This exposure study investigated the absorption of glyphosate and Roundup formulations through dermal (skin) and respiratory (inhalation) pathways, challenging the long-held assumption that glyphosate is poorly absorbed through the skin and poses minimal inhalation risk. The study measured actual absorption rates in controlled conditions mimicking real-world agricultural and residential application scenarios.
Results showed that dermal absorption of glyphosate-based herbicide formulations was significantly higher than previously assumed by regulatory agencies. The co-formulants (adjuvants and surfactants) present in commercial Roundup products dramatically increased skin penetration compared to pure glyphosate alone. Respiratory exposure during spraying was also shown to deliver meaningful doses.
These findings are significant because regulatory safety assessments have historically relied on absorption data for pure glyphosate, not the commercial formulations that people actually encounter. The enhanced absorption from real-world products means that actual human exposure may be substantially higher than models predict.
Key Findings
- •Dermal absorption of commercial Roundup formulations was significantly higher than absorption of pure glyphosate alone.
- •Co-formulants and surfactants in Roundup increased skin penetration of glyphosate by a factor of 2-10x.
- •Respiratory exposure during spray application delivered biologically meaningful doses of glyphosate.
- •Real-world exposure scenarios produced higher internal doses than predicted by regulatory models based on pure glyphosate.
- •Both dermal and respiratory pathways contribute to total body burden, even in non-occupational settings such as residential lawn care.
Methodology
The study used in vitro skin penetration assays with human skin samples, along with controlled spray chamber experiments measuring airborne glyphosate concentrations during simulated application. Both pure glyphosate and commercial Roundup formulations were tested. Internal doses were estimated using physiologically-based pharmacokinetic modeling.
Why This Matters for Families
Families should be aware that exposure to Roundup is not limited to eating contaminated food. Simply being near areas where Roundup is sprayed — including neighbors' lawns, parks, school grounds, and playgrounds — can lead to dermal and respiratory absorption. This underscores the importance of advocating for glyphosate-free policies in schools and public spaces.
Original Source
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