Frequently Asked Questions
Following are some frequently-asked questions about how rotenone might affect humans, pets, wildlife, and the environment.
- How is rotenone applied?
- How can I understand rotenone toxicity?
- Is there any risk from accidentally drinking water treated with rotenone?
- Can we eat fish treated with rotenone?
- Will pets or wildlife that eat fish and drink water treated with rotenone be affected?
- What about nesting birds?
- What if the rotenone gets into the air?
- What will happen to the dead fish after treatment?
- If it's too cold and daylight is too limited to neutralize rotenone by warmth or sunlight, how else can it be neutralized?
- Does rotenone smell?
- Who can I contact for more information?
How is rotenone applied?
Rotenone can be applied in either a wettable powder or liquid form. Depending on lake characteristics, rotenone is typically pumped into the water from a boat. The propeller wash from an outboard motor or pumps can help circulate the rotenone through the water. Backpack sprayers can also be used to apply rotenone to wetland areas or small tributaries.Back to top
How can I understand rotenone toxicity?
CFT Legumine™ is the rotenone formulation under consideration for use by the Department.
Pesticides are controlled by the U.S. government which requires toxicity to be tested according to strict standards. The Environmental Protection Agency requires all pesticide manufactures to test their products and publish a fact sheet about their testing. This fact sheet is called a Materials Safety Data Sheet (MSDS). The MSDS must show the smallest amount that would kill 50 percent of the test organisms, which is called the "LD50". Furthermore, the LD50 must be shown so that people can compare the test results organisms to humans. See more information on the Manufactures website for rotenone.
Millions of dollars have been spent to verify the safety of rotenone so it could be registered and licensed by the EPA. The EPA has concluded that the use of rotenone for fish control does not present a risk to humans or the environment when used according to the label instructions.Back to top
Is there any risk from accidentally drinking water treated with rotenone?
It is not recommend that you drink rotenone-treated waters and the public will be made aware of this through signage and news releases. However, even if people were somehow unaware of the warning and accidentally drank water containing rotenone used to control fish, the risks would be very slight because of the low concentrations used. The EPA states rotenone concentrations <40 parts per billion are safe to drink and most rotenone treatments conducted in Alaska result in rotenone concentrations below that level. Rotenone is not readily absorbed by mammals that consume it. It is estimated that a 160-pound person would have to drink about 23,000 gallons of rotenone-treated water to receive a lethal dose.Back to top
Can we eat fish treated by rotenone?
You are strongly cautioned not to eat fish that have been treated with rotenone because no federal or state guidelines are in place for eating fish taken after rotenone treatment. Also, salmonella and other bacteria may grow on any fish that is not properly preserved, such as fish that have been floating in a lake for some time, making them unsafe to eat.
Why is there no risk from eating fish that have been stocked after treatment?
Fish are not re-stocked into waters treated with rotenone until the rotenone has neutralized. If they were, the un-neutralized rotenone would kill them. Even if trace amounts of rotenone remain, and even if the fish are particularly resistant, the rotenone levels will not last for more than several days because the fish quickly metabolize and excrete the trace amounts of rotenone. Rotenone cannot bioaccumulate in fish.Back to top
Will pets or wildlife that eat fish and drink water treated with rotenone be affected?
To control fish, rotenone is used in very low concentrations. Rotenone residues in treated fish are generally very low, are broken down quickly, and are not easily absorbed through the gut of the animal eating the fish. Birds, cats, dogs, and other mammals that eat treated fish and drink treated water will not be affected. If animals eat fish or drink the treated water, rotenone will be broken down by the strong enzymes naturally present in their stomachs and intestines.
Birds and mammals that rely on the former fish population may be affected slightly because of the temporary absence of fish, but they usually find other food. In Southcentral Alaska, northern pike are not typically a major prey source for other wildlife.
However, animals with gills, such as tadpoles and some aquatic insects, are more susceptible because rotenone is absorbed directly into their bloodstream through the gills. Studies have shown that those animals will naturally repopulate an area after the rotenone neutralizes. The Department can further mitigate this by timing treatments in the late summer or early fall when life stages of some aquatic organisms have fully developed making them less susceptible to rotenone exposure.Back to top
What about nesting birds?
The temporary loss of food for birds during mating or nesting would be carefully considered during the planning process. ADF&G already adjusts netting projects to avoid the time when loons and other water birds are nesting and raising their young. A rotenone project would also be carefully timed so that the least amount of impact to nesting waterfowl would occur. For example, the plan could spell out that rotenone treatments would only start after the year's chicks have fledged and are capable of flying to a neighboring lake or stream. Rotenone treatment could also be timed to occur in the late fall, when most migratory waterfowl have already left the area.Back to top
What if the rotenone gets into the air?
No health effects to the public from rotenone used as a fish management substance are known. In trials of airborne drift in the Lower 48, the highest rotenone concentrations found during treatments were approximately 1,000 times lower than what is estimated to be safe levels. There will not be any drift into air from projects involving liquid rotenone. Liquid rotenone is applied directly to the water.Back to top
What will happen to the dead fish after treatment?
During the planning process, arrangements will be made to handle the expired fish. Most of the dead fish that float to the surface will be collected and properly disposed of. Some of the dead fish will naturally sink to the bottom of the lake where they will decompose and release nutrients back into the water. This process will assist in the production of plankton which will, in turn, help re-establish the invertebrate community in the lake.Back to top
If it's too cold and daylight is too limited to neutralize rotenone by warmth or sunlight, how else can it be neutralized?
If biologists want to quickly neutralize the effects of rotenone, potassium permanganate can be used. Potassium permanganate is an oxidizing agent, used worldwide in water treatment plants to purify drinking water.Back to top
Does rotenone smell?
Some report a mothball-like aroma, which often comes from the substances added to liquid rotenone to help it spread through the water. This smell may last for a few days, depending on air and water temperatures and winds. There are no health effects from this smell. A new rotenone formulation, CFT Legumine™, does not have much of an odor at all.
Who can I contact for more information?
For the best information about your area, contact your local ADF&G office. For questions or comments, contact Kristine Dunker at 907-267-2889 or firstname.lastname@example.orgBack to top