Spraying pesticide in California

Pesticides are used to destroy, repel, or mitigate any pests from crops, warehouses,  homes etc.

Various types are there in the market some of which are listed below

Pesticide Target
Algicides or Algaecides Algae
Avicides Birds
Bactericides Bacteria
Fungicides Fungi
Insecticides Insects
Miticides or Acaricides Mites
Molluscicides Snails
Nematicides Nematodes
Rodenticides Rodents
Virucides Viruses

Some of the pesticides are plant derived and some are chemicals

Lets look at the WHO guidelines for classification of pesticides and related Transport regulations for pesticides by ocean going vessels ( IMDG Code )

was approved by the WHO in 1975 and the guidelines were first published first in 1978 and renewed there after every few years.

In 2002, the United nations committee of Experts on Transport of Dangerous goods and the UNCETDG/GHS issued a document called “The Globally Harmonized System of Classification and Labelling of Chemicals”. This document provide guidance for a globally harmonized system to address the classification of chemicals, labelling and safety data sheets.

Basis above, GHS, WHO hazard classes had to be aligned as per GHS Acute Toxicity  for acute oral or dermal as the triggering point for allocating pesticides to WHO Hazard Class.

The revised Document is published by WHO as  The WHO Recommended Classification of Pesticides by Hazard and  Guidelines to Classification 2009

Click here to download above document.

Structure of  The WHO Recommended Classification of Pesticides by Hazard and Guidelines to Classification 2009


This part sets out the basis of classification considering acute risk to health , single or multiple  exposures, that might be encountered by any person handling the product as per the manufactures guidelines.

Basis of Classification

The Classification is based primarily on the acute oral and dermal toxicity to the rat as this is the standard procedure in toxicology.

In practice, the majority of classifications will be made on the acute oral LD50 value. However, dermal toxicity must always be considered since it has been found that, under most conditions of handling pesticides, a high proportion of the total exposure is dermal. Classification based on dermal data in a class indicating a great risk is necessary when the dermal LD50 values indicate greater hazard than oral LD50 values. ( Source WHO )

Revised criteria for classification (Triggered by GHS )

WHO Class LD50 for the rat
(mg/kg body weight)
Oral                 Dermal
Ia Extremely hazardous < 5 < 50
Ib Highly hazardous 5–50 50–200
II Moderately hazardous 50–2000 200–2000
III Slightly hazardous Over 2000 Over 2000
U Unlikely to present acute hazard 5000 or higher 5000 or higher

This  part is consists of 5 tables

Table 1 EXTREMELY HAZARDOUS (Class Ia) active ingredients (technical grade) of pesticides

Table 2 HIGHLY HAZARDOUS (Class Ib) active ingredients (technical grade) of pesticides

Table 3 MODERATELY HAZARDOUS (Class II) active ingredients (technical grade) of pesticides

Table 4 SLIGHTLY HAZARDOUS (Class III) active ingredients (technical grade) of pesticides

Table 5 Active ingredients unlikely to present acute hazard in normal use

In addition, the following tables show the details stated:

Table 6 Active ingredients not included in the Classification and believed to be obsolete or discontinued for use as pesticides

Table 7 Pesticides subject to the prior informed consent (PIC) procedure
Table 8 List of gaseous or volatile fumigants not classified under the WHO Recommended classification of pesticides by hazard

ANNEX How to find the hazard class of a formulation
INDEX by CAS number
by name of active ingredient

Lets look at one of the table and understand what each column is indicating

Table 1. Extremely hazardous (Class Ia) technical grade active ingredients in pesticides


Column 1 : Common Name  [ISO] denotes  common name of the active ingredient approved by the International Organization for Standardization

Column 2 : CAS Registry number

Column 3 : UN Number as per UN Recommendations on the transport of dangerous goods, Eleventh revision     (1999) . UN Number is given only in tables 1,2,3 & 4

Column 4 : Chemical type

Below are the codes and corresponding chemical types

AS Arsenic compound                                

BP Bipyridylium derivative                           

C Carbamate

CO Coumarin derivative

OT Organotin compound
CU Copper compound

HG Mercury compound

NP Nitrophenol derivative 

OC Organochlorine compound

OP Organophosphorus compound

PZ Pyrazole
PY Pyrethroid
T Triazine derivative
TC Thiocarbamate

Column 5 :  Physical state. Refers only to the active ingredient. L denotes liquid, including
solids with a melting point below 50oC; oil denotes oily liquids and S solids, including waxes.

Column 6 : Main use

AC acaricide                                           L larvicide
AP aphicide                                            M molluscicide
B bacteriostat (soil)                                 MT miticide
FM fumigant                                           N nematocide
F fungicide, other than for seed                 O other use for plant pathogens
treatment                                               PGR plant growth regulator
FST fungicide, for seed treatment              R rodenticide
H herbicide                                             RP( ) repellant (species)
I insecticide                                           -S applied to soil: not used with herbicides
IGR insect growth regulator or plant growth regulators
Ix ixodicide (for tick control)                      SY synergist

Column 7: GHS: This column indicates the classification of the pesticide according to
“The Globally Harmonized System of Classification and Labelling of Chemicals” (GHS).

WHO Classification

See The categories for oral and
dermal routes are used

Column 8 : LD50 :

The LD50 value is a statistical estimate of the number of mg of toxicant per kg of body weight required to kill 50% of a large population of test animals: the rat is used unless otherwise stated.

Column 9: Remarks. This column is used to indicate cases in which the classification of a
technical product has been adjusted (i.e., the oral LD50 value is not directly used as the basis
of classification); Major irritant properties are also noted although they do not affect the

Publications mentioned in column 9 can be found at

IMDG Code Requirements

Apart from meeting all the requirements of IMDG Code, when applicable, pesticides requiring technical name to supplement the proper shipping name  ISO common name(s), other name(s) in the WHO Recommended Classification of Pesticides by Hazard and Guidelines to Classification, or the name(s) of the active substance(s) may be used.

Details of classification of pesticides for sea transport can be found in section of IMDG Code

Entry in Dangerous Goods List may have been assigned with Special Provision in which case the stakeholders shall read, understand and ensure consignment meets all the relevant requirements of IMDG Code.

International Code of Conduct on the Distribution and Use of Pesticides, FAO (2003), available at;

Guidelines on Good Labelling Practice for Pesticides, FAO (1995), available at The categories for oral and
dermal routes are used.

Ensure use and disposal of pesticides are carried out in the correct recommended manner and follow all applicable regulations and guidelines.

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