Before a new active substance can be tested in complex studies, its identity, composition, and chemical and physical properties must be documented. This applies to the active substance, all significant metabolites and all formulated products. All test requirements are described in detail in OECD, EU, J-MAFF, US-EPA, or CIPAC guidelines.

To obtain efficacy information, extended field or greenhouse testing is needed. Field tests must be conducted in several growth areas and climatic zones. Efficacy must be demonstrated for all target organisms and for all formulations intended for marketing. Field studies are often conducted by local specialized field trial contractors or by government affiliated agricultural research stations. To conclude this work successfully, a good strategy and careful planning is required. It can be time consuming and expensive when formulations or application rates are changed half way through the development program.

Validated analytical methods must be submitted to the authorities for each active ingredient and the relevant metabolites. Validations are required for methods used during the development phase and also for monitoring after a registration is granted. These "enforcement methods" are intended for use by government laboratories for monitoring product quality and residues in food, feed and the environment.

Toxicology studies are required for the active substance and all plant protection products. The studies must be carried out in compliance with GLP. Monitoring of toxicity studies and assessment of toxicology requires special expertise and experience. After critical observations during a study, a second expert opinion can help to find solutions. "Negative" findings must be discussed immediately and can be addressed by modifying the strategy.

Food safety is a key issue in modern society. Tests with plant protection products are required to determine the risk of residues in the raw agricultural commodity (RAC) and the processed products. The first step is to identify the critical crops and the compounds for which residue studies must be conducted.

The breakdown and reaction products (metabolites) must be identified in treated plants, food animals and products obtained by processing of the RAC. These studies are often carried out with C-14 labeled test substance. These studies provide the Residue Definition. This is a critical step in the development program, since an incorrect residue definition can lead to long delays and high additional costs.

After the significant compounds are identified, the field studies are conducted to determine experimentally the level of residues in crops that were treated according to good agricultural practice (GAP). Field trials are required in 4 different locations in typical growth areas and in different climate zones. The program must be repeated in a second year.

Samples of the crops are sent to the analytical laboratory and analysed for residues of all compounds included in the residue definition. Other samples of the crop are shipped to specialized food processing labs. Typical food products are produced to assess the degradation or accumulation of residues during processing.

All crop protection chemicals that can come into contact with the environment are subject to an environmental risk assessment. The basis for this risk assessment is provided by data from environmental fate studies that are carried out in the laboratory or under field conditions.

Usually the fate (adsorption, degradation and metabolism) must be studied in soil, water and sediments. The laboratory studies are frequently performed with 14C-labelled substances.A large study program is required to study the fate in soil. Mobility in soil is studied under laboratory, semi-field (lysimeter) or field conditions.

Model calculations can support the conclusions and are an integrated part of the risk assessment. Authorities can ask for field monitoring studies during normal use of the product to support the conclusions of the laboratory studies.

 

The second component of an environmental risk assessment for plant protection products which can come into contact with the environment are ecological toxicity tests. Monitoring and interpretation of higher tier ecotoxicity studies requires extensive experience and expertise.