as a biocide in many of our everyday products and can cause lasting contamination of the indoor environment in apartments, houses and offices.
This pollution results in continuous exposure of occupants and, like many chemicals, chronic exposure to permethrin poses a health risk.
What are the regulations regarding permethrin?
In the European Union and the United Kingdom, permethrin (CAS 52645-53-1) cannot be used by agricultural professionals for the treatment of cereals, orchards and vineyards. However, European regulations allow its use as a biocide for domestic (e.g. wood treatment) and veterinary applications.
Permethrin is permitted in almost all other countries in the world for agricultural and domestic applications.
What consumer products contain permethrin?
The most obvious use of permethrin is the use of insecticides in your home, apartment or office to control insects (mosquitoes, cockroaches, ants, wasps, hornets, fleas, bed bugs...).
Commercially available in the form of insecticide spray, smoke, sticker and electric diffuser, these insecticides contain varying amounts of permethrin and the mode of dispersal is the main factor in the pollution of the indoor environment.
The sprays, smoke and diffusers disperse the insecticide in the ambient air. Permethrin residues will spread throughout the house and impregnate clothing, food, floors, furniture, fabrics, cushions and bedding.
In countries affected by parasitic or viral diseases such as malaria, dengue fever and chikungunya, the use of insecticides such as permethrin is common in the control of mosquitoes that transmit these diseases.
The treatment of domestic animals is also a source of intentional indoor air pollution with permethrin. The product is applied to dog hair and persists for a long period of time. The presence of the treated animal indoors can contaminate the indoor environment and caresses deposit the insecticide on the hands. Due to its high toxicity to cats, the application of permethrin to a cat can be fatal.
There are many other sources of indoor air pollution by permethrin because many consumer products contain it without it being clearly indicated, including treatments for protection against wood-boring insects, bedding and dust mite control products, and clothing.
How much permethrin is found in homes and offices?
Permithrin is a semi-volatile organic compound (COSV) that is present on dust particles. Pollution of the indoor environment of dwellings with this insecticide is assessed by analyzing dust samples collected using a pump or a household vacuum cleaner.
Recent scientific studies reveal significant pollution of the indoor environment by permethrin
In a study conducted in California in 2006, all selected dwellings contained permethrin residues in varying amounts: between 45.9 and 9690 ng/g for dwellings in agricultural areas and between 11.6 and 46800 ng/g in urban areas.
These observations were also confirmed in two studies conducted in France: all the dwellings studied were contaminated with this insecticide with concentrations measured up to 19141 ng/g.
High concentrations of permethrin measured in homes make this insecticide one of the most worrisome pesticides in indoor air.
Measurements after six months show persistence of permethrin in the indoor environment with a variation in the measured amount between -19% and +251%.
Why is permethrin persistent in the indoor environment?
It is the light and microorganisms contained in the soil that allow the degradation of this chemical. Outdoors, therefore, the half-life of permethrin in the soil is 40 days, i.e. after this period, half of the initial amount of the chemical remains. In theory, after 10 half-life periods, i.e. 400 days (more than one year), 1% of the initial amount of permethrin would be expected to remain in the soil.
In an indoor environment, only light allows its degradation (photo-degradation) and consequently, the half-life is extended. In addition, the sources of pollution inside homes and offices continuously release permethrin into the indoor air. Permithrin is very stable and, as confirmed by the results of the measurement campaigns, pollution levels do not decrease over time.
Permethrin is very persistent and produces sustainable pollution of the air and indoor environment
Pesticide monitoring in the indoor and outdoor environment of housing is very recent and the persistence of insecticides in the indoor environment has been poorly studied.
What are the health risks of exposure to permethrin?
Permethrin is a chemical that affects the functioning of the insect nervous system. According to the University of Hertfordshire, permethrin is carcinogenic, neurotoxic, endocrine disrupting and affects reproduction and development.
Permethrin is an endocrine disruptor toxic to humans at low doses of exposure.
Permethrin is often used with piperonyl butoxide (PBO, CAS 51-03-6) which acts as a synergizer. This chemical is a typical example of the cocktail effect because it multiplies the toxicity of permethrin by 100 to 1000.
The commercial formulations of permethrin contain a synergist that multiplies the toxicity of the insecticide by 100 to 1000.
It is therefore essential to limit as much as possible one's exposure to permethrin and in particular that of children.
The analysis of dust collected in your apartment, house or office makes it possible to assess indoor air pollution by permethrin and to act to limit your exposure to this insecticide toxic to humans.
How to eliminate and limit indoor air pollution by permethrin?
The use of air purifiers or air treatment equipment can remove permethrin residues. To be effective, the air purification equipment must be equipped with at least a HEPA filter and, if possible, an activated carbon filter. Because of the presence of chlorine atoms in permethrin, photocatalyst treatments can produce phosgene (CAS 75-44-5), a potent war toxicant that causes severe respiratory tract irritation.
A dust analysis makes it possible to control the effectiveness of the means implemented to eliminate permethrin from the air and indoor environment of an apartment, house or office.
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