Technical equivalence of pesticide technical materials explained

Active ingredients are traded as technical material (TC) or technical concentrate (TK): material from a manufacturing process that comprises the active ingredient together with its associated impurities [1]. The FAO/WHO manual quotes the International Code of Conduct on Pesticide Management, which defines equivalence as the determination of the similarity of the impurity and toxicological profile, and of the physical and chemical properties, of supposedly similar technical material from different manufacturers, in order to assess whether they present similar levels of risk [1]. This guide follows the manual’s third edition (2025) [1] and the EU guidance document SANCO/10597/2003 [2].

1. Why equivalence matters

A chemical impurity is a by-product of manufacturing the active ingredient, or a substance derived from it during formulation or storage [1]. Which by-products form depends on how the material is made: the EU guidance notes that significant impurities may result directly from the synthesis process and conditions used, or from cross-contamination within the production cycle [2]. The FAO/WHO manual therefore asks for impurity profiles to be defined separately where the manufacturing route differs between sites or the manufacturers differ [1].

The hazard data behind an approval were produced on a particular reference material. The UK regulator describes the purpose of an equivalence assessment as ensuring that a new source is equivalent to, or of no greater hazard than, that reference [3]. FAO/WHO specifications follow the same logic: they do not apply to other manufacturers’ products, or to products made by different processes, unless these have been evaluated as equivalent [1].

A new source is not only a new company. The EU guidance also counts a switch from pilot to industrial scale and a change in the method of manufacture or manufacturing location [2]. The UK regulator adds a change in the technical specification, for example when new, relevant or significant impurities are noted [3].

2. The reference profile

Every equivalence decision needs a benchmark. In the FAO/WHO system it is the reference profile: the purity and impurity, toxicological and ecotoxicological profiles on which the original specification for a technical material is based, generally those of the material with the most complete toxicological and ecotoxicological data [1]. It works alongside the reference specification, the current published FAO or WHO specification, which is the first criterion in determining the equivalence of a later manufacturer’s material [1].

A reference profile is not amended by data from materials later judged equivalent, although a JMPS review may replace it with a new one [1]. Where one manufacturer produces at several sites, five-batch data are required from every site and one site’s profile is identified as the reference profile [1]. The EU guidance speaks of a reference source, the source on which the risk assessment was based and for which the Commission took a regulatory decision; where several exist, a new source is equivalent if it meets the criteria against one of them [2].

3. How the FAO/WHO assessment works

The FAO/WHO Joint Meeting on Pesticide Specifications (JMPS) evaluates hazards to decide which impurities are relevant, to set their limits and to determine equivalence; it does not evaluate the hazards of the active ingredient itself [1].

Equivalence is determined in a two-tiered approach [1]. Tier 1 checks that the material meets the existing FAO/WHO specification and that its manufacturing process, impurity profile and bacterial mutagenicity (in vitro) results meet the Tier 1 criteria in the table below; the same test applies when a producer changes the process of a material already covered by a specification [1]. Where Tier 1 cannot decide on equivalence or non-equivalence, Tier 2 compares toxicological and, where required, ecotoxicological data with the reference profile [1].

An assessment of the proposed material by a competent registration authority is taken into account in Tier 1 [1]. Where a material does not strictly pass these tests but the JMPS considers it of acceptable or improved quality, a modification of the existing specification will be considered [1]. Formulations follow their technical material: classical formulations are generally considered equivalent if the technical material has been judged equivalent and they comply with the same specification, while slow-release formulations such as capsule suspensions may need additional evidence [1].

4. Relevant impurities decide the outcome

A relevant impurity is a by-product of manufacture or storage which, compared with the active ingredient, is toxicologically significant to health or the environment, is phytotoxic to treated plants, causes taint in food crops, affects the stability of the pesticide, or causes any other adverse effect [1].

Relevance is relative: because it is judged against the hazards of the active ingredient, the same compound can be non-relevant in one pesticide and relevant in another [1]. By default an impurity becomes relevant when its concentration in the technical material reaches 10% of its maximum acceptable limit; for mutagens and carcinogens in GHS Category 1A or 1B that threshold is 0.1 g/kg [1]. Relevant impurities occur in certain technical materials only; the manual cites four in malathion technical material and formulated products [1].

This is where equivalence meets the idea of an FAO specification, which is meant to be an international point of reference against which product quality can be judged, for regulatory purposes or in commercial dealings [1]. A specification publishes the minimum active ingredient content and the identity and maximum levels of relevant impurities; information on non-relevant impurities is kept confidential [1]. Only relevant impurities may appear in a specification [1], and their average measured level must not exceed the declared maximum [1]. A new relevant impurity, or a higher limit for an existing one, takes the case to Tier 2 [1].

5. Data usually involved

Tier 1 data cover the identity and properties of the active ingredient, the route of manufacture, the minimum content, impurity limits, information on relevant impurities, intentionally added compounds and bacterial mutagenicity data [1]. Key elements:

• Route of manufacture: solvents, intermediates and catalysts, and a process description (without engineering details) that lets the evaluator check that the claimed purity is plausible [1].
• Five-batch analysis: maximum limits for impurities at or above 1 g/kg, supported by at least five typical batches; recent five-batch studies must be Good Laboratory Practice (GLP) studies [1].
• Relevant impurities below 1 g/kg: limits also supported by at least five typical batches [1].
• Unidentified fraction: typically not more than 20 g/kg of the technical material [1].
• Minimum content: the manual recommends the five-batch mean minus three standard deviations, although other soundly justified proposals may be accepted [1].
• Original study reports: required for batch analysis and mutagenicity data [1].

Tier 2 data cover skin and eye irritation and skin sensitisation and, when the JMPS considers it necessary, 28-day or 90-day repeated-dose studies in rodents [1]. Irritation studies are required only where the proposed minimum purity is below 990 g/kg and the reference material is not a Category 1 eye or skin irritant [1]. Acute oral, inhalation and dermal studies are no longer mandatory for a second manufacturer, which the manual links to animal welfare [1].

6. Other frameworks

European Union

The EU guidance document SANCO/10597/2003 sets out a harmonised procedure for assessing new sources of technical material against the reference source under Article 38 of Regulation (EC) No 1107/2009. The latest revision we could retrieve is rev. 10.1 of 13 July 2012, a Commission working document that does not intend to produce legally binding effects [2]. A new source is equivalent if, due to its impurities, it has the same or less harmful effects than the reference source [2].

The Tier I criteria are: certified minimum purity not lower than the reference source; no new impurities; relevant impurity limits not increased; and non-relevant impurity limits exceeded by no more than 3 g/kg where the reference limit is 6 g/kg or less, or by no more than 50% above that. These quantitative criteria are based on the FAO/WHO manual [2]. A lower minimum purity means the source is not equivalent and needs its own risk assessment; other unresolved cases go to Tier II, where acute toxicity data within a factor of 2 count as equivalent but a more severe hazard classification rules equivalence out [2]. The guidance does not cover micro-organisms or poorly defined substances such as plant extracts [2].

OECD

The FAO/WHO manual notes that the OECD references FAO and WHO specifications in its harmonised recommendations for registration, and the repeated-dose studies in the manual’s Tier 2 refer to OECD test guidelines 407 and 408 [1]. The OECD’s own equivalence guidance (2018) covers microbial pesticides only: changes to the same strain of an already approved micro-organism [4].

China

China’s data requirements for pesticide registration (Ministry of Agriculture Announcement No. 2569, in effect from 1 November 2017) define a same technical material (相同原药) as one whose active ingredient content and other main quality specifications are not lower than those of the registered technical material, and whose impurities cause adverse effects essentially the same as, or smaller than, the registered material’s [5]. Registering an identical pesticide requires an identical-pesticide determination under Annex 10, and the product chemistry data for a chemical technical material include a full composition analysis report and an analysis of how impurities form [5].

7. What it means for buyers of generic technical material

Equivalence belongs to a source, not to an active ingredient name. FAO/WHO specifications apply only to the products of manufacturers whose technical materials have been evaluated, and a significant change in the manufacturing process requires re-evaluation by the JMPS [1]. Regulators likewise treat a new site, process or production scale as a new source [2][3]. Formulators that use an evaluated technical material must declare its source and undertake to notify FAO or WHO if an alternative source is used [1].

For a buyer, the published clauses of a specification are the minimum active ingredient content and the limits for relevant impurities; the rest of the impurity profile behind an equivalence decision stays confidential [1]. Equivalence also has limits: equivalent products are not necessarily suitable for the same uses or of equal efficacy, and equivalence means only that they comply with similar basic quality criteria [1]. The registration in each destination country decides which crops, uses and rates are allowed.

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