1. New scientific concepts to improve the regulatory assessment of pesticide toxicity
The case of glyphosate
Robin Mesnage, PhD, King’s College London, UK
PEST Committee
Public Hearing on 28 June 2018 from to in Brussels

2. Human exposures to glyphosate are rising
Glyphosate-based herbicides are the most heavily applied herbicide in the world and usage continues to rise
Human exposures to glyphosate are rising
Is glyphosate health risk assessment reliable?

3. 1/ Chronic effects of commercial formulations have to be tested
Glyphosate
Co-formulants
Glyphosate health risk assessment
Tested alone to calculate acceptable daily intake
Not included in glyphosate acceptable daily intake calculation
The company asking for the pesticide commercialization is free to choose the molecule that they want to declare as an active principle.

4. If the toxic agent is not glyphosate, then what is it?
Are you sure co-formulants of pesticides are safe and do not need to be tested?
Glyphosate formulations are up to 1000 times more toxic than glyphosate alone
Formulations
X 1000
X 1
Glyphosate
If the toxic agent is not glyphosate, then what is it?

5. We have tested toxicity and measured the composition
of 9 Roundup formulations, their co-formulants,
and glyphosate on human cells
The toxicity was proportional to the concentration in co-formulants
The toxicity of glyphosate commercial formulations was due to co-formulants and not to glyphosate itself

6. Chemicals used as co-formulants can be among the most toxic pollutants in the environment
Some adjuvants are associated with birth defects among populations exposed to pesticides (Carmichael et al, 2013)
Some surfactants in rivers cause gender disturbances in fish,
which affects reproduction
(Jobling et al., 2009)
Some highly toxic co-formulants are found in beehive samples and honey, and could be involved in bee colony collapse disorder
(Chen and Mullin, 2014)

7. 1/ Pesticides should be assessed as whole mixtures
What can be done?
1/ Pesticides should be assessed as whole mixtures
Whole-mixture approach is recommended for any unidentified materials in the mixture and for any interactions among mixture components
(EU Scientific committees, 2011)
2/ Adding a safety factor to glyphosate acceptable daily intake
Proposed ADI calculation :
Toxicity threshold in laboratory animal: 50 mg/kg/day
Safety factor for population variability and species differences of 100: 0.5 mg/kg/day
+ Adjuvant safety factor of 10: 0.05 mg/kg/day

8. from endocrinology (hormone dosages)
What else can be done to improve EU pesticide risk assessment?
2/ Some pesticides are suspected endocrine disruptors. Studies should incorporate testing principles
from endocrinology (hormone dosages)
3/ Future studies should use designs that examine the full lifespan of the animal, including a prenatal period
4/ New studies should be performed to test the effects of pesticides on the gut microbiome

9. The human body is a complex ecosystem
… 38,000,000,000,000 bacteria in the human body
Changes in human gut microbiome composition have profound effects on human health
Cani et al., (2017) Nat Rev Gastroenterol Hepatol. 14:

10. Glyphosate effects on the gut microbiome?
… suggests that Roundup could cause an alteration of the gut microbiome
A new study testing the effects of glyphosate and glyphosate-based herbicide on the gut microbiome in a larger cohort of rats is ongoing

11. Open-access publications on the topic:
Twitter: Robin_Mesnage Thank you for your attention!
Open-access publications on the topic:
Mesnage R, Antoniou MN (2018) Ignoring Adjuvant Toxicity Falsifies the Safety Profile of Commercial Pesticides. Front Public Health. 5:361.
Mesnage R, Antoniou MN (2017) Facts and Fallacies in the Debate on Glyphosate Toxicity. Front Public Health. Nov 24;5:316.
Myers JP et al. (2016) Concerns over use of glyphosate-based herbicides and risks associated with exposures […] Environ Health. 15:19.