Pesticides are considered to be a hazardous substances as they include a combination of chemicals which can cause serious harm to humans. Safe handling of pesticides is important to yourself and others on the farm safe.

We have produced guidance for farmers and others handling pesticides on farms.

Organophosphates: Health effects, health checks and first aid

This fact sheet provides guidance on the potential health effects on humans due to chemical exposure.  It also gives advice for establishing regular health checks and first aid procedures.

Organophosphates: health effects, health checks and first aid (PDF 67 KB)

While this guidance has not been updated to reflect current work health and safety legislation (the Health and Safety at Work Act 2015 and regulations), it may still contain relevant information and practices to keep workers and others healthy and safe.

Please read this guidance in conjunction with all relevant industry standards that apply to you as a PCBU. This guidance will be progressively reviewed and either updated, replaced with other guidance, or revoked.

Organophosphates: Health effects, health checks and first aid (Fact sheet)

Organophosphates are an active ingredient  in insecticides that kill bugs and insects in  orchards, vineyards, vegetable and cereal  crops. They are usually applied from a  knapsack sprayer or from spraying equipment  pulled by a tractor. Because of their chemical  make-up, they’re also harmful to human  health. However, different sprays affect your  health in different ways, and the amount of  harm they may cause you can also vary.

This factsheet applies to employers,  employees, contractors, principals and  self-employed people who work with  organophosphates.

Organophosphate health effects

When organophosphates are sprayed, the fine  mists and droplets can enter your body by  breathing them in, or by absorption through  your skin. They’re dangerous because they  disrupt the way your nervous system works.

There are different types of organophosphates,  with different concentrations. Harmful effects  can differ according to the organophosphate  brand and concentration. The effects will  also depend on how long or how often you’ve  been exposed.

It’s not a good idea to be exposed to  any amount, because they’re capable of  causing a lot of harm. Depending on how  you’re exposed, and how concentrated the  organophosphates are, you could experience  symptoms ranging from mild fatigue and  headaches, numb fingers and toes, muscle  twitches or pupil constriction through to  unconsciousness, rattling sounds in the lungs,  heart attacks or even death.

Organophosphate health checks

Before you use or handle organophosphates,  you should have your blood tested to find out  what your base cholinesterase levels are.

Cholinesterase helps the nervous system  work properly, and it’s affected by  organophosphates, so it’s important to see  what your levels are before you start working  with them. The levels will vary from person  to person, so there’s no level that’s correct  for everyone.

Blood tests are the best way to find out if  you’re affected by organophosphates because  they are absorbed through the skin and into  your blood.

When you’re working with organophosphates,  you should have regular blood tests to check  your cholinesterase levels. If the tests show that  your cholinesterase levels have dropped, you  have to stop working with organophosphates  until they return to normal levels.

Your medical provider will tell you when you  should have the tests, and whether or not it’s  safe for you to work with organophosphates.

Informed consent

If you’re an employer, you need to get  informed consent from employees if you are  going to monitor their health with blood tests.

Informed consent consists of:

  • good communication between the  employer, employees, unions (where  applicable) and medical provider
  • providing information so employees  can make an informed choice about  medical monitoring
  • employees freely giving their consent  for monitoring.

Issues with blood tests

There are many reasons why you might not  want to have a blood test – cultural or religious  reasons, pre-existing medical conditions, or  you’re frightened of needles or blood.

However, if you work with organophosphates,  you need to have your blood tested, since there  aren’t any other effective ways to check your  health. If you’re an employee or a contractor,  talk to your employer or principal about this,  as you might be able to do work that doesn’t  involve handling organophosphates, or work  in areas where they are not being sprayed.  If that isn’t possible, you might not be able to  work at the site.

First aid

If someone has been poisoned by  organophosphates, here is some first aid advice:

  • Make sure it is safe to help the patient.  Protect yourself if large quantities of  organophosphates are present.
  • Move the person to a safe area – wear  personal protective clothing to protect  yourself from organophosphates that might  be on the person’s clothing or skin.
  • Call the National Poisons Centre for advice  on 0800 764 766.
  • Phone 111 for an ambulance if the person  isn’t breathing.
  • Remove the person’s contaminated  clothing, and follow the advice below:

If inhaled

  • Loosen tight clothing and check  the person’s airway, breathing and  circulation.
  • Give oxygen if it is available.
  • Keep the person warm and comfortable.

Skin contact

  • Loosen tight clothing, check  the person’s airway, breathing  and circulation.
  • Wash contaminated skin thoroughly  with water and soap. Continue washing  the skin for at least 15 minutes.
  • Keep the person warm and comfortable.

Eye contact

  • Loosen tight clothing, check the person’s  airway, breathing and circulation.
  • Flush the eyes thoroughly with water  for at least 15 minutes. Have the person  blink as much as possible.
  • Hold the eyelids open if necessary.
  • Do not attempt to remove contact  lenses until after the eyes have been  flushed. Remove the lenses with  clean fingers.


  • Loosen tight clothing, check the person’s  airway, breathing and circulation.
  • If the person is awake and can drink, give  them a small amount of fluid to drink.
  • Do not administer chemical antidotes  or medicine unless told to do so by a  medical professional.
  • Keep the patient warm and comfortable.
  • Do not give fluids or induce vomiting if  the person is unconscious.

Further information

Environmental Protection Authority, See Using Insecticides Safely.(external link)