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Agricultural Chemicals-The least you need to know

Last updated: November 2001 

There are many text books, user manuals and codes of practice on agricultural chemicals available (for a cost).

IMPORTANT: As information gets out of date and changes, you many not have the most recent information. So make sure you ask the supplier for the latest product safety information. Your health could depend on this.

Here's some general notes on basic principles, before you get into more detailed texts and manuals.

What do Ag. chemicals do?
  • They protect plants and animals from pests and diseases.
  • They kill pests and cure diseases.
  • They prevent plants and animals from pests and diseases.
  • They stimulate plants and animals to perform better, hopefully to be more profitable.
Broad classification and their use?
  • Bacteriacides - to kill bacteria
  • Fungicides - to kill fungi.
  • Herbicides - to kill plants.
  • Weedicides - to kill weeds.
  • Miticides - to kill mites.
  • Mollusicides - to kill mollusces (snails).
  • Nematicides - to kill nematode worms.
  • Rodenticides - to kill rodents.
  • Growth regulators - to control the growth of plants and animals.
  • Animal remedies - products to improve the health or welfare of livestock.
  • WSP - water soluble powders
  • D - dusts.
  • WP - wettable powders (suspension).
  • CP - colloidal powders (very fine ground).
  • G - granules
  • P - prills (toxic outside coating).
  • B - bait
  • AC - aqueous concentrated - make a true solution when added to water.
  • NAC - non-aqueous concentrate - dissolved in a solvent (oil) with water added to make a solution.
  • EC - emulsified concentrate - dissolved in solvent with water added to make an emulsion.
  • FUM - fumigants - materials that vapourise.
  • A - aerosol - spray of fine particles suspended in gas (air).
  • Benefits of Ag. chemicals
For effective use, agricultural chemicals should be:
  • Cost effective.
  • Easy and quick to apply.
  • Selective.
  • Have a range of residual life.
  • Give quick results.
Potential risks of Ag. chemicals
There are always risks with agricultural chemicals and care is needed to avoid:
  • Accidental poisoning.
  • Irritation of eyes, nose and skin.
  • Allergies.
  • Chemical residues on food.
  • Environmental damage and pollution.
  • Build up of resistance.
  • Fire.
  • Corrosion.
  • Problems with disposal.
How dangerous are Ag. chemicals?

Any chemical is dangerous if taken in large enough quantities - even water.

  • Class 1. Deadly Poison. I drop orally or on the skin will kill a 63kg human.
  • Class 2. Dangerous Poison. Less than 1 teaspoon will do similar damage.
  • Class 3. Poisons. 1 - 2 teaspoons will do similar damage.
  • Class 4. Harmful Substance. 25g - 500g will do similar damage.
  • Class 5. Others.
How do Ag. chemicals get into the body?
  • Dermal - through the skin. 85% get in this way.
  • Inhalation - breathed in as chemical fumes and small droplets (aerosols).
  • Both dermal and inhalation - when handling or mixing.
  • Ingestion - through the mouth after eating, drinking, smoking.
  • Eyes - splashes via the mucous membranes.
Be especially careful with the concentrate chemical before mixing and dilution.
Types of poisoning
  • Acute - from a single exposure with symptoms soon after the event.
  • Chronic - from many doses over a longer time. Damage may be permanent may occur before discovery.
  • Secondary poisoning - where one animal eats another poisoned one.
Poisoning - what to watch out for?
Severe poisoning
  • Muscular spasms
  • Convulsions
  • Fits
  • Loss of consciousness
Less severe poisoning
  • Dry mouth
  • Headache
  • Fatigue
  • Nausea
  • Excessive sweating
  • Vomiting
  • Loss of balance
  • Giddiness
  • Blurred vision
  • Skin rashes
  • Nose bleeds
What to do if you think you (or someone else) have been poisoned?
  • Stop work immediately.
  • Seek help immediately.
  • Contact a doctor.
  • Phone an ambulance.
  • Take the container or label with you to the doctor.
  • If eyes are affected flush under water for at least 15 minutes.
  • Phone the National Poisons Centre - (03) 474-0999.
  • ASk for advice - eg if you should get the patient to drink or induce vomiting - getting it wrong could be fatal.
  • Provide CPR.
  • Precautions when using Ag. chemicals
Make it your policy to tell someone:
  • Where you are going.
  • What time you expect to be back.
  • What you are spraying for.
  • What chemical you’ll be using.
  • Where to get help if needed.
  • What to do in an emergency.
Protective clothing -you must wear it! What sort?
  • Rating 1 - for Class 1, Deadly Poison.
  • Rating 2 - for Class 2, Dangerous Poison.
  • Rating 3 - for Class 3, Poisons.
  • Rating 4 - for Class 4, Harmful Substances.
  • Rating 5 - for Class 5, Others.
What is “protective clothing”?

Wear protective clothing BEFORE you start to mix and decant spray chemicals - this is often the most dangerous time when handling the concentrate.

  • Washable cotton are OK
  • Wash regularly
  • Cotton combination
  • Buttoned at wrist and neck
  • Worn outside your boots
  • If likely to get wet - use PVC or chemical-proof
  • Wash separately to other clothes
  • Preferably rubber
  • Not leather as they absorb chemicals
  • Free from cracks and holes.
  • Worn always when handling or mixing chemicals
  • Should be PVC or chemical resistant.
  • for eye protection only
Face shields
  • Protect against splashes and spray drift.
  • Wear them when mixing and decanting
Half-face respirator
  • Only covers mouth and nose.
  • Has sealing problems with beards.
  • Prevents inhalation of toxic dust or vapour.
  • Needs correct cartridge fitted.
  • Cartridge has limited life - depends on toxicity and time.
  • Store cartridge in clean airtight container.
  • Life not longer than 8 hours - test with perfume (should not smell).
  • After spraying - wash with soap and water and dry properly.
  • Seal in plastic bag - separate to cartridge.
Full-face respirator (gas mask)
  • Should cover the entire face.
  • Protects at high levels of concentration of chemical in the air.
  • Take care of filter cartridges (see above).
Spray helmet
  • Provides the best protection
  • Has air pump to provide fresh air.
  • Protects you from drift
  • Has cartridge filter.
  • Use a special apron - not the one for milking or gardening.
  • It will protect against spills or splashes.
  • Can save a change of overalls.
Disposal of Ag.chemicals
  • To avoid risk to people or the environment.
  • To find a use for them - rather than dumping.
  • To return to the manufacturer if possible.
  • To dispose of them in an approved or registered land fill.
NO-NO places for disposal
  • Rural drains or waterways.
  • Sewerage systems.
  • Soak holes.
  • Offal holes.
Disposal of empty containers
  • Check with your local authority (local or regional council).
  • Ag.chemical containers should be used for Ag. chemicals.
  • It’s illegal to use them for other purposes - eg rafts, feed troughs, etc.
  • Burning can be dangerous to the environment - check with local authority.
  • Washing out - you need to flush them at least 3 times, preferably more.
Storage of Ag. chemicals
  • Get copies of AGCARM leaflets on storage.
  • Record all new containers going into the store and check for leakage.
  • Store to avoid risk of contamination to people, animals, crops and the environment.
  • Store in a suitable building - sound, dry, ventilated and well lit.
  • Store must be locked and secure. Vermin proof.
  • Keep away from the reach of children.
  • Do not mix chemicals in the store - mix in the open air.
  • Watch for damaged and leaking containers.
  • Floor should be sealed or bonded, or with a drip tray to contain spills
  • Watch for wrong labels and for labels falling off.
  • Be highly suspicious of a substance in an unmarked container.
  • Do not smell or taste it to try to guess what it is.
  • Segregate products -   Fumigants, herbicieds and oxidising agents in own area
  •                                 Deadly and dangerous poisons under lock and key
  •                                 Powder, liquid and aerosol formations kept apart
  • Stacking -  Cardboard/paper containers off floor - keep dry 
  •                 Maximum of two tiers high for drums
Golden rules to avoid disasters
  • Always read the label
  • If not sure what it means, ask for help.
  • Make sure you are using the correct chemical for the target.
  • Identify the target before use.
  • Calibrate your equipment - get help if needed.
  • Wear protective clothing yourself and make staff do the same.
  • Use “integrated control” a mixture of all the best methods.
  • Use the chemical with least risk to people, stock and the environment.
  • Watch for spray drift - errors could bankrupt you.
  • Keep a spray diary - what you used, when and where.
  • Attend to personal hygiene - wash properly after use.
  • Adhere to all “withholding periods”.
  • Know about correct disposal of containers - see AGCARM leaflets.
  • Know about correct rinsing of containers - see AGCARM leaflets.
Further Information
  • AGCARM Inc Leaflets. New Zealand Association for Animal Health and Crop Production
  • Regional Council publications

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