Pesticide Registration in the United States, EPA

Registration of pesticides in the USA is covered by OSCPP harmonised test guidelines (835, 850, 860 & 870 series) some of which correspond with OECD guidelines. As in the EU, radiolabelled compounds are required for some studies such as pesticide residues in crops and livestock whilst for others, such as hydrolysis, water photolysis, dermal penetration and in vivo toxicokinetics; they are preferred, especially where information on transformation and mass balance is required.

The EPA set out the data requirements for Pesticides in 40 CFR 158.1410-Residue chemistry data requirements table, covered by Residue Chemistry Test Guidelines OPPTS 860.1300-Nature of the Residue—Plants, Livestock.

The purpose for conducting metabolism studies is to determine the qualitative metabolic fate of the active ingredient when it is applied to a plant or administered to livestock. To obtain this information, the pesticide is radiolabeled, to follow the compound to see if and where it breaks down within a plant or livestock.

Residue Chemistry Test Guidelines OPPTS 860.1850 Confined Accumulation in Rotational Crops are conditionally required under 40 CFR part 158 for uses of pesticides on food crops. The confined study uses radiolabelled material applied to a small plot. Results of these studies are used to determine whether field studies using non-radiolabeled pesticide are needed.

Antimicrobial Pesticides

The Environmental Protection Agency (EPA) regulates all Antimicrobial Pesticides in the USA under the Federal Insecticide Fungicide and Rodenticide Act (FIFRA).

Antimicrobial Pesticides (referred to as Biocides in Europe) are subject to new Data Requirements established in 2013, codified under the Code of Federal Regulations Chapter 40-Protection of the Environment part 158 subpart W.

Antimicrobial Pesticides include disinfectants, fungicides, microbiological water purifiers, santiizers, sterilants, Tuberculocides and Viucides.

Antimicrobial use patterns include both premises and equipment in; Agricultural; Food Handling/storage; commercial; institutional; industrial; and medical. Use in residential and public access premises, swimming pools and aquatic areas is also covered along with use in; human drinking water; industrial processes and water systems; materials preservatives; anti-foul ant paints and coatings; and wood preservatives.

Examples of Data obtained using Radiolabelled compounds PAIRA (Pure Active Ingredient-radio labeled) as the test substance is as follows:

158.2230 Toxicology

Metabolism and pharmacokinetics: PAIRA or PAI (Pure active Ingredient)

Dermal penetration: Choice

158.2280 Environmental fate

Degradation studies Laboratory

Hydrolysis: PAIRA or TGAI (technical grade active ingredient)

Photodegreadation in water: PAIRA or TGAI

Photodegreadation in soil: PAIRA or TGAI

Mobility studies

Leaching and adsorption/de-sorption: PAIRA or TGAI

Metabolism studies Laboratory

Aerobic soil metabolism: PAIRA or TGAI

Anaerobic soil metabolism: PAIRA or TGAI

Aerobic aquatic metabolism: PAIRA or TGAI

Anaerobic aquatic metabolism: PAIRA or TGAI

158.2290 Residue Chemistry

Nature of residues on surfaces: PAIRA or TGAI

Nature of residues in plants: PAIRA

Nature of residue in livestock: PAIRA

Plant metabolism studies are required to determine transformation products that may enter the human diet.

If livestock are exposed to one or more residues differing from those found in animals then one or more additional livestock metabolism studies involving these residues may be required.


Examples of studies using Radiolabeled compounds:

835 2120 Hydrolysis
835 4100 + 4200 Aerobic & Anaerobic Soil Metabolism
835 4300 + 4400 Aerobic & Anaerobic Aquatic Metabolism
835 2410 Photodegradation in Soil
835 1230 Adsorption/Desorption soil
835 2240 Photodegradation in water
835 2370 Photodegreadation in Air
870 7485 Metabolism and Pharmacokinetics
870 7600 Dermal Penetration
860 1300 Nature of the Residue Plants, Livestock
860 1850 Confined Accumulation in Rotational Crops

Information on the Radiolabelled Test Substance can be found on the Nature of the Radiolabelled Test Substance for Registration Studies page.