QAloha,I am writing about pesticide/herbicide use with GMO crops specifically GMO corn and Soy parent crops grown here in Hawaii. 1. Have there been studies to show that buffer zones keep pesticides/herbicides out of public spaces like homes, water ways et

Aloha, I am writing about pesticide/herbicide use with GMO crops specifically GMO corn and Soy parent crops grown here in Hawaii. 1. Have there been studies to show that buffer zones keep pesticides/herbicides out of public spaces like homes, water ways etc. and if so how large does the buffer zone need to be? 2. Atrazine has been shown to cause several health problems including miscarriage, irregular bleeding, premature birth, babies with IUGR and SGA. Several University studies have been done showing strong correlation/ causation. My question is if it was pulled from EU markets for being unsafe why is it still allowed to be used in the US and especially here in Hawaii where we are one big water shed? 3. Is there a "safe" limit of exposure to Atrazine and Glyphosphate in humans and if so how is it studied and measured? Thank you for your time

AExpert Answer

As parents, farmers, and community members ourselves, we care as much as anyone else about the health and well-being of our families, neighbors and environment.


A buffer zone is typically an untreated area between an agricultural field and a protected structure or area.  Currently, there are no across-the-board, “one size fits all” buffer zones mandated for pesticide users, and with good reason: the scientific evidence does not support buffer zones as the best approach to minimize undesired drift; and the factors that influence drift of pesticide sprays have been well studied (Ozkan and Zhu). Each pesticide label contains essential instructions on how to apply the product (Penn State Extension Bulletin). Professional pesticide applicators receive extensive training on how to apply pesticides properly, and it is in fact a violation of federal law to use any pesticide in a manner inconsistent with its labeling. 


In reality, farmers do not rely on a single method of pest control, but rather, they use a variety of management practices to control pests and to minimize or avoid the movement of pesticides away from the intended application areas.  Like many farms around the globe, the seed farms in Hawaii use a multi-pronged approach to pest management called Integrated Pest Management (IPM).  IPM is fundamental to modern agricultural operations.  It considers all available tools (agronomic, biological, and chemical) to limit crop damage.


As examples, farmers may ―

  • use physical barriers to keep pests out of fields, akin to window screens that keep flies out of your home;
  • plant cover crops that suppress weeds, improve soil healthy and increase biodiversity; and
  • promote biological controls (e.g., ‘good bugs’ eating ‘bad bugs’).


Fields are evaluated frequently to monitor plant health and pest populations. Should pest pressures increase to a level where pesticides become necessary, very precise sprayers can ensure that the right amount is applied in the right location. In modern agriculture, precision pesticide application takes into account various factors, such as spray droplet sizes, lower air pressures, minimum heights for spray release, shielding of spray equipment, and acceptable wind speed and direction.  Combining technologies, tools and best practices will provide the most accurate placement of the pesticide application.


In some cases, a pesticide’s label may require a specific buffer zone for its application. That determination is based upon extensive scientific data, gathered prior to that pesticide being approved for use by federal and state authorities. And, as mentioned earlier, pesticide applicators are required by law to follow those label instructions.


You may be surprised to learn that farmers in Hawaii are actually a minority user of pesticides, collectively accounting for only about one-third of all restricted use pesticides sold in the state.  The seed companies that operate in Hawaii account for less than 5 percent  of restricted-use pesticides.


Data gathered by the Hawaii Department of Agriculture (HDOA) and the Hawaii Department of Health (HDO) indicate that farming operations, including the seed companies, are not a cause of concern regarding pesticide use.


  • In 2015, the HDOA reported that, out of 16 school evacuations in the last 8 years due to complaints about pesticides, none were due to activities of seed companies. (10 were due to homeowners, 1 to a turf grower, 1 to a school custodian, 1 was because of a mulch pile, and 3 could not be attributed to pesticide.)


  • A 2014 HDOH and HDOA study of pesticides in surface water samples taken throughout the state found that urban areas on Oahu showed the highest number of different pesticides.




Penn State Extension Bulletin


Ozkan and Zhu, Ohio State University Extension Fact Sheet

AExpert Answer

Thank you for submitting your question to GMO Answers. Each part of your question will be answered by a different expert, and we will be posting each answer as it becomes available. This is an evolving topic in Hawaii. Following are links to news articles which discuss legislation recently introduced related to buffer zones:


The Hawaii Department of Agriculture governs the use, certification and licensing of pesticides in Hawaii. More information is available here.


We thought you may be interested in the “Kauai Agricultural Good Neighbor Program.” This program “was developed by the Pesticides Branch of the Hawaii Department of Agriculture (HDOA) to provide more information and education on pesticide use on the island.”


More on the program from its website:


“Under the program, the five agricultural companies mentioned in Kauai County Bill 2491 (Dow AgroSciences, Pioneer, Syngenta, BASF, and Kauai Coffee Company) will report each month the type of restricted-use pesticides (RUP) that are applied on their fields on Kauai.


“Participating companies will also implement a 100-foot buffer zone between RUP application areas and schools, medical facilities and residential properties, unless regulations by the Environmental Protection Agency are stricter.  By law, all requirements found on the pesticide label must be followed.


“The voluntary pesticide-use guideline went into effect on Dec. 1, 2013, with the first posting of RUP on Jan. 15, 2014.


“The voluntary guidelines are in addition to federal guidelines established by the EPA.”

AExpert Answer

Over atrazine’s 50+-year history, the U.S. Environmental Protection Agency (EPA), along with other regulatory agencies around the world, has conducted and reviewed more than 7,000 scientific studies to evaluate its safety, including any reproductive or developmental toxicity. These studies consistently have shown atrazine does not cause harmful effects to human health, including potential for birth defects or reproductive complications.


In fact, the World Health Organization specifically stated in a 2007 report atrazine is not a cause of birth defects. And in 2011, an EPA Scientific Advisory Panel also reported that atrazine does not affect reproductive or developmental outcomes, even at levels much higher than would ever be found in the natural environment. Further, a review that same year by the Australian government found similar results.


Regarding atrazine’s status in the European Union (EU), after examining this trusted herbicide for the EU, the UK’s Scientific Committee on Plants gave it a favorable safety review. Specifically, the Committee found: “It is expected that the use of atrazine, consistent with good plant protection practice, will not have any harmful effects on human or animal health or any unacceptable effects on the environment.” So while atrazine is not currently used in the EU, many European farmers rely on a sister compound.


The facts are clear. Atrazine does not, cannot and will not cause adverse health effects at levels people would ever be exposed to in the real world.

AExpert Answer

There is a lot of really great information regarding glyphosate on GMO Answers.  I have authored a few of them myself and let me start by emphasizing the long history of safe use for glyphosate both at home and in agriculture.  Specifically to address your question about a “safe” limit, here is the short version:


EPA has established an acceptable daily intake, or ADI, based on toxicity studies that look at a variety of toxic effects, such as immediate or acute toxicity, effects on reproductive processes, cancer-causing and other long-term effects, etc.  Just to be on the safe side, the EPA sets the ADI a minimum of 100-times lower than any dose level that showed any kind of toxicity in any study conducted.


Whether taken in as food or drink, these ADI levels are conservatively calculated based on animal models, crop residues and typical diets to account for daily exposures throughout our lives.  Daily consumption of residues below the ADI is considered safe.


A recent risk assessment was conducted by EPA for glyphosate exposures through both food (agricultural products) and water, and it concluded glyphosate exposure is no more than 13 percent of the ADI. This risk assessment takes the conservative approach that all fruits, vegetables and grains in the diet treated with glyphosate had the maximum allowable residue levels remaining on those food crops when eaten, which is a very conservative assumption for glyphosate residue levels in food.


For the longer (much) and far more technical version please read my full response on the safety of glyphosate.  

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