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Pyriproxyfen — toxicity, side effects, diseases and environmental impacts

Tuesday, November 21, 2017 by

Pyriproxyfen is an insecticide used to control pests that affect public health, such as mosquitoes, cockroaches, ticks, and fleas. This chemical works by mimicking a natural hormone present in insects, disrupting their growth in the process. Due to its mechanism of action, pyriproxyfen is typically utilized against young insects and insect eggs to prevent them from reaching adulthood and multiplying.

List of known side effects

In 2016, pyriproxyfen came under intense scrutiny from scientists following the rash of microcephaly cases in Brazil. These cases have been linked to mosquitoes carrying the Zika virus, though some experts believe that pyriproxyfen was the cause. Their points were:

  • Pyriproxyfen was added to the nation’s supply of drinking water in late 2014, the year prior to the explosion of microcephalic babies. This was part of the country’s efforts to eliminate breeding mosquitoes.
  • A study by researchers from New England Complex Systems Institute (NECSI) and Duke University has indicated that pyriproxyfen can interfere with human brain development. Specifically, by imitating the role of juvenile hormones such as retinoic acid, a vitamin A metabolite that’s been found to cause microcephaly.

Because of this, the research team has recommended that Brazil cease the usage of pyriproxyfen for mosquito control, and instead opt for other methods like ovitraps, which are small containers that mosquitoes can lay their eggs in.

According to the Centers for Disease Control and Prevention (CDC), pyriproxyfen can have substantial health effects with long-term or repeated exposure. This chemical has been found to impact the liver and blood, and may cause anemia, impaired liver function, and tissue lesions.

If ingested, pyriproxyfen can irritate or burn the esophagus and gastrointestinal tract. Moreover, pyriproxyfen is partially absorbed by the gut, and may be stored in fat deposits and breast milk.

As a respiratory irritant, inhaling pyriproxyfen can result in dizziness, headaches, weakness, and nausea. In severe cases, acute lung injury may occur.

This chemical is believed to be a potential endocrine disruptor, and has been shown to have an estrogenic effect.

Upon exposure to elevated temperatures, pyriproxyfen will decompose and emit toxic fumes that contain carbon monoxide and nitrogen oxides.

Pyriproxyfen is very toxic to aquatic life and may leave long-lasting effects on water-based plants and animals. Ergo, it shouldn’t be used near bodies of water or allowed to seep into water sources.

Body systems affected by pyriproxyfen

Pyriproxyfen is thought of as a possible liver and blood toxicant, making it harmful to those parts of the body. Additionally, pyriproxyfen can irritate the gastrointestinal and respiratory system.

Items that can contain pyriproxyfen

There are more than 300 registered products believed to have pyriproxyfen as an ingredient. Among these are pesticides for lawns and the insides of homes, leaf treatments for food crops, and in flea- and tick-control products for pets. The most notable brands to use pyriproxyfen as an active ingredient are:

  • Admiral
  • Atominal
  • Juvinal
  • Pyriproxyfen 10EC

In addition, these companies have been involved or remain involved in the supplying and manufacturing of pyriproxyfen-containing products:

  • BePharm Ltd.
  • Sumitomo
  • Syngenta

How to avoid pyriproxyfen

The main routes of exposure to pyriproxyfen are inhalation, ingestion, and contact. As such, to prevent this chemical from causing harm, local exhaust systems should be available in areas where this chemical is being handled; drinking, eating, and smoking during work should be avoided; and protective gloves and safety goggles should be worn at all times.

Additionally, pyriproxyfen is a combustible liquid and should be kept away from open flames.

Ensure that pyriproxyfen is separated from food, feedstuffs, fertilizers, and medication to prevent cross-contamination.

Where to learn more


Pyriproxyfen is an insecticide that could be a possible liver and blood toxicant, as well as an eye, respiratory, and gastrointestinal systems irritant. High heat will cause this chemical to release toxic fumes.

Pyriproxyfen is believed by some to be responsible for the rash of microcephalic babies in Brazil from 2015 to 2016. This is because pyriproxyfen was used on the country’s drinking water supply, in addition to pyriproxyfen being linked to impeded brain development in children.

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