SOT Spotlight: Q&A with Daniel Kougias

Posted on Behalf of  Daniel Kougias

What is the title of your presentation?

Comparative Evaluation of Passive Dosimetry and Biomonitoring to Assess Glyphosate Exposure with Simulated Heavy Residential Consumer Application of Roundup®

What was the scope of your research?

To comparatively evaluate passive dosimetry and biomonitoring data in estimating internal doses across 12 individuals that simulated heavy residential consumer application. Dermal and inhalation routes of exposure were evaluated separately as half the applicators were protected from dermal exposures (n = 6) and the other half protected from inhalation exposures (n = 6). Serial urine samples were collected from each applicator between 30 minutes prior to and up to 36 hours after the simulated exposure. Two breathing zone air samples and four external dermal patches were worn by the dermally protected applicators. Internal doses of glyphosate were independently estimated from air sampling and dermal patch data (passive dosimetry) and from urinary glyphosate residues (biomonitoring).

What did you find?

Average total internal daily doses of glyphosate estimated from passive dosimetry using observational data and precautionary literature estimates of the exposure factors were roughly 5- to 7-fold greater than those estimated from biomonitoring. This total internal dose overestimation was allocated exclusively to the dermal pathway, suggesting uncertainty in dermal absorption, clothing penetration, and/or the number and location of patches used in this study. Regardless of the source(s) of positive bias in the total dose estimates from passive dosimetry, the highest individual internal daily dose of glyphosate derived from passive dosimetry was still below the internal daily dose estimated from the most conservative health-based guidance values (60 mg/kg/day), suggesting little to no concern of any adverse health effects associated with residential glyphosate-containing herbicide use.

What are the next steps/what other research is needed?

To our knowledge, this is the first study to compare internal glyphosate doses estimated from simultaneously collected biomonitoring and passive dosimetry data within the same study population that either isolates inhalation versus dermal exposures or has detectable urinary glyphosate concentrations. Considering that this is a pilot study, large-scale studies may be necessary to corroborate these findings.