Our lake is pristine and we don’t want to put dangerous chemicals in it. Why should we use herbicides now?

A pristine lake is balanced, stable and very rare, especially when lakes are surrounded by homes or used for recreation. The lakes we live near and play in are often inundated by excess nutrients and foreign and invasive species. Most water bodies that require herbicide treatment have experienced explosive growth of invasive aquatic plants. While your lake may seem natural and pristine, there are sufficient nutrients in the water to allow exotic weeds – which don’t belong in the lake – to dominate the system. Control of these weeds will enhance plant diversity and water quality (both of which are degraded by dense weed growth) and will help restore the overall health of the lake.

Your lake association or responsible public agency has evaluated all the options for aquatic plant management and has decided that the most effective means of controlling weeds at this point is to use herbicides. The herbicides that will be used are biodegradable and will not affect the pristine nature of the lake in- the long term. When used by professionals according to label directions, herbicides are not “dangerous chemicals” but instead are curative products that have been extensively tested and can effectively control nuisance and invasive aquatic weeds.

How dangerous are these chemicals? How do we know they’re safe?

Interestingly, aquatic herbicides are one of the smallest niches of specialty weed control products, yet they are also among the most extensively tested. Because these products are added directly to water, the EPA requires extensive data to assess the safety of a herbicide before it can be registered for use in aquatic systems. Many years of testing and use have shown that registered aquatic weed control products can be used safely in all areas of the US. In addition, many years of safety and monitoring tests in the laboratory and in the field have been conducted to determine exactly how a given product should be used in a particular situation. It is also important to remember that the treatment level (or concentration in water) of a herbicide is typically much lower (100- to 1000-fold more dilute) than the concentration that might be harmful to you, your pets or non target organisms that live in the take.

The data required by the EPA for registration of an aquatic herbicide are generated in studies that are conducted according to stringent protocols of conduct, design and evaluation. For example, a single study is conducted using a testing guideline that describes the number of organisms that must be tested, how they are housed and even the temperature and day length under which the organisms must be maintained. The test is also governed by a series of “Standard Operating . Procedures” that have additional parameters for testing and documentation. The guidelines for the test are further supported by a “Standard Evaluation Procedure”, which outlines the criteria that must be met in order for the study to be defined as “acceptable.” The EPA toxicologist produces a process to confidently recreate the entire study using the “raw data” (laboratories are legally required to maintain all data for any submitted study on which registration relies). If a problem is found or the results cannot be reconstructed, not only is the study rejected for regulatory use, but the facility conducting it or the company sponsoring it is likely to undergo a more complete audit of all studies conducted during the same period, at the same facility or on the same product. Penalties for falsifying studies can be severe and include fines and/or imprisonment.

When will it be safe for my kids to swim in the water again?

ach herbicide has a specific label statement regarding water use and swimming after weed treatment. Label statements are based on the results of various studies and the risk assessment process described above. Swimming restrictions listed on the label are most often related to the dissipation of the herbicide in water and added “safety factors” that build in at least a 100-to 1000- fold margin between what is observed in studies as a “no effect level” and the potential exposure level when a lake is treated. Therefore, the restriction interval (if any) is related to all studies conducted on the degradation and dissipation of the product and its dermal, oral and dietary toxicity, as well as any potential to irritate the skin or eyes or penetrate the skin. Herbicides that lack swimming restrictions may dissipate very quickly and/or the toxicity of the product at treatment levels is far below the “no effect level” in studies supporting product registration.

Will herbicide treatments kill the fish in our lake?

Aquatic herbicides are extensively tested for their effects on fish and other non-target aquatic organisms. For the most part, these products are relatively non-toxic to fish because their mode of action (the way they affect the target weed) is based on photosynthesis or other plant processes that differ from animal biochemistry. A few types of aquatic herbicides (usually algicides) are toxic to fish at or near treatment levels, but application techniques that provide fish with the opportunity to escape from treated waters can reduce or prevent the loss of fish populations. This information is on the herbicide label; applicators are required to read and follow all label directions and precautions.
The applicator must consider the amount of plant cover and the manner in which it will be treated in his professional assessment of the needs of the lake. Decomposing vegetation can deplete oxygen levels in water, which can cause fish mortality if application precautions are not taken. Extreme infestations of weeds may require treatment of the lake in stages instead of using a single whole-lake treatment. Partial treatment will allow fish to escape to untreated, oxygenated waters as target plants in the treated area decompose.

Is it safe to eat fish from the lake after herbicides have been applied?

No aquatic herbicides currently registered by the EPA have fish consumption restrictions. There are no restrictions because herbicides have established “tolerances” that are set by the EPA and the FDA. Tolerances are boundaries for acceptable levels of pesticide residues in food and are established after review of submitted data and in accordance with the Federal Food, Drug and Cosmetic Act. If an aquatic herbicide has tolerances set for fish, then the label will instruct whether the fish can be consumed immediately after treatment or if there is a waiting period. Where there is no established tolerance (either because the registrant has not sought it or due to the properties of the product), the label will prohibit the consumption of fish from a treated lake until enough time has passed for no residues of the product to be found in fish tissues. Professional applicators are well aware of the restrictions necessary for fishing and fish consumption, as these restrictions are clearly specified on the herbicide label. Applicators are required to post signs or otherwise clearly
inform lake users of any water use restrictions.

Are aquatic herbicides carcinogens? Will they give me cancer?

There are currently no registered aquatic chemicals that are classified as carcinogens. The treatment of water systems with herbicides ls considered a widespread use with high potential for human and non-target organism exposure. Consequently, products registered for use in water must present a very low risk profile, even when -ln the case of aquatic herbicides -potential exposure to humans_ ls neither pervasive nor long term. Any legitimate evidence of carcinogenicity would immediately put the registration and use of an aquatic herbicide in jeopardy.
This brings up an area that confuses many people -how to interpret different kinds of studies with respect to their validity for use in the “risk equation.” A number of factors contribute to the validity of a study, such as the purity and reliability of the test system (contaminants not found in the product or nature, or the use of unusual species or strains of test animals that could create false results), the statistical power of the experiment itself (inadequate numbers of test organisms or improper statistical analysis of results could yield false conclusions), or the route of exposure (an exposure route impossible ln nature, such as intravenous injection of high concentrations of chemical). For these reasons, some studies are not used ln the risk assessment process, provided there ls a body of reliable information that contradicts their findings. In the event a new finding is of concern, the EPA has the means to restrict use, cancel use or put other protective measures ln place until additional data are generated or assessed.

Plants that have been treated with herbicides rot and sink to the bottom of the fake and cause a buildup of muck. We don’t want muck buildup so we shouldn’t use herbicides, right?

The best time to treat with herbicides ls usually in the spring when plants are very actively growing but still small. This practice results in very insignificant organic matter additions to the lake. Furthermore, research has shown that when the growth of plants is restricted or controlled with herbicides or other means, much less organic matter ls produced than if plants are left untreated. Plants that are not managed in some way grow until they reach their full annual biomass and then naturally die back each winter; as a result, all the material produced by a plant over the course of the year ls added to the lake annually. By reducing plant growth, herbicide use can actually reduce organic matter production and accumulation. Another factor contributing to “muck” is sedimentation. Dense stands of weeds tend to trap particles suspended in the water column and increase sedimentation or “muck” buildup.

I’ve watched herbicide applications in other lakes and the applicators always wear “moon suits” and all sorts of protective gear even though the label says we can swim and fish immediately after application of the herbicide. This makes no sense -what gives?

Pesticide labels are developed to take into consideration both the exposure to workers (handlers and applicators) and the exposure to the environment. Workers repeatedly handle concentrated herbicides before they are diluted for application. Therefore, applicators are required to wear personal protective equipment to minimize their exposure to high doses of chemical if the chemical properties of the concentrated herbicide pose a risk to them. Herbicides are diluted literally millions of times when they are applied to water and they are usually applied once per season. As a result, the same precautions are simply not necessary for any lake water users who are not repeatedly exposed to high concentrations of herbicides. For comparison, a tablespoon of salt in _a batch of yeast dough contributes to the flavor and perfection of the final loaves of bread -but a tablespoon of salt taken alone could be dangerous for you.

I agree that we have to use herbicides to get our weed problem under control but how can we as residents reduce the risks associated with the use of these chemicals?

First of all, by taking the time to read and understand this manual, you have already invested in reducing your own risks, because you now understand the importance of following label directions and the instructions provided to you by your professional applicator.
Second, plan carefully and completely for a herbicide application in the early stages of an aquatic weed infestation so that your lake can be treated at the optimum time of the year with the lowest effective treatment rates, which can reduce the need for multiple treatments. This action will likely provide more effective weed control, reduce costs and lower the total amount of chemical that may be required for adequate weed control.
Additionally, many states have regulatory agencies that conduct additional risk assessments to refine their understanding of product properties as specifically as possible for the conditions in their state. In some cases, specific permits or precautions are required on a treatment-by-treatment basis, thereby further ensuring that lake residents and users understand the restrictions, if any, on the use of the lake or its resources. For example, New York takes an additional precautionary step and adds another layer of protection by restricting swimming in any treated lake for 24 hours after any pesticide application to its waters -even though scientific data, the label and product properties do not call for this additional precaution. The risk-reducing protections necessary for safe use of a registered product are already in place once the product is registered. All you have to do is follow the label, the instructions of the applicator and any additional local regulations.

What exactly is risk? I don’t want any risk!

We cannot live in a risk-free environment. Living near a lake is in itself a “risk.” Risk, as related to the science of risk assessment, is poorly understood by anyone other than risk-assessment scientists. Most people equate “risk” with “being exposed to a risk”, but these are not the same thing. Risk assessors deal with the likelihood (or probability) of an event happening at all, while being at risk is the likelihood of being affected by an event that is known to happen. Thus, the risk assessor will come to a conclusion (for example) that a given dose of a chemical has a one in a million chance of causing cancer, while the statistician following causes of death will report that an individual has approximately a one in four chance of dying from cancer. Two very different endpoints.
When we put actual quantifiable risks in perspective, the risk of harm from an aquatic herbicide (or any pesticide, for that matter) is negligible. The National Safety Council (2005) reports the following:

0f the leading causes of death in the US are heart disease, cancer, stroke, respiratory disease and unintentional accidents, in that order.

Of unintentional accidents, the fourth ranked cause of death is drowning. The odds of drowning in natural water (as opposed to a swimming pool) are 1 in 2,378.

No risk estimate for the effects that might result from exposure to a pesticide even begins to approach this number.
In risk assessment, the end point sought is that the probability of a risk is so low that it is expected to not occur. In risk assessment, “risk” is defined as the relationship between hazard and the likelihood of exposure. When aquatic herbicides are used in a lake, most residents and lake users will have little or no exposure to the product used for weed treatment, based on the application methods, precautions taken and infrequency of treatment. Your risk of suffering from an event related to herbicide use and exposure is minuscule.

Who else studies these chemicals besides the EPA?

Chemical use and its effects on the environment are closely scrutinized by many groups, including independent university scientists, state regulatory agencies, environmental groups and even the chemical companies themselves. Additionally, as the world economic and regulatory systems become more global, there is a closer coordination between countries in their requirements for and review of data on chemicals.
There are also protections written into FIFRA with respect to the discovery of previously unobserved effects. If a legitimate finding is made known to the company holding the registration for the chemical, that company must, within 15 days, report that finding and its significance to the EPA If the EPA deems that the event is critical, it can immediately stop the sale or otherwise limit the use of the product. If the significance of the event is not major, but requires further understanding, the EPA may issue additional data requirements so that the initial finding can be studied and causes for it can be determined. Failure to follow these reporting requirements carries heavy penalties.

Big corporations are only interested in making money – they don’t care whether their product is safe!

The development, registration and marketing of a pesticide take place in a highly visible segment of business in which relatively few companies compete. Add to that the extra burden of registering products for use in water systems and the general business risk couldn’t get much higher. This is a mature industry with extremely high standards, a heavy regulatory obligation and a tremendous amount of exposure. Corporations employ scientists to conduct the research required for pesticide regulation, and these scientists eat the same food and use the same resources that we all enjoy. No company in such an environment would survive negligence, data falsification or poor business ethics. The mistakes of the early years that occurred in an emerging regulatory system and a budding scientific understanding of the environment that surrounds us are simply not inherent to the business today. They are of the past. Today’s aquatic herbicide registrants are heavily invested in the safe and beneficial use of their products, environmental stewardship and sustainable practices. They have to be, or they wouldn’t be here tomorrow. And being here tomorrow is how they survive, not simply by making money with no future in sight.