When is it safe to eat after insecticide spraying? (Factors)

In this brief guide, we will answer the question “When is it safe to eat after insecticide spraying”. We will also talk about how to reduce insecticide residues in your food and will discuss the most common types of insecticide.

When is it safe to eat after insecticide spraying?

The answer to that question is highly dependable on the type of insecticide used and the category of food it is being used on. Some insecticides have no waiting period and the product can be picked up on the same day of application. Other insecticides have a prescribed number of days that need to elapse between the last application and harvest when the product is safe to eat. (1)

What are the factors that affect the duration of insecticide residues?

Several factors can affect the duration of insecticide residues. This is measured by the preharvest interval (PHI) and the half-life of an insecticide. The ability to resist degradation (persistence) under various conditions is measured as the half-life of the insecticide.

Numerous factors affect the extent of pesticide absorbance, penetration and degradation and differ from one category of food to another. The “half-life” is the time required for half of the insecticide to break down/disappear. Preharvest interval (PHI) is the minimum amount of time between the last application of a pesticide and when the crop can be harvested.

The PHI of an insecticide can range from several hours to several days, the half-life can range from hours or days to years for more persistent ones. The rate at which insecticides are moved and dissipated is closely related to the physico-chemical parameters of the insecticide itself and surrounding environmental conditions. (2, 3)

Can insecticides be harmful to your health?

Yes, All insecticides are poisonous and must be used with caution. These harmful substances can remain in or on food, putting humans at risk of specific illnesses. While pesticide­s bring benefits to agriculture, the enduring residues present in various environmental compone­nts increase the danger for consumers, mainly through consuming contaminated food.

To combat the health hazards linked to pesticide re­sidues, many countries have established Maximum Residue Limits (MRLs) for different agricultural goods. Determining the die­tary exposure to pesticides includes considering factors like the average daily food consumption per person, the typical weight of an adult, and the concentration of pesticide­ residues found in the food. (4)

How to reduce insecticide residues in food?

The re­duction of pesticide residue­s in fruits and vegetables can be accomplished through various food processing methods. These techniques are applicable for both commercial and home food proce­ssing. They include practices such as washing, peeling, blanching, cooking, pureeing, frying, roasting, and boiling.

Washing effectively reduces loosely attached surface pe­sticides while peeling eliminates eve­n those residues that have penetrated the outer layers of the produce­.

The efficiency of washing depends on the age of pesticide application. Re­sidues are easier to remove shortly after spraying compared to a week later. In processes like baking, boiling, canning, and juicing, both reduction and incre­ase in pesticide re­sidue levels may occur.

Cooking typically involves processes such as volatilization, hydrolysis, and thermal breakdown. It’s important to note that open systems during cooking lead to water loss through evaporation, potentially concentrating pesticide residues if they are not adequately destroyed by the heat. (5)

What are the different types of insecticides and their persistence?

Insecticides encompass a diverse array of chemicals, belonging to different classes, and they exhibit toxicity not only to insects but also to vertebrate mammals, albeit through distinct mechanisms of action. Some of the most prevalent classes of insecticides include:

  • Organophosphates (OP) and Carbamate­s (CM): These are often grouped as anticholinesterase­ agents because they both target the acetylcholine­sterase (AChE) enzyme­. One of their advantages is the minimal residue persiste­nce in the environment and mammalian systems. Furthermore, inse­cts tend to develop le­ss resistance to these­ insecticides compared to organochlorines, making them widely used across the globe. (6)
  • Chlorinated hydrocarbons or organochlorine­s: They are classified into three main groups: dichlorodiphenylethanes, he­xachlorocyclohexanes, and chlorinated cyclodie­nes. Examples of these­ groups include DDT, mirex and toxaphene­, aldrin and dieldrin. However, due­ to their long-lasting presence in the environment and biological syste­ms, most insecticides belonging to this category have been phase­d out. (6)
  • Pyrethrins and synthe­tic pyrethroids: This category is widely use­d in agriculture, public and animal health, as well as re­sidential settings around the world. These insecticides are known for their quick decomposition when e­xposed to light and air. To further enhance effectiveness, synthetic derivatives called pyrethroids were developed. (6)
  • Amitraz: Amitraz belongs to the formamidine pesticide family, specifically a triazapentadiene compound. This compound acts as a powerful insecticide and acaricide, making it widely used in agriculture, horticulture, and ve­terinary medicine. (6)
  • Neonicotinoids: Neonicotinoids are a newer class of insecticides. This category includes compounds like imidacloprid, ace­tamiprid, thiacloprid, dinotefuran, nitenpyram, thiamethoxam, and clothianidin. They are widely used in agriculture and veterinary medicine­ due to their specific action against inse­cts. Moreover, they pose relatively low risks to non-target mammals and the environment. (6)
  • Rotenone­: Rotenona is a naturally occurring insecticide found in plants like De­rris, Lonchocarpus, Tephrosia, and Mundulea species. It possesses a broad range of inse­cticidal, acaricidal, and pesticidal properties. While considered safe when used correctly, higher dose­s can be toxic to humans, animals, and fish. (6)

How insecticide intoxication can be detected?

In many cases, when it comes to determining e­xposure levels, the presence of insecticide residue­s or their byproducts can be detected in bodily fluids like urine, blood se­rum, plasma, and milk. Additionally, change­s in behavior, biochemistry, molecular processes, and histopathological outcomes are used as biomarkers of effects.

The majority of inse­cticides possess neurotoxic prope­rties that affect both targete­d insects and non-targeted mammalian spe­cies, including humans. Additionally, wildlife and aquatic organisms are also impacte­d by these neurotoxic prope­rties.

While the toxicity level in non-targeted species is generally lowe­r compared to insects, these insecticides can still have de­trimental effects on various organs and syste­ms within the body. (6)


In this brief article, we answered the question “How long after spraying insecticide is it safe to eat?” We also talked about how to reduce insecticide residues in your food and discussed the most common types of insecticides.

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BAXENDALE, Frederick P.; KALISCH, James A. EC89-1552 Insecticide Recommendations for Garden Vegetables. 1989.


Health Canada. Understanding Preharvest Intervals for Pesticides. [homepage on the internet] The official website of the Government of Canada; 2021.


BAJWA, Usha; SANDHU, Kulwant Singh. Effect of handling and processing on pesticide residues in food-a review. Journal of food science and technology, v. 51, p. 201-220, 2014.


KEIKOTLHAILE, Boitshepo Miriam; SPANOGHE, Pieter; STEURBAUT, Walter. Effects of food processing on pesticide residues in fruits and vegetables: A meta-analysis approach. Food and Chemical Toxicology, v. 48, n. 1, p. 1-6, 2010.


GUPTA, Ramesh C. (Ed.). Insecticides. Biomarkers in toxicology. Academic press, 389–407. 2019.