The Project's current studies are focusing on the herbicide Roundup and being conducted in collaboration with the UC San Diego
Rancho Bernardo Study of Healthy Aging (RBS), which is a prospective population-based study of older adults residing in a Southern California community.
In response to the need for longitudinal data examining how glyphosate exposure might have changed over the decades since the widespread introduction of GM foods, we measured excretion levels of glyphosate and its primary metabolite aminomethylphosphonic acid (AMPA) in 100 participants from the RBS in samples obtained between 1993 and 2016. The mean participant age at the 2014-2016 sampling is 78.0 years (SD=6.6) (range 60-97).
We found that the mean glyphosate level increased from 0.024 μg/L in 1993-1996 to 0.314 μg/L in 2014-2016, and reached 0.449 μg/L in 2014-2016 for the 70 participants with levels above the LOD (see Table below).
AMPA levels increased from 0.008 μg/L in 1993-1996 to 0.285 μg/L in 2014-2016, and reached 0.401 μg/L in 2014-2016 for the 71 participants with levels above the LOD (see Table below).
The prevalence rates of glyphosate samples above the LOD increased significantly over time, from 0.120 [95% CI=0.064, 0.200] in 1993-1996 to 0.700 [95% CI, 0.600, 0.788] in 2014-2016 (Wald statistic = 80.5, p<0.001).
The prevalence of AMPA samples above the LOD increased significantly from 0.050 [95% CI, 0.016, 0.113] in 1993-1996 to 0.710 [95% CI, 0.611, 0.796] in 2014-2016 (Wald statistic = 103, p<0.001).
In summary, we found that mean glyphosate and AMPA levels as well as the proportion of samples with detectable levels increased over time. Animal and human studies suggest that chronic exposure to glyphosate-based herbicides can induce adverse health outcomes (Myers et al, Environ Health, 2016). Animals chronically fed an ultra-low dosage of Roundup with a 50ng/L glyphosate concentration show hepatotoxicity consistent with non-alcoholic fatty liver disease and its progression to steatohepatosis (Mesnage et al., Sci Rep. 2017) . In July 2017, in accordance with the Safe Drinking Water and Toxic Enforcement Act of 1986, the state of California listed glyphosate as a probable carcinogen.
Next steps in the
Herbicide Awareness and Research Project will be to expand the sample size of the study and examine potential linkages between the observed rising levels of glyphosate and AMPA and clinically-relevant outcomes.
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