Probabilistic Exposure & Risk Model for Fumigants

Exponent consultants help chemical applicators determine chemical buffer zones to help meet EPA requirements


The Probabilistic Exposure & Risk Model for Fumigants (PERFUM) developed by Exponent scientists is approved by the Environmental Protection Agency to assist in estimating buffer zones following pesticide applications to protect bystanders and ecological species.

Estimate buffer zones for fumigant and pesticide applications that satisfy EPA requirements

Exponent scientists Richard Reiss, Sc.D., and John Buonagurio developed the Probabilistic Exposure & Risk Model for Fumigants (PERFUM) in response to an EPA request for a tool to estimate air concentrations and buffer zones following pesticide applications.

PERFUM helps protect human bystanders and ecological species

In farming applications, pesticides, including fumigants, are applied by licensed chemical applicators to improve crop yields and minimize losses to insects, invasive weeds, or diseases. These volatile or semi-volatile chemicals may off gas following application and expose bystanders or ecological species. To reduce potential harm to humans and protect the ecology and biodiversity of the surrounding areas, EPA sometimes requires buffer zones to prevent harmful exposures.

Exponent consultants developed the PERFUM model to help commercial crop dusters and licensed chemical applicators determine chemical buffer zones per EPA requirements.

PERFUM is a practical tool for estimating air concentrations and buffer zones after pesticide applications

Exponent's Dr. Reiss and Mr. Buonagurio developed PERFUM as a practical tool to address the regulatory need to establish buffer zones for some fumigants. A buffer zone defines a distance from the edge of the field where the concentration of the fumigant is at or below a level assumed to be safe. Over time, PERFUM has been used to estimate bystander exposure for building fumigations and for agricultural applications of semi-volatile pesticides.

The evolution of the Probabilistic Exposure & Risk Model for Fumigants

  • Summer 2004: First version of PERFUM submitted to EPA.
  • August 2004: EPA convened a Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) to review the model, finding it to be "scientifically sound." It has been updated several times since the original SAP.
  • June 2006: A peer-reviewed article describing the model published by Reiss and Griffin in Atmospheric Environment.

PERFUM 3.0 includes new capabilities for dispersion calculations, including AERMOD, CALPUFF, and ISCST3

  • The current version of the model, PERFUM 3.0, includes the capability to use AERMOD or CALPUFF, in addition to ISCST3, for dispersion calculations.
  • The downloads below include the files needed to run PERFUM as well as the User's Guide, and the PERFUM Version Control File.

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