Piperonyl butoxide

Last updated
Piperonyl butoxide
Piperonyl butoxide-2D-by-AHRLS-2012.png
Piperonyl butoxide 3D BS.png
Names
Preferred IUPAC name
5-{[2-(2-Butoxyethoxy)ethoxy]methyl}-6-propyl-2H-1,3-benzodioxole
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.000.070 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 200-076-7
KEGG
PubChem CID
UNII
  • InChI=1S/C19H30O5/c1-3-5-7-20-8-9-21-10-11-22-14-17-13-19-18(23-15-24-19)12-16(17)6-4-2/h12-13H,3-11,14-15H2,1-2H3 X mark.svgN
    Key: FIPWRIJSWJWJAI-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C19H30O5/c1-3-5-7-20-8-9-21-10-11-22-14-17-13-19-18(23-15-24-19)12-16(17)6-4-2/h12-13H,3-11,14-15H2,1-2H3
    Key: FIPWRIJSWJWJAI-UHFFFAOYAD
  • CCCCOCCOCCOCC1=CC2=C(C=C1CCC)OCO2
Properties
C19H30O5
Molar mass 338.438 g/mol
Density 1.05 g/cm3
Melting point 21 °C (70 °F; 294 K)
Boiling point 180 °C (356 °F; 453 K) at 1 mmHg
Hazards
Flash point 170 °C (338 °F; 443 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Piperonyl butoxide (PBO) is a pale yellow to light brown liquid [1] organic compound used as an adjuvant component of pesticide formulations for synergy. That is, despite having no pesticidal activity of its own, it enhances the potency of certain pesticides such as carbamates, pyrethrins, pyrethroids, and rotenone. [2] It is a semisynthetic derivative of safrole and is produced from the condensation of the sodium salt of 2-(2-butoxyethoxy) ethanol and the chloromethyl derivative of hydrogenated safrole (dihydrosafrole); [3] [4] or through 1,2-Methylenedioxybenzene.

Contents

History

PBO was developed in the late 1930s and early 1940s to enhance the performance of the naturally derived insecticide pyrethrum. Pyrethrum is a type of potent insecticide that kills mosquitoes and other disease-carrying vectors, thereby providing public health benefits, such as preventing malaria. Although exhibiting little intrinsic insecticidal activity of its own, PBO increases the effectiveness of pyrethrins, thus it is called a synergist. PBO was first patented in 1947 in the US by Herman Wachs. [5]

There are 3 known manufacturer of PBO in the world, Endura, [6] Tagros and Catasynth (Anthea) who manufacture PBO through the MDB route.

Uses

PBO was first registered in the United States in the 1950s. PBO is mainly used in combination with insecticides, such as natural pyrethrins or synthetic pyrethroids, in ratios (PBO: pyrethrins) ranging from 3:1 to 20:1. Appearing in over 1,500 United States EPA-registered products, PBO is one of the most commonly registered synergists as measured by the number of formulas in which it is present. It is approved for pre- and postharvest application to a wide variety of crops and commodities, including grain, fruits and vegetables. The application rates are low; the highest single rate is 0.5 lbs PBO/acre.

It is used extensively as an ingredient with insecticides to control insect pests in and around the home, in food-handling establishments such as restaurants, and for human and veterinary applications against ectoparasites (head lice, ticks, fleas). [7] [8] A wide variety of water-based PBO-containing products such as crack and crevice sprays, total release foggers, and flying insect sprays are produced for and sold to consumers for home use. PBO has an important public health role as a synergist used in pyrethrins and pyrethroid formulations used for mosquito control (e.g. space sprays, surface sprays and bed nets). [9] Because of its limited, if any, insecticidal properties, PBO is never used alone. [10]

Mechanism of action

PBO acts as an insecticide synergist by inhibiting the natural defense mechanisms of the insect, the most important of which is the mixed-function oxidase system, (MFOs) also known as the cytochrome P-450 system. The MFO system is the primary route of detoxification in insects, and causes the oxidative breakdown of insecticides such as pyrethrins and the synthetic pyrethroids [11] – thus when PBO is added, higher insecticide levels remain in the insect to exercise their lethal effect. [12] An important consequence of this property is that, by enhancing the activity of a given insecticide, less may be used to achieve the same result. [5]

PBO does not appear to have a significant effect on the MFO system in humans. [13] PBO is found to be an efficacious, low-potency, neutral antagonist of G-protein-coupled CB1 receptors. [14]

Other synergists for pyrethroid insecticides include Sesamex and "Sulfoxide" (not to be confused with the functional group). [3]

Regulatory

PBO is regulated in the United States and some other countries as a pesticide, even though PBO does not have this property. The United States Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the law that gives United States EPA its authority to regulate pesticides, includes certain synergists in its definition of a “pesticide” and is thus subject to the same approval and registration as products that kill pests, like the insecticides with which PBO is formulated. [15] Pesticide registration is the process through which United States EPA examines the ingredients of a pesticide, where and how the pesticide is used (e.g., whole room fogger, crack-and-crevice, etc.), and the specific use pattern (amount and frequency of its use). United States EPA also evaluates the pesticide to ensure that it will not have unreasonable adverse effects on humans, the environment and non-target species. The United States EPA must register pesticides before they may be sold or distributed in the United States. Registration is required for the pesticide itself, as well as for all products containing it. The World Health Organization recognizes the public health value of PBO when used in conjunction with the synthetic pyrethroids deltamethrin or permethrin used in mosquito nets.

Hazard assessment

Numerous toxicology studies have been conducted over the past 40 years on PBO examining the full range of potential toxic effects. [16] These studies were conducted in accord with regulatory requirements put forth by the United States EPA or other international agencies. Many were conducted following United States EPA Good Laboratory Practices (GLPs), a system of processes and controls to ensure the consistency, integrity, quality, and reproducibility of laboratory studies conducted in support of pesticides registration. The following types of studies have been conducted in support of PBO registration:

Acute toxicity studies

Acute toxicity studies are designed to identify potential hazards from acute exposures. The studies usually employ a single or a few high doses over a short time period. The data are used for the development of appropriate precautionary statements for pesticide product labels. Acute studies identify:

PBO has a low acute toxicity by oral, inhalation, and dermal routes in adults. It is minimally irritating to the eyes and skin. It is a not a skin sensitizer.

Dermal absorption

The available data indicate that less than 3% of the amount on the skin (forearm) is absorbed over an 8-hour period. [18] Other studies with a pediculicide formulation indicate that about 2% crossed the skin and about 8% crossed the scalp. [19]

Endocrine disruption

The Food Quality Protection Act (FQPA) of 1996 required the United States EPA to address the issue of endocrine disruption. Since the passage of the FQPA, the US EPA has developed a two-tiered endocrine disruptor screening program (EDSP) designed to examine potential effects of substances on the estrogenic, androgenic, and thyroid (EAT) hormone systems in both humans and wildlife. Tier 1 consists of 11 assays, and is designed to determine whether a substance has the potential to interact with the EAT hormone systems. If results indicate a relationship, the chemical progresses to Tier 2 testing. The purpose of Tier 2 is to determine whether a substance that interacts with the EAT hormone system exerts an adverse effect in humans or wildlife, and to develop a dose-response that, in association with exposure data, can be used to assess risk. PBO is one of the chemicals selected by EPA to be part of the initial effort under the EDSP. The EPA issued its first list of chemicals for EDSP testing in 2009, consisting of over 60 pesticide chemicals, including the insecticide synergist PBO. The first list of chemicals for EDSP screening is not based on a potential for endocrine activity or a potential for adverse effects. Rather, the list is based on an EPA prioritization regarding exposure potential. PBO was added to this list because of its wide use pattern (1500 products registered with US EPA), and people may be exposed to low levels of PBO in their diets, from treated surfaces in their homes (e.g., carpet), and in certain occupations (e.g., pest control operators).

No evidence suggests that PBO disrupts the normal functioning of the endocrine system. This includes the recently developed data to assess the possible interaction of PBO with the endocrine system. The Piperonyl Butoxide Task Force II, a group of companies that produces or markets PBO-containing products, has conducted all 11 EDSP Tier 1 screens and has submitted all required documentation and study reports.

The US EPA intends to use a weight of evidence (WoE) approach for assessing EDSP Tier 1 results. While the agency issued WOE guidelines, no actual WOE assessments have yet been conducted and released to the registrants. The PBTFII has conducted a WoE analysis for PBO that is consistent with EPA’s guidelines. The WoE analysis for PBO examines each EDSP Tier 1 assay conducted for PBO. It discusses the purpose of the assay, and summarizes the study design and results and provides an overall conclusion for each assay. All 11 individual assays are then considered together to arrive at an overall conclusion for the outcome of the Tier 1 battery. For some assays, other scientifically relevant information is also considered as part of the assessment. The purpose of the WoE analysis is to determine whether PBO has the potential to interact with the endocrine system, as determined by EDSP Tier 1 assays, the Tier 1 battery as a whole and OSRI. A determination that a chemical has the potential to interact with the endocrine system would trigger a need for EDSP Tier 2 testing. The EPA is planning to issue their WOE assessment in late 2014 or early 2015.

Subchronic and chronic/carcinogenicity studies

Subchronic and chronic studies examine the toxicity of longer-term, repeated exposure to chemicals. They may range from 90 days for subchronic studies, to 12–24 months for full lifetime chronic studies, designed to determine potential for carcinogenesis. They are also intended to identify any noncancer effects, as well as a clear no observable adverse effect level (NOAEL) that is used for risk assessment. Studies conducted on PBO include:

NOAELs were derived for PBO from both subchronic and chronic studies. These NOAELs are used by the EPA to conduct risk assessments for all individual uses of PBO to ensure that all registered products with PBO pose a reasonable certainty of no harm used according to the label directions.

PBO caused an increase in liver tumors in mice that ingested high levels of PBO in the diet for their entire lifetimes. The scientific identification and analysis of the key events leading to the formation of the mouse liver tumors suggest that the events are not likely to occur in humans.

The EPA classifies PBO as a group C carcinogen – "possibly carcinogenic to humans." Under the auspices of the United Nations, the Food and Agriculture Organization/World Health Organization (FAO/WHO) Joint Meeting on Pesticide Residues evaluated the entire body of toxicology of PBO several times since 1965. They concluded that, at doses up to internationally accepted standards for a maximum tolerated dose, PBO is not considered to be carcinogenic in the mouse or rat, thus leading to the conclusion that PBO is not carcinogenic to humans. [20]

Developmental toxicity studies

PBO has been found to inhibit the Hedgehog signaling pathway, a critical regulator of brain and face development in all vertebrates, via antagonism of the protein Smoothened (SMO). [21] PBO was found to be capable of causing dose-dependent brain and face malformations in mice exposed during early development, including the rare human birth defect holoprosencephaly. [22] Even doses of PBO that did not cause overt holoprosencephaly associated facial abnormalities were found to cause subtle neuroanatomical defects, [22] for which the cognitive or behavioral consequences are unknown.

An epidemiology study found that PBO exposure was correlated with dose-dependent reductions in neurocognitive development in 3-year old children. [23]

Animal impacts

PBO is moderately to highly toxic to aquatic invertebrates, such as water fleas and shrimp. At lower, long-term doses, water flea reproduction was affected. PBO is highly toxic to amphibians in the tadpole stage. [24]

Exposure assessment

Given the extensive non-dietary use of PBO, manufacturers of PBO and marketers of PBO-containing products formed the Non-Dietary Exposure Task Force (NDETF) in 1996 to develop a long-term research program to more fully understand the phenomenon of human exposure to insecticides used in the home. Most of the studies were conducted with formulations of pyrethrins/PBO and synthetic pyrethroids/PBO, and focused on the indoor use of fogger and aerosol products. Carpet and vinyl flooring surfaces were selected because of their different physical and chemical properties, and because they represent a significant percentage of the floor coverings used in homes in North America. While the focus of the NDETF effort was on total-release foggers, a study was also conducted to determine both dispersion (air levels) and deposition (on flooring) of pyrethrins/PBO resulting from the use of a hand held aerosol spray can. Potential direct exposure of the user was also measured. Air sampling from the breathing zone of the applicator and analysis of residues on cotton gloves was performed. This data was submitted to the United States EPA and was key to the agency’s comprehensive risk assessment for PBO.

Risk assessment

The US EPA, in their re-registration eligibility decision, determined "no risks of concern" existed for householders mixing, loading, handling, or applying PBO-containing products. [16]

Related Research Articles

<span class="mw-page-title-main">Cypermethrin</span> Chemical compound

Cypermethrin (CP) is a synthetic pyrethroid used as an insecticide in large-scale commercial agricultural applications as well as in consumer products for domestic purposes. It behaves as a fast-acting neurotoxin in insects. It is easily degraded on soil and plants but can be effective for weeks when applied to indoor inert surfaces. It is a non-systemic and non-volatile insecticide that acts by contact and ingestion, used in agriculture and in pest control products. Exposure to sunlight, water and oxygen will accelerate its decomposition. Cypermethrin is highly toxic to fish, bees and aquatic insects, according to the National Pesticide Information Center (NPIC) in the USA. It is found in many household ant and cockroach killers, including Raid, Ortho, Combat, ant chalk, and some products of Baygon in Southeast Asia.

Pyrethrum was a genus of several Old World plants now classified in either Chrysanthemum or Tanacetum which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants formerly included in the genus Pyrethrum. Pyrethrum is also the name of a natural insecticide made from the dried flower heads of Chrysanthemum cinerariifolium and Chrysanthemum coccineum. The insecticidal compounds present in these species are pyrethrins.

<span class="mw-page-title-main">Pyrethrin</span> Class of organic chemical compounds with insecticidal properties

The pyrethrins are a class of organic compounds normally derived from Chrysanthemum cinerariifolium that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin naturally occurs in chrysanthemum flowers and is often considered an organic insecticide when it is not combined with piperonyl butoxide or other synthetic adjuvants. Their insecticidal and insect-repellent properties have been known and used for thousands of years.

<span class="mw-page-title-main">Bifenthrin</span> Chemical compound

Bifenthrin is a pyrethroid insecticide. It is widely used against ant infestations.

<span class="mw-page-title-main">Pyrethroid</span> Class of insecticides

A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums. Pyrethroids are used as commercial and household insecticides.

<span class="mw-page-title-main">Permethrin</span> Medication and insecticide

Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto outer clothing or mosquito nets to kill the insects that touch them.

<span class="mw-page-title-main">Imidacloprid</span> Chemical compound

Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system. Specifically, it causes a blockage of the nicotinergic neuronal pathway. By blocking nicotinic acetylcholine receptors, imidacloprid prevents acetylcholine from transmitting impulses between nerves, resulting in the insect's paralysis and eventual death. It is effective on contact and via stomach action. Because imidacloprid binds much more strongly to insect neuron receptors than to mammal neuron receptors, this insecticide is more toxic to insects than to mammals.

Persian powder is an insecticide powder with natural pyrethrin as the active agent. It is also known as Persian pellitory, insect powder and internationally as pyrethrum.

<span class="mw-page-title-main">Persistent organic pollutant</span> Organic compounds that are resistant to environmental degradation

Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released.

<span class="mw-page-title-main">Allethrins</span> Class of synthetic chemicals used as insecticides

The allethrins are a group of related synthetic compounds used in insecticides. They are classified as pyrethroids, i.e. synthetic versions of pyrethrin, a chemical with insecticidal properties found naturally in Chrysanthemum flowers. They were first synthesized in the United States by Milton S. Schechter in 1949. Allethrin was the first pyrethroid.

<span class="mw-page-title-main">Deltamethrin</span> Chemical compound

Deltamethrin is a pyrethroid ester insecticide. Deltamethrin plays a key role in controlling malaria vectors, and is used in the manufacture of long-lasting insecticidal mosquito nets; however, resistance of mosquitos and bed bugs to deltamethrin has seen a widespread increase.

<span class="mw-page-title-main">Phenothrin</span> Chemical compound

Phenothrin, also called sumithrin and d-phenothrin, is a synthetic pyrethroid that kills adult fleas and ticks. It has also been used to kill head lice in humans. d-Phenothrin is used as a component of aerosol insecticides for domestic use. It is often used with methoprene, an insect growth regulator that interrupts the insect's biological lifecycle by killing the eggs.

<span class="mw-page-title-main">Food Quality Protection Act</span> US law about pesticides

The Food Quality Protection Act (FQPA), or H.R.1627, was passed unanimously by Congress in 1996 and was signed into law by President Bill Clinton on August 3, 1996. The FQPA standardized the way the Environmental Protection Agency (EPA) would manage the use of pesticides and amended the Federal Insecticide, Fungicide, and Rodenticide Act and the Federal Food Drug and Cosmetic Act. It mandated a health-based standard for pesticides used in foods, provided special protections for babies and infants, streamlined the approval of safe pesticides, established incentives for the creation of safer pesticides, and required that pesticide registrations remain current.

<span class="mw-page-title-main">Cyhalothrin</span> Synthetic pyrethroid used as insecticide

Cyhalothrin is an organic compound that, in specific isomeric forms, is used as a pesticide. It is a pyrethroid, a class of synthetic insecticides that mimic the structure and properties of the naturally occurring insecticide pyrethrin which is present in the flowers of Chrysanthemum cinerariifolium. Pyrethroids, such as cyhalothrin, are often preferred as an active ingredient in agricultural insecticides because they are more cost-effective and longer acting than natural pyrethrins. λ-and γ-cyhalothrin are now used to control insects and spider mites in crops including cotton, cereals, potatoes and vegetables.

<span class="mw-page-title-main">Prallethrin</span> Chemical compound

Prallethrin is a pyrethroid insecticide. Prallethrin 1.6% w/w liquid vaporizer is a repellent insecticide which is generally used for the control of mosquitoes in the household.

A fogger is any device that creates a fog, typically containing an insecticide for killing insects and other arthropods. Foggers are often used by consumers as a low cost alternative to professional pest control services. The number of foggers needed for pest control depends on the size of the space to be treated, as stated for safety reasons on the instructions supplied with the devices. The fog may contain flammable gases, leading to a danger of explosion if a fogger is used in a building with a pilot light or other naked flame.

<span class="mw-page-title-main">Clothianidin</span> Chemical compound

Clothianidin is an insecticide developed by Takeda Chemical Industries and Bayer AG. Similar to thiamethoxam and imidacloprid, it is a neonicotinoid. Neonicotinoids are a class of insecticides that are chemically similar to nicotine, which has been used as a pesticide since the late 1700s. Clothianidin and other neonicotinoids act on the central nervous system of insects as an agonist of nAChR, the same receptor as acetylcholine, the neurotransmitter that stimulates and activating post-synaptic acetylcholine receptors but not inhibiting AChE. Clothianidin and other neonicotinoids were developed to last longer than nicotine, which is more toxic and which breaks down too quickly in the environment.

<span class="mw-page-title-main">Cyfluthrin</span> Chemical compound

Cyfluthrin is a pyrethroid insecticide and common household pesticide. It is a complex organic compound and the commercial product is sold as a mixture of isomers. Like most pyrethroids, it is highly toxic to fish and invertebrates, but it is far less toxic to humans. It is generally supplied as a 10–25% liquid concentrate for commercial use and is diluted prior to spraying onto agricultural crops and outbuildings.

<span class="mw-page-title-main">Mosquito coil</span> Incense coil designed to repel mosquitoes

A mosquito coil is a mosquito-repelling incense, usually made into a spiral, and typically made using dried paste of pyrethrum powder. The coil is usually held at the center of the spiral, suspending it in the air, or wedged by two pieces of fireproof netting to allow continuous smoldering. Burning usually begins at the outer end of the spiral and progresses slowly toward the center of the spiral, producing a mosquito-repellent smoke. A typical mosquito coil measures around 15 centimetres (6 in) in diameter and lasts around seven to twelve hours. Mosquito coils are widely used in Asia, Africa, South America, Canada, Mexico and Australia.

<span class="mw-page-title-main">Fenpropathrin</span> Chemical compound

Fenpropathrin, or fenopropathrin, is a widely used pyrethroid insecticide in agriculture and household. Fenpropathrin is an ingestion and contact synthetic pyrethroid. Its mode of action is similar to other natural (pyrethrum) and synthetic pyrethroids where in they interfere with the kinetics of voltage gated sodium channels causing paralysis and death of the pest. Fenpropathrin was the first of the light-stable synthetic pyrethroids to be synthesized in 1971, but it was not commercialized until 1980. Like other pyrethroids with an α-cyano group, fenpropathrin also belongs to the termed type II pyrethroids. Type II pyrethroids are a more potent toxicant than type I in depolarizing insect nerves. Application rates of fenpropathrin in agriculture according to US environmental protection agency (EPA) varies by crop but is not to exceed 0.4 lb ai/acre.

References

  1. ↑ National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.[ page needed ]
  2. ↑ National Pesticide Information Center – Piperonyl Butoxide General Fact Sheet
  3. 1 2 Metcalf, Robert L. (2000). "Insect Control". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a14_263. ISBN   978-3-527-30385-4.
  4. ↑ Osimitz, Thomas G. (2010). "The Safety Assessment of Piperonyl Butoxide". Hayes' Handbook of Pesticide Toxicology. pp. 2127–2151. doi:10.1016/B978-0-12-374367-1.00099-9. ISBN   978-0-12-374367-1.
  5. 1 2 Glynne-Jones, D. (1998). History of PBO In "PBO—The Insecticide Synergist" (D. Glynne Jones, ed.). Academic Press, San Diego.[ page needed ]
  6. ↑ "ENDURA". INCITE. Retrieved 2024-08-20.
  7. ↑ "Pyrethrin and Piperonyl Butoxide Topical: MedlinePlus Drug Information". medlineplus.gov. Retrieved 2024-04-03.
  8. ↑ "Pyrethrum Extract And Piperonyl Butoxide (Topical Route) Description and Brand Names - Mayo Clinic". www.mayoclinic.org. Retrieved 2024-04-03.
  9. ↑ US Environmental Protection Agency. Reregistration Eligibility Decision for PBO, June, 2006.
  10. ↑ Devine, G.J.; Denholm, I. (December 1998). "An unconventional use of piperonyl butoxide for managing the cotton whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)". Bulletin of Entomological Research. 88 (6): 601–610. doi:10.1017/S0007485300054262.
  11. ↑ Casida, John E. (May 1970). "Mixed-function oxidase involvement in the biochemistry of insecticide synergists". Journal of Agricultural and Food Chemistry. 18 (5): 753–772. doi:10.1021/jf60171a013. PMID   4919838.
  12. ↑ Moores, G. D., Philippou, D., Borzatta, V., Trincia, P., Jewess, P., Gunning, R., Bingham, G. (2009). "An analogue of piperonyl butoxide facilitates the characterisation of metabolic resistance". Pest Manag. Sci. 65 (2): 150–154. doi:10.1002/ps.1661. PMID   18951417.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ↑ Conney, Allan H.; Chang, Richard; Levin, Wayne M.; Garbut, Arnold; Munro-Faure, A. Douglas; Peck, Anthony W.; Beckenham, Alan Bye (February 1972). "Effects of Piperonyl Butoxide on Drug Metabolism in Rodents and Man". Archives of Environmental Health. 24 (2): 97–106. doi:10.1080/00039896.1972.10666058. PMID   5007655.
  14. ↑ Dhopeshwarkar, Amey S.; Jain, Saurabh; Liao, Chengyong; Ghose, Sudip K.; Bisset, Kathleen M.; Nicholson, Russell A. (2011-03-01). "The actions of benzophenanthridine alkaloids, piperonyl butoxide and (S)-methoprene at the G-protein coupled cannabinoid CB₁ receptor in vitro". European Journal of Pharmacology. 654 (1): 26–32. doi:10.1016/j.ejphar.2010.11.033. ISSN   1879-0712. PMID   21172340.
  15. ↑ Federal Insecticide, Fungicide, and Rodenticide Act7 U.S.C. §136 et seq. (1996)
  16. 1 2 US Environmental Protection Agency. Reregistration Eligibility Decision for PBO, June, 2006
  17. ↑ Children, National Research Council (US) Committee on Pesticides in the Diets of Infants and (1993), "Methods for Toxicity Testing", Pesticides in the Diets of Infants and Children, National Academies Press (US), retrieved 2023-10-07
  18. ↑ (Selim, 1995)
  19. ↑ Wester, RC; Bucks, DA; Maibach, HI (1994). "Human in vivo percutaneous absorption of pyrethrin and piperonyl butoxide". Food and Chemical Toxicology. 32 (1): 51–53. doi:10.1016/0278-6915(84)90036-x. PMID   8132164.
  20. ↑ JMPR (1995) PBO A monograph prepared by the Joint FAO/WHO Meeting on Pesticide Residues, Geneva.)
  21. ↑ Wang, J.; Lu, J.; Mook Jr, R. A.; Zhang, M.; Zhao, S.; Barak, L. S.; Freedman, J. H.; Lyerly, H. K.; Chen, W. (2012). "The Insecticide Synergist Piperonyl Butoxide Inhibits Hedgehog Signaling: Assessing Chemical Risks". Toxicological Sciences. 128 (2). Tox Sci: 517–523. doi:10.1093/toxsci/kfs165. PMC   3493191 . PMID   22552772.
  22. 1 2 Everson, Joshua L.; Sun, Miranda R.; Fink, Dustin M.; Heyne, Galen W.; Melberg, Cal G.; Nelson, Kia F.; Doroodchi, Padydeh; Colopy, Lydia J.; Ulschmid, Caden M.; Martin, Alexander A.; McLaughlin, Matthew T.; Lipinski, Robert J. (2019). "Developmental Toxicity Assessment of Piperonyl Butoxide Exposure Targeting Sonic Hedgehog Signaling and Forebrain and Face Morphogenesis in the Mouse: An in Vitro and in Vivo Study". Environmental Health Perspectives. 127 (10). EHP: 107006. doi:10.1289/EHP5260. PMC   6867268 . PMID   31642701.
  23. ↑ Horton, M. K.; Rundle, A.; Camann, D. E.; Boyd Barr, D.; Rauh, V. A.; Whyatt, R. M. (2011). "Impact of prenatal exposure to piperonyl butoxide and permethrin on 36-month neurodevelopment". Pediatrics. 127 (3): e699-706. doi:10.1542/peds.2010-0133. PMC   3065142 . PMID   21300677.
  24. ↑ "Piperonyl Butoxide (PBO) General Fact Sheet". National Pesticide Information Center. Oregon State University. 2017. Retrieved 13 October 2020.
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