4.2 Names and composition of pesticides

From a legal point of view, one of the main methods of communication between an agrochemical company and the user is the product label.

The most noticeable words on the label will usually be the trade name (or brand), and of course it is in the chemical company’s interest to promote its particular brand of pesticide.

However, it is the active ingredient (AI: also called the active substance) and its concentration that is of most interest from the point of view of efficacy, safety and residue tolerances.

Routine use of brand names can cause confusion because:

Often (and increasingly) the brand name represents a product containing a mixture of active ingredients;
Different brand names may be used for the same product in different countries and languages;
Active ingredients - especially of successful products - may be changed over time;
The formulation names (and numbers used in the name) may not conform to international standards.

Labels should also give the chemical name - which follows rules of nomenclature set by the International Union of Pure and Applied Chemistry (IUPAC) as adapted for indexing in Chemical Abstracts.

In practice, the common names (for which there are ISO standards) are generally used for describing active ingredients.

For example, a commonly used pyrethroid insecticide, used on cocoa is:

Common Name (ISO) - lambda-cyhalothrin - which is easier to remember than the …
Chemical Name - of two stereoisomers: (S)-α-cyano-3-phenoxybenzyl (Z)-(1R,3R)-3-(2-chloro-3,3,3- trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and (R)-α-cyano-3-phenoxy-benzyl (Z)-(1S,3S)-3- (2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate
Trade names are numerous (especially now that the patent for the compound has expired) but they include ‘Karate’, ‘Kung Fu’ and ‘Matador (as used by the same company in different countries) [1].

Fig. 4.1 A pesticide label: the active ingredient and its concentration (in this case a 200 g/l imidacloprid SL formulation) are often in very small writing. Precautions are often described in the form of pictograms (pictures at the bottom right of this label)

4.2.1 Active ingredients (AI), composition, formulation

For the purposes of toxicology, residue analysis and efficacy, it is the AI, as described by its ISO common name that will be the focus of scientific analysis. However, pesticide products very rarely consist of pure technical material.

The AI is usually formulated with other materials and this is the product as sold, but it may be further diluted in use. Formulation improves the properties of a chemical for: handling, storage, application and may substantially influence effectiveness and safety.

Formulation terminology should follow a 2-letter convention, e.g. GR: granules, listed by CropLife International (formerly GIFAP then GCPF) in the Catalogue of Pesticide Formulation Types (Monograph 2 [2]), also recognised by FAO.

Some manufacturers still fail to follow these industry standards, which can cause confusion for users.

By far, the most frequently used products are formulations for mixing with water, then applying as sprays.

Water miscible, older formulations include:

Emulsifiable concentrate EC
Soluble (liquid) concentrate SL
Wettable powder WP
Soluble powder SP

Newer, non-powdery formulations with reduced or no use of hazardous solvents and improved stability include:

Suspension concentrate SC
Capsule suspensions CS
Water dispersible granules WG

Fig. 4.2 The major groups of pesticide formulations can be illustrated as follows

Very occasionally, some pesticides (e.g. malathion) may be sold as technical material (TC - which is mostly AI, but also contains small quantities of, usually non-active, by-products of the manufacturing process).

Ultra-Low Volume (ULV) techniques that use oil-based solution (UL) or suspension (OF) formulations have yet to be extensively tested in cocoa, although fogging techniques were used in certain countries having large cocoa plantations.

Dusts (DP) are now rarely used and known to be inefficient and hazardous (replaced with micro-granules or MG for other crops such as rice).

In the EU, formulation materials are now covered by new regulations called REACH [3] (EC 1907/2006), designed to promote the use of alternative methods for the assessment of the hazardous properties of substances; several chemical groups previously used in pesticide formulations (e.g. Alkyl Phenol Ethoxylate or APE surfactants) have been disallowed.