How dangerous are these chemicals to humans?

Most pesticides are poisonous, but some are more dangerous than others. There are three systems being used in Thailand to classify the risk to human health and warn people of the danger:

  • The Thai Government had introduced a colour code for pesticide containers. A red stripe on the label indicates that the chemical is highly poisonous, yellow indicates moderately poisonous and blue indicates slightly poisonous. These colours are used at the bottom of the pesticide label, with pictures to show the type of protective clothing that should be used.
  • red-pesticide-label-thailand

  • The World Health Organisation (WHO) has created a ‘toxicity classification’ with five classes. This system is used in technical documents, including those produced by the Thai Government.
  • The US Environmental Protection Agency (EPA) has a ‘toxicity ranking’ with four categories. The EPA warnings are often used on pesticide labels.

The following table compares the three systems:

WHO EPA Thai Government Example
Class Description Category Warning Colour code
Ia Extremely Hazardous I ‘Danger-Poison’ Red label  Methyl Parathion
Ib Highly Hazardous  Methamidophos
II Moderately Hazardous II ‘Warning’ Yellow label  Paraquat
III Slightly Hazardous III ‘Caution’ Blue label  Malathion
IV Unlikely to be
IV None Blue label  Glyphosate
Pesticide label
Label of an insecticide. This one has a red colour code.
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