The toxicity of the active compounds in herbicides is used to determine regulatory guideline concentrations, because other components are considered inert. Glyphosate, the active molecule in the herbicide Roundup, was described as an endocrine disrupter because non-cytotoxic concentrations inhibited progesterone synthesis in vitro. Human chorioplacental JAr cells synthesise progesterone in vitro, and increase synthesis when stimulated by chorionic gonadotrophin (hCG), or the transduction molecule cAMP.JAr cells were exposed to two Roundup formulations, and compared with the same concentrations of glyphosate ±cAMP, or ±hCG for 1, 4, 24, 48 or 72h. The surviving viable cells were quantified using an MTT assay, and progesterone was measured in an ELISA.hCG and cAMP stimulated progesterone synthesis as expected. Roundup was more cytotoxic than glyphosate alone; the 24h EC50 was 16 mM for glyphosate, but 0.008 mM when glyphosate was in a 7.2 g/L Roundup formulation. Significant cytotoxicity was caused by glyphosate in Roundup (p<0.01) after 24h, and cytotoxicity was observed in vitro after exposure to a range of concentrations comparable to the Australian Drinking Water Guidelines. In contrast to previous reports, JAr cell death preceded decreased progesterone synthesis, and steroidogenesis was unaffected by low, non-cytotoxic concentrations of Roundup or glyphosate.Endocrine disruption effects were secondary to cytotoxicity. Roundup was more cytotoxic than the same concentration of glyphosate alone, indicating that the other constituents of the herbicide are not inert. There is a need for in vivo studies to characterise the toxicity of glyphosate in a Roundup formulation, to facilitate re-evaluation of existing public health guidelines.
|Number of pages||7|
|Journal||Integrative Pharmacology, Toxicology and Genotoxicology|
|Publication status||Published - 4 Apr 2015|
Bibliographical note©2015 Young F. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
- regulatory guideline concentrations
- endocrine disrupter