Pesticide Registration Toolkit

HHP Criteria 1: WHO class Ia & Ib

Definition and reference

Pesticide formulations that meet the criteria of Classes Ia or Ib of the WHO Recommended Classification of Pesticides by Hazard

Ia = extremely hazardous
Ib = highly hazardous

The WHO classification is primarily based on the acute oral and dermal toxicity of the pesticide. In rare cases, chronic toxicity has also been taken into account.



Identification procedure​

It is the formulated pesticide product that should be classified. If acute LD50 values are available for the formulated product (e.g. in the registration dossier), classification can be done directly based on these values.

Alternatively, the product is classified based on the LD50 values of the active ingredient (A.I.) and the concentration of the A.I. in the product (Equations are provided in the WHO classification guidance – the HHP Identification Tool will conduct these calculations). 

Both oral and dermal toxicity of the pesticide formulation should be classified; the strictest classification of these two will prevail for HHP identification.

It is often useful to cross-check the LD50 values provided in the dossier with those provided in reputable pesticide property databases. Small differences would be normal; large differences may require clarifications by the applicant.

Data sources

LD50 values - Formulated product

Pesticide registration dossier → LD50 of the formulated product (“6-pack”) LD50 values – Active ingredient(s) (A.I.)

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