Vol. 15—1961 - NorthEastern Weed Science Society

changes in populations of various species of aquatic worms, clams, and
various aquatic insects, either shortly after treatment (one week) or six
weeks after treatment. This would certainly indicate that Aquathol would
not adversely affect the fish population by effecting certain aquatic
species either directly effecting the fish or their food chain~ Therefore,
in areas where fish management is a major consideration, this point should
be taken into account.
Considera~:ipn number- four, with respect to chronic toxicity:
'" 1. A two-year chronic study in rats, indicated that at 100,
300, 1000 ppm of disodium endothal in the diet, there was no
significant difference in the survival of the rats or any
indications of intoxication at the above dosages.
2. There was no statistically significant difference in the
weights; however, rats feeding on 1000 ppm of disodium endothal
in the diet showed a lower weight.
Here, I feel that it would be well to go back and review the normal use
dosage which is normally required for control,on an overall aquatic treatment.
This would be 1 to 2 ppm in the water. This foregoing, coupled
with the short residue picture of 48 to 16 hours at 1 to 2 ppm in water,
and even at the maximum dosage of 5 ppm a complete residue disappearance
in four days, would indicate a good safety factor.
The next consideration is with respect to the toxicity to the user and
handler. Aquathol is certainly safer to use than some of the other materials
currently used for aquatic weed control, and other herbicidal and
insecticidal uses. In toxicity tests on rats the oral LD50 for Aquathol
(19.2% solution of disodium endothal) was found to be approximately
200 mg/kg. of body weight. The granular 5% formulation, previously referred
to as Aquathol G, would be correspondingly less.
A 1% solution of disodium endothal (10,000 ppm) was irritating to the
skin without evidence of sensitization. Higher concentrations increased
the degree of skin absorption and toxicity. Under normal recommended
precautions for handling Aquathol this product can be used safely. Once
the material has been applied, there should be no danger of acute toxicity
to either humans or animals. Reasonable precautions considered are as
follows for Aquathol, as well as all other pesticides:
1. Read label warning.
2. Avoid contact with eye and skin with both concentrate
and diluted material as much as possible.
3. Avoid inhaling or breathing dust, granules, or spray.
4. Wash off en)' material spilled, or oth~rwtse applied on
your person, as soon as possible.