Indeed, due to many factors that may influence the test results
it is often difficult to compare data originating from different literature
sources. According Giesy et al. (2000), data reported on
the short-term toxicity of glyphosate and its formulated products
for the aquatic organisms vary remarkably: (1) microorganisms
(3–7 day EC50 0.64–590 mgAE L−1); (2) macrophytes (7–14 day
EC50 1.6–25.5 mgAE L−1); (3) invertebrates (2–10 day EC50 7 –
>1000 mgAE L−1); (4) fish (2–4 day LC50 5.8 – >1000 mgAE L−1).
The large variation of toxicity values may be mostly explained
by the wide variety of the tested glyphosate-based herbicides but
also by different test organisms, test conditions (temperature, test
media) and test designs. In addition, there is a number of different
formulations with analogous brand name (e.g. Roundup),
which exhibit varying degrees of toxicity (Nandula, 2010). The
toxic effect is a resultant of all the components in the formulation,
incl. so-called “other additives”. The unknown additives (e.g.
up to 5% of weight in case of Roundup QuickTM used in this study)
may also modulate the toxicity of the main components (active
compound and surfactant) of herbicide formulations to aquatic
species. Moreover, it is often not clear whether the toxicity data
of glyphosate-based herbicides in literature are presented as the
toxicity of the whole formulation or expressed as the acid equivalent,
complicating the comparison with the existing information
on the toxicity