Definition of Standards for Active Constituents

The Australian Pesticides and Veterinary Medicines Authority (APVMA) has overall responsibility for the regulation of active constituents used in agricultural and veterinary chemical products. Section 14 of the Agricultural and Veterinary Chemicals Code Act (Agvet Code) requires that, before granting an application for approval or registration, the APVMA must be satisfied with regard to the matters mentioned in subsection 14(3)(e) i.e. the use of the active constituent or chemical product will not have a harmful effect on human health, the environment, occupational health and safety, or trade, and that the product is effective for its intended use. In particular, the APVMA is required to separately approve active constituents. An integral part of the evaluation process for an active constituent is the assessment of the chemical composition of the active constituent.

To a large degree, the safety, efficacy and environmental impact of agricultural and veterinary chemical products are dependent on the composition of the active constituents. Upon completion of the approval process a standard for each approved active constituent is established. This typically specifies the minimum purity of the active constituent, and the ratio of isomers/diastereosiomers where relevant, and the maximum level of the relevant impurities, including those of toxicological significance.

Active constituents used in an agricultural chemical product may be required as a condition of the product registration to meet the APVMA standard for that active on an ongoing basis.

In relation to the standard for an active constituent, the mean measured active constituent content of the active constituent shall not be lower than the minimum purity specified in the standard, with no allowed analytical deviation to batch analyses. Where the standard is for an impurity, maximum criteria apply. Where an active constituent has a number of possible isomeric forms, the overall purity of the active constituent, as well as the relative amounts of isomers, may be important. Differences in the relative proportions of the isomeric forms of an active constituent can, and often do, have toxicology and efficacy consequences. Where the isomeric composition of an active constituent is toxicologically relevant, this has been included in the standard for that active constituent.

In some cases, the active constituent is not isolated, and a manufacturing concentrate is prepared by addition of non-active (inert) constituents such as solvents and/or stabilisers. For most manufacturing concentrates it is not practical to recommend a standard for the active constituent content because this can be varied by dilution or concentration of the material. The active constituent content alone does not necessarily reflect the overall quality of the manufacturing concentrate. Batch analysis data on the manufacturing concentrate and on a dry weight basis are required to ensure that undesirable impurities are not present in the manufacturing concentrate.

Toxicologically Significant Impurities

In addition to the situations where maximum impurity standards are listed for specific active constituents, a general list of impurities and classes of impurities of toxicological concern has been prepared. As these impurities can have adverse impact on the human health and/or the environment, the APVMA requires that registrants provide information on the identities and concentration of the impurities in the active constituent. A list of substances and classes of substances to which this applies include:

  • Anilines and substituted anilines
  • Dimethyl Sulphate
  • Dichloro diphenyl trichloroethane (DDT) and DDT related impurities
  • 2,3-diaminophenazine (DAP) and 2- amino-3-hydroxyphenazine (AHP)
  • Ethylene thiourea (ETU) and propylene thiourea
  • Halogenated dibenzodioxins and halogenated dibenzofurans
  • Hexachlorobenzene (HCB)
  • Hydrazines and substituted hydrazines
  • Methyl isocyanate
  • Nitrosamines
  • Oxygen analogues of organophosphates
  • Polychlorinated biphenyls (PCBs)
  • O,O,O',O'-tetraethyl dithiopyrophosphate (S,S-TEPP or Sulfotep) and O,O,O',O'-tetraethyl monothiopyrophosphate (O,S-TEPP)
  • Sulfoxides and sulfones of organophosphates and carbamates
  • 3,3',4,4'-tetrachloroazobenzene (TCAB) and 3,3',4,4'-tetrachloroazoxybenzene (TCAOB)

If you have any queries concerning the standards for active constituents, please contact:

Pesticides Chemistry

Phone: +61 2 6210 4748

Fax: +61 2 6210 4840

Email: pestchemistry@apvma.gov.au

Last updated on 15 October, 2013

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