DOH Report on Atrazine

An awful lot was said about atrazine on Kauai during the furor and frenzy of the deliberations into Bill 2491 (Ordinance 960), some of it true, and much of it false. Now the state Department of Health has reviewed all the available environmental data on atrazine in Hawaii and found “no exceedances of health-based or ecological regulatory standards,” according to its report to the Legislature.

However, the agency acknowledged that a dearth of surface water testing makes it impossible to determine whether “ecological benchmarks for atrazine exposure are being exceeded in streams and near shore waters in Hawaii.” Air studies are also sparse. Yet as the report notes:

The three major off-site transport mechanisms for atrazine are surface runoff, leaching to groundwater, and aerial transport through volatilization and drift. [It] is both persistent and mobile in surface and groundwater.

The report clearly underscores the state's shortcomings in monitoring pesticides within the environment. But it also reveals numerous flaws in how the Kauai County Council has chosen to address the pesticide issue on this island. 

In making its assessment of "no exceedances," the HDOH evaluated calls to the Hawaii Poison Hotline, as well as existing environmental data. The agency reported that atrazine concentrations in drinking water have not exceeded the maximum contaminant level (MCL) of 3 parts per billion since 1993, and “there is a downward trend in atrazine levels in drinking water throughout the state.”

Though the state has “extensive” data on drinking water, the HDOH acknowledged that much less is known about what's happening in surface water, such as streams and estuaries:

This data gap exists because there is no regulatory program requiring surface water monitoring for pesticides, and no existing programs or funding in place within the HDOH or the HDOA [Department of Agriculture] to establish ongoing monitoring.

The report was full of interesting factoids about atrazine, a restricted use pesticide, and how it's being applied in the Islands. Its use in Hawaii has declined from a high of approximately 400,000 pounds per year in 1964 to about 77,000 pounds in 2012, due to the decline of sugar and tighter federal restrictions on how it can be used.

About 76.5 million pounds of atrazine are used annually in the U.S., the study reports. “Currently, the heaviest atrazine uses per unit area occur in portions of Delaware, Iowa, Illinois, Indiana, Ohio, and Nebraska.”

Here's how it's used in the Islands:

Seed corn, sugarcane, sweet corn and macadamia nuts are the only crops currently using atrazine in Hawaii. The sugar industry was and is the largest user of atrazine in Hawaii. About 94% of the atrazine sold in Hawaii is used for weed control on sugarcane. A very small fraction, 44 pounds per year, is used in macadamia orchards, and 326 pounds in sweet corn production. Seed corn production accounts for 6% of the total atrazine used statewide, at an average of 4,771 pounds per year.

For the years 2010-2012, the average annual sales of atrazine on Kauai is 3,457 pounds active ingredient, representing approximately 4% of the total sales for the state during this time period, and 72% of the atrazine used on seed corn statewide.

The seed corn growers in Hawaii grow three crops per year, but they are not planted within the same field each year. For example, both BASF and Syngenta grow one crop per field and don’t plant again until the next year. This is because of concerns about cross contamination with different genetic varieties of corn and crop rotation to control insect pests and maintain the soil fertility. Regardless of the number of seed corn crops grown on a particular field on an annual basis, the total amount of atrazine allowed is 2.5 pounds of active ingredient per acre for a calendar year. According to the label, the total amount of atrazine applied may not exceed 2.0 pounds of active ingredient in a single application or 2.5 pounds (pre- and post-emergence combined) of active ingredient per acre per calendar year.

The report also discusses some of the environmental problems associated with its use:

Atrazine that remains in the soil can dissolve into infiltrating rainwater and be carried down over time to groundwater aquifers. Within coastal zones, atrazine can leach into shallow groundwater and seep into bays, streams and near shore water. Like surface runoff, heavy rain events on bare soils treated with atrazine are likely to result in increased losses to groundwater. In groundwater, both atrazine and its major breakdown products have long half lives because they are resistant to degradation.

Airborne atrazine represents the most likely exposure pathway for people living near agricultural fields where it is used. However, compared to surface runoff and leaching to groundwater, volatilization of atrazine has been studied the least. With normal agricultural practices, atrazine can be dispersed in the air due to volatilization of the applied solution from soil after application or carried away from the target area in the air as tiny droplets or “aerosol”. Atrazine has been detected as far as 180 miles away from the closest application area and is commonly found in rainwater in the seasons following agricultural applications (ATSDR, 2003).

There is no inhalation health-based screening level for atrazine. Notably, the California Department of Pesticide Regulation (DPR), the only state that monitors air as part of its continuous reevaluation of pesticides, does not monitor for atrazine in ambient air. California DPR monitors for 33 pesticides and 5 breakdown products based on potential health risk. Atrazine did not meet the criteria used to select high risk pesticides, which include higher use, higher volatility and higher toxicity.

Recently, however, the EPA has begun to look more closely at risks to bystanders from volatilization of pesticides. EPA has begun to explore the development of an approach for assessing inhalation exposure resulting from the field volatilization of conventional pesticides based on recommendations provided by the FIFRA Science Advisory Panel.

As far as statewide pesticide complaints, there were a total of 293 between 2010 and 2013. Oahu had 127, Big Island 73, Maui 51 and Kauai 42. “According to HDOA, less than half of the complaints are due to agricultural activities. For complaints involving potential atrazine exposure, atrazine was not detected in any environmental samples collected during this time period.”

There were a total of 1,310 fugitive dust complaints made to HDOH from 2010-2013, but just 5 percent involved agriculture. Of the 70 agricultural dust complaints, 35 were from Kauai and 23 from Maui County. Both Hawaii Commercial & Sugar and Monsanto were cited for dust activities on Maui and Molokai, respectively.

The study also included a summary of calls to the Hawaii Poison Center:

Of the 4,800 human pesticide exposure calls, approximately 90% of the exposures occurred in a residence, 4.4% in the workplace and 1% in a school. The remaining 4% consisted of miscellaneous locations (i.e., other/unknown, public areas, health care facilities, and food service.) 

At least 90 percent of the exposures caused no or minimal health effects. There were three deaths. None of the pesticide complaints were linked to atrazine exposures.

Currently, there are no requirements by state or federal agencies to conduct pesticide sampling in wastewater discharges or surface runoff. However, the U.S. Geological Survey has done some limited testing:

In 2012, the HDOH Clean Water Branch (CWB) conducted sampling at 28 stations on Kauai and 3 stations on Maui under the EPA Monitoring Initiative. These samples were analyzed for wastewater constituents, including about 10 common pesticides, and overall, showed low concentration detections of a few contaminants. This sampling found that 8 stations, including six locations in the Nawiliwili drainage, had trace levels of atrazine ranging from 0.01 ppb to 0.04 ppb, far below EPA’s proposed aquatic level of concern of 10 ppb.

On Kauai...two water systems had historic detections of atrazine in drinking water. A well in the Lihue-Kapaa water system registered a high detection of 0.28 ppb in their drinking water supply in 1986, dropping to 0.19 by 2004. The drinking water supply at the Gay & Robinson plantation in Kekaha was sampled from 1993 to 2011, with a single detection (0.081 ppb) in 2008, the last year of the sugar operation there. A sample from Waimea Valley School collected by the community and analyzed through the USDA School Water Testing Program had a detection of 0.006 ppb, well below the 0.050 detection limit used for regulatory drinking water samples. The only detection in irrigation water on Kauai was from a single irrigation well sample collected at Barking Sands in the late 1980s which measured a detection of 3.5 ppb. The status of the well is unknown and no follow up data are available. Surface water samples collected by DOH in 2012 showed trace detections of atrazine in samples from the Nawiliwili drainage.

As a result:

The HDOH recommends additional stream and near shore water sampling for atrazine and other commonly used pesticides to determine whether benchmarks are being exceeded. The HDOH secured limited funding and support through a partnership with the United States Geological Survey (USGS) and HDOA and intends to conduct near shore and stream sampling for a broad spectrum of currently used pesticides in the next several months. The results of the stream sampling will be made available to the legislature and public upon completion of the study.

Air sampling by UH on Kauai did not find detectable levels of atrazine. Given that atrazine was not detected in UH’s passive sampling, the low levels found in air monitoring in other areas nationwide, and that California has not chosen it as a high risk pesticide for air monitoring, HDOH believes further air monitoring for atrazine is not warranted.