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Isofenphos — toxicity, side effects, diseases and environmental impacts

Wednesday, November 29, 2017 by

Isofenphos is an organophosphate insecticide developed in West Germany by Bayer-AG, a German pharmaceutical company. First registered in 1980, isofenphos was marketed and sold for use on soil-dwelling insects like white grubs, Japanese beetles, corn roundworms, and wireworms.

Though once widely used to protect crops and golf courses from insects, isofenphos has since become a restricted use pesticide (RUP), meaning only certified applicators can purchase and use this product. This is because isofenphos was found to possess toxicologic properties that made it highly dangerous to non-target organisms, such as birds, bees, and mammals. As of Dec. 31, 1999, isofenphos can no longer be sold or distributed.

List of known side effects

As an organophosphate compound and cholinesterase inhibitor, isofenphos can cause organophosphate poisoning. This type of poisoning is brought about by the accumulation of acetylcholine, an organic chemical that functions as a neurotransmitter and neuromodulator. Too much acetylcholine the body will cause a build-up of stimulating signals. When organophosphate poisoning occurs, the affected person or persons will usually display any of the following symptoms:

  • Abdominal cramps, vomiting, or diarrhea
  • Blurred or darkened vision
  • Chest tightness, respiratory depression, or wheezing
  • Excessive salivation or sweating
  • Headaches or dizziness
  • Muscle tremors and twitching

Severe organophosphate poisoning will often lead to more serious symptoms, like seizures, loss of consciousness, or incontinence. Combining isofenphos with the insecticide malathion can make this chemical more toxic. Organophosphate poisoning is often brought about through the ingestion, inhalation, or skin contact with isofenphos.

In addition to organophosphate poisoning, isofenphos can lead to acute toxicity as well. Swallowing this compound or breathing in its vapors are the usual routes of exposure, with inhalation being the most potentially dangerous. Inhaling isofenphos can irritate the mucus membrane and upper airways, and may lead to systemic muscarinic, nicotinic, and central effects.

Isofenphos is believed to be a possible reproductive hazard. Cases of lower birth weights and higher neonatal mortality rates have been recorded among animals, and human birth defects caused by isofenphos have been reported. However, the reports of human birth defects have not yet been fully verified.

Though isofenphos does not readily ignite, it’s a combustible material that can produce irritating, corrosive, or toxic gases when exposed to high temperatures. These fumes can contain nitrogen oxides, sulfur oxides, and phosphorus oxides.

Isofenphos is moderately to highly toxic to aquatic organisms, birds, and bees, and is considered to be extremely hazardous to fish and aquatic invertebrates. Furthermore, isofenphos has been found to have a soil half-life of almost one year, so it can persist in soil for a long period of time.

Body systems affected by isofenphos

Isofenphos can irritate or harm the skin, eyes, respiratory, and digestive systems, depending on the exposure route. In addition, the Pesticide Properties Database has noted that isofenphos is a “central, peripheral nervous systems, and blood toxicant.

Items that can contain isofenphos

Isofenphos was originally marketed in Germany by Mobay Chemical Corp., a subsidiary of Bayer-AG. This chemical was sold under a number of trade names, the most well-known of which were Amaze, Oftanol, and Pryfon.

How to avoid isofenphos

In the event that a small amount of isofenphos spills, wipe it up with an absorbent material like cloth or fleece before thoroughly cleaning the surface to avoid residual contamination. If the spill is much larger, stop the flow of this material, if there is no risk involved. Dike the isofenphos if possible and cover with a plastic sheet to stop further spreading. Use vermiculite, dry sand, or earth to absorb the spill and place in a container. Afterwards, flush the area with water.

For storage, keep isofenphos in a tightly closed container and in a well-ventilated area. Keep away from food, medication, and sources of ignition, like open flames or sparks.

Should there be a need to handle isofenphos, ensure that eye/face protection, protective gloves, chemical-resistant clothing, and self-contained breathing apparatuses are worn. Avoid eating, drinking, or smoking when using this material.

Where to learn more


Isofenphos is a toxic insecticide that’s a known cholinesterase inhibitor. As such, exposure can lead to organophosphate poisoning, the symptoms of which range from abdominal pain to blurred vision to muscle twitching. Isofenphos is also a respiratory, dermal, ocular, and digestive irritant, as well as a blood, and central and peripheral nervous system toxicant. Moreover, isofenphos can induce varying levels of toxicity among birds, bees, and aquatic organisms.

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