Harmful Effects of Pesticides

There are 3 types of harmful effects caused by pesticides:

  • acute
  • delayed
  • allergic

Acute Effects – they are visible as diseases or injuries which can occur right away after exposure to a pesticide (usually in the period of 24 hours).

Studying a pesticide’s relative ability to induce acute effects has been the main way to assess and compare how toxic pesticides are. They can also be measured much accurately than delayed effects, and they are easier for the diagnosis of the effects that occur only after a long exposure. Acute effects are usually more evident and are often reversible if the necessary medical help is provided as soon as possible.

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Pesticides Warning Sydney

Pesticides Warning

Types of pesticides acute effects:

  • Oral
  • Inhalation
  • Skin
  • Eye

Acute oral effects ”“ oral cavity, throat and stomach can be damaged by some types of pesticides.

Other types of pesticides that you swallow up will not only burn your digestive system but they can be absorbed and carried throughout human blood system and may cause harm in many different ways.

Some other types of pesticides, by swallowing even a few drops when wiping a mouth with a contaminated glove can make people very sick and can cause problems with eating and drinking.

Types of Effects

Acute inhalation effects ”“  Difficulty breathing and breathing disorders of the human respiratory system can originate from pesticides. Other pesticides that you may breathe in may not damage your respiratory system but are carried rapidly into your blood system where they can spread throughout your whole body and cause extensive damage.

Acute dermal effects ”“ just a small touch with some pesticides can hurt your skin. Some kind of pesticides can cause your skin to itch, blister, rupture or even change colour. Other pesticides can pass through your skin and eyes and get into your body system. Once they are inside your body, these pesticides are carried throughout your system where they can do damage to your body.

Acute eye effects ”“ Some types of pesticides that get into your eyes can cause temporal or constant blindness or serious irritation. Other kinds of pesticides don’t need to irritate your eyes but can go through your eyes and get into your body. These pesticides can travel throughout your body causing irreversible damage to your body.

Delayed effects – Delayed or postponed effects of pesticides are illnesses or injuries that do not appear right away (in the period of 24 hours) after exposing body to a pesticide or some combination of them. The term “chronic effects” is frequently used to describe delayed effects, but more often it is applied only for some types of delayed effects.

Reason for delayed effects:

  • repeated exposure to a pesticide or group of them, or a combination of pesticides over long time

  • single exposure to a pesticide or their combination, that causes a damaging reaction which becomes visible much later.

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Sometimes repeated exposure to a pesticide or family of pesticides will result in a delayed effect but a larger exposure will cause an acute effect. A person who is repeatedly exposed to two or more specific chemicals may become ill even though the chemicals alone would have no harmful health impacts.  Repeated exposures to a pesticide or some kind of them sometimes can result in a delayed effect but a larger exposure will cause an acute effect. In some cases, a single exposure to a pesticide or their combination could negatively affect the exposed person’s health much later.

For instance, large exposures to herbicide paraquat may cause severe or fatal lung injury that does not appear for 3 to 14 days after the initial exposure. After an exposure to paraquat, it slowly develops and it destroys lung cells.

Some harmful effects may not occur unless a certain set of circumstances is present. That kind of effects can occur after the first exposure, but the chance for that are small. Permanent or common exposures over a long period of time make it more likely that all the necessary factors will be present. In this category there are some changes in genetics that can result in cancer development or other delayed effects.

Delayed effects include:

  • chronic effects
  • effects in development and reproduction
  • systemic effects

Chronic effects ”“ usually takes few years after exposure of the body to a pesticide for diseases or injuries to appear. Some delayed effects which are believed to result from chronic toxicity include: production of tumours (oncogenic effect), occurrence of malignancy or cancer (carcinogenic effect) and changes in the genes or chromosomes (mutagenic effect).

Determining delayed effects ”“ It is sometimes hard to identify the cause of a delayed effect for the reason that the time delay between the exposure and the noticeable effect, and because many other types of exposures may have occurred during the delay.

New studies need to be made to define whether pesticides affect people the same way as some pesticides cause delayed effects on animals tested in laboratories.

Pesticide Free Sydney

Pesticide Free

Understanding risks

The Environmental Protection Agency (EPA) will decide what steps need to be made for decreasing or even eliminating the risk because there is obvious evidence that pesticides can produce chronic, development, reproductive or system effects for human health.

Actions need to be made as eliminating pesticide for use, making the warnings about the possible pesticides effects, require for using protective equipment and safety systems while using of the pesticides, making changes in pesticide dosages, frequency or method of application, compliance about waiting times before entry, harvest, slaughter, grazing, and limiting the use of pesticides only for certified farmers.

Avoidance of delayed effects – pesticide manufacturers, scientists, and EPA are not sure of the delayed effects which may be caused of long exposure for combinations of some pesticides or single pesticides. Years can pass before scientists can get the right view to the cause that use of pesticides and their combinations which are used today. Because of that, it is good to reduce our exposure to all kinds of pesticides and be in touch with them as little as possible.


Allergic effects of pesticides ”“ they have damaging effects due to the body’s reaction to the pesticide substance where some people have more harmful side effects that others. First exposure to pesticides will develop the body rejection for pesticide chemicals. The first exposure to that substance will not cause the allergic reactions. Subsequent exposure will cause the allergic reaction. Substances that causes allergies are called sensitisers, and that procedure is known as sensitisation. Some substances can develop allergic reactions in many people, like poison ivy, which can cause serious skin rash. But other substances will cause allergic reaction in a small number of people.  For that example, turf grass can cause a serious skin rash in just a few people.

Kinds of allergic effects ”“ some people are sensitive to certain pesticides. After their exposure to pesticides once or twice with no effects, their body may respond with an allergic reaction in subsequent exposures.

Pesticides Toxic FruitSneyyd

Pesticides Toxic Fruit

Side effects

Systemic effects like asthma, dangerous shock, irritation of skin (rash, blisters, open sores), nose and eye irritation (itchy, tears in the eyes, sneezing). For these effects there is no way to find out which pesticide can cause allergies to which people. But some people are more sensitive to chemicals than others, and therefore they have an allergic response to many chemicals they encounter in their area. Because of that, some people can develop allergies more easily to pesticides.

Usually pesticides have precautionary labels which include: “This product may produce temporary allergic side effects characterised by redness of the eyes, mild bronchial irritation, and redness or rash on exposed skin areas. Persons having allergic reactions should contact a physician.”

Allergic effects avoidance ”“ it depends on what kind of allergic reaction the person has to pesticides. In some cases, people with allergies to some pesticides can work with them in situations where there is reduced exposure.

Occupational Health and Safety

A regulation under the Occupational Safety and Health Act (OSHA), known as the Hazard Communication Standard (HCS) require employers to secure protection for workers who are exposed to dangerous chemicals in normal working conditions and in predictable emergencies.

They also require employers to:

  • have a list of the dangerous chemicals in area of work
  • obtain material safety data sheets for all dangerous substances on their list and keep them in a file that is available to all workers
  • make sure that all containers of dangerous materials are labelled at all times
  • train all workers about the dangerous substances in their workplace.

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