Respirator Service Life Estimation Model for Spraying Pesticides
1Veritox, Redmond, WA
An organic vapor service life estimate and change-out schedule was developed for use of solvent-based pesticides modeled on available pesticide exposure data.
Situation / Problem:
Scant data exists on actual solvent exposure during solvent-based pesticide handling and spraying in orchards. Most data available cover exposure to the pesticide active ingredient instead. Solvent exposures are necessary to input into respirator manufacturers' service life algorithm calculators to establish change-out schedules for organic vapor cartridges.
Minimal solvent exposure data could be found through an extensive search of the literature. Original data on exposure to pesticide active ingredients was also challenging to find. Much of the exposure data available was considered proprietary by pesticide manufacturers. Typical exposure dose for workers can be found in the data from the EPA Pesticide Handler Exposure Database in this format: micrograms of active ingredient per pound handled or sprayed (see https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/exposure-surrogate-reference-table-pesticide-risk). Based on the solvent-to-active ingredient ratio in pesticide mixtures, a formula was developed by Veritox to basically work backward from the EPA data to establish the typical total solvent concentration in the air in a worker's breathing zone. Since many solvents used in pesticide formulations are trade secret aliphatic or aromatic naphthas, a single worst-case solvent, such as cumene, was chosen and entered. A safety factor of about 100 was applied to the entry for the typical exposure level (entered as 10 ppm).
Results / Conclusions:
A typical solvent exposure level was estimated for handling almost any solvent-based pesticide based on the pounds used relative to the normalized EPA database. Depending on the solvent involved and the solvent-to-active ingredient ratio, the service life of organic vapor cartridges was estimated and change-out schedules were chosen.
Exposure Assessment Strategies
Acknowledgements and References
List any additional people who worked on the project or provided guidance and support along with details on the role they played in the research. (Please include first name, last name, organization, city, state and country).
I acknowledge the assistance of my Veritox colleague Nadia Moore, PhD Toxicologist, in formulating the conversion from EPA dose data to airborne concentration data.
What learning level(s) is the presentation content geared towards?
Competent - can perform to basic standards; has a thorough understanding of the content area but limited practical/work experience in the application of the content/concepts.
Experienced - has a thorough understanding of the content area and work experience including application and evaluation of the content/concepts in a variety of contexts; can vary performance based on unique situations.
Expert - has extensive content knowledge and deep understanding of their discipline, notices features and meaningful patterns, can reason through new information, can invent new or better ways to do a job.