Database Structure

The final product of the ARTF was a generic Transfer Coefficient (TC) database that could be used by ARTF member companies and regulatory agencies for doing risk assessments. The database consisted of 28 clusters of specific crop activities that were expected to involve similar transfer of residues from treated crops to the worker performing those activities.  Each of the 28 clusters were represented by one or more studies and a set of TCs for various body parts.  The database could be searched by crop and/or reentry activity with the output being several cluster TCs and associated statistics such as arithmetic and geometric means and standard deviations. The body part TC data could be used to determine the distribution of exposure across the body.


TC data along with product-specific DFR decline curves and toxicology data
are used to calculate the Safe Residue Level (SRL) for each crop and activity associated with the use of each pesticide product.  The crop- and activity-specific SRL is achieved when the DFR has declined to a level that will produce an exposure equal to or less than the USEPA Reference Dose (RfD) or some other applicable toxicity endpoint for that specific active ingredient.  The number of days that it takes to achieve this SRL is called the Restricted Entry Interval (REI) defined as the number of days (or hours) that must pass after the pesticide application before a worker can safely reenter the treated crop to perform that activity.