Toxicity Of Roundup To Australian Freshwater Crustaceans
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Toxicity Of A Herbicide To Australian Freshwater Crustaceans
Date:
Thu, 19 Sep 2002 09:14:49 -0400
From:
Stephen Tvedten <steve@getipm.com>
Organization: Get Set Inc. (www.getipm.com)
To: Paul Helliker <phelliker@cdpr.ca.gov>
Director, State of California, Department of Pesticide
Regulation
cc: Christine Whitman whitman.christine@epa.gov
THE TOXICITY OF A HERBICIDE TO AUSTRALIAN FRESHWATER CRUSTACEANS
Dayanthi Nugegoda, Kristen Hayes, Leah Thompson and Kirsty Thomassen
Department of Applied Biology and Biotechnology, RMIT University.
Herbicides are commonly used as an economical and effective method for the control of weeds and excessive vegetation. This has led to an increase in the number of herbicides being developed for use and their subsequent introduction to the environment. Since many herbicides are formulated to be soluble there is increasing contamination of freshwaters with these chemicals. Legislation requires that these herbicides be tested for their toxicity to aquatic species. However many of these tests are conducted in laboratories affiliated to the manufacturer and involve only a few standard test organisms. Herbicides used in Australia are not routinely tested on Australian species before widespread use. Many endemic crustacean species in Australian freshwaters are increasingly exposed to herbicides and it is vital that research be conducted on both the acute and chronic toxicity of these formulations to such non-target species. In Australia, one of the most commonly used herbicides is 'Roundup', manufactured by the Monsanto Co. U.S.A. Roundup is a non-volatile, water-soluble liquid herbicide which is non-selective. Roundup has an active ingredient of N-phosphonomethyl glycine as the isopropylamine salt, which is more commonly known as glyphosate. Glyphosate has been hailed as the most important herbicide ever developed (Neskovic et. al, 1996) and several formulated products of glyphosate are used in both agricultural and non-agricultural situations. The effect of glyphosate on plants is interference with the formation of aromatic amino acids (Sammons et al. 1995) and it was deemed to have no effect on animals. However there is increasing evidence that formulations based on glyphosate as the active ingredient are toxic to invertebrates. Some of this toxicity has been attributed to the surfactants/dispersants used in the formulations (Folmar et. al 1979, NRA, 1996). This paper reports on the toxicity of Roundup to three species of Australian freshwater crustaceans. The research does not attempt to isolate the active ingredient from the formulated product. We are of the view that it is the entire formulation that is sprayed in the environment and therefore of concern with regard to its effect on non-target species and of relevance in ecotoxicology. The native crustaceans tested were the daphnid Daphnia carinata, the freshwater shrimp Parataya australiensis and two-week old postlarvae of the freshwater crayfish (the Australian 'yabby') Cherax destructor. Predictably Roundup was very toxic to D. carinata with an estimated 48 hour LC50 of 13.2 mg glyphosate/l (0.037 ml/l of Roundup). The 48 hour LC50 of Roundup to the adult P. australiensis was estimated to be much higher at around 700 mg glyphosate/l while the acute toxicity of Roundup to two week old C. destructor ranged between 0.4 and 8 mg glyphosate/l (120 hour LC50) with interbrood variability. The recommended agricultural application rate for Roundup which is 5-7ml/l at the rate of 2-3 l/ha (Monsanto, 1986) may therefore pose an ecological risk to Australian native freshwater crustaceans if sprayed too close to inland aquatic systems. The sublethal toxicity of Roundup to D. carinata was also investigated in 21 day experiments using the citeria: number of broods produced, age at maturity, mean brood size and length. All parameters tested were significantly affected by dissolved Roundup. Results also indicate that Australian native freshwater crustaceans are more sensitive to this herbicide than similar Northern Hemisphere species. It is recommended that further sublethal toxicity testing of agricultural chemicals be conducted and that herbicides and pesticides be routinely tested on non-target native species.
References:
- Folmar, L.C., Sanders, H.O. and Julin, A.M., 1979. Toxicity of the herbicide glyphosate and several of its formulations in fish and aquatic invertebrates. Archives of Environmental Contamination and Toxicology, 8:
- Monsanto, 1986. Roundup herbicide and Roundup CT broadacre herbicide Material Safety Data Sheet ( MSDS).
- Neskovic , N.K., Poleksic, V., Elezovic, I.,Karan, V. and Budimir, M. 1996. Biochemical and histopathological effects of glyphosate on carp, Cyprinus carpio L. Bulletin of Environmental Contamination and Toxicology, 56.
- NRA, 1996. NRA special review of glyphosate 96.1. Sammons, D.R., Gruys, J.K., Anderson, K.S., Johnson, K.A. and Sikorski, J.A. 1995. Re-evaluating glyphosate as a transition-state inhibitor ofEPSP synthase.
Well Mr. Helliker, it is obvious to me that you need to thoroughly test your various POISONS before you "register" them.
Respectfully, Stephen L. Tvedten
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