NIOSHTIC-2 Publications Search

Calculating Reentry Times from Kinetic Data.

NIOSH 1976 May:8 pages
The problem of estimating safe reentry time from pesticide residues on leaves of plants was discussed. Studies have indicates that safe reentry times can be calculated from straight forward chemical data and do not require the exposure of humans to procure them. The calculations depended both on the rate of loss of residues on foliage and enzyme activity, or any other kinetically describable physiological change. Other studies have indicated that the rate of cholinesterase activity lost from the blood of subjects exposed to pesticide residues was of the first order with respect to pesticide concentration and that the rate of loss of pesticide residue on foliage was also of first order with respect to residue concentration. The author indicates that it is possible to calculate the time before individuals can enter treated fields from the loss of residues on the foliage determined for each of the days following application. The data taken from cholinesterase activity in human subjects could also be gained by the exposure of different mammalian forms to these cholinesterase inhibitors in laboratory experiments. If organophosphate pesticides produce similar physiological effects in test animals and in man and the relative toxicities are comparable in both systems, then it is possible to calculate the loss in enzyme activity in man from the loss of enzyme activity in the animal. An example of such calculations was provided.
Pesticides; Agricultural-chemicals; Agricultural-workers; Farmers; Safety-practices; Laboratory-animals; Enzyme-activity; Metabolic-study; Organo-phosphorus-pesticides;
Publication Date
Document Type
Conference/Symposia Proceedings;
Fiscal Year
Source Name
Pesticide Residue Hazards to Farm Workers
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division