TXP-2
Overview
Tetramethrin was first registered with the EPA in 1968. It is a fast working contact insecticide used to target a range of flying and crawling insect species. Tetramethrin hyperactivates nerve cells, ultimately leading to paralysis and death. It is used primarily by home consumers in outdoor pest control applications, although there are also commercial uses as a surface and space spray. It tends to degrade rapidly after it is applied. It is metabolized quickly, so there is little risk to human health in small quantities of exposure. Contact with the skin may cause irritation, and inhalation may cause shortness of breath. Tetramethrin is not registered for any use on any agricultural crops, so not much is known about the effects of ingestion. Tetramethrin is highly toxic to bees, fish, amphibians, and aquatic invertebrates (#EPA).
Chemical Description
Tetramethrin is a synthetic pyrethroid. It is a yellow to brown viscous liquid (#NIOSH). It will melt at 68-70° C (#EPA). Tetramethrin has a low mobility in soil. In soil, it has a half-life of one hour. If released into the air, tetramethrin can exist as a vapor. The half-life of this vapor phase is three hours (#NLM).
Uses
Tetramethrin is an insecticide often used to target insects such as wasps, hornets, roaches, ants, fleas, and mosquitoes. It is oftentimes combined with another active ingredient for more broad range pest control, or for more effective long term treatments (#EPA).
Tetramethrin has a wide range of residential uses including general surface and space sprays, spot and crack treatments, use on indoor and outdoor plants, clothing, bedding, pet premises, direct application onto pets, and perimeter treatments such as sidewalks and decks (#EPA).
Commercially, tetramethrin is frequently used in industrial or institutional sites such as non-food areas, on non-farm animal premises, outdoors on ornamental plants, and perimeter treatments including sidewalks and around buildings. Tetramethrin is not registered for use on any food plants (#EPA).
Human Health Effects
The most likely routes of exposure to tetramethrin are inhalation and dermal contact, through either a workplace where tetramethrin is used, or through the use of home products with tetramethrin (#NLM). However, the EPA determined that there are no significant health risks through dermal absorption. Tetramethrin is categorized as a Group C carcinogen, a possible human carcinogen (#EPA).
Symptoms associated with exposure to pyrethroid compounds include skin and eye irritation, irritability to sound or touch, abnormal facial sensation, sensation of prickling, tingling, or creeping on skin, numbness, headache, dizziness, nausea, vomiting, diarrhea, salivation, and fatigue. At very high levels of exposure, muscle twitching and fluid accumulation in the lungs may occur (#PANNA). Shortness of breath, blisters, welts, and hives are also noted with tetramethrin exposure (#NLM).
Environmental Health Effects
Because most tetramethrin use is residential, applications tend to be small and isolated. Tetramethrin also degrades rapidly, so, unless mixed with other active chemicals, tetramethrin will only affect organisms present near the time of application. This, combined with a low solubility in water, makes tetramethrin unlikely to contaminate water sources in runoff (#EPA).
Tetramethrin is practically non-toxic to birds and mammals. The LD50 in rats exceeded the testing limit of 5000 mg/kg for tests in both ingestion and dermal absorption (#EPA). In a WHO study, Male Wistar rats here given a dose of 500 mg/kg, of which 95% was metabolized and excreted within five days, indicating that tetramethrin is absorbed and secreted relatively quickly (#NLM). Some flea control products containing tetramethrin are even applied directly to pets.
Tetramethrin was found to be highly toxic to non-target bees. In honey bees, the LD50 is 0.155 μg/bee. It also has a very high toxicity to fish, amphibians, and aquatic invertebrates (#EPA).
Regulation
Tetramethrin can not be used on agricultural crops. Some tetramethrin products may only be used by pest control operators, but most are available for general residential use (#EPA).
Precautionary Notes
Tetramethrin should not be applied directly to or near water, due to its high toxicity to aquatic species. Household users should also take care not to use tetramethrin on home grown food, or near other foods. If tetramethrin is used on pets, limit contact with children for a reasonable amount of time. Be aware of other active chemical ingredients. Tetramethrin is commonly combined with other pesticide agents to prolong effectiveness or to target a wider range of insects.
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