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  You are here:  ProgramsPublic Policy InitiativesMaine Board of Pesticides Control ReportsBPC – Sept 2002   
 Machias Forum Addresses Hexazinone Contamination Minimize

By Sharon Tisher

In response to renewed community concern about reported contamination of the Machias public water supply by the blueberry herbicide hexazinone (Velpar) (MOF&G, Sept.-Nov. 2002), Project SHARE (Salmon Habitat and River Enhancement) and the Atlantic Salmon Federation sponsored a public forum entitled “Velpar in Blueberry Culture and the Environment” on September 26 at the University of Maine at Machias. More than 40 people attended the meeting, and some questioning from the audience was heated, with suggestions that the program predominantly promoted the blueberry industry. Originally scheduled to appear was University of Maine Associate Professor of Zoology Rebecca Van Beneden, to report preliminary results from her study of the endocrine disruptive characteristics of blueberry pesticides. Her report was passed out at the meeting, but Van Beneden was unable to attend.

The BPC enforcement director Henry Jennings summarized the Board’s 2000 and 2001 monitoring of two Downeast Atlantic salmon run rivers, the Pleasant and the Narraguagus. Jennings noted that all samples in these rivers were positive for hexazinone, but at low concentrations, less than 2 ppb, well below the lethal dose for salmon. He noted that “hexazinone is not acutely toxic to vertebrates,” but he also questioned “what other more subtle [chronic] effects these levels might be causing … there’s not a lot of data and it’s difficult to get a handle on.” In response to a question by Jonesboro activist Nancy Oden, Jennings acknowledged that their water monitoring was only for the active ingredient hexazinone, not for the inert ingredients that compose the majority of the formulations for Velpar and Pronone, some of which are toxic. Jennings noted that staff was puzzled that hexazinone was found at all times of the year tested, and hence apparently was not influenced by runoff after applications. BPC analyst Julie Chizmas went directly to test springs that replenish the Pleasant River and found hexazinone ranging from 0.17 to 3.08 parts per billion. The staff concluded that groundwater contamination was a major contributor of hexazinone in the rivers.

Impact on Clam Flats and Worms

A member of the audience questioned whether adjacent tidal flats had been tested for hexazinone contamination. Jennings replied that this had not been done, due to limited resources. When later questioned about this, audience member UMM Professor of Marine Ecology Brian Beal noted the significant decline in clam landings in Washington County since 1984, when hexazinone was first used in nearby blueberry barrens. Without research, however, a causal connection cannot be established. Beal indicated that he was very interested in the question of whether clams, which are filter feeders and which support a multi-million dollar harvesting industry, are affected by contaminants from blueberry cultivation. He also questioned the impact on the commercial worm harvest. However, “this is a can of worms,” he quipped. “Someone has decided that this isn’t important, it’s more important to look at salmon…. When someone decides to authorize some actual research, then and only then will we know whether there is a real association between hexazinone and the decline in clam landings.”

Toxicity to Humans Questioned

On the subject of ground and well water contamination by hexazinone, Oden asked Jennings whether they had done any testing for hexazinone in human blood. Jennings replied that they had not, but that Oden should contact the Department of Health for that kind of testing. He cautioned that he was not a toxicologist, but stated that he understood that “Velpar doesn’t bioaccumulate, it’s not fat soluble and is excreted rapidly.” Jennings also noted that concentrations found in drinking water in the region were well below the human health advisory level of 400 ppb over a lifetime.

Audience member Alan Lewis, UMM ecology professor and former Chairman of the BPC, commented, “I hope we all go through this meeting very skeptical about health advisory levels.” Noting that the pesticide Atrazine, with a health advisory level of 3 ppb, caused endocrine and reproductive effects in frogs at 0.1 ppb (Univ. of Calif., Berkeley, research), Lewis said that this should “put a cloud of healthy skepticism as we listen to all these assurances.”

Brian Perkins of the University of Maine spoke regarding the well water testing that he conducts in Orono, in cooperation with Cooperative Extension blueberry specialist and Associate Extension Professor David Yarborough. Perkins noted that hexazinone has been used in blueberry production since 1983, and that in 1991 it was first discovered in ground and surface water during routine testing. Hexazinone has a relatively long half life of 90 to 175 days, compared with one day for glyphosate (RoundUp), 160 days for Atrazine. It is “fairly persistent with a very high leaching potential.” They have two monitoring programs – one for seven test wells directly in or very near blueberry fields, the other for private wells used for drinking water downgrade of blueberry fields. All test wells have consistently shown contamination over the nine years of testing, but “the long term trend is declining levels in five wells, stable or variable in two.”

Approximately 60% of the private drinking water wells tested have consistently shown contamination, year round, always at concentrations less than 6 parts per billion. Perkins argued that the trend was improving, however: “Sixty-six percent of the contaminated wells had lower levels of contamination – 20% or more lower – in 1998 when compared with 1994.” In response to a question from Sharon Tisher as to whether Perkins could attribute these declines to better farming practices, or to the drought in recent years, Perkins said it was impossible to know this, until levels could be monitored after drought conditions end. In response to a question from Nancy Oden, Perkins said he did not test well water for inerts – “I’d love to look at that but have limited resources.” Perkins noted that the Maximum Contaminant Level for hexazinone under the Safe Drinking Water Act was 210 micrograms/liter [ppb], and of all the samples he has tested over the years none has been over 10 micrograms/liter [ppb]. Perkins acknowledged, however, that “whatever I feel about the toxicity of hexazinone, I certainly can understand why people would be upset about someone putting something in their water they don’t want to drink.”

Cooperative Extension’s Positive Trends Questioned

Yarborough presented an overview of the importance of hexazinone to the blueberry industry and of efforts to develop “Best Management Practices” to respond to the water contamination issue. He noted that blueberry production in Maine increased by a factor of 3.8 from 1980 to 2000, with essentially the same acreage, a phenomenon that he attributes to “better management,” including the use of hexazinone. Yarborough reviewed weed management techniques, emphasizing the effectiveness of hexazinone. He did not discuss organic growers’ practices.

Yarborough argued that use of hexazinone by blueberry producers had declined considerably, from over 2 lb./acre to “half the label rate and one-third the maximum rate,” or about 1 lb./acre. He showed a chart he had prepared from a survey of eight processors, voluntarily reporting their average per acre use, fluctuating from 0.9 lb. (1996), to 1.2 lb. (1997), 1.0 lb. (1998), to 1.2 lb. (2000). He presented this as a declining trend.

In response to questions from the audience about the actual quantities of hexazinone applied, Yarborough replied that he did not ask producers to report this, but, when pressed, acknowledged that you could get an idea of total usage by multiplying these figures by 30,000 acres. [This is generally consistent with the most recent BPC 2000 pesticides sales data report, which reports 30,000 lbs. in retail sales of hexazinone. However, the BPC’s recent comparison of 2000 sales data with previous reports raises a question about a “declining trend” in hexazinone sales. It reports 1995 sales at 29,000 pounds active ingredient, 1997 sales at 35,000 pounds, and 2000 sales at 30,000 pounds.]

From the audience, UMM Associate Professor of Marine Ecology Brian Beal asked Yarborough and Perkins how they decide “if a trend’s a trend.” He noted the absence of evidence of a statistical regression analysis in their presentations. “When you get up and call it a trend, it’s just your interpretation, unless you do a regression analysis,” Beal observed. Yarborough acknowledged that “some of this isn’t done statistically. We haven’t applied statistics to everything…” Beal commented to this writer after the presentation that he was “surprised by [Yarborough’s] comment [to the effect that] sometimes statistics had a place and sometimes they didn’t.

“When you present to the public you have to make a commitment to making that an objective presentation,” Beal noted. He explained that “sometimes lines on a graph can fool you. Lines can have a positive or a negative slope, or no slope at all. A regression analysis will tell you whether a slope that appears to be positive or negative, suggestive of a trend, is significantly different from no slope at all.” The analysis makes this determination by analyzing sample size, and the actual association between the two variables (in Yarborough’s case, time and the application rates) being measured.

Beal also questioned Yarborough about a possible remedy for well water contamination. He noted that the blueberry industry taxes itself, and the taxes go into research at the Experiment Station. Carbon filters effectively remove hexazinone and many other water pollutants. Beal asked Yarborough, “Would the blueberry industry be willing to tax itself to take care of providing carbon filters for people with contaminated wells?” Yarborough replied: “If the levels were at 400 ppb (the federal health advisory limit), they probably would do that. But since it’s below that, it’s your choice not to want [the hexazinone], you can invest in the filter yourself.” “I don’t understand the logic,” Beal retorted.

Yarborough concluded his presentation with a slide summarizing the dietary health benefits of blueberries.

Endocrine Disrupter Study

In the absence of Professor Rebecca Van Beneden, conference organizer Mark Whiting (DEP Division of Land Resource Regulation) briefly commented on Van Beneden’s March 20 Progress Report, “Investigation of the Estrogenic Potential of Agrochemicals and their Effect on the Atlantic Salmon.” (Copies are available from Mark.C.Whiting@state.me.us, (207) 941-4566.) Whiting stated that he understood from a conversation with Van Beneden that her study showed hexazinone has no estrogenic effects.

Van Beneden introduces her Progress Report with the observation that “numerous toxicants of natural and anthropogenic origin have been released into the environment in quantities sufficient to disrupt developing endocrine and nervous systems in wildlife and humans…. Many such toxicants have been identified as acute problems in Maine, including organophosphates and other pesticides, herbicides, organo-arsenic, organo-mercury, dioxins and polychlorinated biphenyls (PCBs).” Observations in the Narraguagus River have demonstrated “an extremely high mortality of both pre-smolt and mature Atlantic salmon…. The reason for this mortality is unknown. One hypothesis is exposure to agrochemicals introduced into the watershed from runoff.”

Van Beneden set out to determine whether agricultural chemicals registered for use on Maine blueberry barrens can mimic the action of hormones in wildlife and function as “endocrine disrupters.” She also sought to determine whether pesticides were identifiable in river sediment samples. Studies in 1995 at Tufts University found that the active ingredient hexazinone was not estrogenic, but the formulation actually applied on the field, with inert ingredients, was not tested. Van Beneden tested both active ingredient and field formulations.

A first test for pesticides in river sediment proved negative; the sediments were sampled again and are awaiting analysis. Van Beneden exposed a human breast cancer cell line to the agrochemicals and compared the tendency of these chemicals with the tendency of natural estrogen to quicken growth of the cells. She quantified the RPE (Relative Proliferative Effects) of the chemicals as a percentage of the effects of pure estrogen. An RPE closer to 100% would indicate estrogenic effect, while one closer to zero would indicate a lack of estrogenic effect. The three active ingredients that the report identified as estrogenic were Methoxychlor (RPE as high as 64%), 2,4-D (RPE 91%), and Propiconizol (RPE 80%). Hexazinone was not identified as having an estrogenic effect; the RPE of its pure form was only 14%; however, the field formulation Velpar had an RPE as high as 47 percent.

Alan Lewis questioned from the audience why Velpar was not classified as estrogenic, with an impact nearly half as significant as pure estrogen on cancer cells. He also noted that one of the clearly estrogenic chemicals, Propiconizol, had been identified as a contaminant of Downeast river water in BPC monitoring. Yarborough’s claims of “health benefits of blueberries,” Lewis complained, were “a little bit of an oxymoron.” It was also not clear from the report why Van Beneden did not test guthion, an aerially sprayed blueberry insecticide and the subject of many spray drift complaints. When queried about this, Yarborough speculated that perhaps guthion was “too toxic” for work in the laboratory. (Efforts to contact Van Beneden following the meeting were unsuccessful).

The final presenter at the forum, Kelly Wescott of Cherryfield Foods, described the company’s Integrated Pest Management practices.

Unanswered Questions

Some members of the audience expressed dissatisfaction with the number of unanswered questions they still had about hexazinone and its health impacts. Maggie Van de Sande, a young mother from Columbia, Maine, who lives 1 =BD miles downgrade from blueberry barrens, commented to Whitney, “Nobody’s here to answer our questions. We can’t prove that it’s wrong, we can’t prove that it’s ok. So why the hell is [hexazinone] being allowed in our water?”

    

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